A preliminary investigation of the role of melanin-concentrating hormone (MCH) and its receptors in appetite regulation of winter flounder (Pseudopleuronectes americanus)

In order to better understand the role of melanin-concentrating hormone (MCH) in the regulation of appetite in fish, the mRNAs of two forms of MCH, prepro-MCH and MCH2, and two forms of MCH receptors, MCH-R1 and MCH-R2, were isolated from winter flounder (Pseudopleuronectes americanus). In addition, the mRNA expressions of these peptides and their receptors were determined under fed and fasted conditions. Both MCHs are expressed in forebrain and midbrain, as well as peripheral tissues including gut and gonads. Both MCH-Rs are ubiquitously expressed in the brain and periphery. Fasting induced an increase in the expression levels of MCH and MCH-R1 mRNAs in optic tectum/thalamus and hypothalamus but had no effect on either MCH2 or MCH-R2 mRNA expressions. Our results suggest that MCH and MCH-R1, but not MCH2 and MCH-R2 might have a role in the regulation of appetite in flounder.

► Two forms of MCH and two forms of MCH receptors were isolated from winter flounder. ► MCH and MCHRs are expressed in brain and periphery, including gut and gonads. ► Fasting induced an increase in MCH and MCH-R1 brain expression levels. ► MCH and its receptor (MCH-R1) might have an orexigenic role in winter flounder.