Hyper- and hypothermia induced by non-noxious stress: effects of naloxone, diazepam and gamma-acetylenic GABA.

Rats subjected to non-noxious, anxiogenic stressors were found to exhibit either hyperthermia or hypothermia depending on the nature of the stressor. The present work examines the effects of naloxone (Nx), diazepam (DZP) and gamma-acetylenic GABA (AcG), an inhibitor of GABA catabolism, on these phenomena. Nx reduced stress hyperthermia and basal temperature by similar amounts; it did not affect stress hypothermia. DZP also reduced basal Tb but was able to completely inhibit and even reverse stress hyperthermia and to reduce stress hypothermia. The effects of AcG were similar to those of DZP. In conclusion, it appears that endogenous opioids are not involved in the thermic responses to our emotional stressors whereas GABA would be an important modulator. It is suggested that DZP, through a GABAergic link might inhibit the release of hyperthermic pituitary factors from the neurointermediate lobe and of hypothermic substances from the anterior lobe.