Up-regulation of opiate receptors following chronic naloxone treatment in aged rats

Janet L. Neisewander, Arthur J. Nonneman, Sanders A. McDougall, Michael T. Bardo

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


The present study assessed whether there are age-dependent differences in up-regulation of opiate receptors following chronic naloxone treatment in mature (3 months) and aged (27 months) male Wistar rats. Half of each age group were implanted subdermally with slow-release naloxone pellets for 10 days, and half were given sham surgery. Twenty-four hours after pellet removal, the rats were decapitated and various CNS areas including spinal cord, hindbrain, midbrain, diencephalon, hippocampus, striatum, olfactory tubercles/nucleus accumbens and prefrontal cortex were dissected and assayed for [3H]naloxone binding. The results indicated that aged rats had fewer opiate receptors in the spinal cord, midbrain, striatum, and olfactory tubercle/nucleus accumbens. Despite this age-related decline in opiate receptors, aged rats showed an up-regulation response similar to mature rats in all areas except the hippocampus of the left hemisphere, where they showed enhanced up-regulation relative to mature rats. The maintained plasticity of the opioid system contrasts with findings in other receptors systems where age-related impairments of antagonist-induced up-regulation have been reported.

Original languageEnglish (US)
Pages (from-to)55-58
Number of pages4
JournalNeurobiology of Aging
Issue number1
StatePublished - 1989
Externally publishedYes


  • Aging
  • Central nervous system
  • Naloxone
  • Opiate Receptors
  • Receptor up-regulation

ASJC Scopus subject areas

  • General Neuroscience
  • Aging
  • Clinical Neurology
  • Developmental Biology
  • Geriatrics and Gerontology


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