Mary M. Beck
Date of this Version
Thesis (M.S.)--University of Nebraska--Lincoln, 2002. Department of Animal Science.
Because of increasing numbers in wildlife, immunocontraceptives are being developed to decrease these animals and other birds. This study was conducted in conjunction with the United States Geological Survey Midcontinent Science Center in Fort Collins, Colorado (USGS), to determine whether mammalian GnRH (m-GnRH) can be used as a potential immunocontraceptive to decrease reproductive fertility in mature Japanese quail.
Eighty male and female Japanese quail were injected with either mGnRH, chicken GnRH-I (c-GnRH-I), chicken GnRH-II (c-GnRH-II), or vehicle (controls). Blood samples were analyzed for estrogen (E2) and testosterone (T) levels, in addition to antibody titer (Aby) development against the corresponding conjugated antigen. Testes were weighed and stored in -70° C until histological slides were made. The granulosa layer was isolated and stained for 3β–Hydroxysteroid Dehydrogenase activity (3β–HSD).
The data were analyzed using repeated measures analysis of variance (ANOVA) to determine antibody percentages, repeated measures analysis of covariance (ANCOVA) to determine hormone concentrations, and Pearson correlation coefficient to determine correlation between antibody and hormone concentrations. All analyses were conducted using Proc Mixed (SAS Institute Inc., 2001).
There was a significant difference in Aby concentrations between treatment groups (P=0.001) and the interaction of treatment by week was highly significant (P=0.0094). There was no difference in testes weight of males killed midway (WK 5) (P=0.2259) and those killed at the end of the study (P=0.9995). There were no apparent differences in gross morphology of testicular tissue. Overall, testosterone concentrations between treatment groups approached significance (P=0.1071), but there was no difference between week of treatment (P=0.3551) or between treatment by week (P=0.3876). Correlation between antibody percentages and hormones indicated that antibodies to both m-GnRH and c-GnRH-I were transiently inversely correlated with testosterone concentrations, but that antibodies to c-GnRH-II were not. Dispersed granulosa cells, stained for 3β-HSD, were found to have no differences in staining percentage between treatment groups (P=0.6822). Estradiol concentrations were found to have differences in estradiol concentrations between treatment groups (P=0.1071). The conclusion of this study determined that immunization of Japanese quail using m-GnRH, c-GnRH-I, and c-GnRH-II affected sex steroid hormones, but not to the point that fertility was affected.
Advisor: Mary M. Beck