RESUMO
GABAergic interneurons are local circuit cells that control the excitatory balance in most regions of the nervous system, particularly the cerebral cortex. Because they are integrated in every cortical module, we posed the question whether interneuronal precursors would display some topographic specificity between their origin at the ventral telencephalon and their cortical location after migration. If this was true, GABAergic cells would have to be provided with intrinsic features that would make them able to perform specific functional roles in each specific module. On the other hand, if no topography was found, one would conclude that inhibitory precursors would be functionally naive, being able to integrate anywhere in the cortex, with equal capacity of performing their functions. This issue was approached by use of organotypic cultures of wild mice embryonic slices, into which fragments of the ganglionic eminence taken from enhanced green fluorescent protein (eGFP) mice were implanted, observing the topographic location of both the implant and its destination. Despite the existence of different genetic domains in the ventricular zone of the medial ganglionic eminences (MGE), we found that cells originating in different regions spread in vitro all over the mediolateral axis of the developing cortical wall, independently of their sites of origin. Results favor the hypothesis that GABAergic precursors are functionally naive, integrating into modules irrespective of which cortical area they belong to.
Assuntos
Córtex Cerebral/citologia , Córtex Cerebral/embriologia , Regulação da Expressão Gênica no Desenvolvimento , Interneurônios/fisiologia , Fatores Etários , Animais , Movimento Celular/fisiologia , Córtex Cerebral/transplante , Ventrículos Cerebrais/citologia , Ventrículos Cerebrais/embriologia , Técnicas de Cocultura , Embrião de Mamíferos , Feminino , Proteínas de Fluorescência Verde/genética , Masculino , Camundongos , Camundongos Transgênicos , Técnicas de Cultura de Órgãos , Gravidez , Fatores de Tempo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Ácido gama-Aminobutírico/metabolismoRESUMO
We have previously shown that hypothalamic fetal brain grafts induced recovery of sexual behavior in medial preoptic area (MPOA)-lesioned male rats. In the present series of experiments, male rats with completely abolished sexual behavior by MPOA lesions received either hypothalamic or frontal cortical fetal grafts. The animals that received hypothalamic grafts showed a gradual recovery of sexual behavior. In contrast, those animals who received cortical grafts did not recover sexual behavior during the 15 weeks after the graft. In addition, to evaluate the connectivity of the grafted tissue with the host brain, a retrograde tracer, fluorogold, was injected in the dorsal tegmental area. Fluorogold-labeled cells were found in the hypothalamic, but not in the cortical grafts. These results suggest that specificity of the grafted tissue and connectivity between brain grafts and host tissue are necessary for the recovery of male sexual behavior in MPOA-lesioned rats.
Assuntos
Transplante de Tecido Encefálico/fisiologia , Córtex Cerebral/transplante , Hipotálamo/transplante , Área Pré-Óptica/fisiologia , Comportamento Sexual Animal/fisiologia , Animais , Córtex Cerebral/fisiologia , Estradiol/farmacologia , Feminino , Transplante de Tecido Fetal/fisiologia , Hipotálamo/fisiologia , Masculino , Especificidade de Órgãos , Progesterona/farmacologia , Ratos , Ratos Wistar , Comportamento Sexual Animal/efeitos dos fármacosRESUMO
Three groups of rats showing disrupted taste aversion due to gustatory neocortex lesions, were studied. One group received a transplant of homotopic cortical tissue, another of heterotopic tectal tissue, obtained from 17-day-old fetuses. The third group remained without transplant as a lesioned control group. Comparisons of the taste aversion scores before and after graft, revealed that cortical grafted animals significantly improved the taste aversion, whereas those which received tectal grafts, and the cortical-lesioned controls did not. Moreover, results with horseradish peroxidase (HRP) histochemistry revealed that the homotopic, but not the heterotopic, brain transplants were able to re-establish connections with amygdala and with the ventromedial nucleus of the thalamus areas who normally kept connectivity with the gustatory neocortex. These results support the hypothesis that fetal brain transplants can reestablish cognitive functions, as well as connectivity with its host tissue.