Dynorphin and GABAA Receptor Signaling Contribute to Progesterone's Inhibition of the LH Surge in Female Mice

Cumulative live birth rate of in vitro fertilization cycle via progestin-primed ovarian stimulation versus gonadotropin-releasing hormone antagonist protocol in infertile women with normal ovarian reserve: an open-label, randomized controlled trial

This study aimed to evaluate the cumulative live birth rate (cLBR) of progestin-primed ovarian stimulation (PPOS) protocol versus gonadotropin-releasing hormone antagonist (GnRH-ant) protocol for in vitro fertilization (IVF) cycle in infertile women with normal ovarian reserve (NOR). Infertile women with NOR who underwent their first IVF cycle were enrolled in an open-label randomized controlled trial. Patients were randomly assigned 1:1 to receive a freeze-all strategy with delayed embryo transfer (PPOS group, n = 174) and fresh embryo transfer first (GnRH-ant group, n = 174). The primary outcome was the cLBR per aspiration. The cLBR between the PPOS group and GnRH-ant group were comparable (55.75% vs. 52.87%, p = 0.591). A premature luteinizing hormone surge was not observed in the PPOS group, while there were six cases (3.45%) in the GnRH-ant group, but no premature ovulation in either of the groups. The pregnancy outcomes, including implantation rate, clinical pregnancy rate and miscarriage rate, were all comparable. In addition, the number of retrieved oocytes, mature oocytes and viable embryos were similar (all p > 0.05) between the two groups.

Estrogenic actions of alkaloids: Structural characteristics and molecular mechanisms

This comprehensive review of estrogenic alkaloids reveals that although the number is small, they exhibit a wide range of structures, biosynthesis pathways, mechanisms of action, and applications. Estrogenic alkaloids belong to different classes, different biosynthetic pathways, different estrogenic actions (estrogenic/synergistic, anti-estrogenic/antagonistic, biphasic, and acting as a selective estrogen receptor modulator or SERM), different receptor-initiated signaling pathways, different ways of modulations of estrogen action, and different applications. The future applications of estrogenic alkaloids, such as those for diagnostics, drug development, and therapeutics, are considered with the help of new databases containing comprehensive descriptions of their relationships and more elaborate artificial intelligence-based prediction technologies. Structure-activity studies reveal the significance of the nitrogen atom for their structural and functional diversity, which may help support their broader applications. Based on the summary of previous reports, estrogenic alkaloids have significant potential for future applications.

Deletion of Nuclear Progesterone Receptors From Kisspeptin Cells Does Not Impair Negative Feedback in Female Mice

Reproductive function in mammals depends on the ability of progesterone (P4) to suppress pulsatile gonadotrophin-releasing hormone (GnRH) and luteinizing hormone (LH) secretion in a homeostatic-negative feedback loop. Previous research identified that cells upstream from GnRH neurons expressing the nuclear progesterone receptor (PGR) are required for P4-negative feedback. However, the identity of these cells and the mechanism by which they reduce GnRH/LH pulsatile secretion is unknown. We aimed to address the hypothesis that PGR expressed by a neural population in the arcuate nucleus recently identified as the GnRH pulse generator, cells expressing kisspeptin, neurokinin B, and dynorphin (KNDy cells), mediate P4-negative feedback. To achieve this, we used female mice with the PGR gene conditionally deleted from kisspeptin cells (KPRKO mice) and observed a substantial decrease in the percentage of KNDy neurons coexpressing PGR messenger RNA (mRNA) (11% in KPRKO mice vs 86% in wild-type [WT] mice). However, KPRKO mice did not display changes in the frequency or amplitude of LH pulses in diestrus or estrus, nor in the ability of exogenous P4 to blunt a postcastration increase in LH. Further, mRNA expression of arcuate kisspeptin and dynorphin, which are excitatory and inhibitory to GnRH secretion, respectively, remained unaltered in KPRKO mice compared to WT controls. Together, these findings show that the near-complete loss of PGR signaling from KNDy cells does not affect negative feedback regulation of GnRH pulse generation in mice, suggesting that feedback through this receptor can occur via a small number of KNDy cells or a yet unidentified cell population.

Original delayed-start ovarian stimulation protocol with a gonadotropin-releasing hormone antagonist, medroxyprogesterone acetate, and high-dose gonadotropin for poor responders and patients with poor-quality embryos

Introduction

The delayed-start gonadotropin-releasing hormone antagonist protocol seems effective for patients who are poor ovarian responders, but there are insufficient data on whether it is also effective for patients with poor-quality embryos and low rates of good blastocyst formation. Specifically, the effectiveness of delayed-start gonadotropin-releasing hormone antagonists with progesterone has not been adequately investigated. Therefore, we compared the efficacy of the original delayed-start gonadotropin-releasing hormone antagonist protocol using medroxyprogesterone acetate (MPA) and high-dose gonadotropin in patients with poor ovarian response.

