Intracerebroventricular administration of cholecystokinin reduces stereotypy in dopamine-supersensitive rats.
Cholecystokinin (CCK-8) coexists with dopamine in some neurons and modulates dopaminergic neurotransmission. In the present study we determined the effect of CCK-8 on stereotyped behavior in supersensitive dopaminergic system. Adult male Wistar rats, weighing 200-250 g, were used. Dopaminergic supersensitivity was induced by long-term haloperidol (HAL) treatment (30 days: 1.0 mg/kg twice a day). Seventy-two hours after HAL withdrawal animals received CCK-8 (14.5 nmol/5 microliters) or saline intracerebroventricularly (icv) before being tested for apomorphine (APO, 0.6 mg/kg, sc)-induced stereotyped behavior. Experimental groups were: long-term HAL-treated rats that received saline (HSAL, N = 9) or CCK-8 (HCCK, N = 11) icv and long-term saline-treated rats that received CCK-8 (SCCK, N = 9) or saline (SSAL, N = 8) icv. As expected, HSAL rats showed statistically significant higher stereotypy scores than SSAL rats (42 +/- 1.7 vs 31 +/- 1.6; P < 0.05) and CCK-8 significantly reduced stereotyped behavior in supersensitive rats (42 +/- 1.7 vs 37 +/- 1.5; P < 0.05). These results show that CCK-8 icv reduces stereotypy in dopaminergic-supersensitive rats, and suggest that the dopamine supersensitivity phenomenon can be modulated by CCK-8.
Tieppo
C A
CA
Departamento de Patologia, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, Brasil.
Silva
A M
AM
Palermo-Neto
J
J
Nasello
A G
AG
Felicio
L F
LF
D000704:Analysis of Variance; D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D002766:Cholecystokinin / Q000008:administration & dosage*; D018491:Dopamine Agonists / Q000494:pharmacology; D018492:Dopamine Antagonists / Q000494:pharmacology; D006220:Haloperidol / Q000494:pharmacology; D007276:Injections, Intraventricular; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012844:Sincalide / Q000494:pharmacology; D013239:Stereotyped Behavior / Q000187:drug effects*
D018491:Dopamine Agonists; D018492:Dopamine Antagonists; D002766:Cholecystokinin; D006220:Haloperidol; D012844:Sincalide; D001058:Apomorphine