Soy isoflavone Daidzein resembling the vertebrate steroid structure exhibits neuroprotection via mitochondrial biogenesis in rotenone induced Parkinson's disease in preclinical model.

Parkinson's disease (PD) ranks as the second most prevalent neurodegenerative disorder but is still devoid of neuroprotective treatment. Although approaches with disease modifying ability along with symptomatic relief has become an utmost necessity, the multifactorial nature of PD presents challenges for efficacy evaluation of potential test compound. This study attempts to address these issues by employing a rotenone induced PD model involving intranigral rotenone injection for evaluation of the neuroprotective efficacy of Daidzein (DZ) a soy isoflavone and a phytoestrogen. In this study, male Sprague Dawley rats after bilateral intranigral rotenone (12 μg) injection, were treated with DZ at a dose of 5, 10 and 20 mg/kg for 30 days. The neurobehavioral evaluation comprised of Rota-rod, Open field and Barnes maze test. The biochemical analysis constituting oxidative stress (Reduced glutathione, superoxide dismutase, catalase and lipid peroxidation), inflammation (TNF-α), mitochondrial alteration (complex I activity and biogenesis) was conducted on mid-brain tissue after 30 days of treatment. The Substantia nigra and striatum were subjected to immunohistochemical analysis (IHC) for TH positive neurons and Glial Fibrillary Acidic Protein. The analysis revealed significant improvement by daidzein in motor co-ordination and attenuation in cognitive deficits due to rotenone. The biochemical assessment exhibited significant decrement in oxidative stress as well as inflammation. DZ treatment also prevented complex I inhibition and promoted mitochondrial biogenesis eventually contributing to the neuroprotection apparent in IHC. Thus, the results strongly corroborate the neuroprotective potential of DZ against rotenone induced model of PD.