Distribution of melanin-concentrating hormone-like immunoreactivity in the central nervous system of Rana esculenta

The distribution of salmon and rat melanin-concentrating hormone (MCH)-like and neuropeptide glutamate-isoleucine (NEI)-like immunoreactivity in the brain and spinal cord of the frog Rana esculenta was studied with immunohistochemistry. In the telencephalon, only fibers showed immunoreactivity in the olfactory bulb, lateral pallium, diagonal band, septum, and the amygdala. Immunoreactive fibers were abundant in all diencephalic structures, except the optic tract, the visual neuropils, and the habenula. Several cells in the central thalamic nucleus and a few in the suprachiasmatic nucleus were stained with the MCH antisera. Cells and their processes were intensely stained in the dorsal hypothalamus with the MCH and NEI antisera. Immunoreactive fibers were found in all tegmental nuclei and the white matter of the mesencephalon. They formed terminal plexuses in the deep layers of the optic tectum and the laminar nucleus of the torus semicircularis. Immunoreactive fibers were sparse in the rhombencephalon and the spinal cord.