Antinociception following lesion-induced hyperemotionality and conditioned fear

Abstract

Hyperemotionality and antinociception (during hyperemotional states) followed lesioning of the septal area in rats. Both of these behaviors showed parallel decreases with daily handling as well as significant positive correlations between them. Tail-flick latencies were also elevated when fear was conditioned to the environmental cues associated with the tail-flick procedure. Fear-induced antinociception was very resistant to extinction, being present across 9 daily extinction trials. These results are interpreted as demonstrations of the behavioral activation of endogenous antinociceptive mechanisms and are in agreement with the postulates of centrifugal control of nociception of the gate control theory of pain.