Acylated and unacylated ghrelin confer neuroprotection to mesencephalic neurons. (4th December 2017)

• Record Type: Journal Article
• Authors: Wagner, Johanna; Vulinović, Franca; Grünewald, Anne; Unger, Marcus M.; Möller, Jens C.; Klein, Christine; Michel, Patrick P.; Ries, Vincent; Oertel, Wolfgang H.; Alvarez-Fischer, Daniel
• Is Part Of: Neuroscience. Volume 365(2017)
• Page Start: 137
• Page End: 145
• Publication Date: 2017-12-04
• Subjects: AG acylated -- BBB blood–brain-barrier -- CCCP carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone -- GHSR1a growth hormone secretagogue receptor 1a -- GOAT ghrelin O-acyltransferase -- mDA mesencephalic dopaminergic -- NeuN neuronal nuclei -- OCR oxygen consumption rates -- PD Parkinson disease -- UAG unacylated -- VGCC voltage-gated Ca2+ channels; Parkinson disease -- ghrelin -- ghrelin receptor -- mitochondrial respiratory chain -- MPP+ -- 3-NP; Neurochemistry -- Periodicals; Neurophysiology -- Periodicals; Neurology -- Periodicals; Neurochimie -- Périodiques; Neurophysiologie -- Périodiques; Neurochemistry; Neurophysiology; Electronic journals; Periodicals; Electronic journals; 612.8
• DOI: 10.1016/j.neuroscience.2017.09.045
• Languages: English
• ISSNs: 0306-4522

Abstract

Highlights: Both AG and UAG confer neuroprotective effects against complex I and II inhibitors. The required concentration of UAG is 10-fold higher than that of AG. The effect is dependent on the calcium influx via the L-type Ca 2+ channels. Blockage of GHS-R1a or GOAT, does not impact effect of UAG, whereas it does for AG. Conclusion: Not only AG and UAG, however through different mechanisms. Abstract: The polypeptide ghrelin is an endogenous ligand at the growth hormone secretagogue receptor 1a. To ghrelin multiple functions have been ascribed including promotion of gastrointestinal motility. Postprandial ghrelin levels have been reported to be reduced in patients suffering from Parkinson disease (PD). Experimental studies revealed neuroprotective effects of ghrelin in different PD models. The purpose of the present study was (i) to further elucidate the mechanism underlying the neuroprotective action of ghrelin and (ii) to determine whether these effects occur with both the acylated and the unacylated form. The study was conducted in primary mesencephalic cultures treated with mitochondrial complex I and complex II inhibitors. We show that protective effects of ghrelin against complex I inhibition with MPP + were independent of the acylation status of ghrelin, although acylated ghrelin appeared to be more potent. Protection by both forms was also observed when neurons were exposed to the complex II inhibitor 3-NP. Both forms led to higher oxygen consumption rates upon electron transport chain uncoupling, indicating that the two peptides may exert uncoupling effects themselves. We demonstrate that the rescue provided by ghrelin required calcium influx through L-type voltage-gated calcium channels. Whereas the protective effects of acylated ghrelin required receptor binding, effects of the unacylated form remained unaffected by treatment with a ghrelin receptor antagonist. Importantly, inhibition of ghrelin O-acyltransferase failed to reduce the activity of unacylated ghrelin. Overall, our data suggest that both acylated and unacylated ghrelin afford protection to dopamine neurons but through mechanisms that only partially overlap.