Birds Saliva Nest ameliorates oxidative stress-induced apoptosis in SH-SY5Y human neuroblastoma cells

Birds Saliva Nest ameliorates oxidative stress-induced apoptosis in SH-SY5Y human neuroblastoma cells

Current findings suggest that Birds Saliva Nest extracts might confer neuroprotective effect against 6-OHDA-induced degeneration of dopaminergic neurons, particularly through inhibition of apoptosis. Thus Birds Saliva Nest may be a viable nutraceutical option to protect against oxidative stress-related neurodegenerative disorders such as PD.

Abstract

Background:

Parkinson’s disease (PD) is the second most common neurodegenerative disorder affecting the senile population with manifestation of motor disability and cognitive impairment. Reactive oxygen species (ROS) is implicated in the progression of oxidative stress-related apoptosis and cell death of the midbrain dopaminergic neurons. Its interplay with mitochondrial functionality constitutes an important aspect of neuronal survival in the perspective of PD. Birds Saliva Nest is an animal-derived natural food product made of saliva secreted by swiftlets from the Aerodamus genus. It contains bioactive compounds which might confer neuroprotective effects to the neurons. Hence this study aims to investigate the neuroprotective effect of Birds Saliva Nest extracts in the neurotoxin-induced in vitro PD model.

Methods:

Birds Saliva Nest was first prepared into pancreatin-digested crude extract and water extract. In vitro PD model was generated by exposing SH-SY5Y cells to neurotoxin 6-hydroxydopamine (6-OHDA). Cytotoxicity of the extracts on SH-SY5Y cells was tested using MTT assay. Then, microscopic morphological and nuclear examination, cell viability test and ROS assay were performed to assess the protective effect of Birds Saliva Nest extracts against 6-OHDA-induced cellular injury. Apoptotic event was later analysed with Annexin V-propidium iodide flow cytometry. To understand whether the mechanism underlying the neuroprotective effect of Birds Saliva Nest was mediated via mitochondrial or caspase-dependent pathway, mitochondrial membrane potential (MMP) measurement and caspase-3 quantification were carried out.

Results:

Cytotoxicity results showed that crude Birds Saliva Nest extract did not cause SH-SY5Y cell death at concentrations up to 75 μg/ml while the maximum non-toxic dose (MNTD) of water extract was double of that of crude extract. Morphological observation and nuclear staining suggested that Birds Saliva Nest treatment reduced the level of 6-OHDA-induced apoptotic changes in SH-SY5Y cells. MTT study further confirmed that cell viability was better improved with crude Birds Saliva Nest extract. However, water extract exhibited higher efficacy in ameliorating ROS build up, early apoptotic membrane phosphatidylserine externalization as well as inhibition of caspase-3 cleavage. None of the Birds Saliva Nest treatment had any effect on MMP.

Conclusions:

Current findings suggest that Birds Saliva Nest extracts might confer neuroprotective effect against 6-OHDA-induced degeneration of dopaminergic neurons, particularly through inhibition of apoptosis. Thus Birds Saliva Nest may be a viable nutraceutical option to protect against oxidative stress-related neurodegenerative disorders such as PD.
Keywords: Birds Saliva Nest, Apoptosis, SH-SY5Y, 6-OHDA, Neurodegenerative disorder, Parkinson’s disease, Neuroprotection