carolina Rojas - Academia.edu (original) (raw)

Papers by carolina Rojas

Among mammals, rabbits (Oryctolagus cuniculus) show unusually limited maternal care and only nurs... more Among mammals, rabbits (Oryctolagus cuniculus) show unusually limited maternal care and only nurse for a few minutes once each day. Successful suckling depends on pheromonal cues on the mother’s ventrum, which release a stereotyped and distinctive pattern of nipple-search behaviour in the young, and which have been termed the nipple-search pheromone. The present report summarizes what is currently known about this unusually effective chemical signal and compares this with information in more recent reports of a rabbit mammary pheromone thought to achieve the same function. We draw attention to anomalies in the present state of knowledge regarding the nature and action of these two sets of chemical signals, and thus to the continuing uncertainty as to the chemical nature and source of the cues governing nipple-search behaviour, and thus successful suckling, in the newborn rabbit.

Mammalian Biology, 2005

Rabbit pups are only nursed for about 3 min once a day. They depend on a pheromone on the mother'... more Rabbit pups are only nursed for about 3 min once a day. They depend on a pheromone on the mother's ventrum to locate nipples and on tactile stimulation of the muzzle to grasp them. In a continuing study of the sensory input guiding suckling behavior we investigated the whisker array in newborn pups and the possible contribution of the whiskers to suckling. Rabbits are born with approximately 76 whiskers arranged in seven to nine rows and increasing in length from rostral to caudal. No significant difference was found between pups with whiskers cut and intact controls in latency to perform the stereotyped nipple-search behavior, latency to attach to nipples, time spent on nipples, milk ingested, or in the strength of conditioning to a novel odor paired with suckling. Thus, the whiskers do not seem important for suckling in newborn rabbits.

1-Methyl-4-phenylpyridinium (MPP+) is the major metabolite of 1-methyl-4-phenyl-1,2,3,6-tetrahydr... more 1-Methyl-4-phenylpyridinium (MPP+) is the major metabolite of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) [1], a drug which adminis-tered to non-human primates and mice produces depletion of dopamine and cellular degeneration of the nigrostriatal pathway resembling the ...

Neurochemistry International, 2011

EGb761 is a well-defined mixture of active compounds extracted from Ginkgo biloba leaves. This ex... more EGb761 is a well-defined mixture of active compounds extracted from Ginkgo biloba leaves. This extract is used clinically due to its neuroprotective effects, exerted probably via its potent antioxidant or free radical scavenger action. Previous studies suggest that oxidative stress, via free radical production, may play an important role in depression and animal models for depression-like behavior. Preclinical studies have suggested that antioxidants may have antidepressants properties. The aim of this study was to investigate the antidepressant-like of EGb761 due to its antioxidant role against oxidative stress induced in the forced swimming test, the most widely used preclinical model for assessing antidepressant-like behavior. Male BALB/c mice were pretreated with EGb761 (10mg/kg, ip) daily for 17 days followed by the forced swimming test and spontaneous locomotor activity. Animals were sacrificed to evaluate lipid peroxidation, different antioxidant enzyme activities, serotonin and dopamine content in midbrain, hippocampus and prefrontal cortex. EGb761 significantly decreased the immobility time (39%) in the forced swimming test. This antidepressant-like effect of EGb761 was associated with a reduction in lipid peroxidation and superoxide radical production (indicated by a downregulation of Mn-superoxide dismutase activity), both of which are indicators of oxidative stress. The protective effect of EGb761 is not related to excitatory or inhibitory effects in locomotor activity, and was also associated with the modulation of serotonergic and dopaminergic neurotransmission. It is suggested that EGb761 produces an antidepressant-like effect, and that an antioxidant effect against oxidative stress may be partly responsible for its observed neuroprotective effects.

