Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.24.64 (MPP)
 1,876 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The neurotoxin MPTP reproduces most of the biochemical and pathological hallmarks of Parkinson's disease. In addition to reactive oxygen species (ROS) generated as a consequence of mitochondrial complex I inhibition, microglial NADPH-derived ROS play major roles in the toxicity of MPTP. However, the exact mechanism regulating this microglial response remains to be clarified. The peptide angiotensin II (AII), via type 1 receptors (AT1), is one of the most important inflammation and oxidative stress inducers, and produces ROS by activation of the NADPH-oxidase complex. Brain possesses a local angiotensin system, which modulates striatal dopamine (DA) release. However, it is not known if AII plays a major role in microglia-derived oxidative stress and DA degeneration. The present study indicates that in primary mesencephalic cultures, DA degeneration induced by the neurotoxin MPTP/MPP(+) is amplified by AII and inhibited by AT1 receptor antagonists, and that protein kinase C, NADPH-complex activation and microglial activation are involved in this effect. In mice, AT1 receptor antagonists inhibited both DA degeneration and early microglial and NADPH activation. The brain angiotensin system may play a key role in the self-propelling mechanism of Parkinson's disease and constitutes an unexplored target for neuroprotection, as previously reported for vascular diseases.
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PMID:The inflammatory response in the MPTP model of Parkinson's disease is mediated by brain angiotensin: relevance to progression of the disease. 1924 63

It has recently been shown that the dopaminergic cell loss induced by neurotoxins is enhanced by brain angiotensin II (AII) via type 1 receptors (AT1). However, the mechanisms involved in the dopaminergic degeneration and the brain inflammatory effects of AII have not been clarified. The RhoA-Rho-Kinase (ROCK) pathway may play a critical role in the inflammatory and oxidative effects of AII. In the substantia nigra of mice, administration of the dopaminergic neurotoxin MPTP induced an increase in the expression of RhoA and ROCK II mRNA levels and ROCK activity, which were inhibited by AT1 receptor deletion (i.e., in AT1a null mice treated with MPTP). Administration of the ROCK inhibitor Y-27632 or AT1 deletion induced a significant decrease in MPTP-induced microglial activation and dopaminergic cell death. In rat primary mesencephalic cultures treated with MPP(+), the increase in dopaminergic cell loss induced by AII administration was also inhibited by treatment with Y27632. Intense expression of ROCK II was observed in the microglial cells in the substantia nigra of mice treated with MPTP, and the major role of the microglial ROCK was confirmed by comparing mesencephalic cultures with and without microglia. Activation of the RhoA/ROCK pathway is involved in the MPTP-induced dopaminergic degeneration, and in the enhancing effect of AII/AT1 activation on the microglial response and dopaminergic degeneration. ROCK inhibitors and AT1 receptor antagonists may provide new neuroprotective strategies against the progression of Parkinson's disease.
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PMID:Involvement of microglial RhoA/Rho-kinase pathway activation in the dopaminergic neuron death. Role of angiotensin via angiotensin type 1 receptors. 2254 54