Bombesin-like Peptides

Finally, RNA editing can be involved, as in the case of the amphibian bombesin-like peptides, where nucleotides in the mRNA are changed and the final protein is not a direct reflection of the sequence encoded in the gene. RNA editing is also seen in the glutamate (Ch. 15) and serotonin receptors (Ch. 13 and Ch. 15) and probably will be found elsewhere as detection methods become more sophisticated. 

On reversed-phase HPLC, the sulfones usually appear in an intermediate position between the more hydrophobic t t[CH2-S] peptide and the more polar t t[CH2—SO] sulfoxides, much as seen in the amino acid analysis by oxidation of Met.162 Unlike sulfoxides, once formed, sulfones are resistant to reduction to sulfides or sulfoxides.1[5T Incorporation of the tp[CH2—S] element and its oxidized counterparts into litorin (positions 8-9), a bombesin-like peptide, gives rise to receptor antagonists that are more potent when in the sulfoxide forms than in the sulfone form. 

GRP 119) 53 was isolated from porcine mucosae and causes gastrin secretion. The C-terminal decapeptide of GRP is, with the exception of His20, identical with that of bombesin 54, and also coincides with the sequence of the decapeptide neuromedin C 119b,c) [Gly18-Met27]-GRP. Neuromedin C, a porcine spinal-cord peptide that can also be regarded as a bombesin-like peptide, exerts stimulating effects on rat uterine smooth muscle and functions as a neuromediator in the neural communication systems of mammals. 

Recently Moody et al.,22) discovered that the C-terminal partial sequence of bombesin and bombesin-like peptides (BLPs) can function as autocrine growth factors in human small-cell lung cancer (SCLC) cell lines. 

Varga et al. (1995) determined gastric emptying in rats 5 min after a 3 ml intragastric load of 0.9 % NaCl using phenol red as marker in order to define which bombesin receptors are involved in the delay of gastric emptying by bombesin-like peptides. 

The majority of experimental evidence supports the conclusion that bombesin-like peptides stimulate the activity of TIDA neurons and thereby inhibit pituitary prolactin secretion. Indeed, bombesin administration does not suppress a-methyltyrosine- or haloperidol-induced prolactin secretion suggesting that pharmacological impairment of TIDA neuronal function prevents the prolactin inhibitory actions of bombesin (Collu et al., 1983 Buydens et al., 1988). Moreover, bombesin-like peptides block both opiate -and stress-induced prolactin secretion (Tache et al., 1979 Matsushita et al., 1983 Buydens et al., 1988), prolactin secretory responses known to be due, at least in part, to suppression of the activity of TIDA neurons (Moore and Lookingland, 1995). Central administration of bombesin increases DA synthesis and metabolism in whole hypothalamus (Widerlov... 

Battey J, Wada E (1991) Two distinct receptor subtypes for mammalian bombesin-like peptides. Trends in Neurosci 74 524-528. 

Lin J-Y, Pan J-T (1994) Stimulatory effects of bombesin-like peptides on hypothalamic arcuate neurons in rat brain slices. Brain Res Bull 35 241-246. 

Spindel ER, Giladi E, Segerson TP, Nagalla S (1993) Bombesin-like peptides of ligands and receptors. Recent Prog Horm Res 45 365-391. 

Walsh JH, Wong HC, Dockray GJ (1979) Bombesin-like peptides in mammals. Fed Proc 35 2315-2319. 

New initiatives towards the development of anorectic treatments for obesity are centring on satiety mechanisms of some gastrointestinal peptide hormones, especially within the CNS, including amylin, CCK, and bombesin-like peptides. See amylin receptor agonists cholecystokinin RECEPTOR agonists bombesin receptor agonists. 

Several other gut peptides such as en-terostatin or gastrin-releasing-peptide (and other bombesin-like peptides) are also involved in initiating satiation responses after food intake. The roles of these peptides in regulating food intake have been reviewed elsewhere (34). 

Neuromedin C (NMC), H-Gly-Asn-His-Trp-Ala-Val-Gly-His-Leu-Met -NH2, a bombesin-like peptide identified in porcine spinal cord. It exhibits a potent stimulant effect on the smooth muscle of rat uterus. NMC shows sequence identity with the C-terminal part 18-27 of gastric-inhibitory polypeptide and sequence homology with the C-terminus of bombesin. The name NMC was coined since it is closely related to —> neuromedin B [N. Minamino et al., Biochem. Biophys. Res. Commun. 1984, 119, 14 G. Gasmi et al., J. Peptide Res. 1997, 49, 500]. 

Bombesin and gastrin-releasing peptides have been shown to sensitize C-fiber neurons to subsequent activation by capsaicin and ATP. In addition, these peptides enhance the pulmonary chemoreflex induced by C-fiber stimulants. The relevance of these observations may be heightened in small-cell lung cancers, as the cancer cells are known to secrete various peptides, including bombesin-like peptides (Gu and Lee 2005). 

V. Erspamer, Peptides of amphibian skin active on the gut. II. Bombesin like peptides isolation, structure and basic functions. In Gastrointestinal Hormones (G.B. Jerzy Glass ed.) Raven, New York, 1980, pp. 344-361... 

Erspamer insisted that bombesin is not merely a pharmacological curiosity, that there might be a bombesin-like peptide in the gastrointestinal tract of mammals. He said at a symposium in 1973 that he had prepared an antibody to a bombesinlike decapeptide conjugated with bovine serum albumin and that the antibody showed moderate affinity for bombesin. Methanol extracts of antral and duodenal mucosa of pigs and dogs behaved like bombesin toward the antibody. ... 

Varvarigou AD, Scopinaro F, Leondiadis L, Corleto V, SchiUaci O, De Vincentis G, Sourlingas TG, Sekeri-Pataryas KE, Evangelatos GP, Leonti A, Xanthopoulos S, Delle Fave G, Archimandritis SC. Synthesis, chemical, radiochemical and radiobiological evaluation of a new Tc-labelled bombesin-like peptide. Cancer Biother Radiopharm 2002 17 317-326. 

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