G. Amabeoku - Academia.edu (original) (raw)

Papers by G. Amabeoku

Research paper thumbnail of GABAergic and dopaminergic systems may be involved in seizures induced by pyrimethamine in mice

General pharmacology, 1994

1. The effects of some GABAergic and dopaminergic agents on pyrimethamine-induced tonic seizures ... more 1. The effects of some GABAergic and dopaminergic agents on pyrimethamine-induced tonic seizures were investigated in mice. 2. Pyrimethamine dose dependently induced seizures in mice. 3. Muscimol, AOAA and DABA significantly protected mice against pyrimethamine-induced seizures. 4. Bicuculline and picrotoxin effectively potentiated seizures elicited by pyrimethamine and significantly antagonized the protective effect of muscimol against the seizures. 5. Diazepam and phenobarbitone effectively protected mice against seizures elicited by pyrimethamine. 6. L-Dopa significantly potentiated pyrimethamine-induced seizures. 7. Apomorphine and pargyline significantly reduced the latency of seizures induced by pyrimethamine. 8. Haloperidol and pimozide effectively protected mice against pyrimethamine-elicited seizures and also significantly antagonized the potentiating effects of apomorphine and L-dopa on the seizures. 9. Disulfiram significantly potentiated seizures induced by pyrimethamine...

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Research paper thumbnail of Strychnine-induced seizures in mice: The role of noradrenaline

Progress in Neuro-Psychopharmacology and Biological Psychiatry, 1994

1. The effects of some noradrenergic agents on seizures induced by strychnine were investigated i... more 1. The effects of some noradrenergic agents on seizures induced by strychnine were investigated in mice. 2. Strychnine (0.5-4 mg/kg, i.p.) dose-dependently produced tonic seizures. 3. DOPS (4-8 mg/kg, i.p.) significantly shortened the latency of seizures elicited by strychnine (2 mg/kg, i.p.). Similarly, DOPS (4 mg/kg, i.p.) effectively increased the incidence and significantly shortened the latency of seizures induced by strychnine (1 mg/kg, i.p.). 4. Imipramine (20-40 mg/kg, i.p.) and pargyline (200 mg/kg, i.p.) significantly shortened the latency of strychnine (2 mg/kg, i.p.)-induced seizures. 5. Phentolamine (5-20 mg/kg, i.p.) effectively antagonised the seizures elicited by strychnine (2 mg/kg, i.p.). Furthermore, phentolamine (10 mg/kg, i.p.) attenuated the seizure-potentiating effect of DOPS (4 mg/kg, i.p.). 6. Propranolol (0.5-2 mg/kg, i.p.) and prazosin (1-2 mg/kg, i.p.) reduced the incidence and significantly delayed the latency of seizures induced by strychnine (2 mg/kg, i.p.). 7. Reserpine (5-10 mg/kg, i.p.) significantly prolonged the latency of strychnine (2 mg/kg, i.p.)-induced seizures. 8. Clonidine (0.25-1 mg/kg, i.p.) dose-dependently and significantly antagonised strychnine (2 mg/kg, i.p.)-induced seizures. 9. Idazoxan (1-4 mg/kg, i.p.) in a dose related manner significantly shortened the latency of seizures induced by strychnine (2 mg/kg, i.p.). Similarly, idazoxan (2 mg/kg, i.p.) profoundly potentiated seizures elicited by strychnine (1 mg/kg, i.p.). Idazoxan (4 mg/kg, i.p.) significantly antagonised the protective effect of clonidine (1 mg/kg, i.p.) against strychnine (2 mg/kg, i.p.)-induced seizures. 10. Disulfiram (3 x 25 - 3 x 100 mg/kg, i.p.) significantly attenuated strychnine (2 mg/kg, i.p.)-induced seizures. DOPS (4 mg/kg, i.p.) significantly potentiated strychnine seizures in disulfiram (3 x 100 mg/kg, i.p.)-pretreated animals. 11. These results indicate that enhancement of noradrenergic neurotransmission potentiates strychnine seizures in mice.

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Research paper thumbnail of Chloroquine-induced seizures in mice: the role of monoaminergic mechanisms

