Melanin concentrating hormone (MCH) is a peptide conserved from fish to mammal, and well known as an orexigenic neuropeptide in mammals. Recently, we found MCH-immunopositive fibers in the median eminence of a basal actinopterygian fish, Polypterus senegalus, that is located in the phylogenetic branch of fishes and tetrapod. However, the functions of MCH on the endocrine cells in the adenohypophysis are unknown. In this study, we examined the expression of MCH receptors in the gland of this fish, and their intracellular signal transductions. Phylogenetic analysis showed that P. senegalus has two types of MCH receptor 1 (MCHR1) and two types of MCH receptor 2 (MCHR2), that are close to the MCH receptors of mammal or teleost. In situ hybridization showed that mammal-like MCHR2 (m-MCHR2) and teleost-like MCHR2 (t-MCHR2) are expressed in the endocrine cells of the pars distalis of the gland, that is homologous to the anterior pituitary gland of mammal. HEK293 cells, which were transfected with these receptors separately, showed that both MCHR2s increase intracellular Ca²⁺, and that t-MCHR2, but not m-MCHR2, inhibits the activity of the adenylate cyclase in a concentration-dependent manner. These findings suggest that two types of the MCH receptor 2 regulate release and/or production of adenohypophyseal hormone in this fish.