EFFECTS OF CHLORPROMAZINE ON LIPOLYSIS IN BROWN AND WHITE ADIPOSE TISSUES OF COLD-EXPOSED RATS

Abstract

Effects of chlorpromazine (CPZ) on lipolysis in brown (interscapular: IBAT) and white (epididymal: EWAT) adipose tissues in cold-exposed rats were studied in vitro. Adult male Wistar-Imamichi rats were exposed to 4oC for 1 (acute cold-exposed) or 30 (cold-acclimated) days. The spontaneous free fatty acid (FFA) release from interscapular brown adipose tissue (IBAT) of control rats, was three fold higher than epididymal white adipose tissue (EWAT). FFA release from the EWAT of acute cold-exposed rats was significantly higher than that of control rats. After cold acclimation, FFA release from IBAT increased up to three times that of the control level. CPZ (10-4, 10-3 M) suppressed the elevated lipolytic activity in IBAT of cold- acclimated rats. However CPZ had no effect on FFA release from EWAT or IBAT in all other groups. A single intravenous administration of 10 mg/kg 6-hydroxy- dopamine (6-OHDA) produced a marked decrease in the concentration of noradrenaline and dopamine in IBAT and EWAT of cold-acclimated rats. FFA release from IBAT in 6-OHDA treated, cold-acclimated rats decreased to 50% of untreated, cold-acclimated rats. A further decrease in lipolytic activity in the IBAT of 6-OHDA treated, cold-acclimated rats was produced following CPZ treatment. CPZ also depressed the lipolysis stimulated by the added noradrenaline (3xl0-5 M). These results suggest that the effect of CPZ on the lipolysis in the IBAT from cold-acclimated rats is mediated by a modification of sympathetic activity.