International Journal of Molecular Zoology 2024, Vol.14, No.4, 211-221 http://animalscipublisher.com/index.php/ijmz 213 body temperature and has been proposed as a potential therapeutic strategy for combating obesity by increasing energy expenditure (Maliszewska and Krętowski, 2021). Figure 1 Characteristics and activation of the brown adipose tissue in mammals (Adopted from Bienboire-Frosini et al., 2023) Image caption: When mammals are exposed to cold environments, it activates the sympathetic nervous system and the consequent release of catecholamines, notably NE from the adrenal glands. NE binds to β3-AR located in BAT to start a series of biochemical reactions to produce heat. cAMP production by AC results in the activation of the PKA, a protein that promotes lipolysis and thermogenesis through CREB, P38, and ATF2. Thyroid hormones (T4 and T3) also participate in gene expression and TG uptake, as well as GR and glucose. The conversion of TG to FA is used by the mitochondria to produce heat. In the mitochondria’s membrane, UCP1 receptors and cytochrome c participate in thermogenesis following β-oxidation, the TCA cycle, and the electron transport chain mechanism for thermogenesis. (A) Schematic deposit of BAT; AC: adenylyl cyclase; ATF2: activating transcription factor 2. (B) Mitochondria close-up; β3-AR: beta3-adrenergic receptor. (C) Mitochondrial membrane; cAMP: cyclic AMP; CREB: cAMP response element-binding protein; GR: glucocorticoid; FA: fatty acids; NE: norepinephrine; PKA: protein kinase A; T3/T4: thyroid hormone; TG: triglyceride; UCP1: uncoupling protein 1 (Adopted from Bienboire-Frosini et al., 2023) 3.2 Regulation of body weight and energy balance BAT plays a significant role in regulating body weight and energy balance. The ability of BAT to dissipate energy through thermogenesis makes it a promising target for obesity treatment. Studies have shown that BAT activation can lead to a reduction in body weight and fat mass. For instance, BAT transplantation in mice resulted in improved glucose tolerance, increased insulin sensitivity, lower body weight, and decreased fat mass (Stanford et al., 2013). Additionally, the presence of thermogenically active BAT depots in humans has been associated with lower body mass index (BMI) and visceral adiposity, suggesting an inverse relationship between BAT activity and obesity (Figure 2) (Takeda et al., 2023). The potential of BAT to modulate energy balance and body weight highlights its importance in metabolic homeostasis and obesity prevention (Sidossis and Kajimura, 2015). The study of Takeda et al. (2023) compares the metabolic differences between lean and obese individuals, focusing on the activity of brown adipose tissue (BAT). In lean individuals, BAT is active and helps burn calories through thermogenesis, contributing to weight maintenance. In contrast, obesity is associated with reduced BAT
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