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Parkinson's disease (PD) is the most common neurodegenerative movement disorder in humans. Despite intense investigations, effective therapies are not yet available to halt the progression of PD. Gemfibrozil, a Food and Drug Administration-approved lipid-lowering drug, is known to decrease the risk of coronary heart disease by increasing the level of high-density lipoprotein cholesterol and decreasing the level of low-density lipoprotein cholesterol. This study underlines the importance of gemfibrozil in protecting dopaminergic neurons in an animal model of PD. Oral administration of the human equivalent dose of gemfibrozil protected tyrosine hydroxylase (TH)-positive dopaminergic neurons in the substantia nigra pars compacta and TH fibers in the striatum of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-insulted mice of both sexes. Accordingly, gemfibrozil also normalized striatal neurotransmitters and improved locomotor activities in MPTP-intoxicated mice. Gemfibrozil-mediated protection of the nigrostriatal and locomotor activities in WT but not PPARα−/−mice from MPTP intoxication suggests that gemfibrozil needs the involvement of peroxisome proliferator-activated receptor α (PPARα) in protecting dopaminergic neurons. While investigating further mechanisms, we found that gemfibrozil stimulated the transcription of glial-derived neurotrophic factor (GDNF) gene in astrocytes via PPARα and that gemfibrozil protected nigral neurons, normalized striatal fibers and neurotransmitters, and improved locomotor activities in MPTP-intoxicated Gfafcremice, but notGdnfΔastromice lacking GDNF in astrocytes. These findings highlight the importance of the PPARα-dependent astroglial GDNF pathway in gemfibrozil-mediated protection of dopaminergic neurons in an animal model of PD and suggest the possible therapeutic use of gemfibrozil in PD patients.SIGNIFICANCE STATEMENTIncreasing the level of glial cell-derived neurotrophic factor (GDNF) in the brain is important for the protection of dopamine neurons in Parkinson's disease (PD). Although gene manipulation and GDNF protein infusion into the brain are available options, it seems from the therapeutic angle that the best option would be to stimulate/induce the production of GDNFin vivoin the brain of PD patients. Here, we delineate that gemfibrozil, a lipid-lowering drug, stimulates GDNF in astrocytes via peroxisome proliferator-activated receptor α (PPARα). Moreover, gemfibrozil protected nigral neurons, normalized striatal fibers and neurotransmitters, and improved locomotor activities from MPTP toxicity via the PPARα-dependent astroglial GDNF pathway. These studies highlight a new property of gemfibrozil and suggest its possible therapeutic use in PD patients.

Myalgic Encephalomyelitis and chronic fatigue syndrome is a multisystem illness characterized with extreme muscle fatigue associated with pain, neurocognitive impairment, and chronic inflammation. Despite intense investigation, the molecular mechanism of this disease is still unknown. Here we report two independent case-control studies to demonstrate that autophagy proteins are strongly upregulated in the serum of ME/CFS patients indicative of severe impairment in metabolic events of autophagy. Serum samples collected from two healthy and two age-matched patients were assayed for protein aggregation, screened for autophagy-related factors via an antibody array, quantified with densitometric analyses, and finally reconfirmed with ELISA analyses. Based on that double-blinded and gender-balanced study, the levels of ATG13, p62, and alpha-synuclein (α-syn) were found to be consistently elevated in the serum samples of these two ME/CFS patients. Moreover, our microglia-based oxidative stress response study and nitrite analyses indicated that serum samples of ME/CFS patients evoked the production of reactive oxygen species (ROS) and nitrite in human HMC3 microglial cells, whereas neutralization of ATG13 was shown to strongly diminish the production of ROS and nitrite demonstrating the de novo effect bloodborne autophagy factors on inducing the stress response in microglial cells. Collectively, our results indicate that the impairment of autophagy followed by upregulations of autophagy markers especially ATG13 in serum could be a pathological hallmark in ME/CFS.

Nuclear receptor related 1 protein (Nurr1) is an important transcription factor required for differentiation and maintenance of midbrain dopaminergic (DA) neurons. Since decrease in Nurr1 function either due to diminished expression or rare mutation is associated with Parkinson’s disease (PD), upregulation of Nurr1 may be beneficial for PD. However, such mechanisms are poorly understood. This study underlines the importance of peroxisome proliferator-activated receptor (PPAR)α in controlling the transcription of Nurr1. Our mRNA analyses followed by different immunoassays clearly indicated that PPARα agonist gemfibrozil strongly upregulated the expression of Nurr1 in wild-type, but not PPARα(−/−), DA neurons. Moreover, identification of conserved PPRE in the promoter of Nurr1 gene followed by chromatin immunoprecipitation analysis, PPRE luciferase assay, and manipulation of Nurr1 gene by viral transduction of different PPARα plasmids confirmed that PPARα was indeed involved in the expression of Nurr1. Finally, oral administration of gemfibrozil increased Nurr1 expression in vivo in nigra of wild-type, but not PPARα(−/−), mice identifying PPARα as a novel regulator of Nurr1 expression and associated protection of DA neurons.