A Simple Immunofluorescence Method to Characterize Neurodegeneration and Tyrosine Hydroxylase Reduction in Whole Brain of a Drosophila Model of Parkinson's Disease.

Dopaminergic (DAergic) neurodegeneration in the substantia nigra pars compacta of the human brain is the pathological feature associated with Parkinson's disease (PD). Drosophila also exhibits mobility defects and diminished levels of brain dopamine on exposure to neurotoxicants mimicking PD. Our laboratory demonstrated in a Drosophila model of sporadic PD that there is no decrease in DAergic neuronal number; instead, there is a significant reduction in tyrosine hydroxylase (TH) fluorescence intensity (FI). Here, we present a sensitive assay based on the quantification of FI of the secondary antibody (ab). As the FI is directly proportional to the amount of TH synthesis, its reduction under PD conditions denotes the decrease in the TH synthesis, suggesting DAergic neuronal dysfunction. Therefore, FI quantification is a refined and sensitive method to understand the early stages of DAergic neurodegeneration. FI quantification is performed using the ZEN 2012 SP2 single-user software; a license must be acquired to utilize the imaging system to interactively control image acquisition, image processing, and analysis. This method will be of good use to biologists, as it can also be used with little modification to characterize the extent of degeneration and changes in the level of degeneration in response to drugs in different cell types. Unlike the expensive and cumbersome confocal microscopy, the present method will be an affordable option for fund-constrained neurobiology laboratories. Key features • Allows characterizing the incipient DAergic and other catecholaminergic neurodegeneration, even in the absence of loss of neuronal cell body. • Great alternative for the fund-constrained neurobiology laboratories in developing countries to utilize this method in different cell types and their response to drugs/nutraceuticals.

Neuropharmacological Properties of Withania somnifera - Indian Ginseng: An Overview on Experimental Evidence with Emphasis on Clinical Trials and Patents.

BACKGROUND: Owing to the increasing aged population globally, disorders and diseases of the CNS are anticipated to increase and profoundly impact the health care. As these neurodegenerative diseases (NDD) are complex, multifactorial and do not have identified etiological factors, unfortunately, drugs developed for the purpose have not met with the expected success. Hence, there has been a constant demand for the development of natural therapeutic adjuvants which are safe and possess the potential to attenuate multiple pathways. METHODS: Numerous herbal/natural products have been used as therapeutics in Ayurvedic system of medicine to treat NDD and other memory-related disorders. Withania somnifera (Ashwagandha, WS), popularly called as "Indian Ginseng" is one such plant which possesses a variety of beneficial neuropharmacological properties. In this review, we have attempted to review critically the existing literature and patents related to the neuroprotective efficacy of WS roots and the underlying mechanism/s. RESULTS: Standardized extracts of Withania somnifera (WS) have been demonstrated to possess multidimensional neuromodulatory effects both in vitro and animal models. The spectrum of effects evidenced comprises of attenuation of oxidative damage by enhancing the antioxidant defense system with concomitant enhancement of the expression of marker proteins responsible for growth, differentiation and communication of neural cells. Specific effects of WS are attributable to its potential to modulate neurotrophic factors, cytoskeletal elements, cell adhesion molecules and synaptic proteins. CONCLUSION: Generation of new data by employing systematic contemporary approaches such as bioinformatics, molecular docking studies, identification of specific gene targets and epigenetic regulation would provide the necessary impetus to validate fully the neurotherapeutic potential of the phytochemicals derived from WS. More importantly, well-designed clinical trials are required to exploit the neuromodulatory propensity of WS extract/bioactives in specific neurodegenerative diseases such as AD and PD.

Analysis of dopaminergic neuronal dysfunction in genetic and toxin-induced models of Parkinson's disease in Drosophila.

Drosophila melanogaster has contributed significantly to the understanding of disease mechanisms in Parkinson's disease (PD) as it is one of the very few PD model organisms that allow the study of age-dependent behavioral defects, physiology and histology, and genetic interactions among different PD-related genes. However, there have been contradictory results from a number of recent reports regarding the loss of dopaminergic neurons in different PD fly models. In an attempt to re-evaluate and clarify this issue, we have examined three different genetic (α-synuclein, Pink1, parkin) and two toxin-based (rotenone and paraquat) models of the disease for neuronal cell loss. Our results showed no dopaminergic neuronal loss in all models tested. Despite this surprising result, we found additional phenotypes showing the dysfunctional status of the dopaminergic neurons in most of the models analyzed. A common feature found in most models is a quantifiable decrease in the fluorescence of a green-fluorescent protein reporter gene in dopaminergic neurons that correlates well with other phenotypes found for these models and can be reliably used as a hallmark of the neurodegenerative process when modeling diseases affecting the dopaminergic system in Drosophila. Analyzing three genetic and two toxin-based Drosophila models of Parkinson's disease (PD) through green fluorescent protein reporter and α-tyrosine hydroxylase staining, we have found the number of dopaminergic neurons to remain unchanged. Despite the lack of neuronal loss, we have detected a remarkable decrease in a reporter green-fluorescent protein (GFP) signal in dopaminergic neurons, suggesting an abnormal neuronal status that correlates with the phenotypes associated with those PD fly models.

Roles of Drosophila DJ-1 in survival of dopaminergic neurons and oxidative stress.

The loss of dopaminergic neurons in the substantia nigra is the pathological hallmark of Parkinson's disease (PD). While the etiology of sporadic PD remains elusive, an inherited form of early-onset familial PD is linked to mutations of DJ-1. To understand the biological function of DJ-1 and its relevance to the pathogenesis of PD, we investigated the function of DJ-1 using Drosophila. Drosophila possesses two homologs of human DJ-1: DJ-1alpha and DJ-1beta. We found that DJ-1alpha is expressed predominantly in the testis, while DJ-1beta is ubiquitously present in most tissues, resembling the expression pattern of human DJ-1. Loss-of-function DJ-1beta mutants demonstrated an extended survival of dopaminergic neurons and resistance to paraquat stress, but showed acute sensitivity to hydrogen peroxide treatment. We showed a compensatory upregulation of DJ-1alpha expression in the brain of the DJ-1beta mutant and demonstrated that overexpression of DJ-1alpha in dopaminergic neurons is sufficient to confer protection against paraquat insult. These results suggest that Drosophila homologs of DJ-1 play critical roles in the survival of dopaminergic neurons and response to oxidative stress.