Laboratorio Of Psicobiologia

Ribeirão Preto, Brazil

Laboratorio Of Psicobiologia

Ribeirão Preto, Brazil
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Cunha J.M.,University of Sao Paulo | Cunha J.M.,Laboratorio Of Psicobiologia | Zanoveli J.M.,University of Sao Paulo | Zanoveli J.M.,Laboratorio Of Psicobiologia | And 4 more authors.
Brain Research Bulletin | Year: 2010

The dorsal (dPAG) and ventral (vPAG) regions of the periaqueductal gray are well known to contain the neural substrates of fear and anxiety. Chemical or electrical stimulation of the dPAG induces freezing, followed by a robust behavioral reaction that has been considered an animal model of panic attack. In contrast, the vPAG is part of a neural system, in which immobility is the usual response to its stimulation. The defense reaction induced by the stimulation of either region is accompanied by antinociception. Although GABAergic mechanisms are known to exert tonic inhibitory control on the neural substrates of fear in the dPAG, the role of these mechanisms in the vPAG is still unclear. The present study examined defensive behaviors and antinociception induced by microinjections of an inhibitor of γ-aminobutyric acid synthesis, l-allylglycine (l-AG; 1, 3, and 5 μg/0.2 μl), into either the dPAG or vPAG of rats subjected to the open field and tail-flick tests. Passive or tense immobility was the predominant behavior after l-AG (1 or 3 μg) microinjection into the vPAG and dPAG, respectively, which was replaced with intense hyperactivity, including jumps or rearings, after injections of a higher dose (5 μg/0.2 μl) into the dPAG or vPAG. Moreover, whereas intra-dPAG injection of 3 μg l-AG produced intense antinociception, only weak antinociception was induced by intra-vPAG injections of 5 μg l-AG. These findings suggest that GABA mechanisms are involved in the mediation of antinociception and behavioral inhibition to aversive stimulation of the vPAG and exert powerful control over the neural substrates of fear in the dPAG to prevent a full-blown defense reaction possibly associated with panic disorder. © 2009 Elsevier Inc. All rights reserved.


Hamani C.,Neuroimaging Research Section | Hamani C.,Toronto Western Hospital | Diwan M.,Neuroimaging Research Section | Macedo C.E.,Laboratorio Of Psicobiologia | And 7 more authors.
Biological Psychiatry | Year: 2010

Background: Subcallosal cingulate gyrus (SCG) deep brain stimulation (DBS) is being investigated as a treatment for major depression. We report on the effects of ventromedial prefrontal cortex (vmPFC) DBS in rats, focusing on possible mechanisms involved in an antidepressant-like response in the forced swim test (FST). Methods: The outcome of vmPFC stimulation alone or combined with different types of lesions, including serotonin (5-HT) or norepineprhine (NE) depletion, was characterized in the FST. We also explored the effects of DBS on novelty-suppressed feeding, learned helplessness, and sucrose consumption in animals predisposed to helplessness. Results: Stimulation at parameters approximating those used in clinical practice induced a significant antidepressant-like response in the FST. Ventromedial PFC lesions or local muscimol injections did not lead to a similar outcome. However, animals treated with vmPFC ibotenic acid lesions still responded to DBS, suggesting that the modulation of fiber near the electrodes could play a role in the antidepressant-like effects of stimulation. Also important was the integrity of the serotonergic system, as the effects of DBS in the FST were completely abolished in animals bearing 5-HT, but not NE, depleting lesions. In addition, vmPFC stimulation induced a sustained increase in hippocampal 5-HT levels. Preliminary work with other models showed that DBS was also able to influence specific aspects of depressive-like states in rodents, including anxiety and anhedonia, but not helplessness. Conclusions: Our study suggests that vmPFC DBS in rats may be useful to investigate mechanisms involved in the antidepressant effects of SCG DBS. © 2010 Society of Biological Psychiatry.


