Lorcaserin Inhibit Glucose-Stimulated Insulin Secretion and Calcium Influx in Murine Pancreatic Islets

Muhan Jing; Shanshan Wang; Ding Li; Zeyu Wang; Ziwen Li; Yichen Lu; Tong Sun; Chen Qiu; Fang Chen; Haijuan Yu; Wei Zhang

doi:10.3389/fphar.2021.761966

Lorcaserin Inhibit Glucose-Stimulated Insulin Secretion and Calcium Influx in Murine Pancreatic Islets

Front Pharmacol. 2021 Nov 5:12:761966. doi: 10.3389/fphar.2021.761966. eCollection 2021.

Authors

Muhan Jing¹, Shanshan Wang², Ding Li³, Zeyu Wang¹, Ziwen Li¹, Yichen Lu¹, Tong Sun^{4

5}, Chen Qiu⁴, Fang Chen^{4

5}, Haijuan Yu⁶, Wei Zhang^{4

5}

Affiliations

¹ School of Basic Medical Sciences, Nanjing Medical University, Nanjing, China.
² Laboratory Animal Center, Department of Science and Technology, Nanjing University of Chinese Medicine, Nanjing, China.
³ Department of Forensic Medicine, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, China.
⁴ Key Laboratory of Human Functional Genomics of Jiangsu Province, Nanjing Medical University, Nanjing, China.
⁵ Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, China.
⁶ Department of Obstetrics, Traditional Chinese Medicine Hospital of Jingning, Nanjing, China.

Abstract

Lorcaserin is a serotonergic agonist specific to the 5-hydroxytryptamine 2c receptor (5-HT_2CR) that is FDA approved for the long-term management of obesity with or without at least one weight-related comorbidity. Lorcaserin can restrain patients' appetite and improve insulin sensitivity and hyperinsulinemia mainly through activating 5-HT_2CR in the hypothalamus. It is known that the mCPP, a kind of 5-HT_2CR agonist, decreases plasma insulin concentration in mice and previous research in our laboratory found that mCPP inhibited glucose-stimulated insulin secretion (GSIS) by activating 5-HT_2CR on the β cells. However, the effect of lorcaserin on GSIS of pancreatic β cell has not been studied so far. The present study found that 5-HT_2CR was expressed in both mouse pancreatic β cells and β-cell-derived MIN6 cells. Dose-dependent activation of 5-HT_2CR by lorcaserin suppressed GSIS and SB242084 or knockdown of 5-HT_2CR abolished lorcaserin's effect in vitro. Additionally, lorcaserin also suppressed GSIS in high-fat diet (HFD)-fed mice in dose-dependent manner. Lorcaserin did not change insulin synthesis ATP content, but lorcaserin decrease cytosolic free calcium level [(Ca²⁺)i] in MIN6 cells stimulated with glucose and also inhibit insulin secretion and (Ca²⁺)i in MIN6 treated with potassium chloride. Furthermore, stimulation with the L-type channel agonist, Bay K8644 did not restore GSIS in MIN6 exposed to lorcaserin. Lorcaserin inhibits the cAMP generation of MIN6 cells and pretreatment with the Gα i/o inhibitor pertussis toxin (PTX), abolished lorcaserin-induced suppression of GSIS in β cells, while membrane-permeable cAMP analogue db-cAMP had same effect as PTX. These date indicated lorcaserin coupled to PTX-sensitive Gα i/o proteins in β cells reduced intracellular cAMP level and Ca²⁺ influx, thereby causing GSIS dysfunction of β cell. These results highlight a novel signaling mechanism of lorcaserin and provide valuable insights into the further investigation of 5-HT_2CR functions in β-cell biology and it also provides guidance for the clinical application of lorcaserin.

Keywords: 5-HT 2C R; Ca2+; beta cell; glucose-stimulated insulin secretion; lorcaserin; obesity; type 2 diabetes mellitus.