Plasma Luteinizing Hormone Concentrations Research Articles

Peripheral administration of a κ-opioid receptor agonist nalfurafine inactivates gonadotropin-releasing hormone pulse generator activity in goats

Neurons co-expressing kisspeptin, neurokinin B, and dynorphin A (KNDy neurons), located in the arcuate nucleus (ARC) of the hypothalamus, are indicated to be the gonadotropin-releasing hormone (GnRH) pulse generator. Dynorphin A is reported to suppress GnRH pulse generator activity. Nalfurafine is a selective agonist of the κ-opioid receptor (KOR), a receptor for dynorphin A, clinically used as an anti-pruritic drug. This study aimed to evaluate the effects of nalfurafine on GnRH pulse generator activity and luteinizing hormone (LH) pulses using female goats. Nalfurafine (0, 2, 4, 8, or 16 μg/head) was intravenously injected into ovariectomized Shiba goats. The multiple unit activity (MUA) in the ARC area was recorded, and plasma LH concentrations were measured 2 and 48 h before and after injection, respectively. The MUA volley interval during 0–2 h after injection was significantly increased in the nalfurafine 8 and 16 μg groups compared with the vehicle group. In 0–2 h after injection, the number of LH pulses was significantly decreased in the nalfurafine 8 and 16 μg groups, and the mean and baseline LH were significantly decreased in all nalfurafine-treated groups (2, 4, 8, and 16 μg) compared with the vehicle group. These results suggest that nalfurafine inhibits the activity of the GnRH pulse generator in the ARC, thus suppressing pulsatile LH secretion. Therefore, nalfurafine could be used as a reproductive inhibitor in mammals.

Chronic unpredictable stress (CUS) reduced phoenixin expression, induced abnormal sperm and testis morphology in male rats

Chronic stress caused by prolonged emotional pressure can lead to various physiological issues, including reproductive dysfunction. Although reproductive problems can also induce chronic stress, the impact of chronic stress-induced reproductive dysfunction remains contentious. This study investigates the effects of chronic unpredictable stress (CUS) on reproductive neuropeptides, sperm quality, and testicular morphology. Sixteen twelve-week-old Sprague Dawley rats were divided into two groups: a non-stress control group and a CUS-induced group. The CUS regimen involved various stressors over 28 days, with both groups undergoing behavioural assessments through sucrose-preference and forced-swim tests. Hypothalamic gene expression levels of CRH, PNX, GPR173, kisspeptin, GnRH, GnIH, and spexin neuropeptides were measured via qPCR, while plasma cortisol, luteinizing hormone (LH), and testosterone concentrations were quantified using ELISA. Seminal fluid and testis samples were collected for sperm analysis and histopathological evaluation, respectively. Results showed altered behaviours in CUS-induced rats, reflecting stress impacts. Hypothalamic corticotropin-releasing hormone (CRH) expression and plasma cortisol levels were significantly higher in CUS-induced rats compared to controls (p < 0.05). Conversely, phoenixin (PNX) expression decreased in the CUS group (p < 0.05), while kisspeptin, spexin, and gonadotropin-inhibitory hormone (GnIH) levels showed no significant differences between groups. Despite a significant increase in GnRH expression (p < 0.05), plasma LH and testosterone concentrations were significantly lower (p < 0.05) in CUS-induced rats. Histopathological analysis revealed abnormal testis morphology in CUS-induced rats, including disrupted architecture, visible interstitial spaces between seminiferous tubules, and absence of spermatogenesis. In conclusion, CUS affects reproductive function by modulating PNX and GnRH expression, influencing cortisol levels, and subsequently reducing plasma LH and testosterone concentrations. This study highlights the complex interplay between chronic stress and reproductive health, emphasizing the significant impact of stress on reproductive functions.

