The purpose of the studies reported in this thesis was to provide further evidence in support of the hypothesis that ovulation-inducing factor (OIF) is a component of seminal plasma which is conserved amongst mammals. Based on studies conducted in vivo, the results indicate that males ejaculate a substance during copulation which is responsible for the ovulatory and luteotrophic effect in female camelids. In our lab we have developed an <i>in vivo</i> llama bioassay to study the presence and biological effects of OIF in seminal plasma from different species.<p>
The objective of the first experiment within the first study was to determine if llama seminal plasma would stimulate ovulation in prepubertal mice. Mice were treated with a single 0.1 mL intraperitoneal dose of 1) phosphate-buffered saline (negative control), 2) 5 µg gonadotropin-releasing hormone (GnRH), 3) 5 IU of human chorionic gonadotropin (hCG) or 4) llama seminal plasma. Results indicate that prepubertal mice treated with GnRH, hCG or llama seminal plasma stimulated similar proportions of mice to ovulate, which were all higher than the proportion of mice that ovulated after saline treatment. The number of oocytes observed under a stereomicroscope was also higher in all treatment groups than in mice treated with saline. However, the number of oocytes observed was lower in mice treated with seminal plasma than those treated with GnRH, both of which were similar to the number of oocytes observed in hCG treated mice.<p>
In a second part of this study the corollary that OIF is present in the seminal plasma of horses and pigs was examined. Seminal plasma from horses or pigs was administered intramuscularly to female llamas and ovulation was monitored using transrectal ultrasonography. Llamas were treated with an intramuscular dose of 1) phosphate buffered saline (negative control), 2) llama seminal plasma (positive control), 3) equine seminal plasma or 4) porcine seminal plasma. Ovulations were detected in llamas treated with seminal plasma while none were observed in saline-treated llamas. The proportion of llamas that ovulated when treated with equine seminal plasma was higher than llamas treated with saline. The proportion of llamas that ovulated after porcine seminal plasma tended to differ from negative control groups, but did not reach statistical significance. The proportion of llamas that ovulated after equine or porcine seminal plasma treatment was lower than animals treated with llama seminal plasma which indicates that either OIF is not present in equal concentration among mammals, or that OIF is not structurally the same across mammals.<p>
The second study was carried out to test the hypothesis that OIF stimulates LH secretion at the level of the anterior pituitary gland. The second objective was to determine if the degree of LH release was related to the dose of OIF treatment. Anterior pituitary cells (2 x 10^6 cells/ well) from either llamas (reflex ovulator) or cattle (spontaneous ovulator) were incubated for 2 hours with either media containing no treatment (control), GnRH or OIF. In all experiments, GnRH and OIF stimulated more LH secretion than control groups. An effect of dose was evident in the llama pituitary cell culture where mean LH concentrations were greater in wells treated with a higher dose of OIF in comparison to wells treated with a lower dose, both of which were higher than in wells with no treatment. Although OIF stimulated LH release in bovine cell cultures, an apparent dose response was not detected. Results indicate that the preovulatory LH surge observed after OIF treatment in camelids may be the result of OIF directly stimulating LH release from gonadotrope cells within the anterior pituitary gland.
In conclusion these results illustrate that the presence and the response to OIF is conserved among species that share no relation or common reproductive strategy.
| Identifer | oai:union.ndltd.org:USASK/oai:usask.ca:etd-09142009-112431 |
| Date | 14 September 2009 |
| Creators | Bogle, Orleigh Addelecia |
| Contributors | Pierson, Roger, Singh, Baljit, Verge, Valerie, Adams, Gregg P. |
| Publisher | University of Saskatchewan |
| Source Sets | University of Saskatchewan Library |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://library.usask.ca/theses/available/etd-09142009-112431/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Saskatchewan or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
Page generated in 0.0046 seconds