Brain octopamine and strain differences in avoidance behavior.

According to recent research, a significant relationship seems to exist between brain contents of p-octopamine and two-way avoidance responding in rats. Levels of this amine in hypothalamus and brainstem are higher in rats from the Roman High Avoidance (RHA) strain than in rats from the Roman Low Avoidance (RLA) strain. Intracerebroventricular administration of p-octopamine facilitates avoidance responding. The present paper reports the behavioral and neurochemical effects of p-octopamine administration on rats from the Roman strains. This treatment has no significant effect on cerebral levels of catecholamines, but it temporarily suppresses the strain differences in p-octopamine levels. In parallel, it also suppresses the strain differences in two-way avoidance conditioning, its facilitatory effect being much greater in RLA than in RHA rats. Avoidance behavior appears to be a useful model for the study of octopamine functions in the mammalian brain.