Superovulatory response following transvaginal follicle ablation in cattle

A study was designed to compare superovulatory responses in cattle when gonadotropin treatment followed 1 of 3 different treatments to synchronize follicular wave emergence. Animals at unknown stages of the estrous cycle were randomly assigned to 3 groups: ablation of the 2 largest follicles per pair of ovaries (n = 21); ablation of all follicles > or = 5 mm (n = 19); or intramuscular administration of 5 mg estradiol-17beta plus 100 mg progesterone (n = 23). All animals were given a CIDR-B intravaginally at the time of the respective treatments. Gonadotropin treatment, initiated 1 d after follicle ablation or 4 d after estradiol plus progesterone treatment, in the respective groups, consisted of 200 mg of pFSH divided in decreasing doses twice daily over 4 d. Cloprostenol (500 microg) was given at 48 and 60 h after the first pFSH treatment; CIDR-B devices were removed at the time of the second cloprostenol treatment. Ovarian ultrasonography was done on the days of CIDR-B insertion, first gonadotropin treatment, and at 36 and 72 h after CIDR-B removal. Cattle were inseminated twice, at 60 and 72 h after the first injection of cloprostenol. Ovarian and ova/embryo data were collected at slaughter 5, 6 or 7 d after insemination. No differences were detected among groups in the number of follicles > or = 8 mm at the time of first insemination (20.4 +/- 1.7 vs 16.6 +/- 2.0 vs 19.9 +/- 2.3; P > 0.05). At slaughter, no differences were detected among groups in the numbers of CL (23.3 +/- 1.9 vs 17.9 +/- 1.9 vs 20.1 +/- 2.6; P < 0.05), unovulated follicles > or = 8 mm (2.2 +/- 0.5 vs 2.1 +/- 0.3 vs 3.7 +/- 0.9; P < 0.05), ova/embryos (11.0 +/- 1.4 vs 12.2 +/- 1.3 vs 8.5 +/- 1.3; P < 0.05), fertilized ova (9.4 +/- 1.3 vs 10.1 +/- 1.2 vs 7.5 +/- 1.1; P < 0.05) or transferable embryos (8.2 +/- 1.2 vs 8.4 +/- 1.3 vs 6.5 +/- 0.9; P < 0.05). Variation in the numbers of CL (P = 0.1) and unovulated follicles > or = 8 mm (P < 0.01) was lower in the ablation groups than in the steroid-treated group. Results suggest that follicle ablation is as effective as estradiol plus progesterone in synchronizing follicular wave emergence for superstimulation in cattle, and that ablation of the 2 largest follicles is as efficacious as ablating all follicles > or = 5 mm.

Progesterone exposure prevents matrix metalloproteinase-3 (MMP-3) stimulation by interleukin-1alpha in human endometrial stromal cells

Suppression of endometrial matrix metalloproteinases (MMPs) is necessary to maintain tissue stability during the invasive events of implantation and placental development. Several laboratories have shown that inflammatory cytokines, including interleukin-lalpha (IL-1alpha), can oppose progesterone suppression of MMPs in the human endometrium. Furthermore, we have recently demonstrated colocalization of epithelial cell IL-1alpha and MMP-7 expression at sites of ectopic pregnancy. The current study extends these findings, revealing a previously unrecognized interrelationship between progesterone and IL-1alpha in regulation of MMP-3. Although IL-1alpha is a potent stimulator of MMP-3 in proliferative phase endometrium in organ culture, we demonstrate that progesterone exposure in vivo reduces IL-1alpha stimulation of MMP-3 in secretory phase tissue. This loss of sensitivity to IL-1alpha was duplicated in isolated stromal cells treated with progesterone in vitro, and IL-1alpha stimulation of MMP-3 returned in a dose-dependent manner with progesterone withdrawal. The antiprogestin, onapristone, partially blocked the ability of progesterone to prevent stimulation of MMP-3 by IL-1alpha. These data suggest a novel mechanism by which progesterone may preserve tissue integrity during the establishment and maintenance of pregnancy by limiting stimulation of MMPs by inflammatory cytokines such as IL-1a.

