Depletion of hypothalamic norepinephrine and serotonin enhances the dexamethasone negative feedback effect on adrenocortical secretion.
The role of norepinephrine (NE) and serotonin (5-HT) in the negative feedback effect of dexamethasone (DEX) on the adrenocortical response to ether stress was investigated. Injection of the catecholamine neurotoxin, 6-hydroxydopamine, into the ventral noradrenergic bundle or the paraventricular nucleus of the hypothalamus (PVN) which produced a very significant depletion in hypothalamic NE content enhanced the negative feedback effect of DEX. Injection of the 5-HT neurotoxin, 5,7-dihydroxytryptamine, into the raphé nuclei or PVN, which caused a depletion of hypothalamic 5-HT, produced a similar effect on the adrenocortical response to DEX. The degree of negative feedback may be viewed as a balance of neural stimulatory and glucocorticoid influences of the hypothalamus. Thus the removal of the stimulatory effects of NE and 5-HT on adrenocortical secretion, by the neurotoxic lesions, enhanced the inhibitory influence of DEX.
Feldman
S
S
Department of Neurology, Hadassah University Hospital, Jerusalem, Israel.
Weidenfeld
J
J
D015116:5,7-Dihydroxytryptamine / Q000494:pharmacology; D000302:Adrenal Cortex / Q000294:innervation*; D000324:Adrenocorticotropic Hormone / Q000097:blood; D000818:Animals; D003345:Corticosterone / Q000097:blood; D003907:Dexamethasone / Q000494:pharmacology*; D005246:Feedback; D007031:Hypothalamus / Q000187:drug effects / Q000502:physiology*; D007033:Hypothalamus, Middle / Q000502:physiology; D008297:Male; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology; D009638:Norepinephrine / Q000502:physiology*; D016627:Oxidopamine / Q000494:pharmacology; D010286:Paraventricular Hypothalamic Nucleus / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000502:physiology*
D015116:5,7-Dihydroxytryptamine; D012701:Serotonin; D003907:Dexamethasone; D016627:Oxidopamine; D000324:Adrenocorticotropic Hormone; D003345:Corticosterone; D009638:Norepinephrine