Gonzalez-Tapia D.,Laboratorio Of Psicobiologia | Gonzalez-Tapia D.,University of Guadalajara | Velazquez-Zamora D.A.,Laboratorio Of Psicobiologia | Velazquez-Zamora D.A.,University of Guadalajara | And 2 more authors.
Restorative Neurology and Neuroscience | Year: 2015

Purpose: The presynaptic stimulatory activity of parallel fibers on the dendritic spines of cerebellar Purkinje cells (PC) has a strong influence on the organization of motor learning. Motor learning has been shown to modify the synapses established on PC dendritic spines but the plastic changes of the different spine types, possibly underlying motor learning, have not been studied. Methods: Adult male Sprague-Dawley rats were trained daily for 26 days using an acrobatic paradigm (AC), at the end of which dendritic spine density and the proportion of the different types of spines was assessed. Results: The learning curves of AC rats reflected a robust decrease in the latency for resolution and in the errors committed during the first week of training, which subsequently stabilized until the end of training. Dendritic spine density was greater in these AC rats, reflected in a larger proportion of thin, mushroom and stubby spines. Conclusions: Since thin spines are associated with acquiring novel information whilst mushroom spines are associated with long-term information storage, there appears to be a strong relationship between AC motor learning and consolidation. The increase in stubby spines could be related to the regulation of excitatory stimulation underlying motor overactivity. © 2015 - IOS Press and the authors.


PubMed | Laboratorio Of Neurofisiologia Experimental and Laboratorio Of Psicobiologia
Type: Journal Article | Journal: Restorative neurology and neuroscience | Year: 2015

The presynaptic stimulatory activity of parallel fibers on the dendritic spines of cerebellar Purkinje cells (PC) has a strong influence on the organization of motor learning. Motor learning has been shown to modify the synapses established on PC dendritic spines but the plastic changes of the different spine types, possibly underlying motor learning, have not been studied.Adult male Sprague-Dawley rats were trained daily for 26 days using an acrobatic paradigm (AC), at the end of which dendritic spine density and the proportion of the different types of spines was assessed.The learning curves of AC rats reflected a robust decrease in the latency for resolution and in the errors committed during the first week of training, which subsequently stabilized until the end of training. Dendritic spine density was greater in these AC rats, reflected in a larger proportion of thin, mushroom and stubby spines.Since thin spines are associated with acquiring novel information whilst mushroom spines are associated with long-term information storage, there appears to be a strong relationship between AC motor learning and consolidation. The increase in stubby spines could be related to the regulation of excitatory stimulation underlying motor overactivity.


Velazquez-Zamora D.A.,Laboratorio Of Psicobiologia | Velazquez-Zamora D.A.,University of Guadalajara | Martinez-Degollado M.,Laboratorio Of Psicobiologia | Martinez-Degollado M.,University of Guadalajara | And 2 more authors.
International Journal of Developmental Neuroscience | Year: 2011

The posterior cerebellum is strongly involved in motor coordination and its maturation parallels the development of motor control. Climbing and mossy fibers from the spinal cord and inferior olivary complex, respectively, provide excitatory afferents to cerebellar Purkinje neurons. From post-natal day 19 climbing fibers form synapses with thorn-like spines located on the lower primary and secondary dendrites of Purkinje cells. By contrast, mossy fibers transmit synaptic information to Purkinje cells trans-synaptically through granule cells. This communication occurs via excitatory synapses between the parallel fibers of granule cells and spines on the upper dendritic branchlets of Purkinje neurons that are first evident at post-natal day 21. Dendritic spines influence the transmission of synaptic information through plastic changes in their distribution, density and geometric shape, which may be related to cerebellar maturation. Thus, spine density and shape was studied in the upper dendritic branchlets of rat Purkinje cells, at post-natal days 21, 30 and 90. At 90 days the number of thin, mushroom and thorn-like spines was greater than at 21 and 30 days, while the filopodia, stubby and wide spines diminished. Thin and mushroom spines are associated with increased synaptic strength, suggesting more efficient transmission of synaptic impulses than stubby or wide spines. Hence, the changes found suggest that the development of motor control may be closely linked to the distinct developmental patterns of dendritic spines on Purkinje cells, which has important implications for future studies of cerebellar dysfunctions. © 2011 ISDN.

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