Shanti Diwakarla1,2, Ross A D Bathgate1,3, Xiaozhou Zhang1, Mohammed Akhter Hossain1,4, John B Furness1,2. 1. Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Vic., Australia. 2. Department of Anatomy and Neuroscience, University of Melbourne, Parkville, Vic., Australia. 3. Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Vic., Australia. 4. School of Chemistry, University of Melbourne, Parkville, Vic., Australia.
Abstract
BACKGROUND: Insulin-like peptide 5 (INSL5) is a hormone stored in colonic enteroendocrine cells that also contain the unrelated hormones, GLP-1 and PYY. It acts at the relaxin family peptide 4, RXFP4, receptor. RXFP4 is expressed by enteric neurons in the colon, and it has been speculated that INSL5, through its action on enteric neurons, might be involved in the control of colonic contractions. Similar to insulin and relaxin, INSL5 consists of A and B peptide chains linked by three disulfide bonds, two between the chains and one intrinsic to the A chain. Because of its complex structure, it is difficult to synthesize and to prepare peptide analogues to investigate its roles. We have recently developed a potent simplified peptide analogue, INSL5-A13 (INSL5 analogue 13). METHODS: In the present work, we have investigated the actions of INSL5-A13 in mice. We investigated the ability of INSL5-A13 to increase the speed of emptying of a bead from the colon, after expulsion had been slowed by the peripherally restricted opioid agonist, loperamide (1 mg/kg). KEY RESULTS: INSL5-A13 was a full agonist at the mouse RXFP4 expressed in HEK cells, with an EC50 of ~9 nmol/L. INSL5-A13 caused an acceleration of colorectal bead propulsion in mice constipated by loperamide in the dose range 0.2 to 60 µg/kg, with an EC50 of ~6 µg/kg in vivo. It also accelerated bead propulsion in untreated mice. Bead expulsion was not accelerated in RXFP4-/- mice. CONCLUSION AND INFERENCES: Our data suggest that RXFP4 agonists could be useful in the treatment of constipation.
BACKGROUND:Insulin-like peptide 5 (INSL5) is a hormone stored in colonic enteroendocrine cells that also contain the unrelated hormones, GLP-1 and PYY. It acts at the relaxin family peptide 4, RXFP4, receptor. RXFP4 is expressed by enteric neurons in the colon, and it has been speculated that INSL5, through its action on enteric neurons, might be involved in the control of colonic contractions. Similar to insulin and relaxin, INSL5 consists of A and B peptide chains linked by three disulfide bonds, two between the chains and one intrinsic to the A chain. Because of its complex structure, it is difficult to synthesize and to prepare peptide analogues to investigate its roles. We have recently developed a potent simplified peptide analogue, INSL5-A13 (INSL5 analogue 13). METHODS: In the present work, we have investigated the actions of INSL5-A13 in mice. We investigated the ability of INSL5-A13 to increase the speed of emptying of a bead from the colon, after expulsion had been slowed by the peripherally restricted opioid agonist, loperamide (1 mg/kg). KEY RESULTS:INSL5-A13 was a full agonist at the mouseRXFP4 expressed in HEK cells, with an EC50 of ~9 nmol/L. INSL5-A13 caused an acceleration of colorectal bead propulsion in miceconstipated by loperamide in the dose range 0.2 to 60 µg/kg, with an EC50 of ~6 µg/kg in vivo. It also accelerated bead propulsion in untreated mice. Bead expulsion was not accelerated in RXFP4-/- mice. CONCLUSION AND INFERENCES: Our data suggest that RXFP4 agonists could be useful in the treatment of constipation.
Authors: Ada Koo; Ruslan V Pustovit; Orla R M Woodward; Jo E Lewis; Fiona M Gribble; Mohammed Akhter Hossain; Frank Reimann; John B Furness Journal: Cell Tissue Res Date: 2022-05-21 Impact factor: 4.051
Authors: Ruslan V Pustovit; Xiaozhou Zhang; Jamie Jm Liew; Praveen Praveen; Mengjie Liu; Ada Koo; Lalita Oparija-Rogenmozere; Qinghao Ou; Martina Kocan; Shuai Nie; Ross Ad Bathgate; John B Furness; Mohammed Akhter Hossain Journal: ACS Pharmacol Transl Sci Date: 2021-08-30