Reproductive hormones are essential to mating systems, behavior, fertility, gestation, parturition, and lactation in mammals and understanding the role of hormones in these processes is essential for species conservation. Sirenia is a unique order of marine mammals that include manatees, dugongs, and the extinct Steller\'s sea cow. Extant Sirenian species are all listed as vulnerable due to habitat loss, cold stress, boat strike trauma, harmful algal bloom toxicity, entanglements, and illegal hunting. Therefore, successful reproduction is essential to maintaining and increasing Sirenian populations. Understanding Sirenian reproductive behavior, endocrinology, and mating strategies will aid conservation and management efforts to protect and provide the proper conditions for successful reproduction. The objectives of this review were to synthesize the current knowledge regarding reproductive cycles and endocrinology of Sirenians and identify knowledge gaps for future investigation. The current literature on Sirenian reproductive physiology reports reproductive seasonality, sexual maturation, estrous cyclicity and acyclicity, pregnancy, and sex differences. However, there remain significant knowledge gaps on the cyclicity and pulsatile release of gonadotropins, maturation in females, and characterization of pregnancy hormone profiles throughout gestation. To date, there is no explanation for confirmed pattern for ovarian acyclicity, nor understanding of the function of the numerous accessory corpus luteum described in manatees. Research including a greater number of longitudinal and postmortem studies on a wider variety of wild manatee populations are important first steps. Taken together, understanding the reproductive endocrinology of these vulnerable and threatened species is critical for policy and management decisions to better inform protection initiatives.

Human gonadotropins are glycoprotein hormones with a highly complex structure, which demands the application of sophisticated analytical methodologies to assess their quality. The principal objective of this study was a comparative evaluation of gel electrophoretic techniques and mass spectrometry-based methods for the quality study of the two urinary-derived, highly purified, human menopausal gonadotropin preparations, Menopur 75/75 I. U. and Meriofert 75 I. U. Molecular mass (Mr), isoelectric point (pI), and isoform pattern of studied compounds were estimated via SDS-PAGE and 2D gel electrophoresis, whereas matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was used for the downstream characterization of peptides obtained after in-gel tryptic digestion of selected protein spots. Additionally, for the estimation of the glycosylation pattern of these biologics, the enzymatic release of oligosaccharides was performed, and the isoform pattern was studied. Gel electrophoresis showed a typical electrophoretic behaviour for protein biotherapeutics medicines consisting of extremely complex spot patterns migrating at different masses and pIs. MS analysis proved to be a powerful tool for the identification and detailed characterization of the gonadotropins and the relevant peptides were identified with high sequence coverages. The results of this study are not only useful for the quality assessment of this class of complex biopharmaceuticals but may also serve as a supporting platform for further development of biopharmaceuticals based on modulation of the glycosylation pattern to enhance efficacy or reduce side effects.

OBJECTIVE: Ovarian stimulation (OS) with high daily gonadotropin doses are commonly offered to patients attempting social/elective egg freezing. However, the optimal daily gonadotropin dose that would allow a higher oocyte yield in the successive IVF cycle attempt was not settled and should be determined.
METHODS: Data from all women admitted to our IVF unit for social/EEF, who underwent two consecutive IVF cycle attempts, with only those who used in the first attempt a starting daily gonadotropin dose of 300IU were analyzed. Patients characteristics and OS variables were used in an attempt to build a logistic model, helping in determining the daily gonadotropin dose that should be offered to patient during their second EEF attempt, aiming to further increase their oocyte yield.
RESULTS: Three hundred and thirteen consecutive women undergoing two successive IVF cycle attempts were evaluated. Using logistic regression model, two equations were developed using individual patient-level data that determine the daily gonadotropin dose needed aiming to increase the oocyte yield in the successive cycle. (a): X=-0.514 + 2.87*A1 + 1.733*A2-0.194* (E2/1000) and (b): P = EXP(X) / [1 + EXP(X)].
CONCLUSIONS: Using the aforementioned equations succeeded in determining the daily gonadotropin dose that might result in increasing oocyte yield, with an AUC of 0.85. Any additional oocyte retrieved to these EEF patients might get them closer to fulfil their desire to parenthood.

