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Determining Basal Energy Expenditure and the Capacity of Thermogenic Adipocytes to Expend Energy in Obese Mice
Published on: November 11, 2021
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Pinealectomy increases thermogenesis and decreases lipogenesis.
Mikyung Kim1, So Min Lee2, Jeeyoun Jung2
1Department of Biochemistry, School of Medicine, Keimyung University, Daegu 42601, Republic of Korea.
Molecular Medicine Reports
|October 1, 2020
Summary
Pinealectomy (Pnx) in rats reduced obesity by decreasing melatonin receptor expression. This surgery enhanced insulin sensitivity, stimulated brown fat thermogenesis, and reduced fat accumulation in white adipose tissue and the liver.
Area of Science:
- Endocrinology
- Metabolism
- Obesity Research
Background:
- The pineal gland produces melatonin, a hormone implicated in metabolic regulation.
- Obesity is a complex metabolic disorder associated with hormonal imbalances and altered energy expenditure.
Purpose of the Study:
- To investigate the role of pineal gland-derived melatonin in obesity using a rat pinealectomy (Pnx) model.
- To determine the impact of melatonin deficiency on adipose tissue function, insulin sensitivity, and hepatic lipid metabolism.
Main Methods:
- Establishment of a rat model involving high-fat diet followed by pinealectomy or sham surgery.
- Analysis of melatonin receptor (MTNR1A, MTNR1B) expression in adipose tissues using RT-qPCR.
- Assessment of insulin sensitivity, serum leptin levels, and gene expression related to thermogenesis and lipogenesis in adipose tissue, liver, and brown adipose tissue (BAT).
- Histological examination of lipid droplet size and uncoupling protein 1 (UCP1) expression in BAT and liver.
Main Results:
- Pinealectomy significantly decreased melatonin receptor expression in both white adipose tissue (WAT) and brown adipose tissue (BAT).
- Pnx rats exhibited improved insulin sensitivity and reduced serum leptin levels compared to sham-operated controls.
- Pinealectomy stimulated thermogenic gene expression (e.g., UCP1) in BAT and attenuated lipogenic gene expression in WAT and the liver.
- Histological analysis showed reduced lipid droplet size in BAT and liver, along with increased UCP1 expression in BAT.
Conclusions:
- Pinealectomy-induced melatonin deficiency promotes thermogenesis in brown adipose tissue.
- Melatonin deficiency attenuates lipogenesis in white adipose tissue and the liver, contributing to reduced fat accumulation.
- The pineal gland and its hormone melatonin play a significant role in regulating energy balance and preventing obesity.
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