European Neuropsychopharmacology, 1993

The influence of some dopaminergic and noradrenergic agents on seizures induced by chloroquine (4... more The influence of some dopaminergic and noradrenergic agents on seizures induced by chloroquine (45-100 mg/kg, i.p.) was investigated in mice. Apomorphine (0.2-0.8 mg/kg, s.c.). L-dopa (25-50 mg/kg, s.c.) benserazide (5 mg/kg, i.p.) plus L-dopa (50 mg/kg, s.c.), pargyline (100 mg/kg, i.p.), FLA-63 (10-20 mg/kg, s.c.) and FLA-63 (10 mg/kg, s.c.) plus L-dopa (50 mg/kg, s.c.) profoundly shortened the latency of seizures induced by chloroquine (65 mg/kg, i.p.). L-Dopa (50 mg/kg, s.c.) weakly reduced the latency and weakly increased the incidence of chloroquine (50 mg/kg, i.p.)-induced seizures. alpha-Methyl-p-tyrosine (25-100 mg/kg, i.p.) dose-dependently and significantly reduced the incidence and significantly prolonged the latency of chloroquine (65 mg/kg, i.p.)-induced seizures. However, L-dopa (50 mg/kg, s.c.) effectively increased the proportion of animals convulsing and effectively reduced the latency of seizures induced by chloroquine (65 mg/kg, i.p.) in alpha-methyl-p-tyrosine-pretreated mice. Haloperidol (0.25-1.0 mg/kg, i.p.) and pimozide (2-4 mg/kg, i.p.) markedly reduced the incidence and markedly prolonged the latency of seizures induced by chloroquine (65 mg/kg, i.p.) in a dose-related manner. However, apomorphine (0.4-0.8 mg/kg, s.c.) and L-dopa (25-50 mg/kg, s.c.) profoundly attenuated the protective effects of haloperidol (0.5 mg/kg, i.p.) and pimozide (4 mg/kg, i.p.) against chloroquine (65 mg/kg, i.p.)-induced seizures.(ABSTRACT TRUNCATED AT 250 WORDS)

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Research paper thumbnail of Effects of some GABAergic agents on quinine-induced seizures in mice

Experientia, 1992

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Research paper thumbnail of Propranolol-induced seizures in mice: the role of noradrenaline

Cellular and Molecular Life Sciences (CMLS), 1997

The effects of some noradrenergic agents, phenobarbitone, diazepam and phenytoin on seizures prod... more The effects of some noradrenergic agents, phenobarbitone, diazepam and phenytoin on seizures produced by propranolol were investigated in mice. Isoprenaline and DL-threo-3,4-dihydroxyphenylserine (DOPS) effectively antagonized the seizures elicited by propranolol. Pargyline and imipramine significantly attenuated propranolol-induced seizures and also significantly potentiated the protecting effect of DOPS against the seizures. alpha-Methyl-p-tyrosine, disulfiram and reserpine significantly potentiated propranolol-elicited seizures. However, DOPS significantly antagonized the seizure-potentiating effects of alpha-methyl-p-tyrosine, disulfiram and reserpine. Phenylephrine, clonidine, prazosin, idazoxan, phenobarbitone, diazepam and phenytoin did not significantly alter propranolol-induced seizures. These results suggest that propranolol-induced seizures in mice may involve a noradrenergic mechanism mediated via central beta-adrenoceptors.

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Research paper thumbnail of Cimetidine-induced seizures in mice antagonism by some gabaergic agents

Biochemical Pharmacology, 1993

The effects of muscimol, aminooxyacetic acid (AOAA), diamino-n-butyric acid (DABA), baclofen, bic... more The effects of muscimol, aminooxyacetic acid (AOAA), diamino-n-butyric acid (DABA), baclofen, bicuculline, picrotoxin, strychnine, diazepam, phenobarbitone and phenytoin on cimetidine-induced seizures were studied in mice. Cimetidine (400-1000 mg/kg, i.p.) induced dose-dependent tonic convulsion. Muscimol, AOAA and DABA effectively protected mice against cimetidine-induced seizures. Bicuculline and picrotoxin significantly potentiated the seizures induced by cimetidine and effectively antagonized the protective effects of muscimol, AOAA and DABA against the seizures. Diazepam and phenobarbitone significantly protected the mice against cimetidine-induced seizures while phenytoin and strychnine did not significantly alter the seizures. These results indicate that the attenuation of central gamma-aminobutyric acid neurotransmission may underlie cimetidine-induced seizures in mice.

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Research paper thumbnail of Factors modifying duration of drug action: a practical for large undergraduate classes on limited laboratory space, staff and budget

Medical education, 1989

A desperate need for health professionals is answered by yearly increases in university student a... more A desperate need for health professionals is answered by yearly increases in university student admissions in many developing countries. Yet economic constraints dictate that subventions for teaching and research remain static or even decrease as student populations increase. Practical teaching, for example in pharmacology, is susceptible to inadequate funding because of the capital and recurrent expenditure needed to procure and maintain laboratories, staff, animals, instruments and chemicals. Class demonstrations, although they provide a partial answer to the problem, are beset with a number of disadvantages. Provision of good training on low funds demands ingenuity to modify teaching/learning processes while still achieving the desired objectives. This paper illustrates such a procedure by describing the logistics of a practical class on 'Factors modifying duration of drug action' to large classes of undergraduate medical and pharmacy students, on limited laboratory space...

