Bombesin/GRP-preferring and neuromedin B-preferring receptors in the rat urogenital system

Published

Journal Article

Bombesin binding sites were localized in the rat urogenital system by autoradiography of 125I-Tyr4-bombesin binding to frozen tissue sections. Saturable binding was observed in the bladder, seminal vesicle, uterus, and oviduct. In all organs, the binding sites corresponded to layers of smooth muscle. Radioligand binding studies were performed on homogenized membrane preparations from bladder, uterus, and seminal vesicle. Membrane binding was saturable, reversible, time- and temperature-dependent, and specific for bombesin and related peptides. Analysis of saturable equilibrium binding from all three organs yielded a best fit to a one-site model of high affinity binding with apparent Kds of 720 pM for bladder, 470 pM for uterus, and 700 pM for seminal vesicle. Neuromedin B was potent in displacing saturable 125I-Tyr4-bombesin binding from bladder and seminal vesicle but not uterus membranes. In order to characterize these binding sites further, the ability of these membranes to interact with a specific bombesin receptor antagonist, [Leu13-psi-CH2NH-Leu14]-bombesin, and with GTP-gamma-S was determined. [Leu13-psi-CH2NH-Leu14]-bombesin was much more potent in displacing saturable 125I-Tyr4-bombesin binding from uterus than from bladder and seminal vesicle membranes, further supporting the distinction between the uterus and the bladder/seminal vesicle binding sites as bombesin receptor subtypes. GTP-gamma-S inhibited saturable 125I-Tyr4-bombesin binding to membranes from all three organs, indicating that both receptor subtypes are linked to GTP-binding proteins. We conclude that smooth muscle in the rat urogenital system expresses bombesin receptors and that endogenous GRP and neuromedin B may regulate some reproductive and excretory functions. The bladder and seminal vesicle express the neuromedin B-preferring subtype and the uterus expresses the bombesin/GRP-preferring subtype of bombesin receptor. © 1992.

Full Text

Duke Authors

Cited Authors

  • Kilgore, WR; Mantyh, PW; Mantyh, CR; McVey, DC; Vigna, SR

Published Date

  • January 1, 1993

Published In

Volume / Issue

  • 24 / 1

Start / End Page

  • 43 - 52

International Standard Serial Number (ISSN)

  • 0143-4179

Digital Object Identifier (DOI)

  • 10.1016/0143-4179(93)90039-D

Citation Source

  • Scopus