Involvement of somatotrophic hormones in the postpartum regulation of ovarian activity in mares

Mares resume ovarian activity rapidly after foaling. Besides follicle-stimulating hormone (FSH) and luteinizing hormone (LH), the pituitary synthesizes prolactin and growth hormone which stimulate insulin-like growth factor (IGF) synthesis in the liver. We tested the hypothesis that follicular growth is initiated already antepartum, mares with early and delayed ovulation differ in IGF-1 release and that there is an additional IGF-1 synthesis in the placenta. Plasma concentrations of LH, FSH, IGF-1, IGF-2, activin and prolactin. IGF-1, IGF-2, prolactin and their receptors in placental tissues were analyzed at the mRNA and protein level. Follicular growth was determined from 15 days before to 15 days after foaling in 14 pregnancies. Mares ovulating within 15 days postpartum formed group OV (n=5) and mares not ovulating within 15 days group NOV (n=9). Before foaling, follicles with a diameter >1 cm were present in all mares and their number increased over time (p<0.05). Follicle growth after foaling was more pronounced in OV mares (day p<0.001, group p<0.05, day x group p<0.05) in parallel to an increase in LH concentration (p<0.001, day x group p<0.001) while FSH increased (p<0.001) similarly in both groups. Plasma concentrations of IGF-1 and prolactin peaked one day after foaling (p<0.001). The IGF-1 mRNA abundance was higher in the allantochorion but lower in the amnion of OV versus NOV mares (group p=0.01, localization x group p<0.01). The IGF-1 receptor mRNA was most abundant in the allantochorion (p<0.001) and IGF-1 protein was expressed in placental tissue without differences between groups. In conclusion, follicular growth in mares is initiated before foaling and placental IGF-1 may enhance resumption of ovulatory cycles.

The GLP-1 agonist, Exendin-4, stimulates LH secretion in female sheep.

Our previous studies showed that microinjection into the median eminence of the sheep of glucagon-like peptide- 1 (GLP-1) or its receptor agonist Exendin-4 stimulates luteinizing hormone (LH) secretion but it is unknown whether the same effect may be obtained by systemic administration of the same. The present study measured the response in terms of plasma LH concentrations, to intravenous (iv) infusion of Exendin-4. A preliminary study showed that infusion of 2mg Exendin-4 into ewes produced a greater LH response in the follicular phase of the oestrous cycle than the luteal phase. Accordingly, the main study monitored plasma LH levels in response to either 0.5mg or 2mg Exendin-4 or vehicle (normal saline) delivered by jugular infusion for 1h in the follicular phase of the oestrous cycle. Blood samples were collected at 10 min intervals before, during and after infusion. Both doses of Exendin-4 increased mean plasma LH concentrations and increased LH peripheral pulse amplitude. There was no effect on inter-pulse interval or timing of the preovulatory LH surge. These doses of Exendin-4 did not alter plasma insulin or glucose concentrations. Quantitative PCR of the gastrointestinal tract samples from a population of ewes confirmed expression of the preproglucagon gene (GCG). Expression increased aborally and was greatest in the rectum. It is concluded that endogenous GLP-1, most likely derived from the hind-gut may act systemically to stimulate LH secretion. The present data suggest that this effect may be obtained with levels of agonist that are lower than those functioning as an incretin.

Estropause, Sex Hormones and Metal Homeostasis in the Mouse Brain.

Alterations in brain metal ion homeostasis have been reported with aging and are implicated in the pathogenesis of neurodegenerative diseases. To assess whether age-related changes in hypothalamic-pituitary-gonadal (HPG) hormones might be involved in modulating brain metal ion homeostasis, we treated 7.5-month intact, sham-ovariecomized and ovariectomized C57B6SJL mice with vehicle or leuprolide acetate (for 9-months) to differentiate between whether sex steroids or gonadotropins might modulate brain metal ion concentrations. Unlike other aging mammals, there was no increase in plasma luteinizing hormone (LH) and follicle-stimulating hormone (FSH) concentrations following estropause in mice, suggesting there was sufficient residual production by the follicle depleted ovary, of sex steroids like estrogens and protein hormones like the inhibins, in order to suppress pituitary LH/FSH production. Castration on the other hand induced significant increases in circulating LH and FSH. Modulation of plasma sex steroid and gonadotropin levels did not significantly alter the concentrations of brain metals tested (Fe, Zn, Cu, Mn, Co, Ni, Al, Li), although there was a tendency for a decrease in all brain metals following ovariectomy (low estrogens and progesterone, high gonadotropins), a response that was reversed with leuprolide acetate treatment (low sex steroids, low gonadotropins). Brain Cu concentration was the only metal correlated with plasma LH (−0.37, n = 30, p < 0.05) and FSH (−0.42, n = 29, p < 0.01). This study demonstrates that sex hormones do not markedly alter brain metal ion homeostasis, unlike previously reported studies of circulating metal ion homeostasis. The role of gonadotropins in regulating metal ion homeostasis does however warrant further study.

