High density of
cannabinoid receptors type 1 (CB1) in the brain suggests that
endocannabinoid system plays an important role in the functioning of the central nervous system. Natural and synthetic
cannabinoids are known to attenuate learning and memory processes. The adverse effects of
cannabinoids are reversed by
SR141716A, at first reported to be a selective
CB1 receptor antagonist, later shown to possess also inverse agonist properties. The present study was performed in an attempt to determine the influence of different doses of
AM251, a member of the same
cannabinoid group as
SR141716A, on recognition memory evaluated in an object recognition test. Because
cannabinoids may alter motor function and affect anxiety, the influence of
AM251 on psychomotor activity and anxiety was assessed in an "open-field" test and elevated plus maze, respectively. While the lowest dose of
AM251 (1.0 mg/kg) significantly improved recognition memory, higher doses (2.5 mg/kg and 5.0 mg/kg) did not have an influence on it. Moreover,
AM251 did not affect anxiety but in the highest dose significantly attenuated psychomotor activity in rats. The main finding of the present study indicates that
AM251, at the dose of 1.0 mg/kg, improves recognition memory in rats without alteration of their psychomotor activity and anxiety. The pro-cognitive effect exerted by compounds belonging like
AM251 to diarylpyrazole group may be beneficial in
therapeutic use of these compounds, especially in patients with
cognitive dysfunctions.