Brief Summary of Minutes of Annual Meeting

Basic studies concerning the regulation of luteal function during the estrous
cycle have prompted interest in the role of the corpus luteum at day 30 of
pregnancy in pregnancy loss or retention. Studies of factors affecting pregnancy wastage in ewes have shown some effects of the concentration of progesterone on complete loss of pregnancy. Partial losses distributed throughout pregnancy, however, are not readily explained by hormonal patterns or environmental conditions at various stages of pregnancy, and will require additional investigation.

Initial experiments examining the effects of hyperthermic conditions on
follicular steroidogenesis and luteal steroidogenesis in vitro indicate that
hyperthermic exposure affects follicular cells, but not luteal cells. Basal and gonadotropin-stimulated steroidogenesis by follicular cells was affected by heat exposure to 39C and 41C for up to 96h. The inhibitory effects of elevated temperature on estradiol and androstenedione secretion contrasted with the stimulatory effect on progesterone secretion. Conversely, preliminary trials in which luteal cells were exposed to heat (41C) for 48h did not result in an alteration of progesterone production.

Studies designed to examine seasonal effects on follicular development and the follicular to luteal transition, as they relate to embryonic/fetal mortality, are underway. Approximately 66 cows have been examined ultrasonically during the ‘Winter Season‘ (January-April) of this past year with the results pending further analysis of estradiol concentrations. An experiment is currently underway to examine additional cows during the ‘Summer Season‘ (July-September)for comparative purposes.

Bridges PJ and Fortune JE 2003 The characteristics of developing prolonged dominant follicles in cattle. Domestic Animal Endocrinology (In Press).

Butler ST and Butler WR 2002 The effects of a chronic elevation in plasma insulin during the early postpartum period on luteinizing hormone pulsatility and plasma estradiol in dairy cows. J Dairy Sci 84 (Suppl. 1):304.

Cannon MJ and Pate JL 2003 Expression and regulation of interferon-gamma-inducible proteasomal subunits LMP7 and LMP10 in the bovine corpus luteum. Biol Reprod 68:1447-1454.

Cannon MJ and Pate JL 2003 Effects of prostaglandin F2 alpha and progesterone on the ability of luteal cells to stimulate T lymphocyte proliferation. Biol Reprod (In Press).

Cannon MJ and Pate JL 2003 The role of major histocompatibility molecules in luteal function. Reprod Biol Endocrinol (In Press).

Cavicchio VA, Pru JK, Davis BS, Davis JS, Rueda BR, Townson DH 2002 Secretion of monocyte chemoattractant protein-1 by endothelial cells of the bovine corpus luteum: Regulation by cytokines but not prostaglandin F2 alpha. Endocrinology 143:3582-3589.

Inskeep EK 2002 Factors that affect embryonic survival in the cow: Application of technology to improve calf crop. In Factors Affecting Calf Crop: Biotechnology of Reproduction, Michael J. Fields, Robert S. Sand, Joel V. Yelich, Eds. CRC Press, Boca Raton FL, Chapter 19:255-279.

Inskeep EK and Smith DL 2002 Hormonal regulation of the bovine estrous cycle. Proc Sixteenth Annual South Carolina Large Animal Medicine Short Course. Focus on Reproductive Problems. pp5-15.

Inskeep EK 2002 Synchronization of estrus for artificial insemination in small herds of beef and dairy cattle. Proc Sixteenth Annual South Carolina Large Animal Medicine Short Course. Focus on Reproductive Problems. pp55-63.

Knights M, Baptiste QS, Dixon AB, Pate JL, Marsh DJ, Inskeep EK, Lewis PE 2003 Effects of dosage of FSH, vehicle and time of treatment on ovulation rate and prolificacy in ewes during the anestrous season. Small Ruminant Res. (In Press).

Knights M, Hoehn T, Marsh DJ, Lewis PE, Pate JL, Dixon AB, Inskeep EK 2003 Reproductive management in the ewe flock by induction or synchronization of estrus. West Virginia Agricultural and Forestry Experiment Station Bulletin (In Press).

Marr AL, Piepenbrink MS, Overton TR, Lucy MR, Butler WR 2002 The somatotropic axis and lipid metabolism in transition dairy cows in relation to timing of first postpartum ovulation. J. Dairy Sci 85 (Suppl. 1):66.

Pate JL 2003 Lives in the balance:Responsiveness of the corpus luteum to uterine/embryonic signals. Reproduction Supplement (In Press).

Stewart AB, Inskeep EK, Townsend EC, Dailey RA 2003 Effects of gram-positive bacterial pathogens in ewes:peptidoglycan as a potential mediator of interruption of early pregnancy. Reproduction 125:295-299.

Townson DH, Liptak AR 2003 Chemokines in the corpus luteum: Implications of leukocyte chemotaxis. Reprod Biol Endocrinol (In Press).