Plasma levels of luteinizing hormone and prolactin in relation to double brooding in Great Tit (Parus major)

The reproductive behaviors of birds are mainly controlled by the hypothalamus-pituitary-gonad axis. Many studies have shown that reproductive hormones are tightly linked to the breeding sub-stages. However, only a few studies have examined the temporal trend of hormone levels among different reproductive stages in multiple brooded species. We investigated the changes in plasma luteinizing hormone (LH) and prolactin (PRL) concentrations during different reproductive stages of the facultative double-brooded Great Tit (Parus major). We found that the concentrations of LH and PRL in females were significantly higher than those in males. Females had significantly higher LH and lower PRL concentrations in the pre-breeding period than in the first/second brooding periods, and there were no significant changes between the first and second brooding periods. The concentrations of LH and PRL in males had no significant difference between the pre-breeding period and the first brooding periods, while LH and PRL concentrations in the second brooding period were significantly higher than those in the first brooding period. We conclude that there are sex-based differences between LH and PRL at different stages of reproduction. The changes in LH and PRL in both males and females should be related to their physiological functions. Especially for males, individuals with higher levels of LH and PRL are more likely to maintain second clutches.

Tacrolimus-Based Immunosuppressive Therapy Influences Sex Hormone Profile in Renal-Transplant Recipients—A Research Study

Simple SummaryAlthough renal-transplant-recipients can lead much more comfortable life in comparison to patients on dialysis, they need to face other problems. One of them is lifetime immunosuppressive therapy on daily basis. Immunosuppressive regimen contains usually three different drugs and although each one of them is crucial to keep graft in good condition and to suppress immune response against the transplanted organ, they influence, among the other, reproductive system. In current paper we have observed that immunosuppressive therapy based on tacrolimus significantly affected the hormonal balance of sex hormones in both men and women. It is of great importance, as nowadays infertility is rising problem even in health people, therefore more attention should be paid to choose the best suitable immunosuppressive regiment for recipient in reproductive age.It is estimated that approximately 20% of couples suffer from infertility worldwide and within renal-transplant recipients, this problem is 10 times more common. An intake of immunosuppressants may lead to hormonal imbalance. The aim of the study was to investigate the influence of tacrolimus-based therapy on the hormonal status of grafted patients. Blood samples were obtained from patients from the Department of Nephrology, Transplantology, and Internal Medicine of Independent Public Clinical Hospital No. 2, Pomeranian Medical University. All 121 patients had stable graft function for over 6 months. The blood plasma concentrations of luteinizing hormone, follicle-stimulating hormone, prolactin, testosterone, estradiol, cortisol were assessed by the electrochemiluminescence method. We observed decreased levels of prolactin (11.9 ng/mL) and cortisol (87.4 μg/mL) in patients under tacrolimus-based therapy. Tacrolimus-based therapy was also associated with increased testosterone and follicle-stimulating hormone in males, 4.04 ng/mL and 6.9 mLU/mL, respectively, and decreased testosterone levels in females, 0.121 ng/mL. We also assessed that immunosuppressive therapy based on tacrolimus is less nephrotoxic in comparison to other regimens. Concluding, tacrolimus-based therapy may influence the hormonal status of transplant recipients in the current study. Results presented here are believed to be helpful for clinicians and patients, especially within the aspect of willingness for biological offspring.

