Effect of restraint stress on cannabis-induced catalepsy in rats

The effect of restraint stress (1, 2 and 4 hr) on cannabis-induced catalepsy, was investigated in rats. Restraint stress produced a time-related-potentiation of the cataleptic effect of a sub-cataleptic dose of cannabis. Stress (4 hr)-induced potentiation of cannabis catalepsy was attenuated after pretreatment of the animals with drugs known to decrease central 5-HT and prostaglandin activity, but was unaffected by metyrapone, an inhibitor of endogenous corticoid synthesis. The results suggest the involvement of 5-HT and prostaglandins in restraint stress-cannabis interaction. The results have been discussed in the light of earlier investigations, from this laboratory, indicating increased rat brain 5-HT and prostaglandin activity, following restraint stress, and possible 5-HT mediation in central effects of prostaglandins. It is suggested that restraint stress first enhances rat brain prostaglandins, which in its proposed role as the first mediator' of stress, activates the serotonergic system in this species. This prostaglandin 5-HT link, thus mediates the observed potentiating effect of restraint stress on cannabis catalepsy.