Estrogen agonist genistein differentially influences the cognitive and motor disorders in an ovariectomized animal model of Parkinsonism

Objective(s): Parkinson's disease (PD) is a progressive neurological disorder associated with motor disabilities and cognitive dysfunction as well. Evidence indicates that PD occurs less frequently in women than men, confirming a role for steroid hormones in protection of dopaminergic nigrostriatal neurons. It is reported that soy genistein, an estrogen agonist phytoestrogen, display neuroprotective effects against neuronal death. In this study we evaluated the effect of genistein in animal models of Parkinsonism (P) and Parkinsonism + ovariectomized (OP). Materials and Methods: The experiments were carried out on the control, P and OP animals. Learning and memory abilities were evaluated using Morris water maze. The latency and speed of locating the platform were measured as cognitive indices. Motor behaviors were assessed by testing the animals in rota rod and the latency to fall from the rod was scored. Results: We found that Parkinsonism leads to the cognitive and motor disabilities; ovariectomy intensified these disorders. Whereas genistein treatment improved the maze performances in both P and OP animals it failed to influence the kinetic problems. Genistein displayed a neuroprotective effect on dopaminergic neurons. Conclusion: Positive impact of genistein on the spatial learning and memory may reflect its effects on the nigrostriatal pathway and striatum. Nevertheless, ineffectiveness of genistein on the motor disorders, despite its neuroprotective impacts, led us to conclude that the cognitive improvement by genistein may also contribute to its effects in other areas of brain.