Date of Award

1996

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

First Advisor

Joseph D. Roussel

Abstract

A series of experiments were designed to determine the cyclooxygenase (COX) isoform responsible for prostaglandin release during ovulation and luteolysis. Initially, a reliable, serum-free culture system was developed to produce large numbers of bovine granulosa cells originally harvested from the small antral follicles of abattoir ovaries. This method allowed adequate numbers of cells to be obtained for the subsequent study involving cyclooxygenase regulation. In a second experiment, bovine granulosa cells from small antral follicles were isolated and cultured as in the first experiment for 6 days. Granulosa cells were then exposed to medium alone or medium containing arachidonic acid (10 $\mu$M arachidonic acid) or forskolin (10 $\mu$M). Bovine granulosa cells were capable of being induced into secreting elevated concentrations of prostaglandins following exposure to forskolin, in a manner similar to preovulatory granulosa cells stimulated in vivo. Prostaglandin formation was inhibited by the addition of hydrocorticosterone to the medium, implicating the COX-2 isoform as being responsible for this prostaglandin formation. Also, data from a third experiment revealed the presence of COX-2 in the granulosa cells of women previously stimulated with FSH. A fourth experiment was performed to determine if dexamethasone regulates COX formation in the bovine uterus during luteolysis. Plasma estradiol concentrations indicated that daily administration of dexamethasone (days 13-22) during the estrous cycle resulted in an inhibition of follicle development. Although luteal regression occurred at the normal time in these animals, uterine biopsies on days 16, 19 and 22 of the cycle and western blot analysis revealed that COX-2 was not produced by the uterine endometrium at these times.

ISBN

9780591133318

Pages

125

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