Gregory Oxenkrug - Academia.edu (original) (raw)

Papers by Gregory Oxenkrug

Research paper thumbnail of Use of propranolol for provoked and unprovoked episodes of rage

American Journal of Psychiatry, 1983

The use of propranolol to treat unprovoked rage episodes in brain-damaged patients has recently b... more The use of propranolol to treat unprovoked rage episodes in brain-damaged patients has recently been reported. The authors report three cases that indicate a role for its use in the treatment of overall aggressiveness in brain-damaged or mentally retarded patients.

Research paper thumbnail of Is serum cholesterol a biological marker for major depressive disorder?

American Journal of Psychiatry, 1983

An abnormally high serum cholesterol level has been suggested as a biological marker for major de... more An abnormally high serum cholesterol level has been suggested as a biological marker for major depression. However, in 192 depressed and normal subjects, age and sex influenced serum cholesterol level, but the diagnosis of major depression did not.

Research paper thumbnail of Disturbed circadian rhythm of 5HT uptake by blood platelets in depressive psychosis

Activitas nervosa superior

Research paper thumbnail of The effect of MAO-A inhibition and cold-immobilization stress on N-acetylserotonin and melatonin in SHR and WKY rats

MAO — The Mother of all Amine Oxidases, 1998

Selective monoamine oxidase (MAO) A inhibitors and cold-immobilization stress (which increases th... more Selective monoamine oxidase (MAO) A inhibitors and cold-immobilization stress (which increases the production of the endogenous MAO-A inhibitor, tribulin) stimulate rat pineal melatonin biosynthesis in Sprague-Dawley and Fisher 344N rats. Considering the hyperactive sympathetic response of the hypertensive rats, it was interesting to compare the effect of clorgyline and cold-immobilization stress on pineal melatonin and related indoles levels in SHR and WKY rats (HPLC-fluorimetric method). Clorgyline (0.5 mg/kg and 1.5 mg/kg, sc) induced a higher elevation of pineal melatonin and N-acetylserotonin (NAS) in SHR than in WKY rats. Cold immobilization stress resulted in lower serotonin, and higher NAS levels in SHR than in WKY rats with similar elevations in melatonin levels. Our results suggest increased serotonin conversion into NAS and decreased NAS conversion into melatonin with decreased production of tribulin in SHR in comparison with WKY rats.

Research paper thumbnail of Does moclobemide stimulate melatonin synthesis as the other selective MAO-A inhibitors do?

Amine Oxidases and Their Impact on Neurobiology, 1990

It has been reported that selective MAO-A inhibitors, clorgyline and brofaromine, but not the MAO... more It has been reported that selective MAO-A inhibitors, clorgyline and brofaromine, but not the MAO-B inhibitors, deprenyl and pargyline, stimulated rat pineal melatonin synthesis in humans and animals. Recent studies, however, found no effect of moclobemide, a selective MAO-A inhibitor, on human plasma melatonin levels. Present study found that in vitro moclobemide produced very weak stimulation of rat pineal NAT activity. However, in vivo moclobemide induced a significant increase of rat pineal NAS and melatonin content, and a dramatic decrease of 5-HIAA content (HPLC-fluorimetric procedure). Moclobemide's effect on melatonin and related indoles could be detected as early as 30 min after the injection and lasted, at least, for 2 h. The possible reasons for discrepancies between human and animal data are discussed.

Research paper thumbnail of Synergistic sedative effect of selective MAO-A, but not MAO-B, inhibitors and melatonin in frogs

Amine Oxidases: Function and Dysfunction, 1994

Total suppression of righting reflex in frogs (Rana pipiens, 25-35 mg b.w.) was observed after co... more Total suppression of righting reflex in frogs (Rana pipiens, 25-35 mg b.w.) was observed after combined administration of melatonin (12.5 mg/kg) and selective inhibitors of MAO-A: clorgyline (2.5 mg/kg) and moclobemide (50 mg/kg) but not MAO-B: selegiline (25 mg/kg) and Ro-19-6327 (50 mg/kg). None of these drugs alone affected the righting reflex. Clorgyline and selegiline selectively inhibited brain MAO-A and MAO-B activity (by more than 90%), resp. Frogs might represent a convenient model to study the selective MAO-A and B type inhibitors since they provide the opportunity to correlate behaviour and biochemical changes induced by MAO inhibitors.