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Research paper thumbnail of An Anticonvulsant Diterpene Lactone Isolated From the Leaves of <i>Leonotis leonorus</i> (L) R. BR

East and Central African Journal of Pharmaceutical Sciences, 2007

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Research paper thumbnail of Influence of some dopaminergic agents on antinociception produced by quinine in mice

Progress in Neuro-Psychopharmacology and Biological Psychiatry, 1992

1. The analgesic effect of quinine and the influence of some dopaminergic agents on it were studi... more 1. The analgesic effect of quinine and the influence of some dopaminergic agents on it were studied in mice. 2. Quinine (25-130mg/kg, ip) effectively elicited antinociceptive effect in a dose related manner. 3. D-Amphetamine (2.5-4mg/kg, ip), L-dopa (25mg/kg, sc), L-dopa (25mg/kg, sc) plus benserazide (12.5mg/kg, sc), alpha-methyl-p-tyrosine (50mg/kg, ip) plus L-dopa (25mg/kg, sc) and pargyline (50mg/kg, ip) significantly attenuated the antinociceptive effect of quinine (50mg/kg, ip), while DOPS (4mg/kg, ip) did not affect quinine antinociception. 4. Pimozide (4mg/kg, ip), L-sulpiride (40mg/kg, ip), SCH 23390 (0.2mg/kg, sc) and alpha-methyl-p-tyrosine (50mg/kg, ip) effectively potentiated the antinociceptive effects of quinine (50mg/kg, ip). 5. Pimozide (4mg/kg, ip) also antagonised the antagonistic effect of d-amphetamine (4mg/kg, ip) on the antinociceptive effect of quinine (50mg/kg, ip). 6. These data indicate that quinine elicited antinociception dose dependently. Furthermore, the influence of pimozide, L-sulpiride and SCH 23390 on quinine antinociception suggests the involvement of dopaminergic mechanisms.

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Research paper thumbnail of Anticonvulsant activity of aqueous extract of Leonotis leonurus

Phytomedicine, 2002

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Research paper thumbnail of An assessment of two Carpobrotus species extracts as potential antimicrobial agents

Phytomedicine, 2003

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Research paper thumbnail of Effects of Tarchonanthus camphoratus and Eriocephalus africanus on nociception in mice and pyrexia in rats

Phytomedicine, 2000

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Research paper thumbnail of Antipyretic and antinociceptive properties of mentha longifolia Huds. (Lamiaceae) leaf aqueous extract in rats and mice

Methods and Findings in Experimental and Clinical Pharmacology, 2009

The antipyretic and antinociceptive properties of Mentha longifolia Huds. (Lamiaceae) leaf aqueou... more The antipyretic and antinociceptive properties of Mentha longifolia Huds. (Lamiaceae) leaf aqueous extract were investigated using lipopolysaccharide (LPS)-induced pyrexia in rats, and acetic acid and hot plate analgesia tests in mice. Pentoxifylline, paracetamol and morphine were used as standard drugs for comparison. M. longifolia leaf aqueous extract and pentoxifylline (37.5-150 mg/kg i.p.) significantly (P &lt; 0.05-0.02) reduced the LPS (50 g/kg i.m.)-elicited pyrexia. Pentoxifylline (50 mg/kg i.p.) also significantly (P &lt; 0.01) reduced LPS (50 g/kg i.m.)-induced pyrexia. M. longifolia leaf aqueous extract (6.25-100 mg/kg i.p.) and paracetamol (500 mg/kg i.p.) profoundly inhibited the writhes produced by 3% acetic acid. Furthermore, the plant extract (25-400 mg/kg i.p.) and morphine (10 mg/kg i.p.) significantly (P &lt; 0.001) delayed the hot plate reaction time in mice. The LD(50) values for oral and intraperitoneal administration of the plant extract were &gt; 3200 mg/kg and 1730 mg/kg, respectively. Phytochemical analysis revealed the presence of flavonoids, saponins, tannins, reducing sugars, cardiac glycosides and triterpene steroids in the leaves of M. longifolia. These data indicate that M. longifolia leaf aqueous extract has antipyretic and antinociceptive properties. Furthermore, the relatively high LD(50) values obtained for oral and intraperitoneal administration of the plant extract demonstrate that the plant extract is non-toxic to mice.

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Research paper thumbnail of Antimicrobial and anticonvulsant activities of Viscum capense

Journal of Ethnopharmacology, 1998

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Research paper thumbnail of Analgesic and antipyretic effects of Dodonaea angustifolia and Salvia africana-lutea

Journal of Ethnopharmacology, 2001

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Research paper thumbnail of Anticonvulsant activity of Cotyledon orbiculata L. (Crassulaceae) leaf extract in mice

