Distribution of neuropeptide Y-like immunoreactivity in the brain of the bichir, Polypterus senegalus, with special regard to the terminal nerve.
The distribution of neuropeptide Y (NPY)-like immunoreactivity in the brain of the bichir, Polypterus senegalus, was examined immunohistochemically. NPY-like immunoreactivity was distributed widely in the brain, with the highest density in the diencephalon. NPY-positive perikarya were found in various areas, including the terminal nerve, the pallial zones of the telencephalon, the periventricular preoptic nucleus, the thalamic nucleus, the ventral hypothalamus of the diencephalon, the tegmentum of the mesencephalon, and the area intermedioventralis of the rhombencephalon. In the hypothalamus, NPY-positive liquor-contacting neurons were frequently observed. Immunoreactive neuron-like cells also appeared in the distal lobe of the hypophysis. NPY fibers were densely distributed in the ventral telencephalon, the hypothalamus, and the ventrolateral area of the rhombencephalon. They were also demonstrated in the terminal nerve. In the hypophysis, NPY fibers were dense in the median eminence, but sparse in the neural lobe. Electron-microscopic double immunostaining of the terminal nerve revealed the coexistence of NPY-like antigen with gonadotropin-releasing hormone-like and molluscan cardioexcitatory tetrapeptide-like antigens in the same cytoplasmic granules. These results suggest that NPY or a related substance is involved in neuroregulation of various areas of the bichir brain, by mainly acting as a neurotransmitter or neuromodulator.
Chiba
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Department of Biology, Nippon Dental University School of Dentistry at Niigata, Niigata 951, Japan.
D000818:Animals; D001921:Brain / Q000033:anatomy & histology; D001923:Brain Chemistry; D019835:FMRFamide; D005260:Female; D005399:Fishes; D007987:Gonadotropin-Releasing Hormone / Q000032:analysis; D008297:Male; D009478:Neuropeptide Y / Q000032:analysis*; D009479:Neuropeptides / Q000032:analysis; D010903:Pituitary Gland, Anterior / Q000737:chemistry
D009478:Neuropeptide Y; D009479:Neuropeptides; D007987:Gonadotropin-Releasing Hormone; D019835:FMRFamide