Effect of levothyroxine replacement therapy on adipocyte expression in subclinical hypothyroidism rats / 中华地方病学杂志

ABSTRACT

Objective To observe the changes of adiponectin (APN),chemerin and tumor necrosis factor-α (TNF-α) in subclinical hypothyroidism (SCH) rats,and to clarify the effect of L-thyroxine (L-T4) replacement therapy.Methods Sixty-five male Wistar rats were randomly divided into five groups via the random number table method:control group (n =10),SCH group A (n =15),SCH group B (n =15),SCH group C (n =15) and L-T4 treatment group (SCH + L-T4,n =10).Rats in groups SCH A,B and C were fed with 5,15 and 20 mg·kg-1·d-1 methimazole (MMI) once daily by gavage.The rats in SCH + L-T4 group were given 20 mg·kg-1·d-1 MMI once daily through gavage,after 8 weeks,6 μg·kg-1· d-1 of L-T4 was intragastrically added (50 μg/tablet) and the model was completed at the 16th week.The levels of serum APN,chemerin and TNF-α were measured via the enzyme linked immunosorbent assay (ELISA) method.The mRNA and protein levels of APN,chemerin and TNF-α in visceral adipose tissue of 5 groups were determined by real-time PCR (RT-PCR) and Western blotting,respectively.Results Compared with the control group [(202.20 + 17.27) ng/L,(143.70 ± 18.46) ng/L,(114.69 ± 4.18) μg/L],the serum chemerin levels in the SCH A,B,C groups were significantly higher [(314.33 ± 16.80),(355.00 ± 17.10),(365.00 ± 11.63) ng/L,P ＜0.05] and TNF-α levels also increased significantly [(222.60 ± 14.13),(279.20 ± 12.79),(288.30 ± 15.89) ng/L,P ＜0.05],and APN levels were significantly decreased [(77.21 ± 3.08),(68.58 ± 2.92),(59.45 ± 2.41) μg/L,P ＜0.05];but compared with SCH group C,the levels of chemerin and TNF-α in the SCH + L-T4 group were decreased [(260.07 ± 10.80),(178.40 ± 10.29) ng/L] and the level of APN [(102.35 ± 3.17) μg/L] was increased (P＜ 0.05).The mRNA and protein levels of APN in SCH A,B,C groups were significantly lower than those in the control group (P ＜0.05).The APN mRNA and protein levels in the SCH + L-T4 group were significantly higher than those in the SCH group C (P ＜ 0.05).The mRNA and protein levels of chemerin and TNF-α in the SCH A,B,C groups were higher than those in the control group (P ＜ 0.05).However,the mRNA and protein levels of chemerin and TNF-α in the SCH + L-T4 group were significantly lower than those in the SCH group C (P ＜ 0.05).Conclusion The expression levels of serum chemerin and TNF-α in SCH rats have increased,and APN levels decreased,but L-T4 can ameliorate these changes.