OBJECTIVETo observe the expression of connective tissue growth factor (CTGF) in the tubulointerstitium in type 2 diabetic KKA(y) mice and the effect of rosiglitazone on it.

METHODSKKA(y) and C57 BL/6 mice aged 16 weeks ( n = 5 in each group) were sacrificed as controls before treatment. Another 20 KKA(y) mice were treated with rosiglitazone (30 mg x kg (-1) d (-1), n = 10) or placebo (n = 10). The mice were sacrificed at 20 and 24-week-age (n = 5 at each time point). Protein expression of transforming growth factor-beta1 (TGF-beta1 ), CTGF, peroxisome proliferator-activated receptor-gamma (PPARgamma) , and fibronectin were assayed by Western blot, while protein CTGF, PPARgamma, and alpha-smooth muscle actin ( alpha-SMA) were assayed by immunohistochemistry in kidney tissue sections.

RESULTSProteinuria was significantly decreased in mice aged 24 weeks treated by rosiglitazone than same-aged mice treated with placebo [ (44. 53+/-1. 96) vs (63. 66 +/-5. 57) microg/24 h, P < 0. 05 ]. The expressions of TGF-beta1, CTGF, and fibronectin in mice aged 20 weeks treated with rosiglitazone decreased by 37% , 21% , and 52% than same-aged control (P <0. 01) , and those were decreased by 61% , 50% , and 51% in mice aged 24 weeks treated with rosiglitazone compared with same-aged control mice (P < 0. 01). CTGF in the tubulointerstitium were respectively downregulated by 25% and 44. 9% in treated mice aged 20 weeks and 24 weeks compared with the same-aged control mice ( P < 0. 01). The PPARgamma appeared in diabetic mice and increased by 18. 1% in mice aged 24 weeks and treated with rosiglitazone than the same-aged control mice (P <0. 05).

CONCLUSIONHeterogeneous rosiglitazone may upregulate the expression of PPARgamma in renal cortex, and remarkably inhibit the expressions of CTGF in the tubulointerstitium and renal cortex in diabetic KKA(y) mice.