Repeated oestrus synchronisation of beef cows with progesterone implants and the effects of a gonadotrophin-releasing hormone agonist at implant insertion

A group of 97 spring-calving beef cows were initially oestrus synchronised with controlled internal drug release (CIDR) intravaginal progesterone implants inserted for nine days and a prostaglandin injection on day 7. Approximately half the cows were given 10 microg buserelin when the implants were inserted, and they all received a single fixed-time artificial insemination (AI) 56 hours after the withdrawal of the implants. The overall pregnancy rate to the first synchronised AI was 55 per cent, the buserelin-treated cows having a pregnancy rate of 63 per cent compared with 47 per cent in the untreated cows (P>0.05). Sixteen days after the first synchronised AI all the cows were re-implanted with used CIDR implants which were removed five days later, and the cows received a second synchronised AI on days 23 to 24. Cows which received the second AI were implanted with new CIDR devices 16 days later and these were removed after five days and the non-pregnant cows received a third synchronised AI. The pregnancy rates to the second and third synchronised services were 74 per cent and 75 per cent, respectively.

Endometrial cancer. Prevention, detection, management, and follow up

OBJECTIVE

To review risk factors for uterine cancer; to discuss strategies for detecting uterine cancer; to outline prognostic factors and treatment; and to review the role of follow up for patients who have completed primary therapy.

QUALITY OF EVIDENCE

MEDLINE was searched from January 1996 to June 1998 using the terms endometrial neoplasms, estrogen replacement therapy, hormone replacement therapy, tamoxifen, and screening. Only English language articles were reviewed. Study types included reviews. Bibliographies of articles found were searched for further relevant titles. Causation literature is available from well conducted cohort trials. Treatment recommendations are based in part on prognostic information and a few randomized controlled trials.

MAIN MESSAGE

Risk factors, both intrinsic and extrinsic, are associated with uterine cancer. Family physicians have a role in preventing disease by ensuring that all women with uteri in situ using hormone replacement therapy (HRT) have progesterone therapy as part of the HRT regimen. Detection is crucial; abnormal uterine bleeding or undiagnosed postmenopausal bleeding warrants investigation with endometrial biopsy. The goal of surgery is to remove the uterus and ovaries and identify factors that make the disease at high risk of recurrence. Although adjuvant radiation therapy does not prolong survival, it does alter the pattern of disease recurrence. The goal of follow up after primary therapy is to identify recurrent disease while it is still curable.

CONCLUSIONS

Family physicians play an important role in preventing uterine cancer, initiating early diagnosis of disease, and in the future, might be more actively involved in caring for patients following primary therapy.

Pregnancy and sex steroid hormones enhance circulating calcitonin gene-related peptide concentrations in rats

Calcitonin-gene-related peptide (CGRP) is a 37 amino acid neuropeptide synthesized primarily in dorsal root ganglia (DRG) and distributed widely in the perivascular nerves, suggesting that this peptide may play a role in the regulation of peripheral vascular tone. Since female sex steroid hormones have been implicated in the regulation of peripheral vascular tone during pregnancy, we postulated that they may alter the concentration of CGRP in the circulation and thus modulate the increased blood flow observed during pregnancy. In the present study, we measured changes in plasma concentrations of CGRP in non-pregnant, pregnant, and post-partum rats. Groups of ovariectomized rats were treated s.c. for 3 days either with 17beta-oestradiol (2.5 microg per injection twice daily), progesterone (2 mg per injection twice daily), or vehicle. Another group of adult, non-pregnant rats at dioestrus stage of the oestrous cycle was also used in this study. Plasma concentrations of CGRP were higher (P < 0.05) in rats on day 19 of pregnancy (22.0 +/- 3.0 pmol/l) compared to that during delivery (5. 0 +/- 2.0), post-partum day 2 (2.0 +/- 0.7) or in non-pregnant (4.9 +/- 1.6) state. Furthermore, in adult ovariectomized (6.0 +/- 0.6) rats, plasma CGRP concentrations were increased significantly (P < 0. 05) by oestradiol (10.0 +/- 1.0), progesterone (9.5 +/- 1.0) and oestradiol + progesterone (14.0 +/- 1.0). Thus, circulating concentrations of CGRP are elevated during pregnancy and by oestrogen and progesterone, suggesting that the elevated concentrations of CGRP may play an important role in vascular adaptations that occur during pregnancy.

