We investigated the effects of gonadotropin releasing hormone (GnRH) agonist on expressions of GnRH receptor (GnRHR), follicle-stimulating hormone receptor (FSHR) and luteinizing hormone receptor (LHR) proteins in the ovaries and follicular development in the ewes. Forty-two pre-pubertal ewes were assigned to experimental groups 1 to 5 (EG-I to EG-V) and control group (CG). Ewes in EG-I, EG-II and EG-III were subcutaneously injected with 200, 300 or 400 μg alarelin antigens twice (on days 0 and 14), respectively. Ewes in EG-IV and EG-V were subcutaneously injected with 200 μg and 300 μg alarelin antigen four times (on days 0, 7, 14 and 21). Ewes in CG were subcutaneously injected with a solvent twice (on days 0 and 14). Serum concentrations of GnRH antibody in the EGs increased and were higher than (P<0.05) that of CG from day 14 to day 60. GnRH antibody concentrations in EG-IV and EG-V were higher than that in EG-I, EG-II and EG-III from days 35 to 45. Expressions of GnRHR protein in EG-IV and EG-V were lower than that in CG (P<0. 01). Expressions of FSHR and LHR proteins in EGs increased. Levels of FSHR and LHR proteins in EG-IV and EG-V (P<0.05) were higher than CG. Ovarian weights in EGs increased. Values of follicle vertical diameter, follicle transverse diameter, follicle wall thickness, follicle externatheca thickness and follicle internatheca thickness in EG-III and EG-V were greater than other groups. Primordial follicles and primary follicles developed quickly in alarelin-immunized animals. Secondary follicles and mature follicles became more abundant. Mitochondria, mitochondrial cristaes and cortical granules increased. Serum FSH concentrations of EGs remained higher than that in CG from days 28 to 70 (P<0.05). Alarelin immunization stimulated GnRH antibody production, suppressed expression of GnRHR protein, enhanced expressions of FSHR and LHR proteins in ovaries, promoted FSH secretion and thereby accelerated the development of ovaries and follicles in ewes.

To investigate the LHR protein expressions in the ovine uteri and LH secretion, and to determine whether the alarelin active immunity affects the uterine development in ewes. Twenty-eight ewes (five to six months) were assigned to four experimental groups. Animals in EG-1, EG-2 and EG-3 were subcutaneously injected with 200, 300 and 400 mg alarelin antigens (day 0 and 14), respectively. Animals in the CG were injected with 2.0 mL solvent (day 0 and 14). Uterine horns were dissected aseptically on day 70. The serum LH concentrations were measured using ELISA. Tissue slices were observed and photographed under optical and electron microscopes. The images were measured using Images software. The results showed that the expressions of LHR protein in EGs increased. The level of LHR protein in EG-3 was higher than that in CG (P B0.05). Serum LH concentrations in EGs were lower than that in CG from day 21 to day 45 (P B0.05). Uterine weights in EG-1, EG-2 and EG-3 reduced by 4.66%, 10.20% and 16.63% (PB0.05), respectively. Uterine wall thickness (UWT) in EG-1, EG-2 and EG-3 reduced by 1.41%, 5.84% and 8.75% (P B0.05), respectively. The endometrial epithelium thickness (EET) in EG-1, EG-2 and EG-3 decreased too (P B0.05). The uterine wall shrank obviously and the glandular cavity reduced. The microvilli shortened. The mitochondria and mitochondrial crista decreased. Summarily, alarelin immunity could promote LHR protein expression in the uteri, and decreased serum LH concentrations, including decreased EET, UWT and uterine weights, could affect the uterine microstructure and ultrastructure, resulting in the inhibition of uterine development dose-dependently.