Heterologous beta-nerve growth factor (β-NGF) given at the LH surge enhances luteal function in dairy heifers

Genetic selection for high yield milk production has led to a decline in dairy cattle's reproductive performance over the last 40 years. Low progesterone (P4) plasma content following ovulation is associated with suboptimal fertility in dairy cattle. Several pieces of evidence indicate that the protein beta-nerve growth factor (β-NGF) that is present in the male seminal plasma exerts potent ovulatory and luteotrophic effects following systemic administration in camelids but also in other species. In this study, we determine whether systemic administration of purified llama β-NGF given at the induced preovulatory luteinizing hormone (LH) peak improves corpus luteum (CL) function in dairy heifers subjected to an estradiol (E2) / P4 estrus-synchronization protocol. To achieve this, we first determined plasma E2 and LH hormone profiles to establish the timing of the estradiol benzoate (EB)-induced LH peak in estrus-synchronized heifers. Then, we tested whether the administration of β-NGF given at the end of this peak affects the CL and its function by analyzing diameter, vascular area, and P4 output. Our results show that, with the estrus-synchronization protocol applied, plasma LH concentrations peaked (P < 0.01) 40-h and 16-h after removal of the bovine intravaginal device (DIB; containing 1.0 g of P4) plus cloprostenol injection and subsequent EB administration, respectively; after peaking, plasma LH concentrations remained stable for the next 8-h to then return to basal levels. Heifers synchronized with this protocol and receiving a dose of 1 mg of β-NGF at the end of the LH peak (ie, 48-h after DIB removal) did not show significant differences in CL diameter, but these exhibited a greater CL vascular area (P = 0.01) than the observed in vehicle-injected heifers. Furthermore, plasma P4 concentration in β-NGF-treated heifers was higher (P = 0.001) than those quantified in vehicle-injected heifers. These results support the use of β-NGF in estrus-synchronization protocols to improve the early luteal function in dairy heifers.

Functions of the GABAergic system on serum LH concentrations in pre-pubertal Nellore heifers

This study was conducted to evaluate the luteinizing hormone (LH) secretion pattern after gamma-aminobutyric acid (GABAA) antagonist to determine the effects of the GABAergic system on LH secretion during reproductive maturation in pre-pubertal Nellore heifers. Nellore heifers (n = 10) were administered a picrotoxin injection of 0.18 mg/kg, i.v. Blood samples were collected every 15 min for 3 h at different developmental stages (8, 10, 14 and 17 mo of age). Plasma concentrations of LH were quantified using an RIA (sensitivity of 0.04 ng/mL and CV of 15 %). There was an interaction between treatment and age (P = 0.034). Picrotoxin-treated heifers had lesser (P ≤ 0.05) LH mean concentrations during a 3 h period at 10 and 17 mo of age compared to control heifers (P ≤ 0.05). Comparing the period before and after Picrotoxin injection in the same animals, there was a 33 % decrease in LH concentration at 8 mo of age (P = 0.0165). These results indicate the GABAergic system has a stimulatory function in inducing LH secretion in pre-pubertal Nellore heifers. These findings corroborate previous results that GABA increases GnRH/LH secretion in other species during the pre-pubertal period.

104 Induction of cyclicity in seasonally anestrous recipient mares

Anestrous (AN) recipient mares’ natural cyclicity must be manipulated to produce foals from transferred embryos early in the year. One approach uses sulpiride to stimulate prolactin (PRL) that appears to have an important reproductive role effecting seasonality in mares. While previous research utilized sulpiride to induce ovulation (OV) in AN mares, few have transferred embryos after treatment. This study was designed to evaluate the effect of a treatment of estradiol cypionate (ECP) and sulpiride on inducing OV and subsequent pregnancy outcome in AN recipient mares of various reproductive status performed on a commercial embryo transfer farm. Anestrous recipient mares (n = 32) were randomly assigned to 4 treatment groups based on records of ovarian activity. Transitional (T, n = 8), AN (n = 11), and progesterone pre-treated (P, n = 9, received 4 mg altrenogest IM 3 wk prior) groups were treated January 20 with 50 mg of ECP IM and 3 g of sulpiride IM 24 h later. A control group (C, n = 4) of AN mares received the carrier. Jugular blood samples were collected at 0, 3, 6, 12, and 24 h post-treatment followed by daily collection for 10 d and collection every other day for 32 d thereafter and analyzed for luteinizing hormone (LH) and PRL. Ovaries were transrectally scanned every 2 to 3 d for 60 d. Embryos were transferred to 10 mares (5 T, 3 P, 2 AN) after at least the second estrous cycle up to the sixth cycle depending on their synchrony to the donor. Binomial data was analyzed via PROC GLIMMIX of SAS, and number of days to OV and hormonal data were analyzed via PROC MIXED with repeated measures. Nonparametric data were natural log-transformed and analyzed if normality was improved. Differences of least squares means were determined using the PDIFF option in SAS with ∝ ≤ 0.05 used to declare significance. There was an effect of treatment on the number of mares that achieved first OV ( P < 0.001) with 23 of 28 (82.1%) treated mares having a first OV within 22 d of treatment; and second OV ( P = 0.018) with 15 of the 23 (65.2%) mares that had a first OV achieving a second OV within 43 d. The mean number of days to first OV of T, AN, and P groups together were 32 ± 5 d earlier ( P < 0.001) than C. The transitional group ovulated sooner ( P = 0.05) than AN and tended ( P = 0.07) to ovulate sooner than P. There was an effect of the treatment-by-day interaction on plasma mean PRL ( P < 0.001) and LH ( P = 0.021) concentrations. Of the 10 embryos that were transferred, 7 (70%) resulted in a confirmed pregnancy at 60 d. Overall, the treatment protocol using ECP and sulpiride appeared to hasten OV and resulted in sustained pregnancy after embryo transfer.

