Wheel running prevents the accumulation of monounsaturated fatty acids in the liver of ovariectomized mice by attenuating changes in SCD-1 content

Abstract

Decreases in female sex steroids enhance the accumulation of visceral fat mass, leading to a predisposition to developing metabolic diseases. The purpose of this study was to determine whether loss of ovarian function alters the amount and (or) the fatty acid (FA) composition of triacylglycerol (TAG) levels in the liver of ovary-intact (SHAM) or ovariectomized (OVX) mice. We also sought to determine whether voluntary wheel running could attenuate the associated changes in the liver. Twenty-two C57/BL6 female mice were divided into 2 groups (SHAM, OVX) and were then subdivided into sedentary and exercising groups (SHAM-Sed, SHAM-Ex, OVX-Sed, OVX-Ex). Visceral fat mass significantly increased in the OVX-Sed animals; however, the effect was attenuated in the OVX-Ex animals. Total hepatic TAG content did not significantly increase in the OVX-Sed animals; however, SHAM-Ex and OVX-Ex animals demonstrated significant decreases in TAG levels. A significant increase in the FA desaturase index (18:1/18:0 and 16:1/16:0) was detected in the OVX-Sed animals compared with all other groups, which corresponded to increases in stearoyl-CoA desaturase (SCD-1) content. These results indicate that loss of ovarian function alters FA composition of hepatic TAG mediated by increases in SCD-1. These data indicate that female sex steroids influence lipid metabolism in the liver and provide important insight concerning the influence of exercise on hepatic function.

BRCA1 is a novel regulator of metabolic function in skeletal muscle

“…Isolation of RNA and subsequent cDNA synthesis from the gastrocnemius or plantaris muscles and mouse testes (positive control) was performed according to the previously described techniques ( 15,16 ). Specifi c primers for mouse Brca1 were as follows: forward 5 ′ -CAC AGC GTA TGC CAG AGA AA-3 ′ and reverse 5 ′ -ATC CTG GGA GTT TGC ATT TG-3 ′ .…”

“…Mouse skeletal muscle was mechanically homogenized according to previously described techniques ( 15,19 ). Human skeletal muscle biopsies were homogenized on ice using glass-on-glass homogenizers in RIPA buffer [150 mM NaCl, 10 mM Tris-HCl, 5 mM EDTA, 0.5% Na deoxycholate, 0.1% SDS, 1% Triton X-100, and protein inhibitor cocktail complete mini (Roche Diagnostics)].…”

“…Immunoblotting for either BRCA1 immunoprecipitation solution or whole muscle homogenate protein was performed as previously described ( 15,20,22 ). Membranes were probed with an antibody specifi c for BRCA1 (I-20 or D-20, 1:200; Santa Cruz Biotechnology), ACC-p or ACC total (1:1,000; Cell Signal, Boston, MA), Akt-p or Akt total (1:1,000; Cell Signal), ␣ -actinin (1:5,000; Sigma-Aldrich, Saint Louis, MO), red fl uorescent protein (RFP) (1:2,000; Thermo Scientifi c, Waltham, MA).…”

Voluntary exercise improves hypothalamic and metabolic function in obese mice

“…Exercise stimulates glucose uptake by skeletal muscle from the blood (Goldstein et al 1953), decreases fat content from the adipose tissue (Gollisch et al 2009), and prevents fat accumulation in the liver (Jackson et al 2011). Besides the effects of exercise on peripheral tissues, voluntary exercise also improves brain function.…”

Female rats selectively bred for high intrinsic aerobic fitness are protected from ovariectomy-associated metabolic dysfunction

“…While low aerobic fitness is a powerful independent risk factor for all-cause mortality and metabolic disease risk (24), the impact of aerobic fitness on postmenopausal metabolic function per se is largely unknown. Animal studies have demonstrated that loss of ovarian hormones causes a reduction in physical activity and that exercise can offset these effects (18), but no studies have investigated the unique role played by intrinsic aerobic fitness, independent of exercise, on the changes in energy balance, body composition, and insulin resistance following ovariectomy (OVX). Accordingly, the purpose of the present study was to test the hypothesis that high intrinsic aerobic fitness protects against the metabolic dysfunction associated with OVX in rats.…”