Growth hormone promotes human endometrial glandular cells proliferation and motion through the GHR-STAT3/5 pathway

Growth hormone inhibits the JAK/STAT3 pathway by regulating SOCS1 in endometrial cells in vitro: a clue to enhance endometrial receptivity in recurrent implantation failure

Recurrent implantation failure (RIF) is defined as failure to achieve clinical pregnancy after at least 3 transfers of good-quality embryos by natural or artificial means. RIF is often a complex problem with a wide variety of etiologies and mechanisms as well as treatment options. In this study, using immunohistochemistry and Western blot, we demonstrated that the expression of leukemia inhibitory factor (LIF), Janus kinase 1 (JAK1), and signal transducer and activator of transcription 3 (STAT3) was increased, while that of suppressor of cytokine signaling 1 (SOCS1) was decreased in RIF patients. Growth hormone (GH) administration proved to have positive effects on embryo implantation in RIF patients, but the action mechanism of GH has not been elucidated yet. To this aim, we studied the effects of GH on the proliferation in vitro of endometrial adenocarcinoma Ishikawa cells. GH stimulated the expression of LIF and SOCS1, and through SOCS1 inhibits the expression of phosphorylated STAT3, and finally inhibits the occurrence of RIF. Excessive phosphorylation of STAT can lead to decreased endometrial receptivity and abnormal embryo implantation. We also examined the effects of LIF overexpression and an LIF inhibitor (EC330) on the JAK/STAT pathway. LIF promoted cell proliferation, and the up-regulation of LIF increased the expression of SOCS1 and JAK1/STAT3 pathway-related genes in Ishikawa cells. As GH can inhibit the JAK1/STAT3 pathway through LIF, we hypothesize that upregulating SOCS1 may be a potential approach to treat RIF at the molecular level. GH can inhibit the JAK1/STAT3 pathway through LIF, up-regulating SOCS1 to treat RIF at the molecular level.

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.

Effects of zearalenone on ovarian development of prepubertal gilts through growth hormone axis

This experiment aimed to establish the effects of zearalenone (ZEN) on ovarian development in prepubertal gilts through the growth hormone axis [growth hormone-releasing hormone (GHRH) / growth hormone (GH) / growth hormone receptor (GHR)]. In a 40-day experiment, 48 Landrace × Yorkshire crossbred prepubertal gilts were randomly allocated to four dietary treatments, including a basal diet supplemented with 0 (control), 400 (T1), 800 (T2), and 1,600 (T3) μg/kg ZEN. The ovary index of T2 (P = 0.058) and T3 (P = 0.065) increased compared to the control group. Besides, histopathological examination revealed that ZEN promoted the development of ovaries and follicles. The GHR content, relative expression levels of GHR, janus activated kinase 2 (JAK2) mRNA, and mean optical density of GHR in the ovaries of prepubertal gilts in the T2 experimental group increased significantly at P &lt; 0.05 compared to the control group. The T3 group had significantly higher GHR content, relative JAK2 expression levels, and signal transducer and activator of transcriptions 3 (STAT3) mRNA. In conclusion, ZEN enhances the biological effect of GH, promotes the development of the ovary (follicle), and exerts reproductive toxicity by increasing the expression level of GHR, JAK2, and STAT3 mRNA ovary and immune intensity of GHR protein.