Chronic exposure of bisphenol S (BPS) affect hypothalamic-pituitary-testicular activities in adult male rats: possible in estrogenic mode of action

BackgroundThe industrial revolution has resulted in increased synthesis and the introduction of a variety of compounds into the environment and their potentially hazardous effects have been observed in the biota. The present study was aimed to evaluate the potential endocrine-disrupting effects of chronic exposure to the low concentrations of bisphenol S (BPS) in male rats.MethodsWeaning male Sprague-Dawley rats (22 days old) were either exposed to water containing 0.1% ethanol for control or different concentrations of BPS (0.5, 5, and 50 μg/L) in drinking water for 48 weeks in the chronic exposure study. After completion of the experimental period, animals were dissected and different parameters (hormone concentrations, histology of testis and epididymis, oxidative stress and level of antioxidant enzymes in the testis, daily sperm production (DSP), and sperm parameters) were determined.ResultsResults of the present study showed a significant alteration in the gonadosomatic index (GSI) and relative reproductive organ weights. Oxidative stress in the testis was significantly elevated while sperm motility, daily sperm production, and the number of sperm in epididymis were reduced. Plasma testosterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) concentrations were reduced and estradiol levels were high in the 50 μg/L-exposed group. Histological observations involved a significant reduction in the epithelial height of the testis along with disrupted spermatogenesis, an empty lumen of the seminiferous tubules, and the caput region of the epididymis.ConclusionThese results suggest that exposure to 5 and 50 μg/L of BPS for the chronic duration started from an early age can induce structural changes in testicular tissue architecture and endocrine alterations in the male reproductive system which may lead to infertility in males.

Detection of urinary luteinizing hormone in Japanese black cows after administration of gonadotropin-releasing hormone.

The blood luteinizing hormone (LH) surge in cows is well studied. However, little is known about urinary LH in cows. This study examined urinary LH concentrations after administration of gonadotropin-releasing hormone (GnRH) in six Japanese black cows to induce LH secretion from the pituitary gland into the bloodstream. Abrupt rises in plasma and urinary LH were observed after GnRH administration. Plasma and urinary LH peaked at 2 and 5 hr, respectively. A positive correlation was observed between plasma LH concentrations and urinary LH amounts. Ovulation was confirmed in the cows after 48 hr of GnRH administration. These data strongly suggest that urinary LH is derived from plasma LH, which triggers ovulation in cows.

Altered production of reproductive neuropeptides in rats subjected to chronic intermittent hypoxia.

