Nicotine Alone and in Combination with [formula omitted]-DOPA Methyl Ester or the D2 Agonist N-0923 in MPTP-Induced Chronic Hemiparkinsonian Monkeys

Abstract

Nicotine, the soluble methyl ester of l-DOPA, and the D2 agonist N-0923 were given alone and in combination im to five hemiparkinsonian monkeys. Daily nicotine in doses of 32–320 μg/kg for 6 days each, surprisingly, had slight effects on motor activity. When combined with N-0923, nicotine did not further enhance its effects. However, l-DOPA methyl ester plus nicotine produced greater contraversive circling than l-DOPA methyl ester plus 0.9% NaCl. Similar effects were obtained on significant motor movements of both the affected (contralateral) and normal (ipsilateral) arm and hand. The results indicate that nicotine is synergistic with l-DOPA methyl ester, but not with the postsynaptic D2 agonist N-0923.