Leukaemia inhibitory factor in the endometrium of the common marmoset Callithrix jacchus: localization, expression and hormonal regulation

In the present study, changes in the immunohistochemical localization of leukaemia inhibitory factor (LIF) in the endometrium during various phases of ovarian cyclicity of the common marmoset have been reported. LIF was absent during the early and late follicular phases. LIF was observed mainly in the cytoplasm of the endometrial glands during the early luteal phase, reached maximum intensity during the mid-luteal phase and declined again during late luteal phase. In-situ hybridization also showed a similar cyclic pattern in the expression of LIF. Stromal cells only showed signals for LIF during the mid-luteal phase. In ovariectomized marmosets, graded dosages of oestradiol alone failed to induce the appearance of LIF protein. Progesterone treatment following oestradiol priming, however, induced distinct glandular localization of LIF, indicating that LIF is a progesterone-dependent protein. Thus endometrial LIF is under maternal control and is secreted in response to the increased progesterone concentrations in circulation. It is possible that high concentrations of LIF during mid-luteal phase may prepare the endometrium for blastocyst implantation in marmosets.

Intramuscular versus vaginal administration of progesterone for luteal phase support after in vitro fertilization and embryo transfer. A comparative randomized study

A total of 156 patients were randomly treated with exogenous natural progesterone (intramuscularly, 50 mg/day) and vaginal gel (90 mg/day) P or nothing (Controls) from the day before embryo transfer (ET) for two weeks. In case of positive beta-HCG, the treatment was continued for 12 weeks. Plasma P and 17 beta-Estradiol concentrations were estimated and compared with the control not supplemented group. Both treatments were able to increase significantly the luteal plasmatic values of P versus controls. The ongoing pregnancy and the living birth rates per transfer were significantly higher in the patients supplemented with intramuscular P than in those treated with vaginal gel P. The intramuscular natural P appears the most suitable route of administration for luteal phase support in IVF-ET procedures.

Comparison of the pharmacokinetics of crinone 8% administered vaginally versus Prometrium administered orally in postmenopausal women(3)

OBJECTIVE

Compare the pharmacokinetics of vaginal progesterone gel (Crinone 8%, 90 mg) with that of oral progesterone (Prometrium, 100 mg).

DESIGN

Open-label, randomized, parallel-group protocol.

SETTING

Outpatient clinic.

PATIENT(S)

Twelve healthy postmenopausal women.

INTERVENTION(S)

Six subjects each were randomized to receive progesterone, which was administered either as 90 mg of progesterone gel (Crinone 8%) given vaginally or 100 mg progesterone in a capsule (Prometrium) given orally.

MAIN OUTCOME MEASUREMENT(S)

Serum progesterone levels were measured by both radioimmunoassay (RIA) and liquid chromatography-mass spectrometry (LC-MS).

RESULT(S)

Progesterone given vaginally resulted in greater bioavailability with less relative variability in absorption than oral progesterone (mean AUC(0-24) = 1.48 +/- 0.16 ng. h/mL per milligram vs. 0.035 +/- 0.0052 ng. h/mL per milligram). Mean C(max) for oral progesterone was much lower than that of vaginal progesterone (i.e., 2.20 +/- 3. 06 ng/mL vs. 10.51 +/- 0.46 ng/mL). Mean T(max) occurred earlier for oral progesterone than for Crinone (1.00 +/- 0.41 hours vs. 7.67 +/- 3.67 hours). Radioimmunoassay is inappropriate for determining serum progesterone levels after oral administration, because it provided erroneously high values that were approximately eightfold higher than those obtained with LC-MS.

CONCLUSION(S)

Crinone (progesterone gel) given vaginally results in greater bioavailability with less relative variability than oral progesterone, thus providing more reliable delivery of progesterone, compared with oral progesterone. Measuring circulating progesterone with use of direct RIA is not appropriate after oral progesterone administration.

