Alteration of the Endometrial EGF Profile as a Potential Mechanism Connecting the Alterations in the Ovarian Steroid Hormone Profile to Embryonic Loss in Repeat Breeders and High-producing Cows

Poor reproductive efficiency is a worldwide problem that has affected the dairy industry during the last several decades. In an attempt to explain the changes in reproductive physiology caused by high milk production, a model of elevated steroid metabolism in lactating dairy cows has been proposed. A slow increase in levels and low peak levels of estradiol (E₂) and progesterone (P₄) characterize endocrine changes in high producing cows. Similar changes have been reported in the repeat breeder cows. The abnormal changes in E₂ and P₄ concentrations of these cows may cause an improper uterine environment due to disturbed expression of growth factors and cytokines in the endometrium. This review focuses on the alteration in epidermal growth factor (EGF) profile in the endometrium during the estrous cycle. The normal cow has two peaks of EGF concentrations on days 2–4 and 13–14. Low concentrations of EGF on these days distinguished both high-producing and repeat breeder cows from normal cows. Alteration of the EGF profile could be found in 70 and 40% of the repeat breeder and high-producing cows, respectively. Treatment with a high dose of estradiol benzoate and an intravaginal progesterone-releasing device restored the normal EGF profile in about 70% of the affected cows. The cows having a normal EGF profile after treatment showed a higher pregnancy rate than the cows with the altered profile. Further studies to understand the etiology of the alteration in the EGF profile are needed to develop another treatment option and preventive management for this problem.     

Effects of progesterone on water,sodium, potassium and calcium contents in striatum of rats with focal cerebral ischemia/reperfusion

AIM: To explore the neuroprotective action of progesterone(PROG), which has been proved to be a "neuroactive steroid". METHODS: The model of focal cerebral ischemia was established in rats by reverserble inserting a nylon thread with a diameter of 0.2 mm into the anterior cerebral artery through the internal carotid artery. The effect of PROG was assessed by determining water,sodium, potassium, and calcium contents in striatum of rats subjected to 2 h ischemia followed by 22 h reperfusion. RESULTS: The water,sodium,and calcium contents of middle cerebral artery occlusion(MCAO) striatum were obviously higher,the potassium content was obviously lower than those of non-MCAO striatum in I/R and DMSO groups,but there was no significant difference between these two groups.Compared with the result in I/R and DMSO groups , water, sodium and calcium contents significantly decreased, but potassium(P＜0.01) obviously elevated in MCAO striatum in the PROG-pretreated group and PROG-pre or posttreated group.There was also significant reduction in water and sodium, but not significantly changed in calcium and potassium in PROG-posttreated group. The water,sodium,potassium,and calcium contents of MCAO striatum in each PROG-treated group were not remarkably different in comparision with those in dexamethasone treatment group(P＞0.05). CONCLUSION: Treatment with PROG can significantly reduce the striatal injury of rats with cerebral ischmia-reperfusion.     

Effect of subluteal concentrations of progesterone on luteinizing hormone and ovulation in lactating dairy cows