Neurotoxicology, 2005

Zinc is an essential trace element in the central nervous system and is located in three distinct... more Zinc is an essential trace element in the central nervous system and is located in three distinct pools: free zinc, vesicular zinc and protein-bound zinc. Zinc may serve as an endogenous neuromodulator and has been associated with neuropathologies. This study was undertaken to determine whether levels of vesicular zinc in neuronal terminals would decrease in response to the dopaminergic neurotoxin 1-methyl-4-phenylpyridinium ion (MPP + ). Adult male C-57 black mice were injected with MPP + (0.72 mg/kg) into their right lateral ventricle. All animals were killed at 1, 2, 24 h and 7 days after MPP + or saline administration. The brains were stained for zinc sulfides and the density of zinc-positive terminal fields was evaluated after MPP + administration. The relative optical density analysis of zinc-positive terminal fields showed significant decreases in the striatum at 1, 2 and 24 h (24, 18 and 14%, respectively, versus control) and ventricular epithelium (1, 2, 24 h and 7 days). The hippocampus showed increase in the stratum oriens and stratum radiatum at different times. MPP + administration reduced dopamine levels at 24 h and 7 days (36 and 40%, respectively, versus control) as a result of the neurotoxic action of MPP + . The decrease of zinc-positive neuronal terminal fields in the striatum after MPP + administration is most likely due to a neuronal release of vesicular zinc in response to its dopaminergic neurotoxicity.

Neurochemical Research, 2000

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is a drug that induces parkinsonism in humans... more 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is a drug that induces parkinsonism in humans and non-human primates. Free radicals are thought to be involved in its mechanism of action. Recently, metallothionein has been proposed to play a role as a scavenger of free radicals. In the present work, we studied the effect of MPTP neurotoxicity on brain metallothionein-I (MT-I) mRNA expression. Male C-57 black mice were treated with MPTP (30 mg/kg, i.p., daily) for 3 or 5 days. All animals were killed by cervical dislocation 7 days after the last MPTP dose. The brains were removed quickly and immediately frozen, and quantitative in situ hybridization was performed using MT-I cDNA probe. MT-I mRNA content in striatum, a region which is known to be highly predisposed and sensitive to MPTP-induced oxidative stress, decreased by 30% (3 days) and 39% (5 days) respectively, after the last MPTP administration. These results suggest that MT-I gene expression is decreased in MPTP neurotoxicity. It is suggested that the reduction of MT, an anti-oxidant and a free radical scavenger, in the striatum by MPTP enables the neurotoxin to exert maximal oxidative damage to the striatum.

Neurochemical Research, 2001

EGb761 has been suggested to be an antioxidant and free radical scavenger. Excess generation of f... more EGb761 has been suggested to be an antioxidant and free radical scavenger. Excess generation of free radicals, leading to lipid peroxidation (LP), has been proposed to play a role in the damage to striatal neurons induced by 1-methyl-4-phenylpyridinium (MPP+). We investigated the effects of EGb761 pretreatment on MPP+ neurotoxicity. C-57 black mice were pretreated with EGb761 for 17 days at different doses (0.63, 1.25, 2.5, 5 or 10 mg/kg) followed by administration of MPP+, (0.18, 0.36 or 0.72 mg/kg). LP was analyzed in corpus striatum at 30 min, 1 h, 2 h and 24 h after MPP+ administration. Striatal dopamine content was analyzed by HPLC at the highest EGb761 dose at 2 h and 24 h after MPP+ administration. MPP+-induced LP was blocked (100%) by EGb761 (10 mg/kg). Pretreatment with EGb761 partially prevented (32%) the dopamine-depleting effect of MPP+ at 24 h. These results suggest that supplements of EGb761 may be effective at preventing MPP+-induced oxidative stress.

