Alterations in the Opioid Control of LHRH Release From Hypothalami Isolated From Aged Male Rats

Several lines of evidence have suggested that the opioid control of gonadotropin secretion in the male rat is altered with aging. Because neural control of gonadotropins is mediated through luteinizing hormone releasing hormone (LHRH) secreting neurons, we examined the postulated changes in the opio...

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Published in:The journals of gerontology. Series A, Biological sciences and medical sciences Biological sciences and medical sciences, 1998-05, Vol.53A (3), p.B191-B195
Main Authors: Nazian, Stanley J., Landon, Carol S., Dietz, John R.
Format: Article
Language:English
Subjects:
Aging
Aging - physiology
Analysis of Variance
Animal reproduction
Animals
Body Weight
Dose-Response Relationship, Drug
Gonadotropin-Releasing Hormone - metabolism
Hormones
Hypothalamus - drug effects
Hypothalamus - growth & development
Hypothalamus - metabolism
Luteinizing Hormone - blood
Male
Naloxone - pharmacology
Organ Culture Techniques
Organ Size
Prostate - anatomy & histology
Prostate - growth & development
Rats
Rats, Sprague-Dawley
Rodents
Testosterone - blood
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Summary:Several lines of evidence have suggested that the opioid control of gonadotropin secretion in the male rat is altered with aging. Because neural control of gonadotropins is mediated through luteinizing hormone releasing hormone (LHRH) secreting neurons, we examined the postulated changes in the opioid control of gonadotropins more directly by studying isolated hypothalamic fragments in vitro. Hypothalami from young (75–90 days) and old (18–20 months) males were examined for their ability to release LHRH when incubated with increasing doses of naloxone in a semi-static culture system. Serum concentrations of testosterone and luteinizing hormone (LH) in the donor animals were both significantly lower in old male rats compared with young males. Basal secretion of LHRH was similar in both age groups. Two-way repeated measures ANOVA indicated that naloxone stimulated a significant dose-dependent increase in the release of LHRH into the media. ANOVA also indicated a significant effect of age. We conclude that the changes in the endogenous opioid systems reported to occur with aging are, in fact, linked to differences in LHRH secretion and thus to differences in the dynamic relationship between testosterone and LH in older male rats.
ISSN:1079-5006
1758-535X
DOI:10.1093/gerona/53A.3.B191