A. Stricker-krongrad et al., Central and peripheral dysregulation of melanin-concentrating hormone in obese Zucker rats, MOL BRAIN R, 92(1-2), 2001, pp. 43-48
Melanin concentrating hormone (MCH) is a peptide synthesized in the lateral
hypothalamus which stimulates food ingestion and leptin secretion in roden
ts. In this experiment, we measured the expressions of MCH as well as of it
s receptor (SLC-1) in the hypothalamus of obese hyperphagic and lean Zucker
rats by quantitative real time RT-PCR. MCH mRNA expression in the obese ra
ts was significantly increased by a factor of five (P <0.01) whereas expres
sion of SLC-1 was decreased by more than 50% (P <0.05). Circulating levels
of leptin and MCH were increased in the plasma of obese Zucker rats when co
mpared to lean rats (38-fold and 1.7-fold, respectively, P <0.001 and P <0.
01). However, individual MCH levels were not directly correlated to leptin
levels in the lean (functional leptin receptor) or in the obese (non-functi
onal leptin receptor) Zucker rats. These results indicate that the absence
of leptin signaling in rats is associated with an increased hypothalamic ex
pression and circulating release of MCH, contributing to their obesity synd
rome. (C) 2001 Elsevier Science BY All rights reserved.