Negri L
Eur J Pharmacol. 1986 Dec 16;132(2-3):207-12. doi: 10.1016/0014-2999(86)90606-0.
Two novel amphibian peptides, [Ser7]litorin-like peptide (Ser-LIT) and [Ser7]bombesin-like peptide (Ser-BN), recently isolated from the skin of the South American frog Phyllomedusa sauvagei, are characterized by the occurrence of a Ser residue in place of His7 in the C-terminal tripeptide. For testing on food intake in fasted rats the peptides were injected intraperitoneally (i.p.) and intracerebroventricularly (i.c.v.) and their activity compared with that of bombesin (BN) and litorin (LIT). Ser-LIT was completely ineffective on food intake while Ser-BN was about ten times less potent than LIT by i.p. injection; given i.c.v., Ser-BN inhibited food intake in the first 15 min after injection but its effect faded within 60 min. The i.c.v. administration of both [Ser7]-substituted peptides, elicited intense scratching with a potency equal to or higher than that of BN or LIT. The existence of two different kinds of receptors for BN-like peptides may be hypothesized: the first, specific for the C-terminal tripeptide sequence, is apparently involved in the inhibition of feeding; the second, responsible for the stimulating activity on the urinary bladder and for scratching, shows higher affinity for the N-terminal portion of the biological active sequence.
最近从南美蛙皮氏叶泡蛙的皮肤中分离出两种新型两栖类肽，即[Ser7]铃蟾肽样肽（Ser-LIT）和[Ser7]蛙皮素样肽（Ser-BN），其特征在于C末端三肽中His7被Ser残基取代。为了测试禁食大鼠的食物摄入量，将这些肽腹腔内（i.p.）和脑室内（i.c.v.）注射，并将它们的活性与蛙皮素（BN）和铃蟾肽（LIT）的活性进行比较。Ser-LIT对食物摄入量完全无效，而Ser-BN腹腔注射时的效力比LIT低约十倍；脑室内注射时，Ser-BN在注射后的前15分钟内抑制食物摄入，但其作用在60分钟内消失。两种[Ser7]取代肽的脑室内给药均引发强烈抓挠，其效力等于或高于BN或LIT。可以推测存在两种不同类型的蛙皮素样肽受体：第一种对C末端三肽序列具有特异性，显然参与抑制进食；第二种负责对膀胱的刺激活性和抓挠，对生物活性序列的N末端部分具有更高的亲和力。
