Adipose tissue of female Wistar rats respond to Ilex paraguariensis treatment after ovariectomy surgery.

BACKGROUND AND AIM: Metabolic disturbances are known for their increasing epidemiological importance. Ilex paraguariensis presents a potential option for mitigating lipid metabolism imbalance. However, most of the literature to date has not considered sex bias. This study aimed to evaluate the effect of Ilex paraguariensis on the metabolism of different adipose tissue depots in males and females. EXPERIMENTAL PROCEDURE: After ovariectomy, female Wistar rats received daily treatment with the extract (1 g/kg) for forty-five days. Biochemical serum parameters and tissue metabolism were evaluated. Oxidation, lipogenesis and lipolysis were evaluated in brown, white visceral, retroperitoneal and gonadal adipose tissues. RESULTS AND CONCLUSION: The results showed that treatment with the extract led to a reduced weight gain in ovariectomised females in comparison to control. The triglyceride concentration was decreased in males. Glucose oxidation and lipid synthesis in visceral and retroperitoneal adipose tissues were restored in ovariectomised females after treatment. The response to epinephrine decreased in visceral adipose tissue of control males; however, lipolysis in females did not respond to ovariectomy or treatment. These findings highlight the enormous potential effects of I. paraguariensis on lipid metabolism, modulating lipogenic pathways in females and lipolytic pathways in males. Furthermore, the sex approach applied in this study contributes to more effective screening of the effects of I. paraguariensis bioactive substances.

Enhanced sympathetic activity in mice with brown adipose tissue transplantation (transBATation).

Brown adipose tissue (BAT) burns calories to produce heat, and is thus relevant to energy balance. Interscapular BAT (IBAT) of donor mice was transplanted into recipient mice (transBATation). To test whether transBATation counteracts high-fat diet (HFD)-induced obesity, some sham-operated and recipient mice were fed a HFD (HFD-sham, HFD-trans) while others remained on a standard chow (chow-sham, chow-trans). HFD-trans mice had lower body weight and fat and greater energy expenditure, but similar caloric intake compared with HFD-sham mice. We hypothesized that HFD-trans mice had elevated sympathetic activity compared with HFD-sham mice, contributing to increased energy expenditure and fuel mobilization. This was supported by findings that HFD-trans mice had greater energy expenditure during a norepinephrine challenge test and higher core temperatures after cold exposure than did HFD-sham mice, implicating enhanced whole-body metabolic response and elevated sympathetic activity. Additionally, transBATation selectively increased sympathetic drive to some, but not all, white adipose tissue depots and skeletal muscles, as well as the endogenous IBAT, heart, and liver. Collectively, transBATation confers resistance to HFD-induced obesity via increase in whole-body sympathetic activity, and differential activation of sympathetic drive to some of the tissues involved in energy expenditure and fuel mobilization.

High-fat diet action on adiposity, inflammation, and insulin sensitivity depends on the control low-fat diet.

Animal studies using a high-fat diet (HFD) have studied the effects of lipid overconsumption by comparing a defined HFD either with a natural-ingredient chow diet or with a defined low-fat diet (LFD), despite the dramatic differences between these control diets. We hypothesized that these differences in the control diet could modify the conclusions regarding the effects that an increase of fat in the diet has on several metabolic parameters. For 11 weeks, C57bl6/J mice were fed a low-fat chow diet (8% energy from fat), a typical semisynthetic LFD (12%), or a semisynthetic HFD (sy-HF) (40%). Conclusions about the effect of sy-HF on body weight gain, subcutaneous adipose tissue, insulin sensitivity, and adipose tissue inflammation were modified according to the control LFD. Conversely, conclusions about epididymal and retroperitoneal adipose tissue; fat intake effects on liver and muscular lipids, cholesterol, free fatty acids, and markers of low-grade inflammation; and of adipose tissue macrophage infiltration were the same regardless of the use of low-fat chow diet or semisynthetic LFD. For some physiological outcomes, conflicting conclusions were even reached about the effects of increased fat intake according to the chosen low-fat control. Some deleterious effects of sy-HF may not be explained by lipid overconsumption but rather by the overall quality of ingredients in a semisynthetic diet. According to the control LFD chosen, conclusions on the lipid-related effects of HFDs must be formulated with great care because some end points are profoundly affected by the ingredient composition of the diet rather than by fat content.