Studies on interactions between striatal dopaminergic and cholinergic mechanisms in the early abstinence after chronic treatment with barbital in the rat.

Accumulation in the rat striatum of 3,4-dihydroxy-L-phenylalanine (DOPA) after inhibition of the neuronal decarboxylase was not significantly altered in the early abstinence after chronic treatment with barbital for 36-39 weeks in comparison with controls treated with water. Pilocarpine (10 mg/kg i.p.) increased the accumulation of DOPA in rats chronically treated with barbital and also in controls treated with water. Some weak correlations between striatal DOPA accumulation and changes in body weight or fluid consumption during the first three days of the abstinence were observed. There was also a highly significant, positive correlation (r = 0.85) between striatal DOPA accumulation and the number of convulsions in rats chronically treated with barbital and injected with NaCl. The corresponding correlation in rats chronically treated with barbital and injected with pilocarpine was positive but not significant (r = 0.50). No evidence for an increased sensitivity at muscarinic receptors in the striatum was found.