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International Journal Of Bilogical Sciences

.: Home > International Journal Of Bilogical Sciences > 2016 > Volume 12 Number 2 > Jihua Fu, Shaoxin Ma, Xin Li, Shanshan An, Tao Li, Keke Guo, Min Lin, Wei Qu, Shanshan Wang, Xinyue Dong, Xiaoyu Han, Ting Fu, Xinping Huang, Tianying Wang, Siyu He

Long-term Stress with Hyperglucocorticoidemia-induced Hepatic Steatosis with VLDL Overproduction Is Dependent on both 5-HT2 Receptor and 5-HT Synthesis in Liver

Jihua Fu, Shaoxin Ma, Xin Li, Shanshan An, Tao Li, Keke Guo, Min Lin, Wei Qu, Shanshan Wang, Xinyue Dong, Xiaoyu Han, Ting Fu, Xinping Huang, Tianying Wang, Siyu He
1. Postgraduates of China Pharmaceutical University, Nanjing, China 2. Undergraduates of China Pharmaceutical University, Nanjing, China These authors contributed equally to this work Corresponding author: Prof. Jihua Fu, Department of Physiology, China Pharmaceutical University, 639 Long Mian Road, 211198, Nanjing, Jiangsu Province, China. Tel.: +86 025 8618 52 26; Fax: + 86 025 8618 52 26; E-mail address: jihua_fu@cpu.edu.cn
Abstract :

Hepatic triglycerides production and adipose lipolysis are pivotal for long-term stress (LTS) or hyperglucocorticoidemia-induced insulin resistance. 5-hydroxytryptamine (5-HT) has been demonstrated to induce hepatic lipid metabolic abnormality by activating mammalian target of rapamycin (mTOR). In present study, we explored whether 5-HT is involved in LTS effects in liver using restraint stress-exposed rats and cultured primary rat hepatocytes and HepG2 cells. LTS with hyperglucocorticoidemia induced hepatic 5-HT synthetic increase with tryptophan hydroxylase 1 (Tph1) up-regulation, and 5-HT2 receptor (5-HT2R, including 5-HT2A, 2B receptor) up-regulation in liver and visceral adipose, as well as hepatic mTOR activation with triglycerides and VLDL overproduction with steatosis, and visceral adipose lipolytic increase with high blood free fatty acids (FFAs) level. 5-HT exposure exhibited LTS-like effects in both tissues, and both LTS and 5-HT effects could be abolished significantly by blocking 5-HT2R. In HepG2 cells dexamethasone or palmitate-induced mTOR activation with triglycerides and VLDL overproduction were accompanied by up-regulations of 5-HT synthesis and 5-HT2R, which were significantly abolished by gene silencing Tph1 or 5-HT2R and were almost fully abolished by co-silencing of both, especially on VLDL overproduction. Chemical inhibition of Tph1 or/and 5-HT2R in both hepatocytes exhibited similar abolishment with genetic inhibition on dexamethason-induced effects. 5-HT-stimulated effects in both hepatocytes were fully abolished by blocking 5-HT2R, while 5-HT itself also up-regulated 5-HT2R. In conclusion, up-regulated hepatic 5-HT synthesis and 5-HT2R induced by both glucocorticoid and FFAs are crucial for LTS-induced hepatic steatosis with VLDL overproduction, while 5-HT by acting on 5-HT2R mediates mTOR activation in liver.

Keywords :
Long-term stress; 5-hydroxytryptamine 2A, 2B receptor (5-HT2A, 2BRs); 5-hydroxytryptamine synthesis; Triglycerides (TGs) synthesis; Very low-density lipoprotein (VLDL) assembly

Date Deposited : 15 Mar 2016 14:04

Last Modified : 15 Mar 2016 14:04

Official URL: http://www.ijbs.com/v12i2

Volume 12, Number 2, - 2016 , ISSN 1449-2288

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