Cetrorelix and Triptorelin active immunization influences follicle development and receptor expressions of ovaries in mice

Abstract

The study investigated comparatively the effects of active immunization of Cetrorelix and Triptorelin on the follicle development, histological structures, and expressions of FSHR and LHR proteins in the ovary. One hundred and five female mice, 35 days old, and body weight of 26.56±2.89g, were randomly assigned into Cetrorelix (CET), Triptorelin (TRI) and control groups (CG). Mice in CET-1, CET-2 and CET-3 (n=15) were subcutaneously injected with 0.1, 0.2 and 0.4mL Cetrorelix antigen (100μg/mL) for seven days, respectively. Mice in TRI-1, TRI-2 and TRI-3 were injected with 0.1, 0.2 and 0.4mL Triptorelin antigen (100μg/mL) for seven days. Mice in CG (n=15) were injected with 0.2mL saline for seven days. Western blotting was utilized to determine the expressions of follicle stimulating hormone receptor (FSHR) and luteinizing hormone receptor (LHR) proteins. ELISA was used to measure the serum FSH and LH concentrations. The ovarian slices were observed under optical microscopy. The results showed that the ovarian weights of CET and TRI groups increased slightly with a maximum increment of 27.02% of CET-1 mice on day 35. Ovarian weights in TRI group increased dose-dependently with a maximum increment of 45.77% in TRI-3 on day 35. The numbers of the primordial follicle (POF), primary follicle (PF), secondary follicle (SF) and mature follicle (MF) of CET and TRI groups increased at different degrees when compared to CG. The granular layer in SF was arranged tightly and zona pellucida (ZP) was thickened. Follicles developed fully. Follicle longitudinal diameter (FLD), follicle transverse diameter (FTD) and follicle wall thickness (FWT) in CET and TRI groups increased as compared to CG. FLD, FTD and FWT of TRI-3 had a larger increment than CG and CET-1 on days 21 and 35. Expression levels of FSHR and LHR proteins in TRI group increased when compared to CG. Expression levels of FSHR and LHR proteins of CET group decreased. Serum FSH of TRI group was slightly higher than the CG and CET group on day 21. On day 35, serum FSH levels of CET-1 and TRI-1 were greater than CG and the rest of the subgroups. Serum FSH levels had no significant differences among all groups. Expression levels of LHR and FSHR proteins in CET group had obvious negative correlations to FLD, FTD and FWT. However, in the TRI group, these correlations were positive. In conclusion, Cetrorelix and Triptorelin immunization could improve ovarian growth, increase the follicle numbers, enhance dose-dependently the FLD, FTD and FWT, and eventually promote the ovary and follicle development. Cetrorelix decreased expression levels of FSHR and LHR proteins in the ovaries of mice. Triptorelin enhanced expression levels of FSHR and LHR proteins. Triptorelin treatment had more obvious effects than Cetrorelix treatment.