Melatonin Mitigates Rotenone-Induced Oxidative Stress and Mitochondrial Dysfunction in the Drosophila melanogaster Model of Parkinson's Disease-like Symptoms.

Parkinson's disease (PD) is the second most common neurodegenerative disorder; however, its etiology remains elusive. Antioxidants are considered to be a promising approach for decelerating neurodegenerative disease progression owing to extensive examination of the relationship between oxidative stress and neurodegenerative diseases. In this study, we investigated the therapeutic effect of melatonin against rotenone-induced toxicity in the Drosophila model of PD. The 3-5 day old flies were divided into four groups: control, melatonin alone, melatonin and rotenone, and rotenone alone groups. According to their respective groups, flies were exposed to a diet containing rotenone and melatonin for 7 days. We found that melatonin significantly reduced the mortality and climbing ability of Drosophila because of its antioxidative potency. It alleviated the expression of Bcl 2, tyrosine hydroxylase (TH), NADH dehydrogenase, mitochondrial membrane potential, and mitochondrial bioenergetics and decreased caspase 3 expression in the Drosophila model of rotenone-induced PD-like symptoms. These results indicate the neuromodulatory effect of melatonin, and that it is likely modulated against rotenone-induced neurotoxicity by suppressing oxidative stress and mitochondrial dysfunctions.

Effect of melatonin on Aß42 induced changes in the mitochondrial function related to Alzheimer's disease in Drosophila melanogaster.

Alzheimers's disease is one of the alarming neurodegenerative disease and it is of global concern.The hallmarks of the disease are the amyloid beta (Aß) aggregation and presence of neurofibrillary tangles (NFTs). The interaction of Aß with macromolecular targets affects the normal cellular functions. The amyloid peptide interaction with cellular surfaces may trigger the intracellular cascades of signalling. Interaction of Aß with mitochondria leads to the generation of free radicals. Many studies have suggested the involvement of mitochondrial dysfunction in Alzheimer's disease. Melatonin prevents mitochondria stress and by means of activating the antioxidant systems it protects the death of neurons. Although the study have been already conducted on Aß42 infused or injury induced animal models but till date there is no reports of such studies on transgenic model of Drosophila melanogaster. In the present study, we have taken UAS/Gal4 system for the development of transgenic flies that overexpress Aß42 in the brain of Drosophila. With the help of these transgenic flies we have analyse different experiments like behavioural parameters, oxidative stress parameters and protein expression through western blotting in the presence of melatonin. We have found that melatonin significantly ameliorated the toxicity caused by the Aß42 overexpression. Thus the present study could be beneficial to find out the role of melatonin in transgenic flies overexpressing human Aß42.

Melatonin Improves Behavioral and Biochemical Outcomes in a Rotenone-Induced Rat Model of Parkinson's Disease.

Parkinson's disease (PD) is the second most common neurodegenerative disease followed only by Alzheimer's disease and affects millions of people worldwide. Despite the plethora of preclinical and clinical studies, there is currently a paucity of therapeutic agents for PD that can promote neuroprotection. In addition, the therapeutic agents currently available only help with improvement of PD symptoms. Therefore, it is imperative to find new therapeutic avenues for PD patients to minimize the economic and social burden on the concerned families. Rotenone is a frequently used neurotoxin in developing a PD model to aid in understanding the mechanisms of neuronal death. In addition, several studies have investigated the effects of melatonin, a neurohormone that is neuroprotective in various neurological diseases due to its anti-apoptotic, anti-inflammatory, and anti-oxidative properties. Our study investigated the role of melatonin-induced tyrosine hydroxylase (TH) and sensory motor function in a rotenone rat model to determine whether melatonin had any positive effects. Our results revealed that melatonin improves motor function by upregulation of TH in striatum of the brain. In addition, melatonin inhibits the striatal degeneration as shown by histopathological analysis. Therefore, results from the current study provide evidence for melatonin as a promising candidate for effective future therapeutic strategies for PD.

Mitochondrial permeability transition pore: a promising target for the treatment of Parkinson's disease.

Among the neurodegenerative diseases (ND), Parkinson's disease affects 6.3 million people worldwide characterized by the progressive loss of dopaminergic neurons in substantia nigra. The mitochondrial permeability transition pore (mtPTP) is a non-selective voltage-dependent mitochondrial channel whose opening modifies the permeability properties of the mitochondrial inner membrane. It is recognized as a potent pharmacological target for diseases associated with mitochondrial dysfunction and excessive cell death including ND such as Parkinson's disease (PD). Imbalance in Ca2+ concentration, change in mitochondrial membrane potential, overproduction of reactive oxygen species (ROS), or mutation in mitochondrial genome has been implicated in the pathophysiology of the opening of the mtPTP. Different proteins are released by permeability transition including cytochrome c which is responsible for apoptosis. This review aims to discuss the importance of PTP in the pathophysiology of PD and puts together different positive as well as negative aspects of drugs such as pramipexole, ropinirole, minocyclin, rasagilin, and safinamide which act as a blocker or modifier for mtPTP. Some of them may be detrimental in their neuroprotective nature.