Nicotine alone and in combination with L-DOPA methyl ester or the D2 agonist N-0923 in MPTP-induced chronic hemiparkinsonian monkeys

Nicotine, the soluble methyl ester of L-DOPA, and the D-2 agonist N-0923 were given alone and in combination im to five hemiparkinsonian monkeys. Daily nicotine in doses of 32-320 mu g/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 D-2 agonist N-0923. (C) 1999 Academic Press.