Lesão unilateral do córtex somestésico: efeito do lado da lesão e do tratamento com cafeína

• Autor(a) principal: Branco, Danielle Paes Machado de Andrade
• Data de Publicação: 2016
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/12666
• topic: Cryogenic lesion; Somatosensorial neocortex; Animal behavior; Functional recovery; Caffeine; Criolesão; Neocórtex somatossensorial; Comportamento animal; Recuperação funcional; Cafeína; Cafeína; Criolesão; Neocórtex somatossensorial; Comportamento animal; Recuperação funcional; Cafeína; CNPQ::CIENCIAS BIOLOGICAS::FISIOLOGIA::FISIOLOGIA DE ORGAOS E SISTEMAS::NEUROFISIOLOGIA

In rodents, the vibrissae are tactile sensors that play an important role in the exploration of the environment and discrimination of textures. In the somatosensory cortex, the receptive fields of each whisker are arranged in the contralateral hemisphere into discrete columns which are commonly named barrels. A unilateral lesion of the barrel cortex produces a behavioral asymmetry that is characterized by a reduction in the use of the vibrissae contralateral to the lesioned side. Such deficit has been extensively used in studies of plasticity and functional recovery. This work has the main objective to assess: 1) whether lesions of the left and right barrel cortex show differences in functional recovery in adult mice; and 2) whether caffeine administration can mitigate the neurobehavioral deficits observed after unilateral lesions of the barrel cortex of adult mice. Specifically, we studied the thigmotactic scanning of male adult Swiss mice that underwent cryoinjuries of the left or right barrel cortex and then were tested repeatedly in an open-field right after the lesion or weeks later. The side of the animal´s body facing the wall of the open-field while moving at the corners of the arena was evaluated and considered as an asymmetry parameter. Our results indicate a clear effect of the side of the lesion regarding functional recovery. While animals that had right barrel cortex lesions fully recovered from the behavioral vibrissae asymmetry, animals with left-side lesions did not show behavioral recovery. The latter showed predominance in carrying out displacements in a direction contralateral to the lesion side that persisted after repeated testing and up to 48 days after injury. Moreover, such deficit was not influenced by habituation to the testing arena prior to the lesion. In contrast, for the animals that received lesions on the right side, the number of displacements in the direction contralateral to the side of the lesion decreased with the repetition of the testing sessions. Moreover, the behavioral asymmetry was not evident if right-side lesioned animals were habituated to the testing arena prior to the cryoinjury or were tested 48 days after the injury. Regarding the effects of caffeine (0,5g/l), our results show that chronic exposure to caffeine during 48 days after injury induces functional recovery of animals with left barrel cortex lesions (i.e. no directional displacement preference was observed). In addition, exposure to caffeine restored to normal the decrease in cortical dopamine levels observed in the lesioned side of the brain. Overall, our data suggest that the side of the lesion is an important factor when evaluating the functional recovery after barrel cortex injuries and that caffeine may be an important agent to facilitate the recovery of neocortical deficits after injury.