Pharmacological Research Communications, Vol. 19. No. 6, 1987 441 NEUROCHEMICAL AND BEHAVIOURAL CHANGES INDUCED BY ASCORBIC ACID AND d-AMPHETAMINE IN THE RAT. Maria S.DESOLE, V.ANANIA, G.ESPOSITO, Franca CARBONI, A.SENINI'c and E.MIELE Institute of Pharmacology and Chair of Psychology" -University of Sassari - Via Roland0 1 - 07100 Sassari, Italy. Received in final form 2 June 1987 SUMMARY - In male Wistar rats, ascorbic acid (AA) (1 gr/kg i.p.) significantly (PC 0.05) decreased therate of CAR in the shuttle box avoidance test and antagonized the d-amphetamine (d-A) (1 mg/kg s.c.)-induced increase of CAR. Shuttle box test reduced striatal dopamine (DA) levels by about 86% (with a consistent 2-3 fold increase of DOPAC levels). DA levels were greatly reduced also in hypothalamus (HYP) and in hippocampus (HIP). AA further decreased striatal DA but sig- nificantly antagonized the reduction of DA levels in HYP and HIP. d-A antagonized the reduction of DA levels in all the above brain regions. Shuttle box test reduced noradrenaline (NA) levels mainly in HIP (-52%) and again d-A showed a sig- nificant protective effect in all regions; AA did not inter- fere with NA level reduction in striatum (ST) and HYP, but antagonized it in HIP. It is concluded that striatal DA system plays an important role in rat operant active avoidance behaviour. AA seems to exert a negative modulatory activity which can be counteracted by d-A. INTRODUCTION - The central dopaminergic system seems to be involved in operant active avoidance behaviour (Lehr, 1980). The response rate to a number of different avoidance tasks is increased by d-A in the dose range between 0.001 and 1 mg/kg (Clark and Steele, 1966; Niemegeers et al., 1970; McKearney, 1974) by a mechanism related to its ability to release brain DA (Garattini and Samanin, 1981). AA (2 gr/kg) blocked, in mice, the d-A (15 mg/kg) induced increase of stereotyped behaviour, which has been reported to Supported by M.P.I. 60% 0031~989/87/060441-1 O/$03.00/0 0 1987 The Italian Pharmacological Society