Journal of Ethnopharmacology, 2007

The anticonvulsant activity of Cotyledon orbiculata L. (Crassulaceae) was investigated by studyin... more The anticonvulsant activity of Cotyledon orbiculata L. (Crassulaceae) was investigated by studying the effects of both aqueous and methanol extracts of the plant species on seizures induced by pentylenetetrazole, bicuculline, picrotoxin and N-methyl-dl-aspartic in mice. Aqueous extract of Cotyledon orbiculata (50-400mg/kg, i.p.) and methanol extract (100-400mg/kg, i.p.) significantly prolonged the onset of tonic seizures induced by pentylenetetrazole (95mg/kg, i.p.). Methanol extract (400mg/kg, i.p.) also significantly reduced the incidence of the seizures. One hundred to two hundred milligrams/kilogram (i.p.) of aqueous extract of Cotyledon orbiculata significantly delayed the onset of the tonic seizures induced by bicuculline (40mg/kg, i.p.), picrotoxin (12mg/kg, i.p.) and N-methyl-dl-aspartic acid (NMDLA, 400mg/kg, i.p.). Similarly, methanol extract (100-400mg/kg, i.p.) significantly delayed the onset of the tonic seizures induced by bicuculline (40mg/kg, i.p.) and picrotoxin (12mg/kg, i.p.) while 100mg/kg (i.p.) significantly delayed the onset of N-methyl-dl-aspartic acid (NMDLA, 400mg/kg, i.p.)-induced seizures. Methanol extract (200mg/kg, i.p.) significantly reduced the incidence of the seizures induced by bicuculline (40mg/kg, i.p.). Phenobarbitone (12mg/kg, i.p.) and diazepam (0.5mg/kg, i.p.) effectively antagonized only seizures induced by PTZ (95mg/kg, i.p.), bicuculline (40mg/kg, i.p.) and picrotoxin (12mg/kg, i.p.). Phenytoin (30mg/kg, i.p.) did not affect any of the seizures to any significant extent. The data obtained suggest that both aqueous and methanol extracts of Cotyledon orbiculata have anticonvulsant property and may probably be affecting both gabaergic and glutaminergic mechanisms to exert its effect. The phytochemical analysis carried out revealed the presence of cardiac glycosides, saponins, tannins, reducing sugar and triterpene steroids in the plant extract.

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Research paper thumbnail of Some behavioural effects of quinine in mice

Journal of Psychopharmacology, 1989

The effects of quinine on motor activity, pentobarbitone-induced sleep and gross behaviour were e... more The effects of quinine on motor activity, pentobarbitone-induced sleep and gross behaviour were examined in mice. Low doses of quinine (0.1-0.5 mg/kg intraperitoneally) increased locomotor activity in mice; this effect was potentiated by L-dopa (25 mg/kg sub cutaneously), L-dopa (25 mg/kg subcutaneously) plus benserazide (12.5 mg/kg subcutaneously) and pargyline (50 mg/kg intraperitoneally) and antagonized by α-methyl- p-tyrosine (50 mg/kg intraperitoneally), pimozide (0.2 mg/kg intraperitoneally), L-sulpiride (40 mg/kg intraperitoneally) and SCH 23390 (0.2 mg/kg subcutaneously). Similarly, D-amphet amine (2.5 mg/kg intraperitoneally)-induced locomotor activity in mice was blocked by pimo zide (0.2 mg/kg intraperitoneally). On the other hand, pimozide (0.2 mg/kg intraperitoneally), L-sulpiride (40 mg/kg intraperitoneally and SCH 23390 (0.2 mg/kg subcutaneously) potentiated the locomotor depressant effect of high doses of quinine (1-5 mg/kg) intraperitoneally). Furthermore, the onset and duration of pentobarbitone (30 mg/kg intraperitoneally)-induced sleep were respectively shortened and prolonged in a dose-dependent manner. D-Amphet amine (25 mg/kg intraperitoneally) significantly delayed the onset and shortened the duration of sleep induced by the interaction of quinine (100 mg/kg intraperitoneally) with pen tobarbitone (30 mg/kg intraperitoneally). L-sulpiride (40 mg/kg intraperitoneally) and pimozide (4 mg/kg intraperitoneally), on the other hand, significantly shortened the onset and prolonged the duration of sleep resulting from the interaction of quinine with pentobarbitone. The antagonism of pentobarbitone (30 mg/kg intraperitoneally)-induced sleep by D-amphetamine (2.5 mg/kg intraperitoneally) was prevented by pimozide (4 mg/kg intraperitoneally). Quinine (0.1 mg/kg intraperitoneally) desynchronized the EEG and antagonized pentobarbitone (20 mg/kg intraperitoneally)-induced EEG synchronization while 100 mg/kg intraperitoneally of quinine desynchronized the hyperstriatum with marked decrease in EMG activity in chicks and potentiated pentobarbitone (20 mg/kg intraperitoneally)-induced EEG synchronization with profound reduction in EMG activity. Quinine (0.01-5 mg/kg intraperitoneally) exhibited a biphasic dose-related increase in circling. The stereotyped circling induced by D-amphetamine (4 mg/kg intraperitoneally) was dose-dependently reduced by quinine (0.5-25 mg/kg intra peritoneally) while 0.05-0.1 mg/kg intraperitoneally of quinine weakly potentiated this activity. Pimozide (4 mg/kg intraperitoneally) and L-sulpiride (40 mg/kg intraperitoneally) antagonized both the circling and increase in locomotor activity induced by quinine (0.1 mg/kg intra peritoneally) and D-amphetamine (4 mg/kg intraperitoneally) respectively. These results indi cate that quinine exhibits both excitatory and inhibitory effects on the gross behaviour of mice; these biphasic effects were dose-related. Since pimozide, L-sulpiride and SCH 23390 influenced both effects, both D( 1) and D(2) receptors may be involved in the behavioural effects of quinine.

