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Interactions Between Alcohol‐ and Opioid‐Induced Suppression of Rat Testicular Steroidogenesis In Vivo
Author(s) -
Adams Michael L.,
Meyer Edward R.,
Cicero Theodore J.
Publication year - 1997
Publication title -
alcoholism: clinical and experimental research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.267
H-Index - 153
eISSN - 1530-0277
pISSN - 0145-6008
DOI - 10.1111/j.1530-0277.1997.tb03823.x
Subject(s) - naltrexone , testosterone (patch) , endocrinology , medicine , alcohol , opioid antagonist , endogenous opioid , chemistry , opioid , stimulation , agonist , pharmacology , (+) naloxone , receptor , biochemistry
To examine interactions between alcohol and endogenous opioids in their suppressive effects on rat testicular function, the opioid antagonist naltrexone or the opioid agonist morphine was administered to adult male rats alone or in combination with alcohol. Serum testosterone, testicular interstitial fluid (TIF) testosterone, and TIF volumes were measured to assess testicular function. Naltrexone induced dose‐dependent increases in serum and TIF testosterone levels without changes in TIF volume. Alcohol (0.5 g/kg) inhibited naltrex‐one‐induced stimulation of testosterone secretion and shifted the naltrexone dose‐response curve to the right. Conversely, naltrexone (0.05 mg/kg) inhibited alcohol‐induced suppression of testosterone secretion and shifted the alcohol dose‐response curve to the right. Relatively high doses of naltrexone (5 to 30 mg/kg) were needed to stimulate testosterone secretion maximally in rats treated with a low dose of alcohol (0.5 g/kg) and to stimulate normal levels of testosterone secretion in rats treated with a high dose of alcohol (2 g/kg). In addition, combined treatment with 1 and 30 mg/kg of naltrexone and 0.5 to 2 g/kg of alcohol did not alter blood alcohol concentrations significantly, suggesting that the interactions between alcohol and naltrexone were unrelated to gross changes in alcohol metabolism or bioavailability factors. Simultaneous treatments with a low dose of alcohol (0.3 g/kg), near the threshold of efficacy, and low‐moderate doses of morphine (0.3 to 3 mg/kg) were not additive in suppressing testosterone secretion, compared with either agent alone. These results support the hypothesis that opioid antagonists can reverse the suppressive effect of alcohol on testicular steroidogenesis, but the results also suggest that endogenous opioids do not exclusively mediate alcohol's effects on testosterone secretion.