EFFECTS OF REPEATED ADMINISTRATION OF N-[1-(2-BENZO(B)THIOPHENYL)CYCLOHEXYL]PIPERIDINE AND COCAINE ON LOCOMOTOR-ACTIVITY IN C57BL 6 MICE/

The present study investigated the effects of repeated administration of the dopamine reuptake inhibitors N-[1-(2-benzo(b)thiophenyl)cyclohe xyl]piperidine (BTCP) and cocaine on locomotor activity, as well as th eir ability to induce or express cross-sensitization. Male mice were i njected with a fixed dose of BTCP or cocaine (10, 20 or 40 mg/kg i.p.) for 3 consecutive days and challenged on the 4th day with one of seve ral doses of BTCP and/or cocaine. After every daily treatment, locomot or activity was assessed. Repeated administration of cocaine produced sensitization to the locomotor activity produced by different challeng e doses of both cocaine (2.5-56.6 mg/kg i.p.) and BTCP (2.5-80 mg/kg, i.p.) on day 4. Repeated administration of low and intermediate doses of BTCP did not significantly affect the locomotor activity produced b y different challenge doses of BTCP, whereas tolerance-like effects we re observed after the higher dose, 40 mg/kg, particularly during the 3 -day regimen. Repeated administration of BTCP dose-dependently produce d leftward and downward shifts of the cocaine dose-response curve. The se results indicate that, under identical treatment conditions, cocain e and BTCP differ markedly with respect to their ability to cause sens itization, but differ less in terms of their ability to elicit locomot or activity in sensitized animals. The demonstration of cross-sensitiz ation between BTCP and cocaine provides evidence for a shared mechanis m of action; however, the present results also suggest that the chroni c effects of cocaine and BTCP are not identical.