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Research paper thumbnail of GABAergic and dopaminergic systems may be involved in seizures induced by pyrimethamine in mice

General pharmacology, 1994

1. The effects of some GABAergic and dopaminergic agents on pyrimethamine-induced tonic seizures ... more 1. The effects of some GABAergic and dopaminergic agents on pyrimethamine-induced tonic seizures were investigated in mice. 2. Pyrimethamine dose dependently induced seizures in mice. 3. Muscimol, AOAA and DABA significantly protected mice against pyrimethamine-induced seizures. 4. Bicuculline and picrotoxin effectively potentiated seizures elicited by pyrimethamine and significantly antagonized the protective effect of muscimol against the seizures. 5. Diazepam and phenobarbitone effectively protected mice against seizures elicited by pyrimethamine. 6. L-Dopa significantly potentiated pyrimethamine-induced seizures. 7. Apomorphine and pargyline significantly reduced the latency of seizures induced by pyrimethamine. 8. Haloperidol and pimozide effectively protected mice against pyrimethamine-elicited seizures and also significantly antagonized the potentiating effects of apomorphine and L-dopa on the seizures. 9. Disulfiram significantly potentiated seizures induced by pyrimethamine...

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Research paper thumbnail of Strychnine-induced seizures in mice: The role of noradrenaline

Progress in Neuro-Psychopharmacology and Biological Psychiatry, 1994

1. The effects of some noradrenergic agents on seizures induced by strychnine were investigated i... more 1. The effects of some noradrenergic agents on seizures induced by strychnine were investigated in mice. 2. Strychnine (0.5-4 mg/kg, i.p.) dose-dependently produced tonic seizures. 3. DOPS (4-8 mg/kg, i.p.) significantly shortened the latency of seizures elicited by strychnine (2 mg/kg, i.p.). Similarly, DOPS (4 mg/kg, i.p.) effectively increased the incidence and significantly shortened the latency of seizures induced by strychnine (1 mg/kg, i.p.). 4. Imipramine (20-40 mg/kg, i.p.) and pargyline (200 mg/kg, i.p.) significantly shortened the latency of strychnine (2 mg/kg, i.p.)-induced seizures. 5. Phentolamine (5-20 mg/kg, i.p.) effectively antagonised the seizures elicited by strychnine (2 mg/kg, i.p.). Furthermore, phentolamine (10 mg/kg, i.p.) attenuated the seizure-potentiating effect of DOPS (4 mg/kg, i.p.). 6. Propranolol (0.5-2 mg/kg, i.p.) and prazosin (1-2 mg/kg, i.p.) reduced the incidence and significantly delayed the latency of seizures induced by strychnine (2 mg/kg, i.p.). 7. Reserpine (5-10 mg/kg, i.p.) significantly prolonged the latency of strychnine (2 mg/kg, i.p.)-induced seizures. 8. Clonidine (0.25-1 mg/kg, i.p.) dose-dependently and significantly antagonised strychnine (2 mg/kg, i.p.)-induced seizures. 9. Idazoxan (1-4 mg/kg, i.p.) in a dose related manner significantly shortened the latency of seizures induced by strychnine (2 mg/kg, i.p.). Similarly, idazoxan (2 mg/kg, i.p.) profoundly potentiated seizures elicited by strychnine (1 mg/kg, i.p.). Idazoxan (4 mg/kg, i.p.) significantly antagonised the protective effect of clonidine (1 mg/kg, i.p.) against strychnine (2 mg/kg, i.p.)-induced seizures. 10. Disulfiram (3 x 25 - 3 x 100 mg/kg, i.p.) significantly attenuated strychnine (2 mg/kg, i.p.)-induced seizures. DOPS (4 mg/kg, i.p.) significantly potentiated strychnine seizures in disulfiram (3 x 100 mg/kg, i.p.)-pretreated animals. 11. These results indicate that enhancement of noradrenergic neurotransmission potentiates strychnine seizures in mice.

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Research paper thumbnail of Chloroquine-induced seizures in mice: the role of monoaminergic mechanisms

