Abstract: 25

GAP JUNCTIONAL INTERCELLULAR COMMUNICATION (GJIC) IN CULTURED LUTEAL CELLS FROM EWES TREATED WITH LH AND/OR AN ANALOG OF PROSTAGLANDIN F₂ (PGF) DURING THE MID-LUTEAL PHASE OF THE ESTROUS CYCLE.

AT Grazul-Bilska^{1 *}, JJ Bilski¹ , V Doraiswamy^{1 *}, LP Reynolds^{1 *}, DA Redmer^{1 *}
Dept. Anim. Range Sci., North Dakota State Univ., Fargo, North Dakota ¹

Superovulated ewes (n=5/group) were divided into 6 groups: 1) vehicle or 2) LH (125 µg/injection) every 6 h from day 6 to day 9 of the estrous cycle; LH as above followed by injection of PGF analog (Cloprostenol, 250 µg) at 3) 8 h or 4) 24 h before slaughter, or Cloprostenol 5) 8 h or 6) 24 h before slaughter. Blood was collected every 6 h (groups 1-4) and at slaughter (day 10-11 of the estrous cycle, all groups) for progesterone (P) analysis. Corpora lutea were dispersed and luteal cells were cultured with or without LH, PGF or LH+PGF (100 ng/ml each). Media then were collected for P analysis and GJIC was evaluated by laser cytometry. During treatment, plasma P was greater (P<.01) for LH-treatment (groups 2-4; 9.1±.4 ng/ml) than vehicle-treatment (group 1; 4.4±.4 ng/ml). At slaughter, plasma P was lower (P<.05) for 24 h of PGF- treatment (groups 4 and 6; 0.3±.1 and 0.4±.2 ng/ml) than no PGF-treatment (groups 1 and 2; 5.9±2 and 12.1±2.2 ng/ml). For small luteal cells from in vivo vehicle-treatment (group 1), GJIC was increased (P<.05) in vitro by LH and decreased (P<.05) by PGF, but GJIC was not affected for all cell types in groups 2-6. Basal P secretion by luteal cells in in vivo LH-treatment (group 2) was greater (P<.05) than in in vivo vehicle- treatment (group 1), which was greater (P<.05) than in groups 3-6. P secretion was increased (P<.05) in vitro by LH in in vivo vehicle-treatment (group 1) but not in groups 2-6. Thus, in vivo LH and/or cloprostenol administration affected plasma P concentrations and secretion of P by luteal cells in vitro. In addition, in vivo LH and/or cloprostenol treatment did not affect basal GJIC, but decreased the in vitro effects of LH or PGF on GJIC of small luteal cells. Thus, in vivo LH or PGF treatment affects GJIC of luteal cells in vitro. NIH grant R29 HD30348.

    This abstract is being presented on Sunday, August 1 at 8:00 AM to 10:15 AM at CUB 2nd Floor Ballroom.