COMPARISON OF STRAUB TAIL ELEVATION, INCI DENCE AS A MEASURE OF ENDOGENOUS OPIATE SYSTEM ACTIVITY IN RATS OF DIFFERENT STRAINS

Stress-induced and exploratory activity-related Straub tail elevation was studied as a probable measure of endogenous opiate system activity in rats from catalepsy-susceptible GC strain as well as PM(+) and PM( -) strains bred from Wistar stock for the presence and absence of pred isposition to a stereotyped hyperkinesis with pendulum-like movements. All the three strains were characterized by lower incidence of Straub tail elevation than in the control Wistar stock. Moreover, the PM(+) strain demonstrated a lower incidence of the studied reaction than PM( -) the difference between the strains being manifested during explorat ory activity but not in immobilization stress.