European Neuropsychopharmacology, 1993

The influence of some dopaminergic and noradrenergic agents on seizures induced by chloroquine (4... more The influence of some dopaminergic and noradrenergic agents on seizures induced by chloroquine (45-100 mg/kg, i.p.) was investigated in mice. Apomorphine (0.2-0.8 mg/kg, s.c.). L-dopa (25-50 mg/kg, s.c.) benserazide (5 mg/kg, i.p.) plus L-dopa (50 mg/kg, s.c.), pargyline (100 mg/kg, i.p.), FLA-63 (10-20 mg/kg, s.c.) and FLA-63 (10 mg/kg, s.c.) plus L-dopa (50 mg/kg, s.c.) profoundly shortened the latency of seizures induced by chloroquine (65 mg/kg, i.p.). L-Dopa (50 mg/kg, s.c.) weakly reduced the latency and weakly increased the incidence of chloroquine (50 mg/kg, i.p.)-induced seizures. alpha-Methyl-p-tyrosine (25-100 mg/kg, i.p.) dose-dependently and significantly reduced the incidence and significantly prolonged the latency of chloroquine (65 mg/kg, i.p.)-induced seizures. However, L-dopa (50 mg/kg, s.c.) effectively increased the proportion of animals convulsing and effectively reduced the latency of seizures induced by chloroquine (65 mg/kg, i.p.) in alpha-methyl-p-tyrosine-pretreated mice. Haloperidol (0.25-1.0 mg/kg, i.p.) and pimozide (2-4 mg/kg, i.p.) markedly reduced the incidence and markedly prolonged the latency of seizures induced by chloroquine (65 mg/kg, i.p.) in a dose-related manner. However, apomorphine (0.4-0.8 mg/kg, s.c.) and L-dopa (25-50 mg/kg, s.c.) profoundly attenuated the protective effects of haloperidol (0.5 mg/kg, i.p.) and pimozide (4 mg/kg, i.p.) against chloroquine (65 mg/kg, i.p.)-induced seizures.(ABSTRACT TRUNCATED AT 250 WORDS)

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Research paper thumbnail of Effects of some GABAergic agents on quinine-induced seizures in mice

Experientia, 1992

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Research paper thumbnail of Propranolol-induced seizures in mice: the role of noradrenaline

Cellular and Molecular Life Sciences (CMLS), 1997

The effects of some noradrenergic agents, phenobarbitone, diazepam and phenytoin on seizures prod... more The effects of some noradrenergic agents, phenobarbitone, diazepam and phenytoin on seizures produced by propranolol were investigated in mice. Isoprenaline and DL-threo-3,4-dihydroxyphenylserine (DOPS) effectively antagonized the seizures elicited by propranolol. Pargyline and imipramine significantly attenuated propranolol-induced seizures and also significantly potentiated the protecting effect of DOPS against the seizures. alpha-Methyl-p-tyrosine, disulfiram and reserpine significantly potentiated propranolol-elicited seizures. However, DOPS significantly antagonized the seizure-potentiating effects of alpha-methyl-p-tyrosine, disulfiram and reserpine. Phenylephrine, clonidine, prazosin, idazoxan, phenobarbitone, diazepam and phenytoin did not significantly alter propranolol-induced seizures. These results suggest that propranolol-induced seizures in mice may involve a noradrenergic mechanism mediated via central beta-adrenoceptors.

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Research paper thumbnail of Cimetidine-induced seizures in mice antagonism by some gabaergic agents

Biochemical Pharmacology, 1993

The effects of muscimol, aminooxyacetic acid (AOAA), diamino-n-butyric acid (DABA), baclofen, bic... more The effects of muscimol, aminooxyacetic acid (AOAA), diamino-n-butyric acid (DABA), baclofen, bicuculline, picrotoxin, strychnine, diazepam, phenobarbitone and phenytoin on cimetidine-induced seizures were studied in mice. Cimetidine (400-1000 mg/kg, i.p.) induced dose-dependent tonic convulsion. Muscimol, AOAA and DABA effectively protected mice against cimetidine-induced seizures. Bicuculline and picrotoxin significantly potentiated the seizures induced by cimetidine and effectively antagonized the protective effects of muscimol, AOAA and DABA against the seizures. Diazepam and phenobarbitone significantly protected the mice against cimetidine-induced seizures while phenytoin and strychnine did not significantly alter the seizures. These results indicate that the attenuation of central gamma-aminobutyric acid neurotransmission may underlie cimetidine-induced seizures in mice.

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Research paper thumbnail of Factors modifying duration of drug action: a practical for large undergraduate classes on limited laboratory space, staff and budget

Medical education, 1989

A desperate need for health professionals is answered by yearly increases in university student a... more A desperate need for health professionals is answered by yearly increases in university student admissions in many developing countries. Yet economic constraints dictate that subventions for teaching and research remain static or even decrease as student populations increase. Practical teaching, for example in pharmacology, is susceptible to inadequate funding because of the capital and recurrent expenditure needed to procure and maintain laboratories, staff, animals, instruments and chemicals. Class demonstrations, although they provide a partial answer to the problem, are beset with a number of disadvantages. Provision of good training on low funds demands ingenuity to modify teaching/learning processes while still achieving the desired objectives. This paper illustrates such a procedure by describing the logistics of a practical class on 'Factors modifying duration of drug action' to large classes of undergraduate medical and pharmacy students, on limited laboratory space...

