Estradiol Priming Potentiates the Kisspeptin-Induced Release of LH in Ovariectomized Cows.

The present study examined whether priming with estradiol benzoate (EB) for 12 h increased both the peak and duration of LH release in response to kisspeptin (KISS1, KP) in cows. In a Latin square design, ovariectomized Nelore cows (n = 8) received: Control, i.m. 4 mL of 0.9% saline; KP, i.m. 4 mg murine KISS1-10; EBKP, i.m. 4 mg KISS1-10 + i.m. 2 mg EB simultaneously; EB12KP, i.m. 4 mg KISS1-10 + i.m. 2 mg EB 12 h before KISS1-10. Concentrations of LH were determined in blood samples obtained at time 0 (treatment), 20, 40, 60, 90, 120, 150, 180, 210 and 270 min. Concentrations of LH were analyzed by Proc GLIMMIX for repeated measures. In case of significance, the adjusted Tukey test was used to test for differences among treatments. GraphPad 8.0 PRISM® was used to determine the area under the LH-response curve (AUC) after injection of KISS1-10. Plasma LH remained relatively constant throughout sampling after treatment with saline. The peak in LH after injection of KISS1-10 occurred at 20 min in Groups KP and EBKP and at 40 min in Group EB12KP. The peak LH response (∆LH, ng/mL) was greater (p < 0.01) in Group EB12KP (5.6 ± 0.9) than in Groups KP (2.4 ± 0.9) and EBKP (3.5 ± 0.9), which did not differ. AUC (LH ng/mL*min) was greater (p = 0.02) in Group EB12KP (439 ± 73) than in Groups KP (176 ± 73) and EBKP (241 ± 73), with the latter two groups not differing. The findings indicated that 12 h priming with EB increased both the peak and duration of the LH response to treatment with KISS1. The incorporation of EB priming and KISS1 could improve the efficiency of estrus synchronization with fixed-time AI in cows. This would have an important practical application in assisted breeding in beef and dairy cattle.

Comparison of GnRH agonist versus luteal estradiol GnRH antagonist protocol using transdermal testosterone in poor responders.

OBJECTIVE: Transdermal testosterone has been used in different doses and in different stimulation protocols in poor responders. The aim of the present study is to compare the luteal estradiol/GnRH antagonists protocol versus long GnRH agonists in poor responder patients according to the Bologna criteria, in which transdermal testosterone has been used prior to the stimulation with gonadotropins. METHODS: In this retrospective analysis, a total of 141 poor responder patients according to the Bologna criteria were recruited. All patients were treated with transdermal testosterone preceding ovarian stimulation with gonadotropins during 5 days. In 53 patients we used the conventional antagonist protocol (Group 1). In 88 patients (GrH pituitary suppression was achieved by leuprolide acetate according to the conventional long protocol (Group 2). We analyzed the ovarian stimulation parameters and IVF outcomes. RESULTS: Comparing groups 1 and 2, there were no significant differences between cancellation rates and number of oocytes retrieved. However the total gonadotropin dose used and the mean length of stimulation were significantly lower in group 1 when compared to group 2. There were no significant differences in pregnancy outcomes; however, there was a slight increase in the implantation rate in group 1 vis-a-vis group 2, although statistical significance was not achieved. CONCLUSION: TT in poor responder patients can be effective both with the conventional agonist's long protocol and with the conventional antagonist's protocol. However, short regimes with previous estradiol antagonists in the luteal phase facilitate ovarian stimulation by shortening the days of treatment and the consumption of gonadotropins.

Inducción de ovulación en pacientes bajas respondedoras en fecundación in vitro: microdosis de acetato de leuprolide vs priming de estradiol

Objetivo: Comparar los protocolos de microdosis de acetato de leuprolide y priming de estradiol. Métodos: Estudio retrospectivo de 115 pacientes bajas respondedoras (según criterios de Bologna), evaluadas en UNIFERTES desde enero 2010 a diciembre 2012, sometidas a hiperestimulación ovárica controlada según protocolo. La inducción ovárica constó de pauta fija con gonadotropinas (hormona folículo estimulante recombinante 450 UI/día + Gonadotropina menopaúsica humana 150 UI/día); realizando disparo de ovulación con 10.000 UI gonadotropina coriónica humana urinaria al obtener 2 o 3 folículos entre 17-18 mm de diámetro. Se realizó aspiración folicular con aguja bilumen a las 35 horas del disparo, fecundación in vitro en medios secuenciales y transferencia embrionaria al día 3. El soporte de fase lútea constó de progesterona natural micronizada 600 mg/día y valerato de estradiol 4 mg/día. Se realizó prueba de embarazo cuantitativa a los quince días y verificación de embriocardia al mes. Se compara: tasa de cancelación, días de estimulación, número de ovocitos aspirados, tasa de embarazo clínico por transferencia y tasa de aborto. Resultados: Se incluyeron 115 pacientes: 69 al protocolo de microdosis y 46 al de priming de estradiol. No hubo diferencias estadísticas entre ambos protocolos en cuanto a: número de ovocitos aspirados, tasa de embarazo clínico y aborto. Los días de estimulación y la dosis total de gonadotropinas fue mayor con microdosis. Conclusiones: Aunque no hubo diferencias estadísticamente significativas entre ambos protocolos, el de priming de estradiol por tener menos días de estimulación y dosis totales de gonadotropinas menores, implica mayor bienestar de la paciente.

Objective: To compare microdose leuprolide acetate protocols and Estradiol Priming. Methods: Retrospective study of 115 low-responding patients (according to Bologna Criteria), evaluated at UNIFERTES from January 2010 to December 2012, who underwent controlled ovarian hyperstimulation as per Microdose leuprolide acetate protocol or Estradiol Priming Protocols. Ovarian induction consisted of a set standard with gonadotropins, 450UI/day recombinant follicle-stimulating hormone + 150UI/day Human Menopausal Gonadotropin; performing an ovulation trigger shot with 10,000UI urinary human chorionic gonadotropin when obtaining 2 to 3 follicles of 17-18mm diameter. Follicular aspiration is performed with double lumen needle, 35 hours from trigger shot with in vitro fertilization in sequential media, and embryo transfer on day 3. Luteal phase support consisted of 600mg/day micronized natural progesterone and 4mg/day of estradiol valerate. Quantitative pregnancy test was carried out at fifteen days and embryo cardiac activity validation at one month. The following are compared: cancellation rate, stimulation days, number of aspirated oocytes, rate of clinical pregnancy by transfer and abortion rate. Results: 115 patients were included: 69 underwent microdose leuprolide acetate protocol flare and 46 underwent estradiol priming. There were no statistical differences between both protocols with regards to: number of aspirated oocytes, rate of clinical pregnancy by transfer and abortion rate. Stimulation days and therefore, gonadotropins total dosage was greater with microdose leuprolide acetate protocol. Conclusions: Even though there were no significant statistical differences between both protocols, estradiol priming entails greater patient’s wellbeing, since it requires less stimulation days and less gonadotropin total dosages.