Estrus synchronization of lactating dairy cows with GnRH, progesterone, and prostaglandin F2 alpha

The reproductive performance of synchronized cows was compared with that of nonsynchronized cows. In trial 1, cyclic cows in five seasonal herds were randomly divided into two groups. Cows in one group (n = 515) were treated with a GnRH agonist and an intravaginal progesterone device, followed in 7 d by a PGF2 alpha injection, and the device was removed 1 d after PGF2 alpha. Cows in the other group (n = 512) did not receive any treatment and acted as control. In trial 2, the treatments were similar to those used in trial 1 except that the progesterone device was removed at the time of PGF2 alpha injection (synchronized: n = 516; control: n = 512). The estrus synchronization rate was 92.8% in trial 1 and 92.2% in trial 2. Conception rate to first artificial insemination (AI) was lower for synchronized cows than for control cows in trial 1 (56.5 vs. 62.7%), but similar in trial 2 (64.6 vs. 63.3%). Across both trials, the pregnancy rate during the AI breeding period was greater for the synchronized cows (85.6%) than for the control cows (81.2%). The synchronization treatment reduced the interval from start of the breeding season to conception for cows conceiving by AI (8.9 vs. 14.8 d) or by AI or natural mating (14.1 vs. 21.6 d). The synchronization protocol used in trial 2 achieved better conception rate than that used in trial 1, but the precision of estrus was less in trial 2 than in trial 1.

Impact of oestradiol and progesterone on the glycosaminoglycans and their depolymerizing enzymes of the rat mammary gland

The influence of oestradiol and progesterone either singly or in combination with each other on the levels of hyaluronic acid, heparan sulphate, chondroitin sulphate, and on the activity of hyaluronidase and chondroitinase were investigated in the mammary gland of ovary-intact and in ovariectomized rats, administered oestradiol and/or progesterone. Administration of oestradiol to ovary-intact rats elevated the levels of hyaluronic acid and decreased the levels of heparan sulphate while progesterone, when administered alone, could elevate only chondroitin sulphate when compared with controls. The steroids when administered in combination, however, increased the levels of all glycosaminoglycans studied. Ovariectomized animals showed a decrease in heparan sulphate alone as compared with controls while administration of oestradiol to these rats elevated the levels of both heparan sulphate and chondroitin sulphate as compared with ovariectomized rats. Also the administration of progesterone either singly or in combination increased the levels of heparan sulphate and also decreased the levels of hyaluronic acid with no impact on the levels of chondoritin sulphate. In ovary-intact animals administration of oestradiol alone had no effect on hyaluronidase activity. Progesterone either singly or in combination with oestradiol reduced the activity of hyaluronidase, whereas it had no influence on the activity of chondroitinase. The activities of both the enzymes were decreased in ovariectomized animals and administration of oestradiol and/or progesterone to the above groups resulted in an increase. This study demonstrates that oestradiol anzd progesterone play an important role in modulating glycosaminoglycans and their depolymerizing enzymes, thereby influencing the activities of the mammary epithelium.

Direct transport of progesterone from vagina to uterus

OBJECTIVE

To compare progesterone concentrations in serum and endometrial tissue from hysterectomy specimens after vaginal or intramuscular (IM) administration of progesterone gel.

METHODS

This was a randomized open study of 14 post-menopausal women undergoing transabdominal hysterectomies. Participants received either vaginal progesterone gel, 90 mg, or IM progesterone, 50 mg, at 8:00 AM and 8:00 PM on the day before surgery and at 6:00 AM on the day of surgery. Venous blood samples for progesterone measurement were collected at 8:00 AM on the day before surgery (baseline) and during surgery. After removal of the uterus, the endometrium was sampled from the anterior and posterior walls. Results were expressed as ratios of endometrial to serum progesterone concentrations x 100.

RESULTS

Ratios of endometrial to serum progesterone concentrations were markedly higher in women who received vaginal progesterone (14.1 median, 8.5-59.4 range; 95% confidence interval [CI] 9.89, 38.79) compared with IM injections (1.2 median, 0.5-13.1 range; 95% CI -0.48, 7.39) (P < .005).

CONCLUSION

Ratios of endometrial to serum progesterone concentrations were higher after vaginal administration of progesterone than after IM injections. Our findings in endometrial tissue specimens from hysterectomies excluded the possibility of contamination by progesterone that remained in the vagina.

