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Cholecystokinin modulation of apomorphine- or amphetamine-induced stereotypy in rats: opposite effects
C A Tieppo1, L F Felicio, A G Nasello
1Department of Physiological Sciences, Medical School of Santa Casa de São Paulo, 01277-900 São Paulo-SP, Brazil. catieppo@hotmail.com
Abstract:
Stereotyped behavior can be induced by the dopamine agonist apomorphine or by the releasing agent amphetamine. Cholecystokinin influence on dopamine-mediated behaviors has been extensively studied but a real controversy remains. Our purpose was to further characterize the dopamine-cholecystokinin interaction in apomorphine- and amphetamine-induced stereotyped behavior using sulphated cholecystokinin octapeptide (CCK8) and cholecystokinin tetrapeptide (CCK4) treatments. The results showed that CCK8 decreases apomorphine-induced stereotyped behavior and CCK4 has no effect. CCK4 and CCK8 increased the amphetamine-induced stereotyped behavior; CCK4 was more effective. The results confirm the opposite modulation of apomorphine or amphetamine-induced stereotyped behavior by CCK. These data suggest that this modulation is mediated by both CCK receptors on apomorphine-induced and only by CCK(2) receptors on amphetamine-induced stereotyped behavior.