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Abstract:
Abstract: In humans, cannabinoids have been known to produce
a range of cognitive effects, including impairments of short-term
memory (STM). Recent investigations in rodents have also
demonstrated deleterious effects of cannabinoids on STM. However
little is known about the relationship between the specific
mechanisms of action of cannabinoids in the brain and subsequent
STM deficits. The present experiments were performed as a first
step to the elucidation of these mechanisms of action. Cannabinoid
and non-cannabinoid amnesia-inducing drugs were examined in a novel
operant adjusting-delay nonmatching-to-position paradigm. Rats were
administered doses of cannabinoid agonists Win55,212-2 (0-2.0 mg/kg
i.p.) or delta-9-tetrahydrocannabinol (0-4.0 mg/kg i.p.). At the
highest doses, performance deficits consistent with a selective
disruption of STM were observed. In contrast, NMDA antagonist
MK-801 (0-0.25 mg/kg) and muscarinic antagonist scopolamine (0-0.05
mg/kg) produced disruptions of task performance not selective to
STM. Taken together, these results suggest that cannabinoids
modulate STM in the rat in a manner qualitatively different than
other compounds known to impair STM in humans.
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