To investigate the mechanism of soyisoflavones (SIF) alleviate the rats with polycystic ovary syndrome (PCOS) by regulating the miR-29a-3p/insulin-like growth factor 1 (IGF1) molecular axis.

The female SD rats were divided into normal, model and experimental groups, with 12 rats in each group. The model and experimental groups were induced with gavage letrozole to construct the PCOS rat model. After successful modeling, the normal and model groups were given 100 mg·kg^-1 cellulose sodium carboxymethyl by gavage, and the experimental group was given 100 mg·kg^-1 SIF by gavage. Three groups were treated for 21 d with once a day. The apoptosis rate of ovarian tissues was detected by TdT-mediated dUTP nick-end labeling, the serum sex hormone levels were detected by enzyme-linked immunosorbnent assay, the expression levels of miR-29a-3p and IGF1 were detected by real-time fluorescence quantitative plymerase chain reaction, and the positive expression level of IGF1 was detected by immunohistochemistry in ovarian tissues. Ovarian granulosa cells from PCOS model rats were divided into blank group (normal culture), experimental group (100 μg·L^-1 SIF), miR-29a-3p group (after transfection with miR-29a-3p inhibitor, 100 μg·L^-1 SIF culture was given) and IGF1 group (after transfection with miR-29a-3p inhibitor and si-IGF1, 100 μg·L^-1 SIF culture was given). Apoptosis of ovarian granulosa cells was measured by mitochondrial membrane potential analysis, and the expression level of apoptosis-related proteins was detected by Western blotting.

In the animal experiments, the apoptosis rates of experimental, model and normal groups were (16.14±4.09)%, (23.75±5.68)% and (10.83±3.54)%; the luteinizing hormone levels were (26.81±5.99), (41.55±9.84) and (17.63±3.19) mU·mL^-1; the follicle stimulating hormone levels were (51.09±8.72), (41.66±9.87) and (67.91±18.58) pg·mL^-1; the relative expression levels of miR-29a-3p were 0.89±0.08, 0.47±0.06 and 1.00±0.11; the relative expression levels of IGF1 mRNA were 1.42±0.39, 2.36±0.54 and 1.00±0.07; the positive expression levels of IGF1 were 1.37±0.31, 1.98±0.41 and 1.00±0.12, respectively. The differences of above indexes in the experimental and normal groups were statistically different from those in the model group (all P<0.05). In the cell experiments, the mitochondrial membrane potentials of the experimental, miR-29a-3p, IGF1 and blank groups were 1.28±0.13, 0.66±0.05, 1.47±0.19 and 0.54±0.06; the relative expressions levels of the B-cell lymphoma-2-associated X protein were 0.73±0.06, 0.97±0.11, 0.62±0.07 and 1.00±0.08; the relative expression levels of B-cell lymphoma-2 were 1.74±0.23, 1.14±0.18, 2.11±0.37 and 1.00±0.05, respectively. The differences of above indexes in the experimental and IGF1 groups were statistically different from those in the miR-29a-3p group (all P<0.05).

SIF may delay the progression of PCOS rats by regulating miR-29a-3p/IGF1 pathway to mediate the apoptotic process in ovarian cells.