Hypobaric hypoxia is a stressful condition known to decrease fertility both in humans and animals. However, the mechanism by which the hypothalamus-pituitary-gonad axis is altered remains unknown. The aim of the present study was to analyze the effects of chronic intermittent and continuous exposure to hypoxia on hypothalamic-pituitary-gonadal axis regulation in male rats. Thirty adult male Wistar rats were assigned to one of the following three groups: control group; chronic intermittent hypoxia: subjected to 600 mbar for 18 h/d five days a week; and chronic continuous hypoxia: subjected to 600 mbar for 23.5 hours/day seven days a week, for 30 days. Plasma luteinizing hormone and testosterone concentration, hypothalamic GnRh, Kiss1 and Rfrp3 mRNA levels and PGE2 content were determined. Levels of Rfrp3, a negative regulator of GnRH and LH release, were higher in intermittently exposed animals than in controls. Levels of Kiss1, a neuropeptide that stimulates the release of GnRH only increased in animals exposed to continuous hypoxia. Plasma luteinizing hormone and testosterone concentrations and body weight were lower in rats subjected to intermittent hypoxia as compared to the remaining groups. GnRh mRNA levels as well as PGE2 content remained unchanged in all groups. Taken together, results suggest that besides the well documented direct effects of hypoxia on the testes, infertility observed in male rats exposed to hypoxia may also be due to overexpression of negative regulators of GnRH and luteinizing hormone release. Intermittent, rather than continuous, to hypoxia exposure would seem to be more detrimental to fertility.

Long-term effect of neutering on plasma luteinising hormone concentration in cats.

The objectives of this study were to validate a commercially available luteinising hormone (LH) cat ELISA, to determine whether the increases in plasma LH concentration that occur after neutering are maintained throughout cats' lives and if other factors such as calendar seasons in both intact and neutered cats, and neutering age in neutered cats, influence plasma LH concentrations. Stored plasma samples from client-owned cats were used for the measurement of LH concentrations. Clinical data, including age, sex, age at neutering and medical history, were reviewed. Two populations were included in this study: (1) a senior and geriatric cat population (⩾9 years old), including 18 intact and 18 neutered cats matched for age, sex and month of sample collection; and (2) an adult cat population (2-8 years old), including 45 neutered cats. LH concentrations were measured using a commercially available feline ELISA. Senior and geriatric neutered cats had higher plasma LH concentrations than age-matched intact cats (P <0.001). Calendar season did not influence plasma LH concentrations in the adult (P = 0.727) or senior/geriatric (P = 0.745) cats included in this study. No influence of age at neutering was observed on plasma LH concentrations (P = 0.296). Neutering causes a significant long-term increase in LH concentrations in cats and further studies are required to determine the consequences on feline health.

Review of Vasectomy Complications and Safety Concerns.

Vasectomy is a simple, safe, effective, and economical method used worldwide for long-term male contraception. As a surgical operation, it has short-term and long-term complications such as hematoma formation, infection, sterilization failure, sperm granulomas, short-term postoperative pain (nodal pain, scrotal pain, and ejaculation pain), and chronic pain syndrome. Whether it increases the risk of autoimmune disease, cardiovascular disease, testicular cancer, or prostate cancer is still controversial. Changes in plasma concentrations of luteinizing hormone, follicle-stimulating hormone, and testosterone after vasectomy have also been studied, as well as the relation between vasectomy and sexual function. Sperm quality decreases very slowly after vasectomy, and vasovasostomy and intracytoplasmic sperm injection could help a couple achieve a pregnancy if they change their minds at any point. We include a follow-up strategy and suggestions for follow-up care at the end of this review.

SAT-444 Long-Term Effect of Neutering on Plasma Luteinizing Hormone Concentrations in Cats: A Potential Role in the Pathogenesis of Feline Hyperthyroidism

