PROSTAGLANDIN-F2-ALPHA, PROGESTERONE AND OXYTOCIN PRODUCTION BY CULTURED BOVINE LUTEAL CELLS TREATED WITH PROSTAGLANDIN E(2) AND PREGNANCY-SPECIFIC PROTEIN-B

The objectives of this experiment were to study the effects of pregnan cy-specific protein B (PSPB) and prostaglandin E(2) (PGE(2)) on bovine luteal cell progesterone (P4), prostaglandin P-2 alpha and oxytocin p roduction. Corpora lutea were collected during the mid- (days 10-12; n = 5) or late-luteal (days 17-18; n = 5)stages of the estrous cycle. L uteal cells were dispersed and accessory cells removed. Luteal cells ( 1.5 x 10(5)) were incubated in a 3 x 3 factorial arrangement and treat ed with PSPB (0, 2.5, or 5.0 mu g) adn PGE(2) (0, 100, or 200 ng) in 5 00 mu L of Ham's F-12 medium. All cells were incubated for 18 h before adding treatments. Samples were then collected at 6 h and 12 h. Durin g the 18 h pretreatment period, P4, PGF(2 alpha), and oxytocin product ion was similar between the prospective treatment groups. The PSPB fai led to increase P4 production. The PGE(2) x time interaction showed an d 12 h (p < 0.03). Also, the stage x time interaction indicated that m id-stage cells produced more (p < .001) P4 than late-stage cells durin g the pretreatment period at 6 h and 12 h. The PSPB did not alter PGF( 2 alpha) production by mid-stage cells, but increased (P < .05) PGF(2 alpha) secretion by both mid- and late-stage cells; luteal cells treat ed with 200 ng of PGE(2) produced more (P < 0.001) PGF(2 alpha) than 1 00 ng of PGE(2). Oxytocin secretion was not changed by treatment with PGE(2) or PSPB. Oxytocin production was greater (P < 0.001) by mid-sta ge than late-stage cells during the pretreatment period at 6 h and 12 h. Oxytocin production was similar between the 6 h and 12 h culture ti mes within stage of the cycle. These data indicate that PSPB does not change bovine luteal cell P4 or oxytocin production, but elevates PGF( 2 alpha) in late-stage cells. The PGE(2) increases both P4 and PGF(2 a lpha), but does not alter oxytocin production. Lastly, PSPB and PGE(2) do not interact to promote P4, PGF(2 alpha), or oxytocin production b y cultured bovine luteal cells.