Enkephalin and fear-motivated behavior.

AUTOR(ES)

Rigter, H

RESUMO

Leu[Enkephalin (400.0 micrograms/kg) and the enkephalin analog [DAla,DLeu]enkephalin (0.4, 4.0, and 40.0 micrograms/kg) were intraperitoneally administered to rats 5 min before they were trained on aversively motivated tasks. The peptides impaired acquisition of a one-way active avoidance response, facilitated acquisition of an inhibitory avoidance response, and had no effect on acquisition of a swim-escape response. The data indicate that the enkephalin effects are not mediated through actions on locomotor activity, pain perception or reactivity, or light sensitivity. Rather, we suggest that [Leu]enkephalin and its analog strengthen the tendency of rats to suppress behavior in the presence of cues previously associated with aversive stimulation. This effect may be due to an enkephalin-induced increase in fear or arousal. The enkephalin effect on behavior was obtained at low doses and was observed within a few minutes after administration. These findings are consistent with the interpretation that enkephalin effects may be initiated at a peripheral site.

Documentos Relacionados

• Retrieval of memory for fear-motivated training initiates extinction requiring protein synthesis in the rat hippocampus
• Mothers' fear, their children's well-being in hospital, and the study of illness behavior.
• Genetics and Criminal Behavior.
• Coronary-prone behavior. Type A behavior revisited.
• Mobile nucleosomes--a general behavior.