Neurochemical Research, 2004

EGb761 produces reversible inhibition of both monoamine oxidase (MAO) isoforms in the central ner... more EGb761 produces reversible inhibition of both monoamine oxidase (MAO) isoforms in the central nervous system. 1-methyl-4-phenylpyridinium (MPP+) neurotoxicity is prevented by treatment with the MAO inhibitor pargyline. We investigated EGb761's effect on striatal MAO activity during MPP+ neurotoxicity. C-57 black mice were pretreated with EGb761 (10 mg/kg) daily for 17 days followed by administration of MPP (0.72 mg/kg). MPP+ enhanced striatal MAO (30%) activity at 6 h, and EGb761 prevented this effect. MAO-B activity in striatum was enhanced (70%) 6 h after MPP+ administration and was reduced to almost normal levels in EGb761 + MPP+ group compared to MPP+ group. Pretreatment with EGb761 partially prevented (32%) the striatal dopamine-depleting effect of MPP+ and prevented the reduction in striatal tyrosine hydroxylase activity (100%). Results suggest that EGb761 supplements may be effective in reducing MAO activity as well as enhancement in dopamine metabolism, thereby preventing MPP+-neurotoxicity.

International Journal of Gynecology & Obstetrics, 2010

Objective: To evaluate the viability and functional capacity of hematopoietic progenitor cells fr... more Objective: To evaluate the viability and functional capacity of hematopoietic progenitor cells from cord blood samples cryopreserved at the Banco de Células Stem de Colombia. Methods: After thawing and centrifugation of 20 samples, viable white blood cells were numbered by the trypan blue method and CD34 + CD45 + dim hematopoietic progenitor cells were numbered by flow cytometry. Clonogenic assays also tested the functional capacity of viable CD34 + CD45 + dim cells. Results: The median rates of viable CD34 + CD45 + dim cells were 99.6% before freezing and 73.0% after thawing (P < 0.001). The 20 cultures yielded a median of 12 cells with a lineage of red cells, 17.5 cells with a lineage of white cells, and 10 cells with a mixed lineage. Conclusion: Although the rate of viable CD34 + CD45 + dim cells was decreased by 26.6% after thawing by the method we used, the numbers of CD34 + CD45 +dim cells that formed colonies were similar to those obtained by other published methods.

Among mammals, rabbits (Oryctolagus cuniculus) show unusually limited maternal care and only nurs... more Among mammals, rabbits (Oryctolagus cuniculus) show unusually limited maternal care and only nurse for a few minutes once each day. Successful suckling depends on pheromonal cues on the mother’s ventrum, which release a stereotyped and distinctive pattern of nipple-search behaviour in the young, and which have been termed the nipple-search pheromone. The present report summarizes what is currently known about this unusually effective chemical signal and compares this with information in more recent reports of a rabbit mammary pheromone thought to achieve the same function. We draw attention to anomalies in the present state of knowledge regarding the nature and action of these two sets of chemical signals, and thus to the continuing uncertainty as to the chemical nature and source of the cues governing nipple-search behaviour, and thus successful suckling, in the newborn rabbit.

Mammalian Biology, 2005

Rabbit pups are only nursed for about 3 min once a day. They depend on a pheromone on the mother'... more Rabbit pups are only nursed for about 3 min once a day. They depend on a pheromone on the mother's ventrum to locate nipples and on tactile stimulation of the muzzle to grasp them. In a continuing study of the sensory input guiding suckling behavior we investigated the whisker array in newborn pups and the possible contribution of the whiskers to suckling. Rabbits are born with approximately 76 whiskers arranged in seven to nine rows and increasing in length from rostral to caudal. No significant difference was found between pups with whiskers cut and intact controls in latency to perform the stereotyped nipple-search behavior, latency to attach to nipples, time spent on nipples, milk ingested, or in the strength of conditioning to a novel odor paired with suckling. Thus, the whiskers do not seem important for suckling in newborn rabbits.

1-Methyl-4-phenylpyridinium (MPP+) is the major metabolite of 1-methyl-4-phenyl-1,2,3,6-tetrahydr... more 1-Methyl-4-phenylpyridinium (MPP+) is the major metabolite of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) [1], a drug which adminis-tered to non-human primates and mice produces depletion of dopamine and cellular degeneration of the nigrostriatal pathway resembling the ...

