Neuropsychpharmacological study on the role of the basal forebrain regions for regulation of emotion

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We tried to find chemical nature of brain pathways through the basal forbrain area involved in feeding response using both in vivo reverse microdialysis and immunohistochemical techniques. Muscimol, a GABA agonist, injected locally into the nucleus accumbens shell (NACs), caused a significant increase in food intake. This muscimol-induced feeding was accompanied by both marked increases in the micro-dialysate concentration of dopamine of the NACs and Fos-expression in neurons of accumbofugal target areas such as the ventral pallidum (VP), the lateral hypothalamus and the ventral tegmental area. Sequential staining of Fos- and orexin-immunoreactivities revealed that a portion of these hypothalamic neurons were doublelabelled. In contrast, local muscimol injected into the medial VP caused a significant decrease in food intake.These findings show that muscimol in the NACs would disinhibit accumbofugal target neurons (including a portion of A10 neurons and hypothalamic orexin neurons), resulting in an increase in.food intake. This raises the view that basal forebrain regions exert inhibitory influence on the neurons of the hypothalamic center, thereby regulating emotional behavior such as feeding.