Intraventricular (ivt) injections of sub-cataleptic doses of β endorphin in rats were observed to result in wet-dog shakes. Subsequent to the wet-dog shakes, copious salivation accompanied by a clonic, seizure-like state was occasionally observed to occur. This sialogogic effect of β endorphin was blocked by naloxone and diminished by injections of thyrotropin releasing hormone. None of these behaviors were observed following ivt injection of morphine in equi-antinociceptive doses. Furthermore, hypophysectomy was observed to attenuate or block these behaviors. Both the wet-dog shakes and "sialogogic seizures" were demonstrated to be dependent upon dose as well as ambient temperature. It appears possible that the occurrence of initial wet-dog shakes may result in the elevated body temperature which then precipitates excess salivation. Since both β endorphin induced wet-dog shakes and salivation were shown to be correlated with alterations in temperature, it is possible that these effects of β endorphin indicate a physiological role for that peptide in thermoregulation.
Bibliographical noteFunding Information:
We thank Me. Barbara Hitzemoor, Mr . J.D . Nelson, and lls. Judy Quinn for their ezpert assistance . We gratefully acknowledge the critical review of thin manuscript by G. R. Sessions and G. L. Belmky. Suppported is part by Walter Breed Army Institute of Research, NIDA Grant DA-00565, and NIl~ Grant MH-30245 . HHL is the recipient of our NII1H Career Development Award, R2-DA-70554 .