Morphine, Endogenous Opioid Peptides, and Reproduction in the Male Rhesus Monkey
Abstract
This study examines the effects of opioid agonists and antagonist on reproductive hormones in the male primate and explores the role of the endogenous opioid peptides (EOF) in the neuroendocrine control of primate reproductive function, specifically in the control of gonadotropin secretion. The prototype narcotic used was morphine sulfate, which acts via the mu opiate receptor type. The stable leucine-enkephalin analogue [D-Ala(expn 2), D-Leu(expn 5)]-enkephalin (DADLE) and Beat-endorphin (beta-end) were used as representatives of the HOP. DADLE acts via the delta type opioid receptor, whereas B-endorphin has mixed opiate receptor activities (both mu and delta). The opiate receptor blocker naloxone was used as a competitive antagonist to the pharmacologic effects of both the narcotic and the EOP. These drugs or their vehicles were administered to adult male rhesus monkeys fitted with jugular catheters. The drugs were given Intravenously and blood was drawn through the catheters to reduce the stress associated with these procedures. Blood was collected at 20 minute intervals for periods of four hours and the plasma retained for measurements of testosterone, luteinizing hormone (LH), and prolactin (PRL) by radioimmunoassay. Administration of morphine (1.0 mg/kg) and DADLE (10 micro g/kg) produced marked decreases in LH levels within one hour which were followed by decreases in testosterone levels. Levels of both hormones remained depressed for approximately three hours. 3-endorphln at 10 - 20 micro g/kg had no effect on LH or testosterone levels. Naloxone (2.0 mg/kg) increased LH levels eight-fold and testosterone levels nine-fold; LH levels remained elevated for up to three hours and testosterone levels for up to two hours. Both morphine and beta-endorphin elicited immediate increases in prolactin levels, which remained elevated for up to three hours. In addition, naloxone was seen to decrease prolactin levels, but DADLE produced no significant prolactin changes.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 18, 1983
- Accession Number
- AD1010660
Entities
People
- Pamela M. Gilbeau-scher
Organizations
- Uniformed Services University of the Health Sciences