Testosterone does not influence opiate binding sites in the male rat brain

Theodore J. Cicero, Karin S. Newman, Edward R. Meyer

Research output: Contribution to journalArticlepeer-review

36 Scopus citations


It has been reported previously that castration produces testosterone-reversible increases in the density of 3H-naltrexone binding sites in the male rat brain. Unfortunately, we were unable to replicate these observations in a comprehensive series of studies. Specifically, we found that castration failed to produce changes in the Kd or Bmax of opiate binding sites in whole male rat brain, or in the hypothalamus, utilizing H- dihydromorphine (a mu receptor ligand), 3H-D-alanine, D-leucine enkephalin (delta) or 3H-naltrexone (ubiquitous). Furthermore, we found that the relative proportion of mu and delta binding sites in brain was unchanged by castration. The reasons for the discrepancy between the present results and those previously reported are unclear, but it appears that the provocative hypothesis that testosterone influences opioid receptors in brain must be carefully reevaluated.

Original languageEnglish
Pages (from-to)1231-1239
Number of pages9
JournalLife Sciences
Issue number13
StatePublished - Sep 26 1983


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