OBJECTIVETo observe the effect of Ruxian Pill I (RXP I) on mammary gland hyperplasia (MGH) in rabbits and to explore its mechanism.

METHODSSixty rabbits were divided into the high, medium and low dose of RXP I groups, the Xiaoyao Pill (XYP) group, the model group and the normal control group with 10 in each group. The former 5 groups were injected with diethylstilbestrol and progesterone intramuscularly for one month to induce the MGH model and then given respective medicines via gastrogavage for 3 months. The changes in morphology of mammary gland were observed using light and electronic microscope, the levels of estradiol (E2) and progestogen (P) were measured by radioimmunoassay, and the expression of estradiol receptor (ER) and progestogen receptor (PR) were detected with immunohistochemistry before, at the end of and 3 months after the treatment.

RESULTSCompared with those before treatment and those in the model group, in the high and midium dose of RXP I groups after treatment, obvious decrease of acini number in hyper-plastic lobuli mammae, connective tissues and blood capillaries, layers of glandular epithelium cells and organellers were seen with partial of hyperplastic cell apoptosis in them. Besides, the serum E2 level decreased obviously (P < 0.05), while the serum P level increased, and the ER expression down-regulated significantly (P < 0.05), but no obvious changes of PR expression was found. Three months later, all the above indexes maintained stable without rebound.

CONCLUSIONRXP I treatment could alleviate the hyperplasia of mammary glands, reduce E2 level, and down-regulate ER expression in rabbits with MGH, showing a significant therapeutical effect.