Research paper thumbnail of Cognitive Function and Brain-Adrenal Axis Activity in Aging, Depression and Dementia

Alzheimer’s Disease, 1987

The brain-adrenal axis* represents one of the major adaptation mechanisms maintaining the body ho... more The brain-adrenal axis* represents one of the major adaptation mechanisms maintaining the body homeostatic balance (see Dilman, 1971). Since the 1960s it has become an object of increased attention to psychiatrists and has resulted in the avalanch of publications reviewed elsewhere (Stokes, 1987). This chapter reviews the findings of our research team as well as closely related literature in an attempt to offer a satisfactory explanation of the known facts and to suggest directions for further investigation.

Research paper thumbnail of Antidepressive and antihypertensive effects of MAO-A inhibition: Role of N-acetylserotonin. A review

Neurobiology

Acute administration of irreversible and reversible selective MAO-A inhibitors and high doses (or... more Acute administration of irreversible and reversible selective MAO-A inhibitors and high doses (or chronic administration of low doses) of relatively selective MAO-B inhibitors (but not of highly selective MAO-B inhibitors) suppressed MAO-A activity and stimulated N-acetylation of pineal serotonin into N-acetylserotonin, the immediate precursor of melatonin. Consequent increase of melatonin occurs only in > 21-days-old rats. The effect is strain (spontaneously hypertensive rats > Fisher344N > Wistar Kyoto > Sprague-Dawley) and gender (male > female) dependent. N-acetylserotonin increase after clorgyline was weaker in the light-primed aged (or young animals with lesioned suprachiasmatic nuclei) than in young intact or sham-operated rats. N-acetylserotonin increase after MAO-A inhibitors might mediate their antidepressive (N-acetylserotonin and melatonin exerted antidepressant-like activity in the mouse tail-suspension and frog tests) and antihypertensive effects (N-acet...

Research paper thumbnail of Dexamethasone suppression test: experimental model in rats, and effect of age

Biological psychiatry, 1984

ABSTRACT

Research paper thumbnail of Clinical pharmacology of bupropion and imipramine in elderly depressives

The Journal of clinical psychiatry, 1983

The clinical efficacy and adverse reaction profile of bupropion, an atypical antidepressant, was ... more The clinical efficacy and adverse reaction profile of bupropion, an atypical antidepressant, was compared with the tricyclic imipramine in 63 elderly depressives. Patients were randomly assigned to treatment with 150 or 450 mg/day of bupropion, 150 mg/day of imipramine, or placebo for 35 days. Both doses of bupropion were equivalent to imipramine in antidepressant efficacy. The higher dose of bupropion had a more rapid onset of effect than the low dose and significantly greater anxiolytic activity than either imipramine or the lower dose. Both doses of bupropion had adverse reaction profiles strikingly similar to placebo and, in marked contrast to imipramine, did not produce sedation or anticholinergic side effects. Cognition improved equally in all groups. It was concluded that bupropion has therapeutic advantages over the tricyclics in the treatment of elderly depressives.

Research paper thumbnail of Sex differences in ABO blood types distribution in manic-depressive patients and in the rate of 5-HT uptake by blood platelets in healthy donors of different blood groups

Activitas nervosa superior, 1978

Research paper thumbnail of 1-METHYL and 1-BENZYL Derivatives of Tetrahydroisoquinoline Inhibit 5-HYDROXYTRYPTAMINE Uptake by Human Blood Platelets

Medical biology, 1978

The effect of 1-methyl (salsoline, salsolidine) and 1-benzyl (papaverine) derivatives of tetrahyd... more The effect of 1-methyl (salsoline, salsolidine) and 1-benzyl (papaverine) derivatives of tetrahydroisoquinoline (TIQ) on 5-hydroxytryptamine (5-HT) uptake by human blood platelets was studied. The drugs tested inhibited 5-HT (3 X 10(-6)M 5 min incubation) uptake by 30--60 % at 10(-4)M concentration and by 20--25 % at 10(-5)M concentration.

Research paper thumbnail of Benzodiazepins attenuate clorgyline-induced stimulation of melatonin synthesis

Pharmacological Research Communications, 1988

Research paper thumbnail of Effect of ageing on melatonin synthesis induced by 5-hydroxytryptophan and constant light in rats

Progress in Neuro-Psychopharmacology and Biological Psychiatry, 1991

Research paper thumbnail of Lack of Effect of the Antidepressant Compound Bupropion on Pineal Indoleamines

Pharmacopsychiatry, 1989

The effects of the antidepressant compound bupropion were studied on rat pineal indoleamines. A p... more The effects of the antidepressant compound bupropion were studied on rat pineal indoleamines. A pharmacologically relevant dose of bupropion either acutely (20 mg/kg) or chronically (20 mg/kg/day for 12 days) had no significant effect on pineal melatonin synthesis or other pineal indoleamine concentrations. The significance of this finding is discussed in relation to the lack of effect of bupropion on beta-adrenergic receptors.