Feline hyperthyroidism remains a major area of interest within the veterinary field given its high prevalence, affecting nearly 10% of geriatric cats, and that causal factors leading to this disease are not completely understood.1,2 Feline hyperthyroidism shares clinical and histopathological similarities with Toxic Multinodular Goitre in humans and therefore the discovery of driving cellular mechanisms behind the pathogenesis of this feline disease may bring translational insight into the pathogenesis of the later.3,4 Gonadotropin hormones such as LH are structurally related to other glycoproteins including TSH and cross-reactivity between these and their receptors has been demonstrated.5 It is hypothesized that increased concentrations of gonadotropins in neutered cats might be implicated in the pathogenesis of hyperthyroidism. This study aimed to determine the long-term effect of neutering on plasma LH concentrations in cats. Stored plasma samples from client-owned cats were used for measurement of LH and TSH concentrations. Clinical data, including age, sex, neutering age and medical history were reviewed. Two study populations were included in this study: (1) a geriatric cat population (≥ 9 years old): 18 entire and 18 neutered cats matched for age, sex and date of sample collection; (2) an adult cat population (2-8 years old): 45 neutered cats. LH concentrations were measured using a feline ELISA and TSH concentrations were measured by the Immulite canine TSH assay. Geriatric neutered cats have higher plasma LH concentrations (median, 0.25 ng/ml [25th percentile, 0.25; 75th percentile, 2.1]) than age matched entire cats (0.25 ng/ml [0.25, 0.25], P < 0 .001). Cats neutered between 6-9 months of age have higher LH concentrations than cats neutered before or after that period (P = 0.004). No correlation was found between plasma LH and TSH concentrations (P = 0.422). In conclusion, neutering causes significant long-term increase in LH concentrations in cats. Further research to determine whether this results in activation of the TSH receptor and ultimately in thyrocyte hyperplasia and/or hyperfunction is warranted.

Kisspeptin induces LH release and ovulation in an induced ovulator†.

Kisspeptin has been implicated in the ovulatory process of several species of spontaneous ovulators but in only one induced ovulator. In contrast, NGF in semen is the principal trigger of ovulation in other species of induced ovulators-camelids. We tested the hypotheses that kisspeptin induces luteinizing hormone (LH) secretion in llamas through a hypothalamic mechanism, and kisspeptin neurons are the target of NGF in its ovulation-inducing pathway. In Experiment 1, llamas were given either NGF, kisspeptin, or saline intravenously, and LH secretion and ovulation were compared among groups. All llamas treated with NGF (5/5) or kisspeptin (5/5) had an elevation of LH blood concentrations after treatment and ovulated, whereas none of the saline group did (0/5). In Experiment 2, llamas were either pretreated with a gonadotropin-releasing hormone (GnRH) receptor antagonist or saline and treated 2h later with kisspeptin. Llamas pretreated with saline had elevated plasma LH concentrations and ovulated (6/6) whereas llamas pretreated with cetrorelix did not (0/6). In Experiment 3, we evaluated the hypothalamic kisspeptin-GnRH neuronal network by immunohistochemistry. Kisspeptin neurons were detected in the arcuate nucleus, the preoptic area, and the anterior hypothalamus, establishing synaptic contacts with GnRH neurons. We found no colocalization between kisspeptin and NGF receptors by double immunofluorescence. Functional and morphological findings support the concept that kisspeptin is a mediator of the LH secretory pathway in llamas; however, the role of kisspeptins in the NGF ovulation-inducing pathway in camelids remains unclear since NGF receptors were not detected in kisspeptin neurons in the hypothalamus.

The effect of diet therapy on the anthropometric and metabolic parameters in women with infertility and obesity

Aim: to monitor the anthropometric, hormonal and metabolic parameters in women of reproductive age with infertility and grade I gluteofemoral obesity during treatment with a balanced hypocaloric diet. Materials and methods . The study included 23 infertile women of reproductive age. All patients were prescribed a balanced, low-calorie diet (1200 kcal/day), exercise, and behavioral therapy. The anthropometric, metabolic and hormonal parameters were determined before and 12 months after the treatment. We measured the levels of leptin, total cholesterol, triglycerides, triglycerides, high-density and low-density lipoprotein cholesterol (HDL cholesterol and LDL cholesterol), fasting glycose. Following the measurements, the atherogenic and insulin resistance indices were calculated. In addition, the plasma concentrations of luteinizing hormone, follicle-stimulating hormone, prolactin, estrone, estradiol, testosterone, progesterone, and immunoreactive insulin were measured. Results. Twenty patients completed the study. A decrease in body weight (by average of 10.58 ± 5.70 kg) was found in 87 % of patients; in parallel, the body mass index decreased from 32.53 ± 1.40 to 28.55 ± 2.50 kg/m2 (p < 0.001). The decrease in body weight was accompanied by a statistically significant decrease in the levels of leptin (p < 0.001), estrone (p = 0.049), estradiol (p = 0.032), total cholesterol (p < 0.001), triglycerides (p = 0.004), LDL cholesterol (p = 0.001), fasting glycose (p < 0.001), insulin resistance index (p = 0.002), atherogenic index (p < 0.001) and an increase in the level of progesterone (p = 0.030). The ovulatory menstrual cycle was restored in all women (p = 0.007); within one year, wanted pregnancy occurred in 1 woman. Conclusion. The use of a low-calorie diet for 12 months in infertile women with grade I gluteofemoral obesity leads to normalization of metabolic parameters, weight loss and, the restoration of the ovulatory menstrual cycle in 100 % of cases.

