Facilitation of sexual behaviors in the male rat in the presence of stimuli previously paired with systemic injections of morphine

Pharmacol Biochem Behav. 1990 Feb;35(2):367-72. doi: 10.1016/0091-3057(90)90171-d.


Male rats were tested for sexual behaviors in an environment previously associated with injections of morphine. Both gonadally intact and castrated males displayed more frequent female-directed behavior, such as pursuit of the female, anogenital exploration, and partial mounts, and gonadally intact animals had shorter latencies to initiate copulation when tested for sexual behaviors in the environment previously associated with morphine. These results suggest that a conditioned state induced by stimuli previously paired with the positive incentive effects of an opiate drug can facilitate or modulate behaviors under the control of other primary positive incentives.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Conditioning, Classical / physiology*
  • Environment
  • Male
  • Morphine*
  • Rats
  • Reaction Time
  • Sexual Behavior, Animal / drug effects
  • Sexual Behavior, Animal / physiology*
  • Testis / physiology*


  • Morphine