Molecular mechanisms of neuroprotection by extract from Rosmarinus officinalis (Rosemary) in dopaminergic cell line, SH-SY5Y

Abstract

Parkinson's disease (PD) is characterized by a profound loss of dopaminergic neurons in the substantia nigra. Even though the cause of PD is still unknown, many studies suggest that oxidative stress and mitochondrial dysfunction play a major role in the neurodegenerative process of the diseases. Oxidative stress and/or mitochondrial dysfunction are believed to culminate in the activation of an apoptotic cascade which ultimately results in the loss of dopaminergic cells. Hence regulation of intracellular ROS and modification of the apoptotic cascade may prevent pathological apoptosis in PD. Many drugs have been used for remedy of PD. But these drugs have many side-effects, and can’t use for long-term. So, many natural antioxidants have been tested in both in vivo and in vitro models of PD. For instance, Ginkgo biloba, huperzine A, salvianic acid A, Ginseng and tea catechins have been shown to have neuroprotective. Rosemainus officinalis (Rosemary) is one of the most common traditional medicinal herbs. It has been reported to have various pharmacological properties including exceedingly powerful anti-oxidative, liver supportive, anti-cancer, pain relieving, memory-enhancing agent and anti-bacterial activities. In this study, our results showed that rosemary extracts at the effective concentrations (10 ㎍/㎖) was not cytotoxic and the viability of SH-SY5Y cells was significantly increased by treatment with rosemary extracts. Treatment with rosemary extracts induced the expression of tyrosine hydroxylase (TH) and aromatic amino acid decarboxylase (AADC). Furthermore, rosemary extract increased the mRNAs and protein levels of Brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF) in SH-SY5Y cells. We observed that the viability of the cells was enhanced by treatment with rosemary extract compared with only H2O2 (150 μM)-treated cells. We found that H2O2 caused a significant decrease in cell viability. In contrast, cells exposed to the same amount of H2O2 in the presence of rosemary extract appeared remarkably retained virbility, indicating that rosemary extracts prevented neuronal death. We found that treatment of cells with H2O2 increased Caspase-3, Caspase-9, Bax and Bak. However, treatment with rosemary extracts decreased the caspase-3, caspase-9, Bax, and Bak activities compared with only H2O2-treated cells. Also, treatment of rosemary extract increased mitochondrial memebrane potential, and inhibited nucleus morphological changes. In conclusion, these data indicate that rosemary extract partially inhibit the neuronal death in the early stage of the mitochondrial apoptotic pathway. Therefore, it suggests that rosemary extract acts on reactive oxygen species to inhibit apoptosis in human dopaminergic neuronal cells.