Research paper thumbnail of Peripheral carbidopa affects striatal monoamine oxidase activity

Neurology, 1985

... Peter A. Le Witt, MD Gregory F. Oxenkrug, MD, PhD Iain M. Mclntyre, PhD Roy M. McCauley, PhD ... more ... Peter A. Le Witt, MD Gregory F. Oxenkrug, MD, PhD Iain M. Mclntyre, PhD Roy M. McCauley, PhD Detroit. MI ... Khatri, McQuillen, and colleagues for a splendid study with a convincing result.' Our experience with plasmapheresis and immunosuppressive drugs in 33 patients with ...

Research paper thumbnail of The effect of neuroleptic derivatives of butyrophenone on the uptake of 5-HT by human blood platelets

Journal of Pharmacy and Pharmacology, 1978

The uptake of 5-HT by blood platelets is a useful model for the neuronal uptake of 5-HT (Paasonen... more The uptake of 5-HT by blood platelets is a useful model for the neuronal uptake of 5-HT (Paasonen, 1965) and it is generally accepted that impramine-like drugs are the most potent inhibitors of this uptake (Tuornisto, 1974). Neuroleptic derivatives of phenothiazine inhibit the uptake of 5-HT by human (Todrick & Tait, 1969) and rabbit (Ahtee & Paasonen, 1968) blood platelets. However, the influence of derivatives of butyrophenone on the uptake of 5-HT by blood platelets has not been studied. I have therefore examined the influence of five derivatives of butyrophenone on the uptake of 5-HT by human blood platelets. The rate of uptake was evaluated by the rise of 5-HT content in platelets during 5 min incubation of 1 ml of platelet rich plasma with 1 pg 5-HT a t 37" (Oxenkrug, 1975). 5-HT content in platelets was determined spectrofluorimetrically (Oxenkrug, 1973). IC50 values were calculated by D r V. N. Amatuni according to the program published by Finney (1972). In each experiment a blood pool from 2-3 healthy donors was used. All drugs were dissolved in saline and added (in 0.1 ml) to platelet-rich plasma 5 min before the 5-HT. The derivatives of butyrophenone inhibited the uptake of 5-HT, though not as strongly as irnipramine (see Table 1). The inhibiting effect of the derivatives on 5-HT uptake by blood platelets suggest that they could inhibit 5-HT reuptake in neurons. This supposition corresponds with the observation of Kannengiesser, Hunt & Raynaud (1973) that haloperidol inhibited the uptake of I4C-5-HT by synaptosomes from rat brain. The inhibition of 5-HT reuptake from the synaptic cleft t o Table 1. The effect of compounds on the uptake of 5 f ~ by human blood platelets.

Research paper thumbnail of The content and uptake of 5-HT by blood platelets in depressive patients

Journal of Neural Transmission, 1979

The obtained results and data of literature indicate the increase (absolute or relative) of the r... more The obtained results and data of literature indicate the increase (absolute or relative) of the rate of 5-HT uptake by platelets in depressives. These data suggest that the acceleration of 5-HT reuptake in neurones may be one of the reasons of insufficiency of 5-HT-ergic processes in depression of 5-HT type (Asberg, 1976).

Research paper thumbnail of The effect of 5,7-dihydroxytryptamine on the serum corticosterone resistance to suppression by dexamethasone

Research paper thumbnail of Cognitive impairment and cortisol resistance to Dexamethasone Suppression in elderly depression

Biological Psychiatry, 1989

The present study evaluates the relationship between cognitive impairment and the Dexamethasone S... more The present study evaluates the relationship between cognitive impairment and the Dexamethasone Suppression Test (DST) in elderly persons suffering from depression. Twenty-nine subjects meeting DSM-III criteria for major depressive disorder (MDD) were assessed using the Global Deterioration Scale (GDS) and the DST. Plasma cortisol levels before and after receiving 0.5 mg dexamethasone were compared, and correlations were determined between GDS and postdexamethasone plasma cortisol levels. The results show that there is a positive correlation between the GDS scores and post-DEX cortisol levels (r = 0.57, p less than 0.005). It is suggested that increased activity of the HPA axis, seen in depression, could contribute to the cognitive impairments observed in this disorder.

