Endocrine responses in cows fed Ponderosa pine needles and the effects of stress, corpus luteum regression, progestin, and ketoprofen.

Abstract

Pregnant cows were fed pine needles (PN, 2 kg.cow-1.d-1) mixed with the diet to determine factors that affect abortion response. In Exp. 1, treatments were used to determine the effects of experimental stress and pelleting of pine needles. Pelleting needles and experimental stress delayed abortion response (P < .01). Stress-induced delay was associated with abnormal patterns of progesterone and cortisol (P < .01). In Exp. 2A and 2B, the role of the corpus luteum (CL) in abortion response to PN consumption was investigated by regressing the CL with prostaglandin F2 alpha. Regression of the CL and PN feeding reduced interval to parturition, but the effect of PN feeding was less when the CL was regressed (PN x CL, P < .01). The progesterone increase in response to experimental stress was decreased by CL regression (P < .01). In Exp. 3, melengestrol acetate (MGA) was fed (0, 2, or 4 mg.cow-1.d-1) in addition to PN. Parturition was blocked more effectively as dose of MGA increased (P = .075), but only parturition was blocked rather than the effects of PN. In Exp. 4, CL regression was blocked by feeding ketoprofen. Ketoprofen delayed response to PN, but the effect was only temporary (P < .01). Our conclusions are that 1) experimental stress delays abortion response to PN by increased concentrations of progesterone, 2) pelleting PN decreases their abortifacient activity, and 3) abortions caused by PN can be blocked by feeding a progestin or a prostaglandin inhibitor, but these compounds do not block the primary abortifacient effects of PN.

Evidence that polymorphonuclear neutrophils infiltrate into the developing corpus luteum and promote angiogenesis with interleukin-8 in the cow

“…Cytokines and chemokines, such as prostaglandins (PGs) [4], tumor necrosis factor α (TNFα) [5], interleukin (IL)-1 [6] and IL-8 [7,8] are found in high concentrations in the follicular fluid in the pre-ovulatory phase. Consequently, high numbers of neutrophils and macrophages infiltrate in the pre-ovulatory follicle at the time of ovulation [9].…”

Effect of cortisol on neurophysin I/oxytocin and peptidyl glycine-α-amidating mono-oxygenase mRNA expression in bovine luteal and granulosa cells

“…Cortisol, which is the main GC in cows, can prolong their oestrous cycle (Kanchev et al 1976, Stoebel andMoberg 1982), affect ovulation by inhibition of the LH surge (Suter andSchwartz 1985, Macfarlane et al 2000) and is considered an anti-luteolytic factor in the corpus luteum (CL) (McCracken et al 1999, Lee et al 2007, Komiyama et al 2008. Under physiological conditions, GCs initiate parturition; in contrast, high levels of cortisol, released during stress, can cause abortions in humans and animals (Thong et al 1993, Short et al 1995. One potential explanation for this phenomenon is that cortisol may excessively stimulate OT secretion, which can disrupt "progesterone block" in the myometrium.…”