Sex differences in the progressive model of parkinsonism induced by reserpine in rats.

Parkinson's disease (PD) exhibits sexual differences in susceptibility and pathogenesis in humans, with a high incidence in men and a high severity of motor symptoms in male rodents. Furthermore, studies showed that the administration of low dose of reserpine (RES) induces a progressive appearance of motor alterations similar with parkinsonism in male rodents. Here, we investigated sex differences in motor deficits and tyrosine hydroxylase (TH) immunoreactivity induced by a progressive model of parkinsonism. Gonadally intact male and female Wistar rats and ovariectomized female rats received 15 subcutaneous injections (s.c.) every other day of 0.1 mg/kg of RES or vehicle. The repeated administration of low doses of RES (0.1 mg/kg) produces sexually dimorphic impairments on motor performance (catalepsy and open field test). Intact and ovariectomized females were more resistant to the deleterious effect of repeated administration of reserpine in the early, but this resistance in intact female disappears over time. However, intact females showed a reduction of the TH immunoreactivity in substantia nigra pars compacta, but not in ventral tegmental area and dorsal striatum. These results suggest a possible application of this model in the study of sexual dimorphism throughout the progression of PD.