Two experiments were conducted to determine if administration of progesterone within a low, subluteal range (0.1-1.0 ng/mL) blocks the luteinizing hormone (LH) surge (experiments 1 and 2) and ovulation (experiment 2) in lactating dairy cows. In experiment 1, progesterone was administered to cycling, lactating dairy cows during the luteal phase of the estrous cycle using a controlled internal drug release (CIDR) device. CIDRs were pre-incubated in other cows for either 0 (CIDR-0), 14 (CIDR-14) or 28 days (CIDR-28). One group of cows received no CIDRs and served as controls. One day after CIDR insertion, luteolysis was induced by two injections of prostaglandin (PG) F(2alpha) (25 mg) at 12 h intervals. Two days after the first injection, estradiol cypionate (ECP; 3 mg) was injected to induce a LH surge. Concentrations of progesterone after luteolysis were 0.11, 0.45, 0.78 and 1.20 ng/mL for cows treated with no CIDR, CIDR-28, CIDR-14, and CIDR-0, respectively. LH surges were detected in 4/4 controls, 4/5 CIDR-28, 2/5 CIDR-14 and 0/5 CIDR-0 cows following ECP. In experiment 2, progesterone was administered to cycling, lactating, Holstein cows during the luteal phase of the estrous cycle as in experiment 1. Luteolysis was induced as in experiment 1. The occurrence of an endogenous LH surge and ovulation were monitored for 7 days. Concentrations of progesterone after luteolysis were 0.13, 0.30, 0.70 and 1.20 ng/mL for cows treated with no CIDR, CIDR-28, CIDR-14 and CIDR-0, respectively. LH surges and ovulation were detected in 5/5 controls, 3/7 CIDR-28, 0/5 CIDR-14 and 0/5 CIDR-0 cows. It was concluded that low concentrations of progesterone can reduce the ability of either endogenous or exogenous estradiol to induce a preovulatory surge of LH and ovulation.     

The effect of estrus synchronization treatment on somatic cell count of transitional-anestrus local-Damascus cross breed goats’ milk

An experiment was conducted to examine the effect of estrus synchronization protocols and steroid hormones concentrations on somatic cell count (SCC) of transitional-anestrus local-Damascus cross goats’ milk. Fifty-six goats (2–4-year old) were randomly assigned to three groups: fluorogestone acetate (FGA, n = 19), FGA-Prostaglandin (FGA-PGF, n = 19) and control (n = 18) groups. Intravaginal sponge containing 40 mg FGA was inserted for 13 days and an injection of 600 IU equine chorionic gonadotropin (eCG) was administered for goats of FGA and FGA-PGF groups at the time of sponge removal (day 0). In addition, goats of FGA-PGF group were injected with 10 mg dinoprost tromethamine () on day 0. Five fertile local-Damascus cross bucks were turned-in with all goats on day 0. Blood and milk samples were collected from all goats on days -13 (beginning of experiment), -6, 0, 1, 2, 7, 13 and 20 (end of the experiment). Four-year old and second-parity goats had significantly higher (p < 0.05) SCC of both udder halves than 2- and 3-year old and first-parity goats, respectively. There was a significant effect (p < 0.05) for treatment and number of kids born in the last kidding season on SCC of both udder halves. Neither estradiol nor progesterone concentrations were correlated with SCC in goats in this experiment. The SCC of both udder halves and left udder halves in goats of the control and FGA groups, respectively, increased significantly (p < 0.05) after sponge removal and buck introduction when compared with day 0, with no differences in the FGA-PGF group. This increase in SCC of the control and FGA groups coincided with peak estrus behavior. However, SCC was far below the upper limit of the current standard for normal milk. In conclusion, induction of estrus with progestagen based programs and buck introduction may cause temporary significant increase in SCC. However, the SCC values during this period of temporary increase were still in the range of acceptable values for normal milk. With the current standards for SCC of 1,000,000/ml as legal limit for abnormal milk control programs in goats, estrus synchronization programs and the estrus status should not be considered when bulk-tank milk SCC is being investigated.     

Effect of feeding flax or linseed meal on progesterone clearance rate in ovariectomized ewes

