Adult health and transition stage-specific rotenone-mediated Drosophila model of Parkinson’s disease: Impact on late-onset neurodegenerative disease models

Abstract

Parkinson’s disease (PD) affects almost 1% of the population worldwide over the age of 50 years. Exposure to environmental toxins like paraquat and rotenone is a risk factor for sporadic PD which constitutes 95% of total cases. Herbicide rotenone has been shown to cause Parkinsonian symptoms in multiple animal models. Drosophila is an excellent model organism for studying neurodegenerative diseases (NDD) including PD. The aging process is characterized by differential expression of genes during different life stages. Hence it is necessary to develop life-stage-matched animal models for late-onset human disease(s) such as PD. Such animal models are critical for understanding the pathophysiology of age-related disease progression and important to understand if a genotropic drug/nutraceutical can be effective during late stages. With this idea, we developed an adult life stage-specific (health and transition phase, during which late-onset NDDs such as PD sets in) rotenone-mediated Drosophila model of idiopathic PD. Drosophila is susceptible to rotenone in dose-time dependent manner. Rotenone-mediated fly model of sporadic PD exhibits mobility defects (independent of mortality), inhibited mitochondrial complex I activity, dopaminergic (DAergic) neuronal dysfunction (no loss of DAergic neuronal number; however, reduction in rate-limiting enzyme tyrosine hydroxylase (TH) synthesis), and alteration in levels of dopamine (DA) and its metabolites; 3,4-Dihydroxyphenylacetic acid (DOPAC) and Homovanilic acid (HVA) in brain-specific fashion. These PD-linked behaviors and brain-specific phenotypes denote the robustness of the present fly model of PD. This novel model will be of great help to decipher life stage-specific genetic targets of small molecule mediated DAergic neuroprotection; understanding of which is critical for formulating therapeutic strategies for PD.

Sexual dysfunction precedes motor defects, dopaminergic neuronal degeneration, and impaired dopamine metabolism: Insights from Drosophila model of Parkinson’s disease

“…Immunostaining assay was performed following the protocol of Ayajuddin et al (2022) . In brief, 5 days old male OK flies were fixed in 4% paraformaldehyde (PFA) containing 0.5% TritonX-100, at room temperature for 2 h. The brains were then washed 5 times for 15 min duration each (75 min) at room temperature with phosphate-buffered saline (PBS) containing 0.1% Triton-X 100 (PBST).…”

“…Then the brains were embedded in VECTASHIELD ® mounting medium and proceeded for image acquisition on the same day. Mounting of the whole fly brain for fluorescence microscopy (Carl Zeiss, Axio Imager M2 with ZEN 2012 SP2 software, Germany) was done as described in Ayajuddin et al (2022) .…”

“…The quantification of anti-TH signals was also performed following the protocol described in Ayajuddin et al (2022) . In brief, prepared/stained brains (3–5 brains for each group) were viewed under a fluorescence microscope at a 40 × magnification.…”

Gene Set Enrichment Analysis and Genetic Experiment Reveal Changes in Cell Signaling Pathways Induced by α-Synuclein Overexpression

“…We performed qRT-PCR detection of the Drosophila TNF-α homologue eiger [27] and its two receptors, Grindelwald (Grnd) [28] and Wengen (Wgn) [29]. Tyrosine hydroxylase (TH) is the rate-limiting enzyme for catecholamine synthesis, catalyzes the hydroxylation of tyrosine to dopamine [30], and is widely used to immunolabel DA neurons in Drosophila [31][32][33][34][35][36]. We found that α-Syn.A30P overexpression with a tyrosine hydroxylase promoter driver (TH-Gal4) [37] in dopamine neurons significantly increased the levels of eiger and Grnd in the head (Figure 7A).…”

Polyvinylpyrrolidone-Capped Copper Oxide Nanoparticles-Anchored Pramipexole Attenuates the Rotenone-Induced Phenotypes in a Drosophila Parkinson’s Disease Model

“…D. melanogaster is an excellent model organism in neuroscience research and is used for investigating neurodegenerative disorders such as PD, Alzheimer’s disorder (AD), epilepsy, and so forth. − D. melanogaster strongly depicts most allied PD in humans, such as DJ-1, parkin, PINK1 (PTEN-induced putative kinase1), and leucine-rich repeat kinase 2 (LRRK2) repeats .…”