Effects of continuous conjugated estrogen and micronized progesterone therapy upon lipoprotein metabolism in postmenopausal women

The effects of continuously administering both conjugated equine estrogens (CEE) and micronized progesterone (MP) on the concentration, composition, production and catabolism of very low density (VLDL) and low density lipoproteins (LDL) have not previously been reported. The mechanism of the hormonally induced reductions of plasma LDL cholesterol of S(f) 0;-20 (mean 16%, P < 0.005) and LDL apoB (mean 6%, P < 0.025) were investigated by studying the kinetics of VLDL and LDL apolipoprotein (apo) B turnover after injecting autologous (131)I-labeled VLDL and (125)I-labeled LDL into each of the 6 moderately hypercholesterolemic postmenopausal subjects under control conditions and again in the fourth week of a 7-week course of therapy (0.625 mg/d of CEE + 200 mg/d of MP). The combined hormones significantly lowered plasma LDL apoB by increasing the mean fractional catabolic rate of LDL apoB by 20% (0. 32 vs. 0.27 pools/d, P < 0.03). Treatment also induced a significant increase in IDL production (6.3 vs. 3.7 mg/kg/d, P = 0.028). However, this did not result in an increase in LDL production because of an increase in IDL apoB direct catabolism (mean 102%, P = 0.033). VLDL kinetic parameters were unchanged and the concentrations of plasma total triglycerides (TG), VLDL-TG, VLDL-apoB did not rise as often seen with estrogen alone. Plasma HDL-cholesterol rose significantly (P < 0.02). Our major conclusion is that increased fractional catabolism of LDL underlies the LDL-lowering effect of the combined hormones.

Temporal interrelationships among luteolysis, FSH and LH concentrations and follicle deviation in mares

The effect of altered LH concentrations on the deviation in growth rates between the 2 largest follicles was studied in pony mares. The progestational phase was shortened by administration of PGF2alpha on Day 10 (Day 0=ovulation; n=9) or lengthened by daily administration of 100 mg of progesterone on Days 10 to 30 (n=11; controls, n=10). All follicles > or = 5 mm were ablated on Day 10 in all groups to initiate a new follicular wave. The interovulatory interval was not altered by the PGF2alpha treatment despite a 4-day earlier decrease in progesterone concentrations. Time required for growth of the follicles of the new wave apparently delayed the interval to ovulation after luteolysis. The FSH concentrations of the first post-ablation FSH surge were not different among groups. A second FSH surge with an associated follicular wave began by Day 22 in 7 of 11 mares in the progesterone group and in 0 of 19 mares in the other groups, indicating reduced functional competence of the largest follicle. A prolonged elevation in LH concentrations began on the mean day of wave emergence (Day 11) in the prostaglandin group (19.2 +/- 2.2 vs 9.0 +/- 0.7 ng/mL in controls; P<0.05), an average of 4 d before an increase in the controls. Concentrations of LH in the progesterone group initially increased until Day 14 and then decreased so that by Day 18 the concentrations were lower (P<0.05) than in the control group (12.9 +/- 1.6 vs 20.2 +/- 2.6 ng/mL). Neither the early and prolonged increase nor the early decrease in LH concentrations altered the growth profile of the second-largest follicle, suggesting that LH was not involved in the initiation of deviation. However, the early decrease in LH concentrations in the progesterone group was followed by a smaller (P<0.05) diameter of the largest follicle by Day 20 (26.9 +/- 1.7 mm) than the controls (30.3 +/- 1.7 mm), suggesting that LH was necessary for continued growth of the largest follicle after deviation.

The strategic use of estradiol to enhance fertility and submission rates of progestin-based estrus synchronization programs in dairy herds

