A FOREBRAIN-HYPOTHALAMIC ER STRESS DRIVEN CIRCUIT MEDIATES HEPATIC STEATOSIS DURING OBESITY

Katherine Blackmore, Department of Pharmacology and Physiology, George Washington University School of Medicine and Health Sciences, Washington, DC, 20037, USA.
Claire J. Houchen, Department of Pharmacology and Physiology, George Washington University School of Medicine and Health Sciences, Washington, DC, 20037, USA.
Hayk Simonyan, Department of Pharmacology and Physiology, George Washington University School of Medicine and Health Sciences, Washington, DC, 20037, USA.
Hovhannes Arestakesyan, Department of Pharmacology and Physiology, George Washington University School of Medicine and Health Sciences, Washington, DC, 20037, USA.
Alyssa K. Stark, Department of Pharmacology and Physiology, George Washington University School of Medicine and Health Sciences, Washington, DC, 20037, USA.
Samantha A. Dow, Department of Pharmacology and Physiology, George Washington University School of Medicine and Health Sciences, Washington, DC, 20037, USA.
Han Rae Kim, Department of Pharmacology and Physiology, George Washington University School of Medicine and Health Sciences, Washington, DC, 20037, USA.
Jin Kwon Jeong, Department of Pharmacology and Physiology, George Washington University School of Medicine and Health Sciences, Washington, DC, 20037, USA.
Anastas Popratiloff, Nanofabrication and Imaging Center, George Washington University, Washington, DC, 20037.
Colin N. Young, Department of Pharmacology and Physiology, George Washington University School of Medicine and Health Sciences, Washington, DC, 20037, USA. Electronic address: colinyoung@gwu.edu.

Document Type

Journal Article

Publication Date

12-21-2023

Journal

Molecular metabolism

DOI

10.1016/j.molmet.2023.101858

Keywords

Non-alcoholic fatty liver disease; endoplasmic reticulum; paraventricular nucleus of the hypothalamus; subfornical organ; sympathetic nervous system; unfolded protein response

Abstract

OBJECTIVE: Non-alcoholic fatty liver disease (NAFLD) affects 1 in 3 adults and contributes to advanced liver injury and cardiometabolic disease. While recent evidence points to involvement of the brain in NAFLD, the downstream neural circuits and neuronal molecular mechanisms involved in this response, remain unclear. Here, we investigated the role of a unique forebrain-hypothalamic circuit in NAFLD. METHODS: Chemogenetic activation and inhibition of circumventricular subfornical organ (SFO) neurons that project to the paraventricular nucleus of the hypothalamus (PVN; SFO→PVN) in mice were used to study the role of SFO→PVN signaling in NAFLD. Novel scanning electron microscopy techniques, histological approaches, molecular biology techniques, and viral methodologies were further used to delineate the role of endoplasmic reticulum (ER) stress within this circuit in driving NAFLD. RESULTS: In lean animals, acute chemogenetic activation of SFO→PVN neurons was sufficient to cause hepatic steatosis in a liver sympathetic nerve dependent manner. Conversely, inhibition of this forebrain-hypothalamic circuit rescued obesity-associated NAFLD. Furthermore, dietary NAFLD is associated with marked ER ultrastructural alterations and ER stress in the PVN, which was blunted following reductions in excitatory signaling from the SFO. Finally, selective inhibition of PVN ER stress reduced hepatic steatosis during obesity. CONCLUSIONS: Collectively, these findings characterize a previously unrecognized forebrain-hypothalamic-ER stress circuit that is involved in hepatic steatosis, which may point to future therapeutic strategies for NAFLD.

Department

Pharmacology and Physiology

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