Differential protection against MPTP or methamphetamine toxicity in dopamine neurons by deletion of ppN/OFQ expression.
Nociceptin (N/OFQ) is an endogenous neuropeptide that plays a role in the behavioral deficits associated with Parkinson's disease (PD). The purpose of the present study was to characterize the protective effects of prepro (pp)N/OFQ gene deletion against two dopamine toxins, MPTP and methamphetamine (METH). Results demonstrate that ppN/OFQ gene deletion attenuates the loss of both the number of tyrosine hydroxylase (TH)-positive neurons in the substantia nigra pars compacta (SNpc) and loss of TH and vesicular monoamine transporter-2 (VMAT) immunoreactivity in the caudate putamen (CPu) of MPTP-treated mice. This protection was unaffected by age or gender, although, when loss of TH exceeded 90% in 5-6 month-old mice, the protective effect was greatly diminished. In contrast, METH administration preferentially damaged dopaminergic terminals in the CPu with little effect on dopamine neurons in the SNpc, an effect not reversed by ppN/OFQ gene deletion. To determine if N/OFQ and MPP+ act directly and synergistically on dopamine neurons, differentiated SH-SY5Y cells were incubated with N/OFQ and/or MPP+. N/OFQ did not increase MPP+-mediated cell loss, suggesting an indirect action of N/OFQ. These studies demonstrate that inhibition of the endogenous N/OFQ system may represent a new therapeutic target for prevention of neuronal loss associated with PD.
Brown
Jeffrey M
JM
Department of Pharmacology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, USA. jbrown@usuhs.mil
Gouty
Shawn
S
Iyer
Varsha
V
Rosenberger
John
J
Cox
Brian M
BM
D015632:1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine / Q000037:antagonists & inhibitors*; D000375:Aging / Q000502:physiology; D000818:Animals; D015153:Blotting, Western; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004298:Dopamine / Q000502:physiology*; D015259:Dopamine Agents / Q000633:toxicity*; D018765:Dopamine Uptake Inhibitors / Q000037:antagonists & inhibitors* / Q000633:toxicity*; D005260:Female; D017353:Gene Deletion; D007091:Image Processing, Computer-Assisted; D007150:Immunohistochemistry; D008297:Male; D008694:Methamphetamine / Q000037:antagonists & inhibitors* / Q000633:toxicity*; D051379:Mice; D018345:Mice, Knockout; D009474:Neurons / Q000187:drug effects*; D011498:Protein Precursors / Q000235:genetics / Q000502:physiology*; D011957:Receptors, Opioid / Q000235:genetics / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012727:Sex Characteristics
D015259:Dopamine Agents; D018765:Dopamine Uptake Inhibitors; D011498:Protein Precursors; D011957:Receptors, Opioid; C121527:prepronociceptin; D008694:Methamphetamine; D015632:1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine; D004298:Dopamine