Effect of estrogen and progesterone on L-dopa induced dyskinesia in MPTP-treated monkeys.

A group of 4 cynomolgus monkeys was rendered parkinsonian by the toxin MPTP and then treated daily with L-DOPA until all animals developed dyskinesia. At this point, 17 beta-estradiol, 17 alpha-estradiol and progesterone were injected s.c. singly or in combination for 7 days and the treatment with L-DOPA reinstituted. Our results show that the pretreatment with 17 beta-estradiol reduced the dyskinetic effect without altering the therapeutic response to L-DOPA, while 17 alpha-estradiol did not alter the dyskinetic and the antiparkinsonian effect.