Mississippi State University
Lemley, Caleb O.
Perry, George A.
Date of Degree
Dissertation - Open Access
Animal and Dairy Science
Doctor of Philosophy
College of Agriculture and Life Sciences
Department of Animal and Dairy Sciences
Steroid and eicosanoid metabolism occurs in two phases and primarily within hepatic tissues, but localized metabolism has been examined in several extra-hepatic tissues in humans and rodents. Phase I of metabolism is performed by Cytochrome P450s (CYP) that add hydroxyl groups to the carbon ring structure which is further metabolized by phase II UDP-glucuronosyltransferase (UGT). The overall objectives of the following experiments were to: 1) determine the amount of extra-hepatic steroid metabolism within reproductive tissues of cattle across the estrous cycle; 2) determine the amount of extra-hepatic steroid metabolism and an oxylipin profile within reproductive tissues of cattle based on pregnancy status; and 3) determine the amount of endometrial blood perfusion in cattle using a novel laser Doppler technique. Activity of CYP1A was found within corpora lutea (CL) tissues of both pregnant and non-pregnant cattle, but not within endometrial tissues. Endometrial perfusion, measured using a novel laser Doppler technique, was also validated by measuring angiogenic factors in close proximity to the location of perfusion. A positive correlation (r = 0.28; P = 0.04) was observed between endometrial perfusion and nitrite concentration, an angiogenic factor. Endometrial blood perfusion was affected by the proximity to the CL, but not by the proximity of the dominant follicle. In addition, UGT was categorized across the estrous cycle and the activity was dependent upon the proximity of the CL. Oxylipins, including eicosanoids, were also profiled in CL of cattle that were non-pregnant and pregnant with 5 out of 39 oxylipins differentially expressed. The activity and oxylipin products of steroid and eicosanoid enzymes were not correlated with serum or luteal progesterone. Through these experiments, we have verified that there is localized metabolism of steroids and eicosanoids within reproductive tissues of cattle as well as fetal tissues. Also, we have achieved a full oxylipin profile of non-pregnant and pregnant cattle CL with five oxylipins contained in various amounts between pregnancy status.
Owen, Megan Pauline Theresa, "Investigating Extra Hepatic Steroid And Eicosanoid Metabolizing Enzymes In Cattle" (2017). Theses and Dissertations. 2802.