Two experiments were performed to evaluate the efficacy of a progestin-based estrus synchronization program that incorporated the use of estradiol at the initiation of progestin treatment and at 48 h after progestin withdrawal (Exp. 2). In Exp. 1, cyclic, lactating dairy cows (n = 112) were assigned to receive either 1 (1mg) or 2 (2mg) mg of estradiol benzoate via an i.m. injection on d -9 (d 0 = initiation of the breeding season). All cows received an intravaginal progesterone-releasing insert (IPI; CIDR-B) on d -9. On d -2, the IPI was withdrawn and all cows were administered 500 microg of cloprostenol sodium. Beginning on d 0, cows were bred by AI upon detection of estrus. Estrus was observed in similar proportions of cows in each treatment during the first 6 d of AI (90% across treatments), but the interval to estrus was shorter (P < .05) in 1mg (1.26 +/- .18 d) than in 2mg (1.77 +/- .18 d). Conception and pregnancy rates did not vary among treatments; however, cows in estrus on d 0 tended to be less fertile (P = .11) than those in estrus on d 1. In Exp. 2, 408 cyclic cows from three herds were assigned to receive either no synchrony treatment (Control, n = 214) or the treatments described in Exp. 1 (1mg, n = 100; 2mg, n = 94). Anestrous cows from all herds received an IPI from d -9 to -2 (n = 143; Anestrus). All cows in the 1mg, 2mg, and Anestrus groups, with the exception of those detected in estrus between d -1 and 0, also received 1 mg of estradiol benzoate on d 0. Greater than 90% of cows that received an IPI were in estrus between d -1 and 3, and 92.1% of cows in the Control group were in estrus by d 21. Conception rate to first service in 2mg (61.7%) was similar to Control (57.0%), tended to be higher (P = .06) than 1mg (49.0%), and was greater (P < .05) than Anestrus (39.9%). The mean day of conception was earlier (P < .05) in the 2mg (d 13.1 +/- 2.0) than the Control (d 23.2 +/- 1.6) and Anestrus (d 22.4 +/- 1.9) groups. Conception occurred earlier in 1mg (d 17.4 +/- 2.1) than in Control. The proportion of cows that were pregnant at the end of the breeding season tended (P = .09) to be greater in the 2mg and Anestrus groups. This regimen of estrus synchronization improved reproductive competence in cyclic cows and resulted in similar reproductive performance in anestrous cows and untreated cyclic cows inseminated at a spontaneous estrus.

Comparison between different routes of progesterone administration as luteal phase support in infertility treatments

Different routes of natural progesterone supplementation have been tried as luteal phase support in infertility treatments. Orally administered progesterone is rapidly metabolized in the gastrointestinal tract and its use has proved to be inferior to i.m. and vaginal routes. Progesterone i.m. achieves serum progesterone values that are within the range of luteal phase and results in sufficient secretory transformation of the endometrium and satisfactory pregnancy rates. The comparison between i.m. and vaginal progesterone has led to controversial results as regards the superiority of one or the other in inducing secretory endometrial transformation. However, there is increasing evidence in the literature to favour the use of vaginal progesterone. Vaginally administered progesterone achieves adequate endometrial secretory transformation but its pharmacokinetic properties are greatly dependent on the formulation used. After vaginal progesterone application, discrepancies have been detected between serum progesterone values and histological endometrial features. Vaginally administered progesterone results in adequate secretory endometrial transformation, despite serum progesterone values lower than those observed after i.m. administration, even if they are lower than those observed during the luteal phase of the natural cycle. This discrepancy is indicative of the first uterine pass effect and therefore of a better bioavailability of progesterone in the uterus, with minimal systematic undesirable effects.

Treatment of noncyclic lactating dairy cows with progesterone and estradiol or with progesterone, GnRH, prostaglandin F2 alpha, and estradiol

The efficacy of two programs for treating noncyclic cows was compared. In trial 1, 478 cows in five herds were randomly divided into two groups. Cows in one group (C group) were treated with an intravaginal progesterone device for 8 d followed in 48 h by 1 mg of estradiol benzoate to cows that had not been detected in estrus since device removal. Those in the other group (CGP group) were treated with progesterone and estradiol as for the C group plus 10 micrograms of a GnRH agonist (buserelin) at device insertion and 25 mg of PGF2 alpha 7 d after device insertion. In trial 2 with 729 cows in nine herds, the treatments were similar to those in trial 1 except that the duration of progesterone treatment was 7 d. No significant difference was found between trials and results from both trials were combined. Compared with C group cows, CGP group cows had a greater estrous response rate (93.2 vs. 89.1%), a greater conception rate to first artificial insemination (AI, 47.1 vs. 29.4%), marginally lower conception rate to second AI (52.9 vs. 59.7%), lower nonpregnancy rate (8.3 vs. 11.1%), and shorter intervals from the start of breeding to conception by AI (9.8 vs. 15.3 d) or by AI or natural mating (21.6 vs. 26.3 d). The treatment protocol used for the CGP group achieved better reproductive performance than that used for the C group.