Neurochemistry International, 2011

EGb761 is a well-defined mixture of active compounds extracted from Ginkgo biloba leaves. This ex... more EGb761 is a well-defined mixture of active compounds extracted from Ginkgo biloba leaves. This extract is used clinically due to its neuroprotective effects, exerted probably via its potent antioxidant or free radical scavenger action. Previous studies suggest that oxidative stress, via free radical production, may play an important role in depression and animal models for depression-like behavior. Preclinical studies have suggested that antioxidants may have antidepressants properties. The aim of this study was to investigate the antidepressant-like of EGb761 due to its antioxidant role against oxidative stress induced in the forced swimming test, the most widely used preclinical model for assessing antidepressant-like behavior. Male BALB/c mice were pretreated with EGb761 (10mg/kg, ip) daily for 17 days followed by the forced swimming test and spontaneous locomotor activity. Animals were sacrificed to evaluate lipid peroxidation, different antioxidant enzyme activities, serotonin and dopamine content in midbrain, hippocampus and prefrontal cortex. EGb761 significantly decreased the immobility time (39%) in the forced swimming test. This antidepressant-like effect of EGb761 was associated with a reduction in lipid peroxidation and superoxide radical production (indicated by a downregulation of Mn-superoxide dismutase activity), both of which are indicators of oxidative stress. The protective effect of EGb761 is not related to excitatory or inhibitory effects in locomotor activity, and was also associated with the modulation of serotonergic and dopaminergic neurotransmission. It is suggested that EGb761 produces an antidepressant-like effect, and that an antioxidant effect against oxidative stress may be partly responsible for its observed neuroprotective effects.

Neurotoxicology, 2005

Zinc is an essential trace element in the central nervous system and is located in three distinct... more Zinc is an essential trace element in the central nervous system and is located in three distinct pools: free zinc, vesicular zinc and protein-bound zinc. Zinc may serve as an endogenous neuromodulator and has been associated with neuropathologies. This study was undertaken to determine whether levels of vesicular zinc in neuronal terminals would decrease in response to the dopaminergic neurotoxin 1-methyl-4-phenylpyridinium ion (MPP + ). Adult male C-57 black mice were injected with MPP + (0.72 mg/kg) into their right lateral ventricle. All animals were killed at 1, 2, 24 h and 7 days after MPP + or saline administration. The brains were stained for zinc sulfides and the density of zinc-positive terminal fields was evaluated after MPP + administration. The relative optical density analysis of zinc-positive terminal fields showed significant decreases in the striatum at 1, 2 and 24 h (24, 18 and 14%, respectively, versus control) and ventricular epithelium (1, 2, 24 h and 7 days). The hippocampus showed increase in the stratum oriens and stratum radiatum at different times. MPP + administration reduced dopamine levels at 24 h and 7 days (36 and 40%, respectively, versus control) as a result of the neurotoxic action of MPP + . The decrease of zinc-positive neuronal terminal fields in the striatum after MPP + administration is most likely due to a neuronal release of vesicular zinc in response to its dopaminergic neurotoxicity.

Neurochemical Research, 2000

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is a drug that induces parkinsonism in humans... more 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is a drug that induces parkinsonism in humans and non-human primates. Free radicals are thought to be involved in its mechanism of action. Recently, metallothionein has been proposed to play a role as a scavenger of free radicals. In the present work, we studied the effect of MPTP neurotoxicity on brain metallothionein-I (MT-I) mRNA expression. Male C-57 black mice were treated with MPTP (30 mg/kg, i.p., daily) for 3 or 5 days. All animals were killed by cervical dislocation 7 days after the last MPTP dose. The brains were removed quickly and immediately frozen, and quantitative in situ hybridization was performed using MT-I cDNA probe. MT-I mRNA content in striatum, a region which is known to be highly predisposed and sensitive to MPTP-induced oxidative stress, decreased by 30% (3 days) and 39% (5 days) respectively, after the last MPTP administration. These results suggest that MT-I gene expression is decreased in MPTP neurotoxicity. It is suggested that the reduction of MT, an anti-oxidant and a free radical scavenger, in the striatum by MPTP enables the neurotoxin to exert maximal oxidative damage to the striatum.