The decrease in assisted reproductive technology success among older women, attributed to decreased oocyte quantity and quality, poses a significant challenge. Currently, no consensus on the optimal ovarian stimulation protocol for older women undergoing IVF exists. This retrospectively registered cohort study aimed to compare the cumulative live birth rate (CLBR), time to live birth (TTLB), and cost-effectiveness among women older than 35 years who were receiving either the gonadotropin-releasing hormone agonist (GnRHa) or clomiphene citrate and gonadotropin cotreatment with ovarian stimulation (CC cotreatment) protocol. To compare treatment outcomes, we performed propensity score matching (PSM) on 2871 IVF cycles in women older than 35 years who received either the GnRHa or CC cotreatment protocol, resulting in 375 cycles in each group. Additionally, a decision tree model was utilized to assess the cost-effectiveness of the two protocols. Following PSM, both groups had similar baseline characteristics. The CC cotreatment protocol resulted in a greater rate of cycle cancellation (13.07% vs. 8.00%, p = 0.032), but the groups maintained comparable fertilization rates and embryo quality. Although the TTLB was longer in the CC cotreatment group, the CLBR per initial cycle (41.07% vs. 45.33%, p = 0.269) and delivery outcomes were similar between the two groups at the 24 months follow-up. Additionally, the average cost per live birth in the CC cotreatment group was 21.27% lower than in the GnRHa group (¥32,301.42 vs. ¥39,174.22). In conclusion, for women older than 35 years undergoing IVF, the CC cotreatment protocol offered a comparable CLBR to the GnRHa protocol but with reduced costs, indicating its potential as a viable and cost-effective ovarian stimulation option.Clinical trial registration: https://www.chictr.org.cn/ , identifier [ChiCTR2300076537].

Thyroid and gonadotropin hormones play an essential role in the regulation of regulating various physiological functions. The effects of melatonin and zinc (Zn) on these hormones have already been investigated. The aim of the present study was to investigate the effect of melatonin with and without zinc on the levels of gonadotropin hormones and thyroid hormones (triiodothyronine (T3), thyroxine (T4) and thyroid-stimulating hormone (TSH)) in female rats. In general, 35 sexually mature female rats were randomly divided into five treatment groups, with each group comprising 7 rats, in a completely randomized design (CRD) during the research. The rats were treated daily with Zn and melatonin via gavage as follows T1 (control 1, basal diet), T2 (control 2, treatment with normal saline) and the other experimental groups, including T3, T4 and T5, were treated with Zn (40 ppm), melatonin (5 mg/kg) or a combination of Zn and melatonin at the same dose. The administration of the drugs was continued for 20 days (daily) . Plasma samples were then taken for the determination of LH, FFH, LH/FSH, estrogen, progesterone, T3, T4 and TSH levels. The results showed no significant differences in FSH and LH levels between treatments. Estrogen, progesterone and TSH levels were higher in the rats receiving 5 mg melatonin per day than in the other groups, but not statistically significant (P>0.05). However, T3 levels decreased significantly in the group receiving 40 mg/kg Zn compared to the other experiments. (P<0.05). The results showed no significant difference between the treatments in terms of T4 levels (P>0.05). In conclusion, no remarkable changes in other variables were observed in female rats receiving melatonin, Zn or a combination of melatonin and Zn, with the exception of T3.

GnRH is essential for the regulation of mammalian reproductive processes. It regulates the production and release of pituitary gonadotropins, thereby influencing steroidogenesis and gametogenesis. While primarily produced in the hypothalamus, GnRH is also produced in peripheral organs, such as the gonads and placenta. GnRH analogs, including agonists and antagonists, have been synthesized for the reproductive management of animals and humans. This review focuses on the functions of hypothalamic GnRH in the reproductive processes of cattle. In addition to inducing the surge release of LH, the pulsatile secretion of GnRH stimulates the pituitary gland to release FSH and LH, thereby regulating gonadal function. Various GnRH-based products have been synthesized to increase their potency and efficacy in regulating reproductive functions. This review article describes the chemical structures of GnRH and its agonists. This discussion extends to the gene expression of GnRH in the hypothalamus, highlighting its pivotal role in regulating the reproductive process. Furthermore, GnRH is involved in regulating ovarian follicular development and luteal phase support, and estrus synchronization is involved. A comprehensive understanding of the role of GnRH and its analogs in the modulation of reproductive processes is essential for optimizing animal reproduction.

