[Influence of the habenular complex on the cyclic secretion of plasma corticosterone in rats]

The effect of bilateral lesion of the medial and lateral habenular nuclei on the corticosterone plasmatic levels determined at 8 a.m. and 5 p.m. was studied in adult female rats 30, 60 and 90 days after the lesion. 30 days after the lesion a drop in plasmatic values and the suppression of the normal diurnal fluctuation in corticosterone plasmatic levels were found. At 60th day these changes still persist. At 90th day, the corticosterone levels and its daily fluctuations reversed to normal values. These data suggest that the habenular complex is a nervous area participant in the activity modulation of the hypothalamus pituitary-adrenal system. The possible role of the habenular nuclear complex in the maintenance of the rhythm is discussed taking into account its afferent and efferent connections, especially with the olfactory system and the limbic ventral tegmental area, whose direct involvement in this rhythm has been shown.