The Protective Role of Liraglutide on Experimentally Induced Parkinsonism in the Substantia Nigra of Adult Male Albino Rats: Light and Electron Microscopic Study

Background: Parkinson’s disease is the second most prevalent progressive degenerative brain disorder globally. It presents with progressive reduction of dopamine-secreting neurons within the substantia nigra pars compacta (SNc) of the midbrain. Aim of the work: This research was designed to assess changes in structure of substania nigra of adult male albino rats in rotenone induced Parkinsonism and the possible protective effect of Liraglutide. Materials and methods: Eighty adult male rats were divided into two groups. Group I consisted of 20 rats and was further divided into subgroup IA: rats were provided with standard diet and subgroup IB: rats received Liraglutide. Group II: involved 60 rats which injected subcutaneously by rotenone 1.5 mg/kg/d for four weeks dissolved in dimethyl sulfoxide (DMSO). Then they were subdivided into three equal subgroups: Subgroup IIA: rats continued to receive rotenone, subgroup IIB: rats received Liraglutide injected subcutaneously with 0.3 mg /kg/d and subgroup IIC: rats were left free without treatment for another 8 weeks. Behavioral tests were performed prior to and after the treatment and specimens were collected for examination using light and electron microscopic techniques. Tyrosine hydroxylase (TH) immunostaining was utilized to assess TH-positive dopaminergic cells within the SNc. An image analyzer was used and the measured data was statistically analyzed. Results: Subgroups IIA and IIC showed disturbed normal histological architecture of substania nigra but in Liraglutide treated subgroup IIB showed improvement of the histopathological features. Conclusion: Liraglutide reversed the neuronal loss and the decrease in TH in adult male albino rats experimentally induced with Parkinsonism using rotenone with subsequent improvement in their motor performance.