<b>MOTILIN-LIKE IMMUNOREACTIVITY IN PORCINE, CANINE, HUMAN AND RAT </b><b>TISSUES </b>

Abstract

Eight antisera were obtained from three rabbits and two guinea pigs immunized with synthetic porcine motilin and from three guinea pigs immunized with [15-Glutamine]-rnotilin. Specificities of the antisera were characterized and three of them having different specificities were used in radioimrnunoassay to examine motilin immunoreactivity in extracts of canine, porcine, human and rat gastrointestinal tissues. Immunoreactive motilin in rat tissue extract showed a very low cross-reaction in all of the assay systems used, suggesting a relatively high degree of variation in the amino acid sequence of rat motilin as compared with that of porcine motilin. In the assay system using the carboxyl-terminal specific antiserum R-1105, the inhibition curves of canine, porcine and human tissue extracts were superimposable on that of synthetic porcine motilin. However, in the assay system using antiserum R-1106 or GP-1103, the inhibition curve of canine tissue extract was not parallel to that of synthetic motilin. Human intestinal tissue extract also showed slightly weak inhibition in the assay system with antiserum R-1106. The motilin concentrations in duodenum extracts of the dog, pig and man measured by four different immunoassay systems were variable depending on the species of the tissue and antiserum used. Gel filtration of human duodenum and jejunum mucosa showed that the tissues contain three major components with motilin-like immunoreactivity. The results suggest either the presence of degradation products of motilin precursor or the existence of a new family of related peptides.KEY WORDS motilin-like immunoreactivity / radioimmunoassay / tissue extracts Bollman fistula, duodenal alkalinization resulted in an increase in serum motilin with a corPorcine motilin is a docosapeptide (1, 15): H-Phe-Val-Pro-Ile-Phe-Thr-Tyr-Gly-Glu-LeuGln-Arg-Met-Gln-Glu-Lys-Glu-Arg-Asn-LysGly-Gln-OH, which has been isolated from the duodenal mucosa (2), In dogs with a denervated pouch of the fundus of the stomach and Mann-

Radioimmunoassay with Heterologous Antibody(Hetero-Antibody RIA): Utilization of Highly Cross-Reactive Antibody Present in Polyclonal Antiserum.

“…3A). This might be in accordance with the observations by Yanaihara and his coworkers [9,10], who reported that the assay values for motilin depend on antisera with different specificity to epitopes in the motilin molecule.…”

Can a non-gut mesenchyme support differentiation of gut endocrine cells?

“…These tests for specificity included pre-absorption of every primary antiserum to a gut peptide with the relevant antigen (see Table 2) for 16-22 h at 4 ~ C, substitution of the primary antiserum with non-immune serum of the species in which the primary antiserum had been raised or, in the case of the monoclonal antibody, with a Yanaihara et al (1980) b These gifts are gratefully acknowledged a These gifts are gratefully acknowledged mouse ascites fluid containing IgG2a, and with diluent alone. All antisera to gut peptides were pre-absorbed in turn with serotonin and each of the gut peptides available (see Rawdon and Andrew ]981) and applied to sections of normal chick gut to test for crossreactivity.…”

Heterogeneity of Immunoreactive Motilin

“…We have previously characterized five anti-synthetic porcine motilin sera and each of the antisera was found to have different region-specificities (Yanaihara et al, 1978a(Yanaihara et al, , 1980. Radioimmunoassays using these antisera gave different dose-response curves for motilin immunoreactivity in the canine and rat duodenal extracts (Yanaihara et al, 1980).…”