Differential secretion of adipokines from subcutaneous and visceral adipose tissue in healthy dogs: Association with body condition and response to troglitazone

Abstract

This study aimed to determine the effects of body condition, fat depot, and a peroxisome proliferator-activated receptor γ-agonist (troglitazone) on secretion of adiponectin, interleukin-6 (IL6), and tumor necrosis factor-α (TNFα) from adipose tissue of healthy dogs. Subcutaneous and omental visceral adipose tissue samples were collected from 16 healthy intact female dogs, and body condition score (range 4–8/9) was determined. Concentrations of adiponectin were measured in mature adipocytes cultures and concentrations of IL6 and TNFα were measured in stromovascular cells cultures after 48 h incubation in fresh control medium, or fresh medium containing 10 µM troglitazone.Mature adipocytes and stromovascular cells of subcutaneous origin secreted higher concentrations of adiponectin and lower concentration of IL6 and TNFα, respectively, than corresponding cells of visceral origin, in both the control (P = 0.015, P = 0.004, and P = 0.016, respectively) and troglitazone-treated cultures (P < 0.001, P = 0.004, and P = 0.016, respectively). Troglitazone increased adiponectin secretion from mature adipocytes in visceral (P = 0.019), but not in subcutaneous fat cultures (P = 0.4). Troglitazone decreased IL6 and TNFα secretion from stromovascular cells both in visceral (P = 0.047 and P = 0.016, respectively) and subcutaneous (P = 0.047 and P = 0.016, respectively) fat cultures. Higher body condition score was associated with lower secretion of adiponectin from mature adipocytes (P = 0.007), lower secretion of IL6 (P = 0.040) and higher secretion of TNFα (P = 0.040) from stromovascular cells. This study showed differential secretion of adipokines by subcutaneous and visceral fat depots in dogs and association between body condition and adipokine secretion. Activation of PPARγ altered adipokine secretion.