title: Search for an Endogenous Bombesin-Like Receptor 3 (BRS-3) Ligand Using Parabiotic Mice.
abstract: Bombesin-like receptor 3 (BRS-3) is an X-linked G protein-coupled receptor involved in the regulation of energy homeostasis. Brs3 null (Brs3-/y) mice become obese. To date, no high affinity endogenous ligand has been identified. In an effort to detect a circulating endogenous BRS-3 ligand, we generated parabiotic pairs of mice between Brs3-/y and wild type (WT) mice or between WT controls. Successful parabiosis was demonstrated by circulatory dye exchange. The Brs3-/y-WT and WT-WT pairs lost similar weight immediately after surgery. After 9 weeks on a high fat diet, the Brs3-/y-WT pairs weighed more than the WT-WT pairs. Within the Brs3-/y-WT pairs, the Brs3-/y mice had greater adiposity than the WT mice, but comparable lean and liver weights. Compared to WT mice in WT-WT pairs, Brs3-/y and WT mice in Brs3-/y-WT pairs each had greater lean mass, and the Brs3-/y mice also had greater adiposity. These results contrast to those reported for parabiotic pairs of leptin receptor null (Leprdb/db) and WT mice, where high leptin levels in the Leprdb/db mice cause the WT parabiotic partners to lose weight. Our data demonstrate that a circulating endogenous BRS-3 ligand, if present, is not sufficient to reduce adiposity in parabiotic partners of Brs3-/y mice.
authors.affiliation: Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, 20892, United States of America.
authors.forename: Dalya M
authors.initials: DM
authors.lastname: Lateef
authors.affiliation: Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, 20892, United States of America.
authors.forename: Cuiying
authors.initials: C
authors.lastname: Xiao
authors.affiliation: Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, 20892, United States of America.
authors.forename: Marc L
authors.initials: ML
authors.lastname: Reitman
mesh_terms: D050154:Adiposity; D000704:Analysis of Variance; D000818:Animals; D001823:Body Composition; D001835:Body Weight; D003427:Cross Circulation; D008024:Ligands; D008297:Male; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010227:Parabiosis / Q000379:methods*; D018004:Receptors, Bombesin / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors
chemical_list: D008024:Ligands; D018004:Receptors, Bombesin; C107120:bombesin receptor subtype 3