Date of Award

8-2007

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Animal and Veterinary Sciences

Advisor

Gibbons, John

Committee Member

Bodine , Ashby

Committee Member

Bridges , William

Abstract

Superovulation is an assisted reproductive technique used to hyperstimulate the ovaries in an attempt to proliferate desirable genetics by increasing the number of dominant follicles and oocytes available per estrous cycle. Unfortunately, the process is inefficient and costly due to FSH injection protocols, labor requirements, and animal stress. A sustained release implant as a novel FSH delivery mechanism could increase the efficiency and utility while reducing cost and animal stress. The objectives of these experiments were: to design and fabricate a sustained FSH release implant and evaluate the amount of FSH released in-vitro and in-vivo.
Polyethylene glycol diacrylate (PEGDA) was examined in six in-vitro experiments to determine its usefulness as the base material for a sustained FSH release implant. Overall, PEGDA released a maximum of 36 % of the total protein over 24 h perhaps because the majority of the protein remained bound to the implant, suggesting the protein may have been trapped in the cross-linked matrix during polymerization. A second substance (polyacrylamide) was also examined for efficacy as an implant material, in six in-vitro experiments. A 15 % acrylamide implant containing 2.5 mg pFSH with an outer-scaffolding of a 0.6 ml Eppendorf tube (0.5 ml total volume), released 84 % of the total protein over 24 h.
Two in-vivo trials were performed using two different types of polyacrylamide implants. In the first trial, gelding horses were divided into three groups: control, injection, and implant. Serum FSH concentrations were determined by radioimmunoassay and results were analyzed by ANOVA. The injection group was found to have significantly lower FSH concentrations than both the control and implanted groups. Wide variations (greater then 20 ng/ml) in gelding FSH concentrations apparently masked any treatment effects. In the second trial, Holstein heifers were divided into two groups: FSH injection and FSH implant. Serum FSH concentrations were determined by radioimmunoassay and results were analyzed by repeated measures ANOVA. Follicular development and ovulation numbers were determined by transrectal ultrasonography. There were no significant differences (P= 0.4561) in serum FSH concentrations between groups; however, there were large differences (P= 0.004; Mean ± SEM ovulations/heifer) in the number of ovulations between the injection group (13.5 ± 2.77) and the implant group (1.8 ± 0.20). Additionally, while development of the largest follicle for each heifer remained similar (P > 0.05) between groups the second largest follicle for the implant group was significantly smaller (P= 0.0024) when compared to the injection group. The ovulation and follicular development data suggested that the implant's FSH was unable to stimulate the ovary, despite reaching systemic circulation. One possibility was that the bioactivity of the implanted FSH was impaired.
In-vitro results reveal a consistent release of FSH from polyacrylamide implants; however, further studies are required to determine the usefulness of this sustained FSH release implant in-vivo. Evaluation of the bioactivity of the FSH released from an implant and the effects of this FSH at the level of the ovary will be important to advance this area of research. The preliminary data in this thesis provides a compelling foundation to advance this work and focus on the development of an efficacious FSH implant to facilitate superovulation.

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