The effects of recombinant LHRH fusion proteins on testicular development and histology in ram lambs

Two recombinant luteinizing hormone releasing hormone (LHRH) fusion protein s were evaluated for their effectiveness in suppression of testicular devel opment and histology by injecting together. Recombinant fusion proteins, ov albumin-LHRH-7 and thioredoxin-LHRH-7, were generated using recombinant DNA technology and expressed in E. Coli. Eleven ram lambs ranked by age and bo dy weight were randomly assigned to receive either ovalbumin and thioredoxi n recombinant protein mixture (control group, n=5) or ovalbumin-LHRH-7 and thioredoxin-LHRH-7 recombinant fusion protein mixture, anti-LHRH vaccine, ( immunization group, n=6). Animals in each group were weaned at 17 wk of age and were injected (primary immunization) with either mixture at 18 wk of a ge. Both groups received a booster immunization 8 wks later (26 wk of age). Scrotal circumference, scrotal length, testicular diameter and testicular length were measured in both groups every other week. All animals were slau ghtered at 36 wk of age. Immediately after slaughter, a small testicular ti ssue was taken and processed for histological examination. In the ram lambs in immunization group scrotal circumference and testicular diameter increa sed steadily until second booster and then remained as a plateau until the end of the experiment. The differences in scrotal circumferences and testic ular diameter were significant between the two groups during the last three weeks of the study (p <0.05). There were no differences in testicular and scrotal length throught the study (p >0.05). Semineferous tubules lost thei r regular shape and were decreased in diameter in immunization group. Altho ugh a few spermatozoa were seen in some tubules, in general there were atro phy of the semineferous, tubules and loss of spermatogenesis, nevertheless, it seemed that animals in this group were potentially fertile.