Rat brain regional distribution and spinal cord neuronal pathway of FLFQPQRF-NH2, a mammalian FMRF-NH2-like peptide.
Phe-Leu-Phe-Gln-Pro-Gln-Arg-Phe-NH2 (F-8-NH2) is a peptide, originally detected by FMRF-NH2 antisera, and subsequently isolated from bovine brain. Using a specific radioimmunoassay for F-8-F-NH2, we have examined the regional distribution and characteristics of F-8-F-NH2 immunoreactivity (IR) in rat brain, spinal cord and pituitary gland. In CNS, F-8-F-NH2-IR is highly concentrated in the spinal cord, hypothalamus and pons-medulla (368, 202 and 136 fmol per mg protein, respectively); lowest values are in the cortex and hippocampus. A modest rostrocaudal gradient of F-8-F-NH2-IR was observed; levels in the sacral cord are 50% higher than in the cervical cord. Dorsal cord content is 8 times higher than in the ventral cord. Dorsal rhizotomy failed to change F-8-F-NH2-IR in the affected regions of the spinal cord while significantly reducing substance P levels. F-8-F-NH2-IR was significantly decreased caudal to a spinal transection, indicating the presence of a descending pathway within the spinal cord. The highest concentration of F-8-F-NH2-IR (1008 fmol per mg protein) was found in the neurointermediate lobe of the pituitary, while no F-8-F-NH2-IR could be detected in the anterior lobe. Immunohistochemically, F-8-F-NH2-IR was confined to nerve terminal-like structures in the neural lobe. The anterior and intermediate lobes were devoid of immunoreactive structures. HPLC characterization of F-8-F-NH2-IR in the dorsal spinal cord, medulla-pons and pituitary revealed one major immunoreactive peak which is more hydrophobic than bovine F-8-F-NH2. In addition to this material, the hypothalamus was found to contain another, more abundant F-8-F-NH2-immunoreactive peak. Analysis of F-8-F-NH2-IR from posterior pituitary with various antisera having differing affinities for F-8-F-NH2 and gamma 1-MSH indicates that the F-8-F-NH2-IR of rat pituitary is not due to gamma 1-MSH. The high concentration of F-8-F-NH2-like peptide in the dorsal spinal cord supports a role in mediating nociceptive transmission while the localization of F-8-F-NH2-IR in the posterior pituitary suggests an additional autonomic or endocrine function.
Laboratory of Preclinical Pharmacology, National Institute of Mental Health, St. Elizabeth Hospital, Washington, DC 20032.
E A
EA
Majane
P
P
Panula
H Y
HY
Yang
D000818:Animals; D001921:Brain / Q000378:metabolism*; D019835:FMRFamide; D008297:Male; D009479:Neuropeptides / Q000378:metabolism; D009842:Oligopeptides / Q000378:metabolism*; D010902:Pituitary Gland / Q000378:metabolism*; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains; D013116:Spinal Cord / Q000378:metabolism*
D009479:Neuropeptides; D009842:Oligopeptides; D019835:FMRFamide; C053651:phenylalanyl-leucyl-phenylalanyl-glutaminyl-prolyl-glutaminyl-arginyl-phenylalaninamide