3,5-DIIODO-L-THYRONINE-INDUCED MODIFICATION IN PITUITARY-THYROID AXIS IN RATS FED HIGH-FAT DIET. A PRELIMINARY REPORT

Experimental observations highlight that the administrationof 3,5-diiodo-L-thyronine (T2) may decrease the body weightand the plasma levels of cholesterol and triglycerides and mayprevent the onset of hepatic steatosis in rats fed diets rich inlipids (HFD). On the basis of these findings we have carried outsome in vivo studies to evaluate the effects of increased levels ofT2 on pituitary thyroid axis function in HFD rats. Fifteeen Wistarmale rats were divided in 3 groups. The first group (N) was fedwith a standard diet. The second group (G) was fed with a diethigh in fat (HDF), while the third group (GT2) was additionallyadministered intraperitoneally with T2 (70 ug/100g bodyweight) for 3 days a week up to 4 week. Blood samples fromanimals were collected and stored at -20°C until 3rd generationand TSH, T3, T4, ACTH, triglycerides, cholesterol, glucose ALT,AST, Alkaline Phosphatase were assayed. Furthermore, rat liverfrom rats underwent histological examination to assess thedegree of steatosis. The administration of T2 (70 ug/100 grbody weight 3 times a week up to 4 weeks suppressed TSHsecretion in HDF rats. Unlike observed in the liver of rats fromgroup N and group GT2, the histological examination of theliver from G group rats showed the presence of hepatic steatosis.These preliminary data highlight that the administration of70 ug/100 b.w. of T2 inhibits TSH secretion and prevent theonset of hepatic steatosis in HFD rats.