Impact of novel palmitoylated prolactin-releasing peptide analogs on metabolic changes in mice with diet-induced obesity

PLoS One. 2017 Aug 18;12(8):e0183449. doi: 10.1371/journal.pone.0183449. eCollection 2017.

Abstract

Analogs of anorexigenic neuropeptides, such as prolactin-releasing peptide (PrRP), have a potential as new anti-obesity drugs. In our previous study, palmitic acid attached to the N-terminus of PrRP enabled its central anorexigenic effects after peripheral administration. In this study, two linkers, γ-glutamic acid at Lys11 and a short, modified polyethylene glycol at the N-terminal Ser and/or Lys11, were applied for the palmitoylation of PrRP31 to improve its bioavailability. These analogs had a high affinity and activation ability to the PrRP receptor GPR10 and the neuropeptide FF2 receptor, as well as short-term anorexigenic effect similar to PrRP palmitoylated at the N-terminus. Two-week treatment with analogs that were palmitoylated through linkers to Lys11 (analogs 1 and 2), but not with analog modified both at the N-terminus and Lys11 (analog 3) decreased body and liver weights, insulin, leptin, triglyceride, cholesterol and free fatty acid plasma levels in a mouse model of diet-induced obesity. Moreover, the expression of uncoupling protein-1 was increased in brown fat suggesting an increase in energy expenditure. In addition, treatment with analogs 1 and 2 but not analog 3 significantly decreased urinary concentrations of 1-methylnicotinamide and its oxidation products N-methyl-2-pyridone-5-carboxamide and N-methyl-4-pyridone-3-carboxamide, as shown by NMR-based metabolomics. This observation confirmed the previously reported increase in nicotinamide derivatives in obesity and type 2 diabetes mellitus and the effectiveness of analogs 1 and 2 in the treatment of these disorders.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Binding, Competitive
  • CHO Cells
  • Cricetinae
  • Cricetulus
  • Diet*
  • Male
  • Metabolomics
  • Mice
  • Mice, Inbred C57BL
  • Nuclear Magnetic Resonance, Biomolecular
  • Obesity / etiology
  • Obesity / metabolism*
  • Peptides / chemistry
  • Peptides / pharmacology*
  • Prolactin-Releasing Hormone / chemistry
  • Prolactin-Releasing Hormone / metabolism*
  • beta-Lactamases / metabolism

Substances

  • Peptides
  • Prolactin-Releasing Hormone
  • beta-Lactamases

Grants and funding

This research was financially supported by the Grant Agency of the Czech Republic (Grants No. 15-08679S and 13-14105S) and by institutional supports (RVO: 61388963, 67985823, and 61388971). This project was conducted within the "Prague Infrastructure for Structure Biology and Metabolomics" through the financial support of the Operational Program Prague – Competitiveness (Project No.: CZ.2.16/3.1.00/24023).