Neurochemical Research, 2001

EGb761 has been suggested to be an antioxidant and free radical scavenger. Excess generation of f... more EGb761 has been suggested to be an antioxidant and free radical scavenger. Excess generation of free radicals, leading to lipid peroxidation (LP), has been proposed to play a role in the damage to striatal neurons induced by 1-methyl-4-phenylpyridinium (MPP+). We investigated the effects of EGb761 pretreatment on MPP+ neurotoxicity. C-57 black mice were pretreated with EGb761 for 17 days at different doses (0.63, 1.25, 2.5, 5 or 10 mg/kg) followed by administration of MPP+, (0.18, 0.36 or 0.72 mg/kg). LP was analyzed in corpus striatum at 30 min, 1 h, 2 h and 24 h after MPP+ administration. Striatal dopamine content was analyzed by HPLC at the highest EGb761 dose at 2 h and 24 h after MPP+ administration. MPP+-induced LP was blocked (100%) by EGb761 (10 mg/kg). Pretreatment with EGb761 partially prevented (32%) the dopamine-depleting effect of MPP+ at 24 h. These results suggest that supplements of EGb761 may be effective at preventing MPP+-induced oxidative stress.

Neurochemical Research, 2004

EGb761 produces reversible inhibition of both monoamine oxidase (MAO) isoforms in the central ner... more EGb761 produces reversible inhibition of both monoamine oxidase (MAO) isoforms in the central nervous system. 1-methyl-4-phenylpyridinium (MPP+) neurotoxicity is prevented by treatment with the MAO inhibitor pargyline. We investigated EGb761's effect on striatal MAO activity during MPP+ neurotoxicity. C-57 black mice were pretreated with EGb761 (10 mg/kg) daily for 17 days followed by administration of MPP (0.72 mg/kg). MPP+ enhanced striatal MAO (30%) activity at 6 h, and EGb761 prevented this effect. MAO-B activity in striatum was enhanced (70%) 6 h after MPP+ administration and was reduced to almost normal levels in EGb761 + MPP+ group compared to MPP+ group. Pretreatment with EGb761 partially prevented (32%) the striatal dopamine-depleting effect of MPP+ and prevented the reduction in striatal tyrosine hydroxylase activity (100%). Results suggest that EGb761 supplements may be effective in reducing MAO activity as well as enhancement in dopamine metabolism, thereby preventing MPP+-neurotoxicity.

International Journal of Gynecology & Obstetrics, 2010

Objective: To evaluate the viability and functional capacity of hematopoietic progenitor cells fr... more Objective: To evaluate the viability and functional capacity of hematopoietic progenitor cells from cord blood samples cryopreserved at the Banco de Células Stem de Colombia. Methods: After thawing and centrifugation of 20 samples, viable white blood cells were numbered by the trypan blue method and CD34 + CD45 + dim hematopoietic progenitor cells were numbered by flow cytometry. Clonogenic assays also tested the functional capacity of viable CD34 + CD45 + dim cells. Results: The median rates of viable CD34 + CD45 + dim cells were 99.6% before freezing and 73.0% after thawing (P < 0.001). The 20 cultures yielded a median of 12 cells with a lineage of red cells, 17.5 cells with a lineage of white cells, and 10 cells with a mixed lineage. Conclusion: Although the rate of viable CD34 + CD45 + dim cells was decreased by 26.6% after thawing by the method we used, the numbers of CD34 + CD45 +dim cells that formed colonies were similar to those obtained by other published methods.