Resistance Training Suppresses Intra-abdominal Fatty Acid Synthesis in Ovariectomized Rats

Abstract

Ovarian hormone loss is associated with a shift in fat distribution to intra-abdomin al adipose tissue (intra-AAT) depots and with lipid metabolism disorders, which predisposes individuals to developing insulin resistance. Resistance training (RT) prevents increases in intra-AAT after ovarian hormone loss. However, the molecular mechanisms underlying these changes remain unclear. We investigated the effects of ovariectomy and RT on gene expression related to lipogenesis and fat oxidation in the intra-AAT of ovariectomized rats. Sprague-Dawley rats (n=6/group) were divided into the groups: sham-sedentary, ovariectomized-sedentary, sham-RT and ovariectomized-RT. RT groups performed a 10-week climbing program on a ladder with progressive overload. Intra-AAT was subjected to morphometric and mRNA analysis. Ovariectomized-sedentary group had larger adipocytes and higher expression of peroxisome proliferator-activated receptor-γ (PPAR-γ), sterol regulatory element-binding protein-1c (SREBP-1c), stearoyl-CoA desaturase-1 (SCD-1), acetyl-CoA carboxylase (ACC), hormone-sensitive lipase (HSL) and lower expression of the oxidative carnitinepalmitoyltransferase-I (CPT-1). RT counteracted OVX-induced increases in PPAR-γ and SCD-1 and decreased SREBP-1c. ACC and HSL were downregulated in ovariectomized-RT compared with the ovariectomized-sedentary group. Ovariectomized-RT group had the highest CPT-1 gene expression. Adipocyte size decreased in ovariectomized-RT group. Results suggest that RT reduces intra-AAT adipocyte size in ovariectomized rats by suppressing intra-AAT fatty acid synthesis and enhancing fatty acid β-oxidation.

Estrogen deficiency in ovariectomized rats: can resistance training re-establish angiogenesis in visceral adipose tissue?

“…Thus, postmenopausal women show an increase in AT mass, especially for visceral fat, contributing to deficient vascularization in this tissue 4. Additionally, estrogen plays an important role in body composition by suppressing WAT accumulation through reductions in fatty acids, triglyceride synthesis and lipogenesis 4,18. In our study, ovariectomy resulted in increases in both body mass and adipocyte hypertrophy in VAT.…”

“…Recent studies have indicated that Rt is beneficial for skeletal muscle, bones and liver 17,18,35. Previous studies conducted by our group have shown that Rt is able to decrease fat accumulation and deposition in the livers of Ovx rats 36 and to reduce the gene expression of molecules related to lipogenesis 17.…”

“…Ovx animals have been used as models for studying the effects of ovarian hormone deficiency 18,25. Evidence from rodent models has demonstrated that ovariectomy promotes obesity and its metabolic complications, in particular insulin resistance 26,27.…”

“…In recent years, resistance training (Rt) has been suggested as an important tool to prevent the deleterious physiological and metabolic changes promoted by menopause,including increases in abdominal fat and decreases in lipid metabolism 17,18. However, compared to aerobic exercise, studies evaluating the effects of Rt on angiogenesis in adipose tissue of Ovx rats are scarce.…”

Irisin Signaling Pathway is up Regulated by Resistance Training in Ovariectomized Rats

“…Is well established in the literature that RT promotes irisin release, and also increases cellular thermogenesis and reduces fat storage by suppressing formation of new adipocytes [19,20,[39][40][41]. Therefore, maintaining optimal irisin concentrations seems to be important, especially in our ovariectomy model, which has strong evidences of being a precursor of obesity and other metabolic disorders [42][43][44][45]. We found that the Ovx-Sed group presented similar values of irisin levels when compared to Sham-Sed group (Figure 3).…”