Research paper thumbnail of Use of propranolol for provoked and unprovoked episodes of rage

American Journal of Psychiatry, 1983

The use of propranolol to treat unprovoked rage episodes in brain-damaged patients has recently b... more The use of propranolol to treat unprovoked rage episodes in brain-damaged patients has recently been reported. The authors report three cases that indicate a role for its use in the treatment of overall aggressiveness in brain-damaged or mentally retarded patients.

Research paper thumbnail of Is serum cholesterol a biological marker for major depressive disorder?

American Journal of Psychiatry, 1983

An abnormally high serum cholesterol level has been suggested as a biological marker for major de... more An abnormally high serum cholesterol level has been suggested as a biological marker for major depression. However, in 192 depressed and normal subjects, age and sex influenced serum cholesterol level, but the diagnosis of major depression did not.

Research paper thumbnail of Disturbed circadian rhythm of 5HT uptake by blood platelets in depressive psychosis

Activitas nervosa superior

Research paper thumbnail of The effect of MAO-A inhibition and cold-immobilization stress on N-acetylserotonin and melatonin in SHR and WKY rats

MAO — The Mother of all Amine Oxidases, 1998

Selective monoamine oxidase (MAO) A inhibitors and cold-immobilization stress (which increases th... more Selective monoamine oxidase (MAO) A inhibitors and cold-immobilization stress (which increases the production of the endogenous MAO-A inhibitor, tribulin) stimulate rat pineal melatonin biosynthesis in Sprague-Dawley and Fisher 344N rats. Considering the hyperactive sympathetic response of the hypertensive rats, it was interesting to compare the effect of clorgyline and cold-immobilization stress on pineal melatonin and related indoles levels in SHR and WKY rats (HPLC-fluorimetric method). Clorgyline (0.5 mg/kg and 1.5 mg/kg, sc) induced a higher elevation of pineal melatonin and N-acetylserotonin (NAS) in SHR than in WKY rats. Cold immobilization stress resulted in lower serotonin, and higher NAS levels in SHR than in WKY rats with similar elevations in melatonin levels. Our results suggest increased serotonin conversion into NAS and decreased NAS conversion into melatonin with decreased production of tribulin in SHR in comparison with WKY rats.

Research paper thumbnail of Does moclobemide stimulate melatonin synthesis as the other selective MAO-A inhibitors do?

Amine Oxidases and Their Impact on Neurobiology, 1990

It has been reported that selective MAO-A inhibitors, clorgyline and brofaromine, but not the MAO... more It has been reported that selective MAO-A inhibitors, clorgyline and brofaromine, but not the MAO-B inhibitors, deprenyl and pargyline, stimulated rat pineal melatonin synthesis in humans and animals. Recent studies, however, found no effect of moclobemide, a selective MAO-A inhibitor, on human plasma melatonin levels. Present study found that in vitro moclobemide produced very weak stimulation of rat pineal NAT activity. However, in vivo moclobemide induced a significant increase of rat pineal NAS and melatonin content, and a dramatic decrease of 5-HIAA content (HPLC-fluorimetric procedure). Moclobemide's effect on melatonin and related indoles could be detected as early as 30 min after the injection and lasted, at least, for 2 h. The possible reasons for discrepancies between human and animal data are discussed.

Research paper thumbnail of Synergistic sedative effect of selective MAO-A, but not MAO-B, inhibitors and melatonin in frogs

Amine Oxidases: Function and Dysfunction, 1994

Total suppression of righting reflex in frogs (Rana pipiens, 25-35 mg b.w.) was observed after co... more Total suppression of righting reflex in frogs (Rana pipiens, 25-35 mg b.w.) was observed after combined administration of melatonin (12.5 mg/kg) and selective inhibitors of MAO-A: clorgyline (2.5 mg/kg) and moclobemide (50 mg/kg) but not MAO-B: selegiline (25 mg/kg) and Ro-19-6327 (50 mg/kg). None of these drugs alone affected the righting reflex. Clorgyline and selegiline selectively inhibited brain MAO-A and MAO-B activity (by more than 90%), resp. Frogs might represent a convenient model to study the selective MAO-A and B type inhibitors since they provide the opportunity to correlate behaviour and biochemical changes induced by MAO inhibitors.

