Effect of growth hormone on endometrium growth of intrauterine adhesion and the underlying mechanism.

OBJECTIVES:The main treatment for intrauterine adhesion (IUA) is hysteroscopic adhesiolysis (HA), which most of treatment frequently employs estrogen and progesterone cycle therapy. The growth and coverage of endometrium after operation is a difficult problem, and several hospitals in China have performed growth hormone (GH) in empirically treating IUA, which has achieved excellent curative effects. Unfortunately, the mechanism of action has not yet been clearly elucidated. In previous study, an IUA animal model after surgical abortion and curettage in pregnant rats has been successfully established. In this experiment, the IUA animal model after surgical abortion and curettage in pregnant rats, which is more in line with the mechanism of human intrauterine adhesion, was used for the first time to investigate the therapeutic effect of GH on IUA in the pregnant rat curettage model. The expression of signal transducers and activators of transcription 3(STAT3), phosphorylated STAT3 (p-STAT3), STAT5 and p-STAT5 content were detected by immunohistochemistry to preliminarily explore the possible mechanism of GH involving in promoting endometrial growth of IUA, and to provide a theoretical basis for clinical medication and treatment. METHODS:Pregnant rats were anesthetized, and the bilateral embryos were removed completely. Then the rat endometrium was scraped with a curette in 4 different directions (front, back, left, and right). After the IUA animal model was established, the rats were randomly divided into 3 groups (n=5): a control group, a GH group, and a GH + AG490 group. Normal saline (0.4 mL/100 g) was injected subcutaneously at the 7th day after curettage in the control group；0.15 U/100 g of GH was injected subcutaneously at the 7th day after curettage in the GH group; 0.15 U/100 g of GH was injected subcutaneously and 1 mg/100 g AG490 was injected intraperitoneally at the 7th day after curettage in the GH+ AG490 group. All the rats were injected continuously for 5 days. The rats in each group were sacrificed at the 14th day. The uterus of rats in each group was stained with HE staining to explore the endometrial morphology and the number of endometrial glands in each group, and Masson staining was utilized to observe the degree of endometrial fibrosis. The levels of STAT3, p-STAT3, STAT5 and p-STAT5 were detected by immunohistochemistry. RESULTS:1) The number of glands in the GH group was more than that in the control group on the 14th day, with statistical difference (P<0.05). However, the number of endometrial glands in the AG490+GH group was decreased compared with the GH group on the 14th day (P<0.05). 2) The fibrosis ratio in the GH group was less than that in the control group at the 14th day after operation (P<0.05). However, the area of endometrial interstitial fibrosis in the AG490+GH group was much higher than that in the GH group 14 days after operation (P<0.05). 3) Compared with the control group, there was not significant difference in the levels of STAT3 and STAT5 in GH group (both P>0.05), while the levels of protein p-STAT3 and p-STAT5 were increased in the GH group (both P<0.05). Compared with the GH group, there was not significant difference in the levels of STAT3 and STAT5 in the AG490+GH group (both P>0.05), while the levels of p-STAT3 and p-STAT5 were decreased in the AG490+GH group (both P<0.05). CONCLUSIONS:GH can not only promote the growth of endometrial glands in the IUA model, but also reduce the degree of fibrosis and play a role in the treatment of IUA, which may be related to the activation of the Janus kinase (JAK), JAK/STAT3 and STAT5 signaling pathways.