Prolonged ovarian sex steroid treatment of male rats produces antinociception: identification of sex-based divergent analgesic mechanisms

Simulation of the pregnancy blood concentration profile of 17beta-estradiol (E(2)) and progesterone (P) in nonpregnant ovariectomized rats has been shown to result in a significant elevation of nociceptive response thresholds. The present report demonstrates that spinal opioid antinociceptive responsiveness to these ovarian steroids is not sex-specific. Treatment of orchidectomized sexually mature males with an analogous regimen of E(2) and P also elicits an antinociception, the robustness and temporal profile of which is comparable with that previously observed in females. Neither E(2) nor P, alone, is sufficient to produce antinociception in male rats, as was previously demonstrated in females. Neurobiological substrates and antinociceptive mechanisms underlying ovarian sex steroid antinociception do, however, exhibit sex specificity. In males, the analgesia resulting from ovarian steroid treatment derives from the independent contributions of spinal kappa and mu, not delta, opioid receptor pathways that are additive, not synergistic. Spinal alpha(2)-noradrenergic receptor activity and its attendant analgesic synergy with spinal opioid systems do not contribute to ovarian sex steroid analgesia in males. This is in contrast to the previous demonstrations that ovarian sex steroid-induced antinociception in females results from antinociceptive synergy between activated spinal kappa/delta opioid as well as alpha(2)-noradrenergic receptor systems. The current data reveal that ovarian steroid-activated multiplicative spinal antinociceptive pathways that had been demonstrated in female rats are not manifest in their male counterparts.

Human chorionic gonadotropin as a predictor of outcome in assisted reproductive technology pregnancies

OBJECTIVE

To determine whether serum hCG and progesterone levels obtained 16 days after ovulation are reliable predictors of pregnancy outcome.

DESIGN

A retrospective study.

SETTING

The data were obtained from two integrated Adelaide-based clinics: the Queen Elizabeth Hospital and Wakefield Clinic.

PATIENT(S)

Women who have achieved a pregnancy through ART treatment.

MAIN OUTCOME MEASURE(S)

Analysis of data using logistic regression (STATA v.5.0) to predict a binary outcome: ongoing pregnancy or miscarriage. Ongoing pregnancy was defined as progression to >20 weeks' gestation. Miscarriage included spontaneous abortion, biochemical and ectopic pregnancies, and blighted ovum.

RESULT(S)

Human chorionic gonadotropin was found to be the main determinant of ongoing pregnancy. Age and progesterone had minor effects, whereas stimulation, luteal support, and treatment types were nonpredictive. Low hCG levels between 25 and 50 IU/L are associated with a low probability of ongoing pregnancy (<35%), whereas levels of >500 IU/L predict a >95% chance of ongoing pregnancy.

CONCLUSION(S)

A single serum hCG level 16 days after ovulation provides a useful predictor of pregnancy outcome.

Effect of mating system, flushing procedure, progesterone dose and donor ewe age on the yield and quality of embryos within a MOET program in sheep

Multiple ovulation and embryo transfer (MOET) has the potential to increase the rates of genetic improvement in sheep. However, better realization of this potential requires a higher yield of transferable embryos. Thus we investigated some factors that may contribute to high embryo yield and quality under field conditions, as part of an ongoing MOET program. Comparison of the effects of 2 breeding systems (natural service plus laparoscopic intrauterine AI vs natural service only) on embryo yield and quality indicated that while AI did not affect embryo recovery, it significantly (P < 0.05) improved fertilization rate and embryo quality, and increased (P < 0.05) embryo survival rate after transfer to recipients. Two flushing procedures (the original semi-laparoscopic and a modified version) were compared for effects on embryo recovery. The modifications made to the original collection method increased (P < 0.001) embryo recovery from 69.0 +/- 2.4 to 83.2 +/- 0.6%. The effects of the progestagen priming dosage during superovulatory treatment and ewe age on MOET outcome were also investigated. Donor ewes primed with 30-mg progestagen sponges came into estrus 1.9 h earlier (P < 0.05) than those primed with 45-mg sponges, but there was no difference in ovulation rate or embryo recovery, or in embryo survival after transfer between the 2 regimens. However, Chi-square analysis indicated a significant benefit in favor of the higher progesterone dose on both fertilization (P < 0.01) and embryo quality (P < 0.001). Age of donor ewe did not significantly affect the timing of estrus, fertilization rate or embryo survival after transfer. While adult ewes had higher (P < 0.05) ovulation rates and embryo yields, shearling ewes produced a much higher proportion of Grade 1 embryos (P < 0.05).