SR141716A induces in rats a behavioral pattern opposite to that of CB1 receptor agonists

AIM: To examine the acute actions of the CB1 cannabinoid receptor antagonis t SR141716A [N-piperidino-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methy lpyrazole-3-carboxamide] on typical behavioral pattern of psychoactive cann abinoids in rats. METHODS: At different time after injection the tail-flick response latency, the rectal temperature, the locomotor activity, and the immobility on a ring as well as the numbers of rears, self-grooming episode s (lasting 5 s), and fecal pellets were measured. RESULTS: Acute administra tion of SR141716A (3 mg/kg ip) induced a significant increase in horizontal locomotor activity assayed by an activity meter, in stereotypic activity ( such as rearing and self-grooming) and in defecation, and a decrease in noc iceptive threshold recorded as tail-flick latency. This dose had no effect on ring immobility and did not change the body temperature. CONCLUSION: The se results demonstrate that this cannabinoid antagonist itself was inducing behavior opposite to that of CB1 receptor agonists.