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Research paper thumbnail of An Anticonvulsant Diterpene Lactone Isolated From the Leaves of <i>Leonotis leonorus</i> (L) R. BR

East and Central African Journal of Pharmaceutical Sciences, 2007

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Research paper thumbnail of Influence of some dopaminergic agents on antinociception produced by quinine in mice

Progress in Neuro-Psychopharmacology and Biological Psychiatry, 1992

1. The analgesic effect of quinine and the influence of some dopaminergic agents on it were studi... more 1. The analgesic effect of quinine and the influence of some dopaminergic agents on it were studied in mice. 2. Quinine (25-130mg/kg, ip) effectively elicited antinociceptive effect in a dose related manner. 3. D-Amphetamine (2.5-4mg/kg, ip), L-dopa (25mg/kg, sc), L-dopa (25mg/kg, sc) plus benserazide (12.5mg/kg, sc), alpha-methyl-p-tyrosine (50mg/kg, ip) plus L-dopa (25mg/kg, sc) and pargyline (50mg/kg, ip) significantly attenuated the antinociceptive effect of quinine (50mg/kg, ip), while DOPS (4mg/kg, ip) did not affect quinine antinociception. 4. Pimozide (4mg/kg, ip), L-sulpiride (40mg/kg, ip), SCH 23390 (0.2mg/kg, sc) and alpha-methyl-p-tyrosine (50mg/kg, ip) effectively potentiated the antinociceptive effects of quinine (50mg/kg, ip). 5. Pimozide (4mg/kg, ip) also antagonised the antagonistic effect of d-amphetamine (4mg/kg, ip) on the antinociceptive effect of quinine (50mg/kg, ip). 6. These data indicate that quinine elicited antinociception dose dependently. Furthermore, the influence of pimozide, L-sulpiride and SCH 23390 on quinine antinociception suggests the involvement of dopaminergic mechanisms.

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Research paper thumbnail of Anticonvulsant activity of aqueous extract of Leonotis leonurus

Phytomedicine, 2002

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Research paper thumbnail of An assessment of two Carpobrotus species extracts as potential antimicrobial agents

Phytomedicine, 2003

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Research paper thumbnail of Effects of Tarchonanthus camphoratus and Eriocephalus africanus on nociception in mice and pyrexia in rats

Phytomedicine, 2000

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Research paper thumbnail of Antipyretic and antinociceptive properties of mentha longifolia Huds. (Lamiaceae) leaf aqueous extract in rats and mice

Methods and Findings in Experimental and Clinical Pharmacology, 2009

The antipyretic and antinociceptive properties of Mentha longifolia Huds. (Lamiaceae) leaf aqueou... more The antipyretic and antinociceptive properties of Mentha longifolia Huds. (Lamiaceae) leaf aqueous extract were investigated using lipopolysaccharide (LPS)-induced pyrexia in rats, and acetic acid and hot plate analgesia tests in mice. Pentoxifylline, paracetamol and morphine were used as standard drugs for comparison. M. longifolia leaf aqueous extract and pentoxifylline (37.5-150 mg/kg i.p.) significantly (P &lt; 0.05-0.02) reduced the LPS (50 g/kg i.m.)-elicited pyrexia. Pentoxifylline (50 mg/kg i.p.) also significantly (P &lt; 0.01) reduced LPS (50 g/kg i.m.)-induced pyrexia. M. longifolia leaf aqueous extract (6.25-100 mg/kg i.p.) and paracetamol (500 mg/kg i.p.) profoundly inhibited the writhes produced by 3% acetic acid. Furthermore, the plant extract (25-400 mg/kg i.p.) and morphine (10 mg/kg i.p.) significantly (P &lt; 0.001) delayed the hot plate reaction time in mice. The LD(50) values for oral and intraperitoneal administration of the plant extract were &gt; 3200 mg/kg and 1730 mg/kg, respectively. Phytochemical analysis revealed the presence of flavonoids, saponins, tannins, reducing sugars, cardiac glycosides and triterpene steroids in the leaves of M. longifolia. These data indicate that M. longifolia leaf aqueous extract has antipyretic and antinociceptive properties. Furthermore, the relatively high LD(50) values obtained for oral and intraperitoneal administration of the plant extract demonstrate that the plant extract is non-toxic to mice.

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Research paper thumbnail of Antimicrobial and anticonvulsant activities of Viscum capense

Journal of Ethnopharmacology, 1998

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Research paper thumbnail of Analgesic and antipyretic effects of Dodonaea angustifolia and Salvia africana-lutea

Journal of Ethnopharmacology, 2001

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Research paper thumbnail of Anticonvulsant activity of Cotyledon orbiculata L. (Crassulaceae) leaf extract in mice