Methods

Overall, 156 patients with recurrent assisted reproductive technology failure who underwent the original protocol were included. They received cetrorelix acetate (3 mg) and MPA (10 mg) on cycle day 3, and high-dose gonadotropin was initiated on day 11. When the leading follicle reached 14 mm, ganirelix acetate (0.25 mg) was administered until the trigger day. The number of oocytes retrieved, metaphase II (MII) oocytes, two pronuclear (2PN) zygotes, and good blastocysts and live birth rates were compared between the previous (Cycle A) and original (Cycle B) cycles in three groups (Group A, all patients; Group B, poor responders; and Group C, patients with poor-quality embryos).

Results

In Group A (n=156), the number of MII oocytes (3.6 ± 3.3 versus 4.5 ± 3.6), 2PN zygotes (2.8 ± 2.9 versus 3.8 ± 3.1), good blastocysts (0.5 ± 0.9 versus 1.2 ± 1.6), and live birth rates (0.6 versus 24.4) significantly increased in Cycle B. Similar results were obtained in Group B (n=83; 2PN zygotes [1.7 ± 1.7 versus 2.3 ± 1.8], good blastocysts [0.4 ± 0.7 versus 0.9 ± 1.3], live birth rates [0 versus 18.1]) and Group C (n=73; MII oocytes [5.1 ± 3.8 versus 6.6 ± 4.0], 2PN zygotes [4.0 ± 3.4 versus 5.4 ± 3.4], good blastocysts [0.7 ± 1.1 versus 1.6 ± 1.9], and live birth rates [1.4 versus 31.5]).

Conclusion

This original protocol increased the number of MII oocytes retrieved, 2PN zygotes, good blastocysts, and live birth rates in both poor responders and in patients with poor-quality embryos.

Endogenous opiates and behavior: 2020

This paper is the forty-third consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2020 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (1), the roles of these opioid peptides and receptors in pain and analgesia in animals (2) and humans (3), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (4), opioid peptide and receptor involvement in tolerance and dependence (5), stress and social status (6), learning and memory (7), eating and drinking (8), drug abuse and alcohol (9), sexual activity and hormones, pregnancy, development and endocrinology (10), mental illness and mood (11), seizures and neurologic disorders (12), electrical-related activity and neurophysiology (13), general activity and locomotion (14), gastrointestinal, renal and hepatic functions (15), cardiovascular responses (16), respiration and thermoregulation (17), and immunological responses (18).

Reformulation of PULSAR for Analysis of Pulsatile LH Secretion and a Revised Model of Estrogen-Negative Feedback in Mice

The recent use of the tail-tip bleeding approach in mice has enabled researchers to generate detailed pulse and surge profiles of luteinizing hormone (LH) secretion in mice. However, the analysis of pulsatile LH secretion is piecemeal across the field with each laboratory using their own methodology. We have reformulated the once-popular PULSAR algorithm of Merriam and Wachter to operate on contemporary computer systems and provide downloadable and online pulse analysis platforms. As it is now possible to record the activity of the gonadotropin-releasing hormone pulse generator in freely behaving mice, we have been able to unambiguously define LH pulses in intact and gonadectomized male and female mice. These data sets were used to determine the appropriate PULSAR parameter sets for analyzing pulsatile LH secretion in the mouse. This was then used to establish an accurate model of estrogen negative feedback in the mouse. Intact and ovariectomized mice given Silastic capsules containing 1, 2, and 4 μg 17-β-estradiol/20 g body weight were tail-tip bled at 6-min intervals, and the resultant LH profiles were analyzed with PULSAR. Only the 4 μg 17-β-estradiol capsule treatment was found to return LH pulse amplitude and frequency to that of intact diestrous mice. Ultrasensitive mass spectrometry analysis showed that the 4 μg 17-β-estradiol capsule generated circulating estradiol levels equivalent to that of diestrous mice. It is hoped that the reformulation of PULSAR and generation of a realistic model of estrogen-negative feedback will provide a platform for the more uniform assessment of pulsatile hormone secretion in mice.

Neuroendocrine regulation of pubertal suppression in the naked mole-rat: What we know and what comes next

Puberty is a key developmental milestone that marks an individual's maturation in several ways including, but not limited to, reproductive maturation, changes in behaviors and neural organization. The timing at which puberty occurs is variable both within individuals of the same species and between species. These variations can be aligned with ecological cues that delay or suppress puberty. Naked mole-rats are colony-living rodents where reproduction is restricted to a few animals; all other animals are pubertally-suppressed. Animals removed from suppressive colony cues can reproductively mature, presenting the unique opportunity to study adult-onset puberty. Recently, we found that RFRP-3 administration sustains pubertal delay in naked mole-rats removed from colony. In this review, we explore what is known about regulators that control puberty onset, the role of stress/social status in pubertal timing, the status of knowledge of pubertal suppression in naked mole-rats and what comes next.