OBJECTIVE: The role of osteocalcin (OCN) in pubertal development, male hypogonadism, and the effect of testosterone (Te) replacement therapy (TRT) remains unclear. We aimed to investigate the total OCN (tOCN) concentrations in male patients with Klinefelter syndrome (KS), a model of adult hypergonadotropic hypogonadism.
METHODS: This retrospective longitudinal study investigated 254 male patients with KS (47,XXY) between 2007 and 2021 at an academic referral center, categorized as (1) prepubertal, (2) pubertal, and (3) adults. All prepubertal patients were Te-naïve. Adult patients were subcategorized as (1) eugonadal, (2) hypogonadal, and (3) receiving TRT. We also analyzed 18 adult patients with available tOCN levels before and 3 months after TRT commencement.
RESULTS: The tOCN levels varied throughout the lifespan according to pubertal status, were highest in eugonadal and significantly lower in TRT subjects, correlated with both LH (p = 0.017) and FSH levels (p = 0.004) in adults, and significantly declined after 3 months of TRT (p = 0.006) in the adult KS cohort. HPG-axis hormones levels demonstrated no correlation in prepubertal boys. Adjustment for age and body mass index confirmed previous results and revealed significant inverse correlations with total Te (p = 0.004), calculated free Te (p = 0.016), the Te/LH (p = 0.010), and calculated free Te/LH ratios (p = 0.031).
CONCLUSIONS: In KS, a model of male hypergonadotropic hypogonadism, tOCN levels were not associated with gonadal function during normal prepuberty and pubertal development but were associated with worse testicular function and a higher degree of HPG stimulation in adults. TRT acutely reduced tOCN levels in adults.

BACKGROUND: Gonadotropin precisely controls mammalian reproductive activities. Systematic analysis of the mechanisms by which epigenetic modifications regulate the synthesis and secretion of gonadotropin can be useful for more precise regulation of the animal reproductive process. Previous studies have identified many differential m6A modifications in the GnRH-treated adenohypophysis. However, the molecular mechanism by which m6A modification regulates gonadotropin synthesis and secretion remains unclear.
RESULTS: Herein, it was found that GnRH can promote gonadotropin synthesis and secretion by promoting the expression of FTO. Highly expressed FTO binds to Foxp2 mRNA in the nucleus, exerting a demethylation function and reducing m6A modification. After Foxp2 mRNA exits the nucleus, the lack of m6A modification prevents YTHDF3 from binding to it, resulting in increased stability and upregulation of Foxp2 mRNA expression, which activates the cAMP/PKA signaling pathway to promote gonadotropin synthesis and secretion.
CONCLUSIONS: Overall, the study reveals the molecular mechanism of GnRH regulating the gonadotropin synthesis and secretion through FTO-mediated m6A modification. The results of this study allow systematic interpretation of the regulatory mechanism of gonadotropin synthesis and secretion in the pituitary at the epigenetic level and provide a theoretical basis for the application of reproductive hormones in the regulation of animal artificial reproduction.

Managing patients unable to produce sex steroids using gonadotropins to mimic minipuberty in hypogonadotropic hypogonadism, or sex steroids in patients with Klinefelter or Turner syndrome, is promising. There is a need to pursue research in this area, with large prospective cohorts and long-term data before these treatments can be routinely considered.

The anterior pituitary plays a critical role in the endocrine system, contains gonadotrophs, which regulate reproductive efficiency by secreting follicle-stimulating hormone (FSH) and luteinizing hormone (LH). PPP2R2A is a serine-threonine phosphatase that regulates reproductive functions in both females and males, its function in pituitary cells remain unclear. Hu sheep is a highly prolific breed, which makes it suitable for studying reproductive mechanisms. In this study, the relative abundances of PPP2R2A mRNA expression were higher in the pituitary of high-prolificacy (HF) Hu sheep compared to those of low-prolificacy (LF) Hu sheep. Additionally, we demonstrated that PPP2R2A promotes pituitary cell proliferation and gonadotropin secretion using the EdU assay and ELISA, respectively. Moreover, it inhibits pituitary cell apoptosis using flow cytometry. Furthermore, PPP2R2A may affect pituitary cell function by regulating the AKT/mTOR signaling pathway. In summary, our findings suggest that PPP2R2A may play a role in regulating pituitary function and influencing the secretion of gonadotropins.