The growth hormone secretory response to fentanyl in rat: an involvement of mu type receptors.
Fentanyl, a selective mu opioid receptor agonist, administered intravenously, influences growth hormone secretion in conscious male rats. A dose-response study demonstrated that the maximum growth hormone release was obtained with 10 micrograms/kg while higher doses were less or not effective. MR-2266 (6 mg/kg i.v.), a mu and kappa opioid receptor antagonist, and bremazocine (0.1 mg/kg i.v.) a mu opioid receptor antagonist with kappa agonistic properties, both potently inhibited the growth hormone response to fentanyl (10 micrograms/kg i.v.). In contrast, the effect of fentanyl on growth hormone release was not blocked in rats treated with either ICI-154129 (30 mg/kg i.v. or 150 micrograms/kg intracerebroventricularly a selective delta opioid receptor antagonist, or U-50488 (10 mg/kg i.v.), a specific kappa opioid receptor agonist. These results suggest that opioid receptors of the mu type are involved in the fentanyl-induced growth hormone release.
Govaerts
J
J
Laboratory of Pharmacology, Faculty of Medicine and Pharmacy, Free University of Brussels (V.U.B.), Belgium.
Buydens
P
P
Finné
E
E
Matton
A
A
Vanhaelst
L
L
D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; D000818:Animals; D001575:Benzomorphans / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004743:Enkephalin, Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D005283:Fentanyl / Q000008:administration & dosage / Q000494:pharmacology*; D013006:Growth Hormone / Q000378:metabolism*; D008297:Male; D009292:Narcotic Antagonists; D011759:Pyrrolidines / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000502:physiology*; D017450:Receptors, Opioid, mu
D001575:Benzomorphans; D009292:Narcotic Antagonists; D011759:Pyrrolidines; D011957:Receptors, Opioid; D017450:Receptors, Opioid, mu; C027247:MR 2266; D004743:Enkephalin, Leucine; D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; D013006:Growth Hormone; C036405:ICI 154129; C027248:bremazocine; D005283:Fentanyl