Ovariectomized ewes (n=22; 68.76+/-2.34 kg initial body weight; 2.9+/-0.1 initial body condition score) were individually fed one of three diets: (1) control (phytoestrogen-free; n=7), (2) flax containing diet (n=8), or (3) linseed meal (LSM) containing diet (n=7) to investigate the rate of progesterone (P4) clearance. On day 20 of feeding (day 0=initiation of treatment), a P4 releasing device (CIDR) was placed in the vagina and jugular blood samples were obtained prior to CIDR insertion and 15, 30, 60, and 120 min following CIDR insertion. Further, blood samples were obtained daily between days 21 and 24. On day 25, blood samples were retrieved prior to CIDR removal and 2, 5, 10, 15, 30, 60, 120, and 360 min following CIDR removal. There was no difference in initial or final body weight or body condition score and there were no time by diet interactions on P4 clearance. The fractional rate of P4 uptake measured prior to CIDR insertion through day 4 following insertion tended to be greater (P=0.07) in LSM fed ewes (508.75+/-71.37%/min) compared to flax (295.39+/-66.76%/min) and control fed (287.54+/-71.37%/min) ewes. Diet tended (P=0.10) to influence P4 clearance rate when measured from prior to CIDR removal through 120 min following CIDR removal with LSM fed ewes having a greater (1.26+/-0.2) fractional rate constant than flax (0.929+/-0.09) and control fed (0.922+/-0.09) ewes. Flax fed ewes also had more (P<0.01) omega-3 fatty acids and total fatty acids in plasma. Reports of increased pregnancy rates in dairy cows fed flax may relate to P4 metabolism.     

Effects of plasma progesterone concentrations on LH release and ovulation in beef cattle given GnRH

The effects of plasma progesterone concentrations on LH release and ovulation in beef cattle given 100 microg of GnRH im were determined in three experiments. In Experiment 1, heifers were given GnRH 3, 6 or 9 days after ovulation; 8/9, 5/9 and 2/9 ovulated (P<0.02). Mean plasma concentrations of progesterone were lowest (P<0.01) and of LH were highest (P<0.03) in heifers treated 3 days after ovulation. In Experiment 2, heifers received no treatment (Control) or one or two previously used CIDR inserts (Low-P4 and High-P4 groups, respectively) on Day 4 (estrus=Day 0). On Day 5, the Low-P4 group received prostaglandin F(2alpha) (PGF) twice, 12 h apart and on Day 6, all heifers received GnRH. Compared to heifers in the Control and Low-P4 groups, heifers in the High-P4 group had higher (P<0.01) plasma progesterone concentrations on Day 6 (3.0+/-0.3, 3.0+/-0.3 and 5.7+/-0.4 ng/ml, respectively; mean+/-S.E.M.) and a lower (P<0.01) incidence of GnRH-induced ovulation (10/10, 9/10 and 3/10). In Experiment 3, 4-6 days after ovulation, 20 beef heifers and 20 suckled beef cows were given a once-used CIDR, the two largest follicles were ablated, and the cattle were allocated to receive either PGF (repeated 12h later) or no additional treatment (Low-P4 and High-P4, respectively). All cattle received GnRH 6-8 days after follicular ablation. There was no difference between heifers and cows for ovulatory response (77.7 and 78.9%, P<0.9) or the GnRH-induced LH surge (P<0.3). However, the Low-P4 group had a higher (P<0.01) ovulatory response (94.7% versus 61.1%) and a greater LH surge of longer duration (P<0.001). In conclusion, although high plasma progesterone concentrations reduced both GnRH-induced increases in plasma LH concentrations and ovulatory responses in beef cattle, the hypothesis that heifers were more sensitive than cows to the suppressive effects of progesterone was not supported.     

Luteotrophic and luteolytic effects of nitric oxide in sheep are dose-dependent in vivo

It has been suggested that nitric oxide (NO) acts in either an anti-luteolytic or in a luteolytic manner, but the mechanism for these opposing roles is unclear. We hypothesized that NO may act in a dose-dependent manner to regulate luteal function, whereby low concentrations of NO might stimulate luteal progesterone production (i.e. luteotrophic) and high concentrations of NO might reduce concentrations of plasma progesterone (i.e. luteolytic). To test this hypothesis we infused increasing concentrations of the fast-acting NO donor, dipropylenetriamine NONOate (DPTA), into the arterial supply of sheep with ovarian transplants bearing a corpus luteum (CL). Infusions were performed on sheep with CL 11 days of age (n=9) or over 30 days of age (n=15). We measured changes in the concentration of progesterone in ovarian venous plasma during the 1-h infusion and for 24h after the infusion, and then compared the mean concentration of progesterone between treatment groups for effects by dose and dose by period interactions. Compared with saline-treated controls (n=6), the highest dose of 1000 microg/min DPTA (n=6) reduced (P0.05) in sheep infused with the lowest dose of 1 microg/min DPTA (n=6) compared with controls. We conclude that NO regulates luteal function in a dose-dependent manner in sheep in vivo.     