Research paper thumbnail of Cognitive Function and Brain-Adrenal Axis Activity in Aging, Depression and Dementia

Alzheimer’s Disease, 1987

The brain-adrenal axis* represents one of the major adaptation mechanisms maintaining the body ho... more The brain-adrenal axis* represents one of the major adaptation mechanisms maintaining the body homeostatic balance (see Dilman, 1971). Since the 1960s it has become an object of increased attention to psychiatrists and has resulted in the avalanch of publications reviewed elsewhere (Stokes, 1987). This chapter reviews the findings of our research team as well as closely related literature in an attempt to offer a satisfactory explanation of the known facts and to suggest directions for further investigation.

Research paper thumbnail of Antidepressive and antihypertensive effects of MAO-A inhibition: Role of N-acetylserotonin. A review

Neurobiology

Acute administration of irreversible and reversible selective MAO-A inhibitors and high doses (or... more Acute administration of irreversible and reversible selective MAO-A inhibitors and high doses (or chronic administration of low doses) of relatively selective MAO-B inhibitors (but not of highly selective MAO-B inhibitors) suppressed MAO-A activity and stimulated N-acetylation of pineal serotonin into N-acetylserotonin, the immediate precursor of melatonin. Consequent increase of melatonin occurs only in > 21-days-old rats. The effect is strain (spontaneously hypertensive rats > Fisher344N > Wistar Kyoto > Sprague-Dawley) and gender (male > female) dependent. N-acetylserotonin increase after clorgyline was weaker in the light-primed aged (or young animals with lesioned suprachiasmatic nuclei) than in young intact or sham-operated rats. N-acetylserotonin increase after MAO-A inhibitors might mediate their antidepressive (N-acetylserotonin and melatonin exerted antidepressant-like activity in the mouse tail-suspension and frog tests) and antihypertensive effects (N-acet...

Research paper thumbnail of Dexamethasone suppression test: experimental model in rats, and effect of age

Biological psychiatry, 1984

ABSTRACT

Research paper thumbnail of Clinical pharmacology of bupropion and imipramine in elderly depressives

The Journal of clinical psychiatry, 1983

The clinical efficacy and adverse reaction profile of bupropion, an atypical antidepressant, was ... more The clinical efficacy and adverse reaction profile of bupropion, an atypical antidepressant, was compared with the tricyclic imipramine in 63 elderly depressives. Patients were randomly assigned to treatment with 150 or 450 mg/day of bupropion, 150 mg/day of imipramine, or placebo for 35 days. Both doses of bupropion were equivalent to imipramine in antidepressant efficacy. The higher dose of bupropion had a more rapid onset of effect than the low dose and significantly greater anxiolytic activity than either imipramine or the lower dose. Both doses of bupropion had adverse reaction profiles strikingly similar to placebo and, in marked contrast to imipramine, did not produce sedation or anticholinergic side effects. Cognition improved equally in all groups. It was concluded that bupropion has therapeutic advantages over the tricyclics in the treatment of elderly depressives.

Research paper thumbnail of Sex differences in ABO blood types distribution in manic-depressive patients and in the rate of 5-HT uptake by blood platelets in healthy donors of different blood groups

Activitas nervosa superior, 1978

Research paper thumbnail of 1-METHYL and 1-BENZYL Derivatives of Tetrahydroisoquinoline Inhibit 5-HYDROXYTRYPTAMINE Uptake by Human Blood Platelets

Medical biology, 1978

The effect of 1-methyl (salsoline, salsolidine) and 1-benzyl (papaverine) derivatives of tetrahyd... more The effect of 1-methyl (salsoline, salsolidine) and 1-benzyl (papaverine) derivatives of tetrahydroisoquinoline (TIQ) on 5-hydroxytryptamine (5-HT) uptake by human blood platelets was studied. The drugs tested inhibited 5-HT (3 X 10(-6)M 5 min incubation) uptake by 30--60 % at 10(-4)M concentration and by 20--25 % at 10(-5)M concentration.

Research paper thumbnail of Benzodiazepins attenuate clorgyline-induced stimulation of melatonin synthesis

Pharmacological Research Communications, 1988

Research paper thumbnail of Effect of ageing on melatonin synthesis induced by 5-hydroxytryptophan and constant light in rats

Progress in Neuro-Psychopharmacology and Biological Psychiatry, 1991

Research paper thumbnail of Lack of Effect of the Antidepressant Compound Bupropion on Pineal Indoleamines

Pharmacopsychiatry, 1989

The effects of the antidepressant compound bupropion were studied on rat pineal indoleamines. A p... more The effects of the antidepressant compound bupropion were studied on rat pineal indoleamines. A pharmacologically relevant dose of bupropion either acutely (20 mg/kg) or chronically (20 mg/kg/day for 12 days) had no significant effect on pineal melatonin synthesis or other pineal indoleamine concentrations. The significance of this finding is discussed in relation to the lack of effect of bupropion on beta-adrenergic receptors.

