Effect of Long-Term Continuous Light Exposure and Western Diet on Adropin Expression, Lipid Metabolism, and Energy Homeostasis in Rats.

Mahmoud Abulmeaty,Khalid Alnumair,Ali Almajwal,Abdullah Farraj,Suhail Razak,Amal Fawzy,Mai Hasan,Ghadeer Aljuraiban,Manal Abudawood

doi:10.3390/biology10050413

Abstract

Long-term continuous light exposure (CL) and western diet (WD) effects on Adropin expression, RORα, and Rev-erb-α nuclear receptors and energy homeostasis were studied in rats. Thirty-two male Wistar rats (250-290 g) were enrolled for 3 months in the following groups (n = 8/group): (a) Normal control group (NC), (b) CL group, (c) WD group, and (d) CL + WD group. Then, indirect calorimetry and food intake (FI) were measured. Finally, Adropin, hormone-sensitive lipase (HSL), adipocyte triglyceride lipase (ATGL), and free fatty acids (FFA) were measured. Additionally, the histopathology and gene expression of Enho, RORα, and Rev-erb-α genes were done. The CL alone elevated the Adropin plasma level and gene expression, increased RORα expression, and decreased the Rev-erb-α nuclear receptor expression mainly in the liver and kidney. Besides, CL increased the total energy expenditure (TEE) and decreased the respiratory quotient. WD alone or in combination with the CL reversed gene expression of Enho, RORα, and Rev-erb-α. Combined CL and WD increased the TEE, reduced the food intake, increased the ATGL, and reduced the Adropin level in addition to widespread degenerative changes in the liver, spleen, and renal tissues. The deleterious effects of CL and WD on energy homeostasis may include Adropin with the involvement of the RORα and Rev-erb-α nuclear receptors.

Highlights

The chronobiology is highly sensitive to changes in the light/dark cycle [1]
This study aimed to investigate the effect of long-term continuous light exposure and a Western diet consisting of high fat/added sucrose (WD) on the Adropin expression, expression of RORα, Reverb-α nuclear receptors, key enzymes of lipid metabolism, and energy homeostasis in a rat model
The peak Enho gene expression in the liver, kidney, and spleen coincided with increased RORα expression and decreased Rev-erb-α nuclear receptor expression, mainly in the liver and kidney (Figure 2)

Summary

Introduction

The chronobiology is highly sensitive to changes in the light/dark cycle [1]. Disturbing the light/dark cycle is involved in the disturbance of the normal chronobiologic rhythms of many regulators of the metabolic system, resulting in various disorders such as insulin insensitivity, obesity, type 2 diabetes, and the risk of cardiovascular disease [3]. The extensive controversy is present regarding the effect of continuous light (CL) exposure on the body weight and food intake. Food intake during CL or dim light exposures showed a similar controversy [10]. The light/dark cycle can affect the energy expenditure by modulation of the SCN and consequent effects on the peripheral clocks in the liver, intestine, and pancreas via autonomic signals and the release of hormones [11]

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