Kappa opioid receptor-mediated analgesia in the developing rat.

G. A. Barr, W. Paredes, K. L. Erickson, R. S. Zukin

Research output: Contribution to journalArticlepeer-review

42 Scopus citations


The prototypic kappa opiate ketocyclazocine produced robust analgesia in 10-day-old rats in the tail-flick nociceptive test. The kappa-opiate behavioral response coincided with the onset of a rapid rise to adult levels in brain kappa receptor site density. In contrast, morphine (prototypic mu opiate) was without marked effect until 14 days of age. The period of rapid mu receptor increase did not take place until days 14-16, which was after kappa receptor levels had already plateaued. Further, there was no or incomplete cross-tolerance between ketocyclazocine and morphine at 14 days of age. The present study, therefore, establishes a role for the kappa binding site in thermal analgesia in the tail flick test and differentiates its ontogenetic pattern from that of the mu receptor.

Original languageEnglish (US)
Pages (from-to)145-152
Number of pages8
JournalBrain research
Issue number2
StatePublished - Oct 1986
Externally publishedYes

ASJC Scopus subject areas

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


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