Interaction between morphine, an opioid agonist, and clonidine, an alpha-adrenergic agonist, on the regulation of anterior pituitary hormone secretion in normal male subjects.
In order to investigate the possible interaction between opioid system and noradrenergic system in the regulation of pituitary hormone secretion, the effects of morphine (an opioid agonist, 10 mg i. v.), clonidine (an alpha-adrenergic agonist, infusion of 0.3 mg in 15 minutes) and clonidine + morphine (infusion of the same dose of clonidine beginning 30 minutes before morphine 10 mg i.v.) on anterior pituitary hormone secretion were studied in six normal male volunteers. Morphine alone induced both an increase in TSH and PRL serum levels and a decrease in cortisol serum levels with no changes in GH serum levels. On the contrary clonidine was able to increase GH and TSH levels and to decrease cortisol levels; PRL secretion was not affected. As regards interaction between morphine and clonidine we observed that morphine-induced increase in PRL release was potentiated by clonidine pretreatment; as regards TSH secretion its increase was greater after the administration of the two drugs with respect to the effect of the single drugs. This study, in agreement with our previous data concerning LH secretion, confirms the important link between clonidine and opioid system in neuroendocrine function, too; the possible explanations of our data are discussed.
Pende
A
A
Department of Medical Semciotics, R, University of Genoa.
Musso
N R
NR
Montaldi
M L
ML
Arzese
M
M
Vergassola
C
C
Devilla
L
L
D000328:Adult; D003000:Clonidine / Q000494:pharmacology*; D004347:Drug Interactions; D013006:Growth Hormone / Q000097:blood*; D006801:Humans; D006854:Hydrocortisone / Q000097:blood*; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D011388:Prolactin / Q000097:blood*; D013972:Thyrotropin / Q000097:blood*
D009020:Morphine; D011388:Prolactin; D013972:Thyrotropin; D013006:Growth Hormone; D003000:Clonidine; D006854:Hydrocortisone