The Role of Ocimene in Decreasing α-Synuclein Aggregation using Rotenone-induced Rat Model

Background: Parkinson’s disease is defined by the loss of dopaminergic neurons in the midbrain of substantia nigra associated with Lewy bodies. The precise mechanism is not yet entirely understood. Objective: The study aims to determine whether ocimene has antiparkinsonian activity by reducing α-Synuclein aggregation levels in the brains of rotenone-induced rat models. Methods: 36 male rats were used for six groups, with six animals in each group. Vehicle, control (rotenone, 2.5 mg/kg, i.p), standard (L-Dopa, 10 mg/kg, i.p), Test drug of low dose (66.66 mg/kg, i.p), medium dose (100 mg/kg, i.p), and high dose (200 mg/kg, i.p) were administered to the rats. The open field, actophotometer, hanging wire, and catalepsy tests were used to assess the rat’s motor performance. The expressions of biomarkers such as AchE, D2 Receptor, and α- Synuclein were evaluated, and their level of expression in the brain samples was checked using ELISA. Histopathological analysis was also carried out to determine the degree of neuron degeneration in the brain samples. Results: The open field test showed significant anxiety levels, whereas test groups showed fewer anxiety levels but increased motor activity. The biochemical tests revealed that rotenonetreated rats had higher levels of AchE, but ocimene-treated rats had a significant decrease in AchE levels. The test drug-treated rats also expressed high levels of D2 receptors. In ocimenetreated rats, α-Synuclein aggregation was reduced, however, in rotenone-treated rats' brain samples, higher clumps of α-Synuclein were observed. Conclusion: Ocimene has neuroprotective properties. As a result, this essential oil might be helpful as a therapeutic treatment for Parkinson's disease.