PARENT SESSION
SLIDE SESSION 10: MECHANISMS OF LUTEAL REGRESSION
Chairs: Bo Rueda, Jack Carlson, Carlos Stocco (Trainee)
Arts Hall 026
1:30 PM-3:30 PM

EFFECT OF GONADOTROPINS (LH AND FSH) AND (OR) PROSTAGLANDIN F₂ (PGF₂ ) ON TISSUE INHIBITOR OF METALLOPROTEINASES (TIMP)–1 PRODUCTION BY OVINE CORPORA LUTEA.

Ricke, William¹, McIntush, Eric², Perry, George¹, Niswender, Gordon², Smith, Michael¹, ^{1 2}

ABSTRACT- Tissue inhibitor of metalloproteinases (TIMP)–1 is highly expressed in luteal tissue and appears to be an important regulator of luteal tissue remodeling. TIMP–1 was localized to secretory granules of ovine large luteal cells, which is consistent with a regulated, rather than constitutive, pathway of secretion. We investigated the regulation of luteal TIMP–1 production by gonadotropins and (or) PGF₂ in ovine luteal cells and tissues. The specific objectives were: 1) to determine if TIMP–1 production by mixed, small, or large luteal cells (MLC, SLC, or LLC, respectively) was regulated by LH or FSH, and 2) to determine the effect of LH and (or) PGF₂ on TIMP–1 production by perifused luteal slices. In experiment 1, corpora lutea (CL) were collected on day 10 (day 0 = estrus), pooled (n = 5 pools), and enzymatically dispersed. Each pool consisted of 2 to 3 CL and CL from an animal were not represented in more than one pool. Concentrations of TIMP–1 in media conditioned by MLC treated with LH or FSH (0, .1, 1, 10, or 100 ng/ml) did not differ from untreated MLC. Additionally, concentration of TIMP–1 in media conditioned by SLC was undetectable regardless of treatment. However, treatment of LLC with LH (1, 10, or 100 ng/ml) but not FSH increased (P < .05; 180 to 200%) concentration of TIMP–1 in conditioned media. Neither LH nor FSH affected the DNA content of wells containing MLC or LLC. In experiment 2, an in vitro perifusion system that maintained luteal tissue architecture and progesterone secretion for up to 11 hrs was used to determine the effect of LH and (or) PGF₂ on TIMP–1 production by luteal slices from five ewes. Treatments consisted of control (no treatment), LH (100 ng/ml), PGF₂ (1 M), or LH (100 ng/ml) + PGF₂ (1 M). Treatment with LH did not increase TIMP-1 production relative to the control group; however, PGF₂ decreased (P < .02) TIMP–1 production relative to control and LH treated groups. TIMP–1 production following treatment with LH + PGF₂ was intermediate between the control/LH and PGF₂ groups. In summary, LH stimulated TIMP–1 production by LLC; whereas, PGF₂ decreased TIMP–1 production by luteal slices. The latter observation is consistent with the finding that luteal concentrations of TIMP–1 rapidly decreased following PGF₂ administration, in vivo. Supported by USDA 98–35203–6282 (MFS) and USDA 98–35203–6226 (GWS).

KEY WORDS: Corpus Luteum, TIMP, Prostaglandin F₂