Cannabinoids can disrupt short-term memory in humans and animals and induce learning deficits and other cognitive impairments. In the present study we examined the role of a full cannabinoid agonist in short-term memory, sensorimotor gating, and the acquisition and expression of an operant learning paradigm in rats. We tested the effects of the synthetic cannabinoid WIN 55,212-2 (0.6 and 1.2 mg/kg) on short-term memory in social and object recognition tests, on prepulse inhibition (PPI) of startle, as well as on lever pressing for palatable food. Injections of 0.6 and 1.2 mg/kg WIN 55,212-2 impaired recognition memory and PPI in a dose-dependent manner, but had no effect on lever-pressing acquisition or expression, or on food preference. The PPI deficit was reversed by the administration of 0.1 mg/kg haloperidol. These data suggest that the synthetic cannabinoid WIN 55,212-2 does not lead to a general impairment of learning in an appetitive instrumental task, but significantly affects short-term memory and sensorimotor integration. The impairment in recognition and PPI might be due to deficits in attention-based short-term information processing. (C) 2002 Lippincott Williams Wilkins.
