OBJECTIVETo investigate the inhibitory effects of Kangjia Pill (KJP) on the cell proliferation in rat goiter model induced by methimazole (MMI).

METHODSFifty-six Wistar rats were randomly divided into four groups: the normal group, MMI model group (MMI), low dose of KJP group (LKJP), and high dose of KJP (HKJP). Except the normal group (20 rats), the other groups (12 rats in each) were given 0.04% (w/v) MMI through the drinking water until the end of the experiment. One week later, the rats in the LKJP and HKJP groups were given KJP by gastrogavage at the dose of 250 mg/(kg x d) and 1,000 mg/(kg x d), respectively for 12 weeks. The relative thyroid weight (mg/100 g body weight) of each rat was accessed. The expression of proliferating cell nuclear antigen (PCNA) was determined by immunohistochemistry, and the correlation analysis between the PCNA positive thyrocytes and the relative thyroid weight was performed. The expressions of PCNA and cyclin D1 were examined with Western blotting.

RESULTSAfter KJP treatment for 12 weeks, compared with the MMI group, the relative thyroid weight of the HKJP group decreased significantly, and the positive thyrocyte populations of PCNA in the two KJP groups reduced markedly (all P<0.05). The correlation analysis showed that PCNA was closely correlated with thyrocyte proliferation (r=0.685, P<0.05). KJP significantly decreased the protein expression of PCNA and cyclin D1 in the thyroid specimens (P<0.05), the high dose showed better effects.

CONCLUSIONKJP played a therapeutic role via inhibiting cell proliferation in the rat goitrous glands.