Endogenous opioid systems regulate cell proliferation in the developing rat brain

Ian S. Zagon, Patricia J. MacLaughlin

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210 Scopus citations


The role of endogenous opioid systems in modulating the proliferation of developing cerebellar cells was examined autoradiographically in 6-day-old rats. The blockade of endogenous opioid-opioid receptor interaction by naltrexone, a potent opioid antagonist, was accompanied within 1-2 h by an increased proportion of cells incorporating [3H]thymidine. When high doses of naltrexone (50 mg/kg) were administered this index was still elevated 12 h later; however, when low doses of naltrexone (1 mg/kg) were administered the index of labeled cells was decreased markedly. Injection of methionine-enkephalin, an endogenous opioid peptide, also resulted in a decrease in the proportion of cells incorporating [3H]thymidine. Concomitant injection of 1 mg/kg naloxone, however, blocked the inhibitory effects of methionine-enkephalin on cell division but did not itself affect cell generation. These studies demonstrate that endogenous opioid systems can regulate the proliferation of cell populations in the developing nervous system and do so through an inhibitory mechanism.

Original languageEnglish (US)
Pages (from-to)68-72
Number of pages5
JournalBrain research
Issue number1
StatePublished - May 26 1987

All Science Journal Classification (ASJC) codes

  • General Neuroscience
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology


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