Effect of midbrain raphe lesion on diurnal and stress-induced changes in serotonin content of discrete regions of the limbic system and in adrenal function in the rat
Vermes, I.; Telegdy, G.; Lissák, K.
Acta Physiologica Academiae Scientiarum Hungaricae 45(3-4): 217-224
1974
ISSN/ISBN: 0001-6756 PMID: 4478973 Document Number: 82417
Serotonin level in the mesencephalon, hippocampus, septum, amygdala and hypothalamus, and plasma corticosterone content were measured at 8, 16 and 24 h in midbrain raphe-lesioned animals. Following electrolytic lesion of the midbrain raphe nuclei, diurnal variations of brain serotonin and plasma corticosterone level disappeared, the serotonin level decreased by 50-75% in each brain area investigated and the plasma corticosterone level increased about 3-fold of the normal morning level. The stress response after ether and electric shock was facilitated in raphe-lesioned animals and return to the starting value was delayed. The hypothalamic serotonin level was lower than the control and did not change during stress. The mesencephalic raphe nuclei are probably responsible for the serotonin rhythm of the limbic system which shows a negative correlation with pituitary-adrenal function.