Caffeine alleviates anxiety-like behavior and brainstem lesions in a rotenone-induced rat model of Parkinson's disease

Abstract

Background

Parkinson's disease (PD) is a neurodegenerative disorder characterized by motor and non-motor symptoms. In 2016, approximately 6.1 million individuals were affected by PD, with 211,296 deaths attributed to the disease. The understanding of PD initially came from the observation of dopaminergic system alterations in a specific region of the brainstem, indicating that the core motor and non-motor features of PD are closely associated with brainstem dysfunction. The primary treatment approach for PD revolves around dopamine replacement, as many of the symptoms are responsive to this therapeutic intervention. However, long-term administration of this approach is linked to several complications, and a definitive gold-standard therapy for PD is yet to be identified. The pharmacological management of PD has been challenging and inconsistent, mainly due to the unclear underlying cause of the disease. This study aims to evaluate the effects of caffeine on the brainstem of rats with PD induced by rotenone.

Methodology

Fifty adult male Wistar rats weighing between 150 and 200 g were used in this study. The rats were randomly divided into five groups of ten rats each: Vehicle Group, Rotenone-only treated Group (rotenone only treated with 3 mg/kg, intraperitoneal administration [IP]), Preventive Group (caffeine 30 mg/kg + rotenone 3 mg/kg, IP), Curative Group (rotenone 3 mg/kg + caffeine 30 mg/kg, IP), and Caffeine only treated Group (caffeine only treated with 30 mg/kg, IP). The animals underwent neurobehavioral assessments, followed by sacrifice. The brains were then excised, weighed, and processed histologically. Appropriate brain sections were taken and processed. Photomicrographs were obtained, morphometric and statistical analysis was performed using an Omax LED digital

Results

The results demonstrated a significant (p < 0.05) reduction in body weight and relative brain weight, which were increased by caffeine treatments. Rotenone administration led to histological changes similar to those observed in PD, including neuronal structural derangement, degenerated nerve fibers, loss of myelinated neurons, and Nissl substance, as well as downregulation in the expressions of NRF2 and TH in the midbrain. However, these pathological features were counteracted or ameliorated by caffeine treatment.

Conclusion

Our study contributes additional evidence to the growing body of research supporting the therapeutic potential of caffeine in Parkinson's disease (PD). The results underscore the neuroprotective properties of caffeine and its capacity to mitigate oxidative stress by modulating TH (tyrosine hydroxylase) and cytoplasmic NRF2 (nuclear factor erythroid 2-related factor 2) in the mesencephalon. These findings suggest that caffeine holds promise as a viable treatment option for PD.