The regional distribution and the chemical, chromatographic, and immunologic characterization of motilin brain peptides: the evidence for a difference between brain and intestinal motilin-immunoreactive peptides.

Motilin-like immunoreactive peptides (MLIPs) have been detected in the brain by radioimmunoassay (RIA), (Yanaihara, C., H. Sato, N. Yanaihara, S. Naruse, W. G. Forssman, V. Helmstaedter, T. Fujita, K. Yamaguchi, and K. Abe (1977) Adv. Exp. Biol. Med. 106: 269-283; Chey, W. Y., R. Escoffery, F. Roth, T. M. Chang, and H. Yajima (1980) Regul. Pept. Suppl. 1: 519; O'Donohue, T. L., M. C. Beinfeld, W. Y. Chey, T. M. Chang, G. Nilaver, E. A. Zimmerman, H. Yajima, H. Adachi, M. Roth, R. P. McDevitt, and D. M. Jacobowitz (1981) Peptides 2: 467-477). Previous studies (O'Donohue et al., 1981) demonstrated that MLIPs in rat brain probably differ chemically from porcine intestinal motilin (PIM), the first motilin peptide isolated. The possibility that this rat-pig difference represents a species difference was not examined in the previous study (O'Donohue et al., 1981), neither was the question of the cross-species distribution of MLIP. This study was initiated to examine brain MLIP distribution by RIA in three additional species: cow, pig, and guinea pig. The question of rat-pig species differences was addressed by characterizing MLIP in the brains of these species in comparison to PIM. By RIA, MLIPs were widely distributed in the brains of all species examined. MLIP concentration was highest in rat brain and lowest in pig brain. Some motilin antisera consistently detected less or no MLIPs in some brain regions of all species. Rat pituitary, pineal gland, and retina had substantially higher MLIP concentrations than did brain. MLIPs were abundant throughout the rat gastrointestinal tract and in some other peripheral organs.(ABSTRACT TRUNCATED AT 250 WORDS)