EFFECTS OF HYPOTHYROIDISM ON THE VISCERAL ADIPOSE TISSUE OF RATS

ZYLA L; SANTIANO F; SASSO CV; CARÓN RW; PENNACHIO G; TONEATTO J; GARCÍA S; ORTIZ N; SOAJE M; PIETROBON E; LÓPEZ FONTANA C

Mendoza

Congreso; XXXVI Reunión Científica Anual de la Sociedad de Biología de Cuyo.; 2018

Sociedad de biología de Cuyo

Abnormal thyroid stimulating hormone (TSH) and thyroid hormones levels are frequently associated with changes in body weight (BW) and in the functioning of adipose tissue. Our aim was to characterize the influence of Hypothyroidism (HypoT) on the rat visceral adipose tissue (VAT). Sprague Dawley female rats (55 days old) were divided into two groups: hypothyroid rats (HypoT, 0.01% 6-N-propyl-2-thiouracil in drinking water, n=10) and untreated control euthyroid rats (EUT, n=10). BW and body length were assessed. On day 70 of experiment, animals were decapitated. Trunk blood was collected for measurement of serum hormone concentrations. The VAT was removed for histological, western blot and real time PCR analysis. We evaluated the morphology and differentiation of adipocytes, and the expression of adipokines and their receptors in the VAT. HypoT showed decreased BW and body length. Serum growth hormone, estradiol and progesterone levels were significantly inferior in HypoT rats. The percentage of body fat, the amount of lipids and size of adipocytes were similar to EUT. Nevertheless, leptin and adiponectin were altered by HypoT conditions. Finally, the expression of Perilipin A1 and HSL, both indirect biomarkers of adipocyte maturity, and UCP1 and PRDM16, both biomarkers of browning adipocytes, were significantly lower in HypoT. These findings suggested that adipocytes showed a less differentiated state; despite the fact that the expression of PPARγ, a master regulator of adipocyte differentiation, was increased in VAT of HypoT rats. In addition, the increase of MCT1 expression indicated that the metabolic demands on the adipocyte tissue were altered in HypoT animals. We concluded that hypothyroidism in rats induced a decrease in body size without changing the percentage and the morphology of the VAT, but enhancing White adipocytes dedifferentiation.