No abstract

This report describes the influence of bombesin on the gross behavior of goldfish, frogs, mice, rats, guinea pigs, rabbits, chicks, pigeons and monkeys. Goldfish, frogs, chicks and pigeons were overtly unaffected by bombesin given centrally and/or peripherally. Mice, rats, guinea pigs, rabbits and monkeys responded quickly to intracerebroventricular (i.c.v.) and/or intrathecal (i.th.) administration of bombesin by displaying a range of behaviors suggestive of altered skin sensation. In mice, bombesin was essentially equipotent as a scratch inducer by i.c.v. and i.th. routes (A50 = 0.010-0.019 microgram) but 6800 times less potent i.p. In rats, bombesin-induced grooming and scratching behaviors were shown to be qualitatively different from those associated with ACTH-(1-24) and thyrotropin releasing hormone. Spantide and [D-Arg1, D-Pro2, D-Trp7,9, Leu11]substance P (both at 0.20, 0.50 and 0.80 microgram i.c.v.), two proposed bombesin receptor antagonists, did not markedly influence bombesin-induced scratching or hypothermia in rats.

Several chemically diverse compounds that are agonists at the kappa type of opioid receptor increase urination after subcutaneous injection to normally hydrated rats, for example, bremazocine, ethylketazocine (EK), U-50,488H (3,4-(1-pyrrolidinyl)cyclohexyl]-benzeneacetamide), and tifl~adom.'-~ Agonists at the mu type of opioid receptor (e.g., morphine, 1-methadone) do not share this effect. ' We extended the above studies to the intracerebroventricular (i.c.v.) route of administration to permit examination of opioid peptides that are selective agonists at opioid recognition sites. Accordingly, we compared morphiceptin (mu agonist), dynorphin A (kappa agonist), and [D-Pen', D-Pen'lenkephalin (DPDPE) (delta agonist) relative to the nonpeptide standards, morphine, EK, and U-50,488H, in the rat urination test.