A phase 2a, randomized, double-blind, placebo-controlled trial of the efficacy and safety of the oral gonadotropin-releasing hormone antagonist, ASP1707, in postmenopausal female patients with rheumatoid arthritis taking methotrexate

Objectives Many patients with rheumatoid arthritis (RA) are not able to achieve long-term disease remission. This phase 2a study (NCT02884635) evaluated the efficacy, safety, pharmacokinetics, and pharmacodynamics of the novel, oral, gonadotropin-releasing hormone antagonist, ASP1707, in combination with methotrexate (MTX) for treatment of RA. Methods Postmenopausal women with RA who had been receiving MTX for ≥90 days were randomized to ASP1707 30 mg twice daily or placebo for 12 weeks. The primary endpoint was the American College of Rheumatology 20% improvement criteria (ACR20) response rate at week 12. Secondary endpoints included: ACR20, ACR50, and ACR70 response rates; disease activity score (DAS)28-CRP; DAS28-ESR; Tender or Swollen Joint Counts; and remission rates. Results Of 105 patients screened, 72 were randomized to ASP1707 30 mg twice daily (n = 37) or placebo (n = 35). ASP1707 did not improve ACR20, ACR50, or ACR70 response rates at any time point and did not improve any secondary efficacy endpoint. Plasma luteinizing hormone (LH) concentration decreased >90% in >90% of patients receiving ASP1707, with a rapid decrease to <1 IU/L at week 1 that remained stable throughout the treatment. Conclusion In the current study, ASP1707 did not demonstrate a clinical benefit.

GnRH(1-5), a metabolite of gonadotropin-releasing hormone, enhances luteinizing hormone release via activation of kisspeptin neurons in female rats.

Accumulating evidence suggests that kisspeptin neurons in the arcuate nucleus (ARC), which coexpress neurokinin B and dynorphin, are involved in gonadotropin-releasing hormone (GnRH)/luteinizing hormone (LH) pulse generation, while the anteroventral periventricular nucleus (AVPV) kisspeptin neurons are responsible for GnRH/LH surge generation. The present study aims to examine whether GnRH(1-5), a GnRH metabolite, regulates LH release via kisspeptin neurons. GnRH(1-5) was intracerebroventricularly injected to ovariectomized and estrogen-treated Wistar-Imamichi female rats. Immediately after the central GnRH(1-5) administration at 2 nmol, plasma LH concentration increased, resulting in significantly higher levels of the area under the curve and baseline of plasma LH concentrations compared to vehicle-injected controls. On the other hand, in Kiss1 knockout rats, GnRH(1-5) administration failed to affect LH secretion, suggesting that the facilitatory effect of GnRH(1-5) on LH release is mediated by kisspeptin neurons. Double in situ hybridization (ISH) for Kiss1 and Gpr101, a GnRH(1-5) receptor gene, revealed that few Kiss1-expressing cells coexpress Gpr101 in both ARC and AVPV. On the other hand, double ISH for Gpr101 and Slc17a6, a glutamatergic marker gene, revealed that 29.2% of ARC Gpr101-expressing cells coexpress Slc17a6. Further, most of the AVPV and ARC Kiss1-expressing cells coexpress Grin1, a gene encoding a subunit of NMDA receptor. Taken together, these results suggest that the GnRH(1-5)-GPR101 signaling facilitates LH release via indirect activation of kisspeptin neurons and that glutamatergic neurons may mediate the signaling. This provides a new aspect of kisspeptin- and GnRH-neuronal communication with the presence of stimulation from GnRH to kisspeptin neurons in female rats.