Attenuation of clonidine-induced growth hormone release following chronic glucocorticoid and 5-hydroxytryptamine uptake-inhibiting antidepressant treatments.
Administration of various doses of clonidine increased plasma growth hormone levels in male Wistar rats. Chronic hydrocortisone treatment produced significant decreases in ACTH levels as well as a significant attenuation of clonidine-induced increases in growth hormone levels. Similarly, chronic treatment with 5-HT uptake-inhibiting antidepressants such as fluoxetine, clomipramine and imipramine also significantly attenuated clonidine-induced increases in growth hormone levels. On the other hand, chronic treatment with clorgyline (monoamine oxidase type A-inhibiting antidepressant) and 5-HT agonists, such as m-chlorophenylpiperazine, 1-(2,5-dimethoxy-4- iodophenyl)-2-aminopropane and 8-hydroxy-2-(di-n-propylamino)tetralin, did not have any significant effect on clonidine-induced increases in growth hormone levels. These findings suggest that development of functional subsensitivity of either alpha 2-adrenergic heteroreceptors or 5-HT1C receptors mediating clonidine-induced growth hormone secretion following chronic treatment with glucocorticoids and 5-HT uptake inhibitors.
Aulakh
C S
CS
Laboratory of Clinical Science, National Institute of Mental Health, Bethesda, MD 20892.
Hill
J L
JL
Murphy
D L
DL
D000818:Animals; D000928:Antidepressive Agents / Q000494:pharmacology*; D003000:Clonidine / Q000494:pharmacology*; D003010:Clorgyline / Q000494:pharmacology; D005938:Glucocorticoids / Q000037:antagonists & inhibitors*; D013006:Growth Hormone / Q000037:antagonists & inhibitors* / Q000378:metabolism; D006854:Hydrocortisone / Q000494:pharmacology; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012702:Serotonin Antagonists / Q000494:pharmacology*; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D013997:Time Factors
D000928:Antidepressive Agents; D005938:Glucocorticoids; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; D013006:Growth Hormone; D003010:Clorgyline; D003000:Clonidine; D006854:Hydrocortisone