Effect of a 9-week exercise training regimen on expression of developmental genes related to growth-dependent fat expansion in juvenile rats.

Hisashi Kato,Tetsuya Izawa,Nazibur Rahman,Takuya Shibahara,Hisashi Takakura,Yoshinobu Ohira

doi:10.14814/phy2.13880

Hisashi Kato, Tetsuya Izawa + Show 4 more

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https://doi.org/10.14814/phy2.13880

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Abstract

This study examined the association between changes in mRNA expression of development‐related genes including those of the homeobox (Hox) family and growth‐dependent increases in inguinal, mesenteric, and epididymal white adipose tissue (WAT) at 4, 6, 10, and 14 weeks of age in rats. We also examined the effects of a 9‐week exercise training regimen starting at 5 weeks of age on the mRNA levels of the genes of interest. HoxC8, HoxC9, Gpc4, Bmpr1a, Pparγ, Pgc1α, Adrb3, Hsl, leptin, and adiponectin in each type of WAT – except HoxA5, Gpc4, and Pgc1α in epididymal – showed a positive association between WAT weights and WAT mRNA levels; however, the slope of the regression lines exhibited fat depot‐specific differences. HoxA5 showed no significant association, and Gpc4 and Pgc1α showed a negative association in epididymal WAT. After exercise training, the mean HoxA5, HoxC8, HoxC9, HoxC10, Gpc4, Pparγ, and Pgc1α mRNA levels in inguinal WAT were outliers on the regression line between mean mRNA level and WAT weight in control rats – that is, mean HoxA5 and Pgc1α mRNA level was higher, whereas HoxC8, HoxC9, HoxC10, Gpc4, and Ppar levels were lower in exercise‐trained rats than in same‐age controls. Pparγγ and adiponectin levels were upregulated in epididymal WAT, while HoxA5 was downregulated, but HoxC9, Gpc4, Pparγ, and adiponectin levels were upregulated in mesenteric WAT. These results suggest that some of the developmental genes tested may have fat depot‐specific roles in the growth‐dependent expansion of WAT, and that Hox genes that are activated in response to exercise training also vary among different WAT types.

Highlights

White adipose tissue (WAT) in mammals is largely compartmentalized into two types – visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) – that differ in their biological features (Gesta et al 2007; Wronska and Kmiec 2012; Tchkonia et al 2013; Hilton et al 2015)
We tested whether the mean value of parameters from exercise-trained rats was an outlier on the regression line between the mean rate of increase in mRNA expression and WAT growth rate in control rats
The results showed that some of the developmental genes were dependent on WAT expansion in a fat depot-specific manner: mRNA levels of Tbx15, Shox2, Bmpr1a, leptin, and adiponectin were associated with the expansion of inguinal WAT; HoxC8, HoxC9, Bmpr1a, and leptin levels were positively associated, whereas those of Gpc4 and pgc1a were negatively associated with the expansion of WAT; and HoxC8, Bmpr1a, and leptin levels were associated with the expansion of mesenteric WAT (Fig. 3A)

Summary

Introduction

White adipose tissue (WAT) in mammals is largely compartmentalized into two types – visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) – that differ in their biological features (Gesta et al 2007; Wronska and Kmiec 2012; Tchkonia et al 2013; Hilton et al 2015). Hormone-stimulated adipocyte lipolysis is greater in the former than in the latter, while the opposite is true for the production and secretion of the adipokine, leptin. Preadipocytes in abdominal SAT have a greater capacity for adipogenesis than those in VAT, and excessive accumulation of VAT is associated with increases in insulin resistance and risk of type 2 diabetes and cardiovascular disease, whereas SAT reduces type 2 diabetes risk (Wang et al 2005; Van Gaal et al 2006; Zhang et al 2008). Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

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