Journal of Ethnopharmacology, 2007

The anticonvulsant activity of Cotyledon orbiculata L. (Crassulaceae) was investigated by studyin... more The anticonvulsant activity of Cotyledon orbiculata L. (Crassulaceae) was investigated by studying the effects of both aqueous and methanol extracts of the plant species on seizures induced by pentylenetetrazole, bicuculline, picrotoxin and N-methyl-dl-aspartic in mice. Aqueous extract of Cotyledon orbiculata (50-400mg/kg, i.p.) and methanol extract (100-400mg/kg, i.p.) significantly prolonged the onset of tonic seizures induced by pentylenetetrazole (95mg/kg, i.p.). Methanol extract (400mg/kg, i.p.) also significantly reduced the incidence of the seizures. One hundred to two hundred milligrams/kilogram (i.p.) of aqueous extract of Cotyledon orbiculata significantly delayed the onset of the tonic seizures induced by bicuculline (40mg/kg, i.p.), picrotoxin (12mg/kg, i.p.) and N-methyl-dl-aspartic acid (NMDLA, 400mg/kg, i.p.). Similarly, methanol extract (100-400mg/kg, i.p.) significantly delayed the onset of the tonic seizures induced by bicuculline (40mg/kg, i.p.) and picrotoxin (12mg/kg, i.p.) while 100mg/kg (i.p.) significantly delayed the onset of N-methyl-dl-aspartic acid (NMDLA, 400mg/kg, i.p.)-induced seizures. Methanol extract (200mg/kg, i.p.) significantly reduced the incidence of the seizures induced by bicuculline (40mg/kg, i.p.). Phenobarbitone (12mg/kg, i.p.) and diazepam (0.5mg/kg, i.p.) effectively antagonized only seizures induced by PTZ (95mg/kg, i.p.), bicuculline (40mg/kg, i.p.) and picrotoxin (12mg/kg, i.p.). Phenytoin (30mg/kg, i.p.) did not affect any of the seizures to any significant extent. The data obtained suggest that both aqueous and methanol extracts of Cotyledon orbiculata have anticonvulsant property and may probably be affecting both gabaergic and glutaminergic mechanisms to exert its effect. The phytochemical analysis carried out revealed the presence of cardiac glycosides, saponins, tannins, reducing sugar and triterpene steroids in the plant extract.

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Research paper thumbnail of Some behavioural effects of quinine in mice

Journal of Psychopharmacology, 1989

The effects of quinine on motor activity, pentobarbitone-induced sleep and gross behaviour were e... more The effects of quinine on motor activity, pentobarbitone-induced sleep and gross behaviour were examined in mice. Low doses of quinine (0.1-0.5 mg/kg intraperitoneally) increased locomotor activity in mice; this effect was potentiated by L-dopa (25 mg/kg sub cutaneously), L-dopa (25 mg/kg subcutaneously) plus benserazide (12.5 mg/kg subcutaneously) and pargyline (50 mg/kg intraperitoneally) and antagonized by α-methyl- p-tyrosine (50 mg/kg intraperitoneally), pimozide (0.2 mg/kg intraperitoneally), L-sulpiride (40 mg/kg intraperitoneally) and SCH 23390 (0.2 mg/kg subcutaneously). Similarly, D-amphet amine (2.5 mg/kg intraperitoneally)-induced locomotor activity in mice was blocked by pimo zide (0.2 mg/kg intraperitoneally). On the other hand, pimozide (0.2 mg/kg intraperitoneally), L-sulpiride (40 mg/kg intraperitoneally and SCH 23390 (0.2 mg/kg subcutaneously) potentiated the locomotor depressant effect of high doses of quinine (1-5 mg/kg) intraperitoneally). Furthermore, the onset and duration of pentobarbitone (30 mg/kg intraperitoneally)-induced sleep were respectively shortened and prolonged in a dose-dependent manner. D-Amphet amine (25 mg/kg intraperitoneally) significantly delayed the onset and shortened the duration of sleep induced by the interaction of quinine (100 mg/kg intraperitoneally) with pen tobarbitone (30 mg/kg intraperitoneally). L-sulpiride (40 mg/kg intraperitoneally) and pimozide (4 mg/kg intraperitoneally), on the other hand, significantly shortened the onset and prolonged the duration of sleep resulting from the interaction of quinine with pentobarbitone. The antagonism of pentobarbitone (30 mg/kg intraperitoneally)-induced sleep by D-amphetamine (2.5 mg/kg intraperitoneally) was prevented by pimozide (4 mg/kg intraperitoneally). Quinine (0.1 mg/kg intraperitoneally) desynchronized the EEG and antagonized pentobarbitone (20 mg/kg intraperitoneally)-induced EEG synchronization while 100 mg/kg intraperitoneally of quinine desynchronized the hyperstriatum with marked decrease in EMG activity in chicks and potentiated pentobarbitone (20 mg/kg intraperitoneally)-induced EEG synchronization with profound reduction in EMG activity. Quinine (0.01-5 mg/kg intraperitoneally) exhibited a biphasic dose-related increase in circling. The stereotyped circling induced by D-amphetamine (4 mg/kg intraperitoneally) was dose-dependently reduced by quinine (0.5-25 mg/kg intra peritoneally) while 0.05-0.1 mg/kg intraperitoneally of quinine weakly potentiated this activity. Pimozide (4 mg/kg intraperitoneally) and L-sulpiride (40 mg/kg intraperitoneally) antagonized both the circling and increase in locomotor activity induced by quinine (0.1 mg/kg intra peritoneally) and D-amphetamine (4 mg/kg intraperitoneally) respectively. These results indi cate that quinine exhibits both excitatory and inhibitory effects on the gross behaviour of mice; these biphasic effects were dose-related. Since pimozide, L-sulpiride and SCH 23390 influenced both effects, both D( 1) and D(2) receptors may be involved in the behavioural effects of quinine.

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