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
Pages (from-to)55-58
Number of pages4
JournalNeurobiology of Aging
Issue number1
StatePublished - 1989

Bibliographical note

Funding Information:
We gratefully acknowledge the excellent technical assistance of Lyn Ennis and the secretarial assistance of Jo Moore. We also thank Dr. Norman Pedigo for his helpful suggestions on our Scatchard analysis and his critique of this manuscript. This research was supported in part by USPHS grant DAO3460 and a Sigma Xi Grant-in-Aid. of Research.


  • 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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