Research paper thumbnail of Peripheral carbidopa affects striatal monoamine oxidase activity

Neurology, 1985

... Peter A. Le Witt, MD Gregory F. Oxenkrug, MD, PhD Iain M. Mclntyre, PhD Roy M. McCauley, PhD ... more ... Peter A. Le Witt, MD Gregory F. Oxenkrug, MD, PhD Iain M. Mclntyre, PhD Roy M. McCauley, PhD Detroit. MI ... Khatri, McQuillen, and colleagues for a splendid study with a convincing result.' Our experience with plasmapheresis and immunosuppressive drugs in 33 patients with ...

Research paper thumbnail of The effect of neuroleptic derivatives of butyrophenone on the uptake of 5-HT by human blood platelets

Journal of Pharmacy and Pharmacology, 1978

The uptake of 5-HT by blood platelets is a useful model for the neuronal uptake of 5-HT (Paasonen... more The uptake of 5-HT by blood platelets is a useful model for the neuronal uptake of 5-HT (Paasonen, 1965) and it is generally accepted that impramine-like drugs are the most potent inhibitors of this uptake (Tuornisto, 1974). Neuroleptic derivatives of phenothiazine inhibit the uptake of 5-HT by human (Todrick & Tait, 1969) and rabbit (Ahtee & Paasonen, 1968) blood platelets. However, the influence of derivatives of butyrophenone on the uptake of 5-HT by blood platelets has not been studied. I have therefore examined the influence of five derivatives of butyrophenone on the uptake of 5-HT by human blood platelets. The rate of uptake was evaluated by the rise of 5-HT content in platelets during 5 min incubation of 1 ml of platelet rich plasma with 1 pg 5-HT a t 37" (Oxenkrug, 1975). 5-HT content in platelets was determined spectrofluorimetrically (Oxenkrug, 1973). IC50 values were calculated by D r V. N. Amatuni according to the program published by Finney (1972). In each experiment a blood pool from 2-3 healthy donors was used. All drugs were dissolved in saline and added (in 0.1 ml) to platelet-rich plasma 5 min before the 5-HT. The derivatives of butyrophenone inhibited the uptake of 5-HT, though not as strongly as irnipramine (see Table 1). The inhibiting effect of the derivatives on 5-HT uptake by blood platelets suggest that they could inhibit 5-HT reuptake in neurons. This supposition corresponds with the observation of Kannengiesser, Hunt & Raynaud (1973) that haloperidol inhibited the uptake of I4C-5-HT by synaptosomes from rat brain. The inhibition of 5-HT reuptake from the synaptic cleft t o Table 1. The effect of compounds on the uptake of 5 f ~ by human blood platelets.

Research paper thumbnail of The content and uptake of 5-HT by blood platelets in depressive patients

Journal of Neural Transmission, 1979

The obtained results and data of literature indicate the increase (absolute or relative) of the r... more The obtained results and data of literature indicate the increase (absolute or relative) of the rate of 5-HT uptake by platelets in depressives. These data suggest that the acceleration of 5-HT reuptake in neurones may be one of the reasons of insufficiency of 5-HT-ergic processes in depression of 5-HT type (Asberg, 1976).

Research paper thumbnail of The effect of 5,7-dihydroxytryptamine on the serum corticosterone resistance to suppression by dexamethasone

Research paper thumbnail of Cognitive impairment and cortisol resistance to Dexamethasone Suppression in elderly depression

Biological Psychiatry, 1989

The present study evaluates the relationship between cognitive impairment and the Dexamethasone S... more The present study evaluates the relationship between cognitive impairment and the Dexamethasone Suppression Test (DST) in elderly persons suffering from depression. Twenty-nine subjects meeting DSM-III criteria for major depressive disorder (MDD) were assessed using the Global Deterioration Scale (GDS) and the DST. Plasma cortisol levels before and after receiving 0.5 mg dexamethasone were compared, and correlations were determined between GDS and postdexamethasone plasma cortisol levels. The results show that there is a positive correlation between the GDS scores and post-DEX cortisol levels (r = 0.57, p less than 0.005). It is suggested that increased activity of the HPA axis, seen in depression, could contribute to the cognitive impairments observed in this disorder.