Effects of progesterone on the maturation and immunologic function of dendritic cells from human peripheral blood

AIM: To study the effects of progesterone (P₄) on the maturation and immunologic function of dendritic cells (DCs) from human peripheral blood. METHODS: Cultured DCs were treated with P₄ at doses of 10-7 mol/L and 10-6 mol/L. The morphologic changes were observed under the scanning electronic microscope. The immunophenotypes of DCs in control and treated groups were analyzed by flow cytometry. IL-10 and IL-12 production in culture supernatant was examined by ELISA assay. The capability of the stimulatory activity of the DCs on allogeneic T cells in mixed reaction was tested by incorporation of ［3H］-TdR. RESULTS: Compared with control group, cultured DCs in the presence of P₄ displayed less dendritic pseudopod, expressed low levels of MHC-II, CD40, CD80 and CD86, and exhibited weakly activity in stimulating the proliferation of allogeneic T cells. Increase in IL-10 production and decrease in IL-12 production were observed. CONCLUSION: P₄ exerts negative effect on the maturation and immunologic function in dendritic cells from human peripheral blood.     

Comparative profiles of different lipoprotein cholesterol parameters and Growth Hormone during hot humid and winter season in Murrah Buffaloes

Now, it is well known that in bovines HDL-C act as substrate for ovarian steroidogenesis. The restriction of entry of other lipoprotein parameters is due to ovarian blood barrier, which restricts the entry of other lipoproteins, which are bigger in size. In vitro studies have indicated their role in mediating proliferation of cells. Besides gonadotropin, Growth Hormone (GH) is also gaining importance in the field of reproduction. GH receptors have been localized on the ovaries and follicle of bovines. Further it has been suggested that it can be the direct role of the hormone or it can be mediated through IGF-I. It has been assigned various roles in mediating follicle development, ovulation and corpus luteum maintenance. The river buffaloes are capable of breeding throughout the year, but during certain period of time were found to be more favourable than the others. It has been found that, winter season and hot humid season exhibit two extreme conditions of temperature variation; Hot humid season being unfavourable than the winter season because of high humidity and reasonably high temperature. It has been observed that during June to August months, conception rate and exhibition of estrus behaviour is low. This study was undertaken to analyze different lipoprotein cholesterol parameters namely Total cholesterol (TC), High-density lipoprotein cholesterol (HDL-C), Triglycerides (TG) and Low density lipoprotein cholesterol (LDL-C) in the plasma of cyclic Murrah buffaloes throughout the estrous cycle. The mean plasma concentration (μg/ml) of different lipoproteins during hot humid season were TC 592 ± 40, HDL-C 229 ± 42, TG 345 ± 95, LDL-C 285 ± 94.Where as in winter season their concentrations were 1381.0 ± 31.0, 1793.0 ± 110.0, 511.0 ± 21.0, 608.0 ± 94.0 respectively.

The mean ± SEM circulatory level of GH was low during HH season than during winter (6 ± 2 ng/ml vs. 17 ± 2 ng/ml). During estrous cycle only one peak of GH was exhibited during hot humid season where as three peaks were exhibited during winter season. It can be concluded that winter season is favourable for maintaining physiological levels of hormones and metabolic parameters, which in turn may increase the reproductive efficiency of bovines. During winter season average temperature was 15 ±5 °C. During hot humid season average temperature was 34 ± 3 °C. THI was more than 75%.