Appetite-Boosting Property of Pro-Melanin-Concentrating Hormone_131–165 (Neuropeptide-Glutamic Acid-Isoleucine) Is Associated with Proteolytic Resistance

Abstract

Melanin-concentrating hormone (MCH) is a cyclic neuropeptide, with a major role in stimulation of feeding behavior in mammals. MCH signals in the brain occur via two seventransmembrane G protein-coupled receptors, namely MCH1 (SLC-1, MCH 1 , MCH-R1, or MCH-1R) and MCH2 (SLT, MCH 2 , MCH-R2, or MCH-2R). In this study, we demonstrate that the pro-MCH 131-165 peptide neuropeptide-glutamic acid-isoleucine (NEI)-MCH is more potent than MCH in stimulating feeding in the rat. Using rat MCH1-expressed human embryonic kidney 293 cells, we show that NEI-MCH exhibits 5-fold less affinity in a binding assay and 2-fold less potency in a cAMP assay than MCH. A similar 7-to 8-fold shift in potency was observed in a Ca 2ϩ i assay using rat MCH1 or human MCH2-transfected Chinese hamster ovary cell models. This demonstrates that NEI-MCH is not a better agonist than MCH at either of the MCH receptors. Then, we compared the proteolysis resistance of MCH and NEI-MCH to rat brain membrane homogenates and purified proteases. Kinetics of peptide degradation using brain extracts indicated a t 1/2 of 34.8 min for MCH and 78.5 min for NEI-MCH with a specific pattern of cleavage of MCH but not NEI-MCH by exo-and endo-proteases. Furthermore, MCH was found highly susceptible to degradation by aminopeptidase M and endopeptidase 24.11, whereas NEI-MCH was fully resistant to proteolysis by these enzymes. Therefore, our results strongly suggest that reduced susceptibility to proteases of NEI-MCH compared with MCH account for its enhanced activity in feeding behavior. NEI-MCH represents therefore the first MCH natural functional "superagonist" so far described.

Narcolepsy patients have antibodies that stain distinct cell populations in rat brain and influence sleep patterns

“…administration of acetylated αMSH (52). It has been shown that NEI-MCH propeptide (preproMCH ) represents a functional superagonist of the mature MCH peptide, because it is much more resistant to proteolytic digestion (53). However, NEI-MCH was detected mostly in peripheral organs, whereas the matured MCH and NEI were found to be the main forms in the CNS, at least during resting conditions (54).…”

The Role of Melanin-Concentrating Hormone and Its Receptors in Energy Homeostasis

“…The highest doses of S38151, 30 and 50 nmol per rat, completely blocked MCH-induced food intake for 6 h (Audinot et al, 2009). The orexigenic effect of proMCH (131–165), which is more potent than MCH in stimulating feeding, was blocked for 2 h by 50 nmol/kg of S38151 administered ICV (Maulon-Feraille et al, 2002; Della-Zuana et al, 2012). Once daily ICV injections of 20 nmol/kg of S38151 into male Zucker fa/fa rats, reduced food intake, water intake, motility, and body weight (Della-Zuana et al, 2012).…”

New aspects of melanocortin signaling: A role for PRCP in α-MSH degradation

“…NEI, a peptide originating from the pro-MCH 131–164 region, has been found to be stronger than MCH in stimulating rat feeding behavior [134]. Thus, its effect on food intake would not be in line with the phenotype that was observed in the PRCP-ablated mouse.…”