ACUTE ADMINISTRATION OF NICOTINE INCREASES THE INVIVO EXTRACELLULAR LEVELS OF DOPAMINE, 3,4-DIHYDROXYPHENYLACETIC ACID AND ASCORBIC-ACID PREFERENTIALLY IN THE NUCLEUS-ACCUMBENS OF THE RAT - COMPARISON WITH CAUDATE-PUTAMEN

Using in vivo dialysis and voltammetry, the effect of acute administration of (-)-nicotine (0.8 mg/kg free base, s.c.) on extracellular levels of dopamine, 3,4-dihydroxyphenylacetic acid, 5-hydroxyindoleacetic acid and ascorbic acid in the nucleus accumbens and caudate-putamen of chloral hydrateanaesthetised rats has been examined. Nicotine stimulated release of dopamine only in the nucleus accumbens, measured using dialysis. After a short time delay levels of 3,4-dihydroxyphenylacetic acid in both the nucleus accumbens and caudate-putamen also increased. In both regions, 5-hydroxyindoleacetic acid was unaffected by nicotine. Using voltammetry the effect of nicotine on extracellular levels of 3,4-dihydroxyphenylacetic acid and ascorbic acid was examined. An increase in 3,4 dihydroxyphenylacetic acid was observed in both regions after nicotine. This increase was blocked by pretreatment with the central nicotinic receptor antagonist mecamylamine (5 mg/kg). Nicotine increased the level of ascorbic acid in the nucleus accumbens and caudate-putamen; while in animals pretreated with mecamylamine, nicotine decreased levels of ascorbate. These results show that acute administration of nicotine stimulated release of dopamine in the nucleus accumbens and increased the levels of DOPAC and ascorbic acid in the nucleus accumbens and caudate-putamen. This effect is probably mediated by nicotinic receptors as it was antagonised by mecamylamine. © 1990.