Luteinizing Hormone Synthesis Research Articles

Characteristics of the hemomicrocirculatory channel of the ventricular myocardium in triptorelin-induced central deprivation of the synthesis of luteinizing hormone and correction of this condition by the introduction of quercetin

The study of the microcirculatory channel of the connective tissue of the myocardium of the ventricles improves the understanding of the features of pathological processes, such as ischemia, hypoxia and remodeling of the myocardium, the evaluation of the effectiveness of drug therapy, as well as rehabilitation methods. The purpose of the study is to determine the changes in the hemomicrocirculatory channel of the ventricular myocardium in triptorelin-induced central deprivation of the synthesis of luteinizing hormone and the correction of this condition by the introduction of quercetin. The experiment was conducted on 60 sexually mature white male rats weighing 140-160 g. The rats were divided into 3 groups. 1 group – control, rats injected with physiological solution (10 animals). Group 2 – rats that were injected subcutaneously with diphereline (triptorelin embonate) at a dose of 0.3 mg of the active substance per kg of body weight for 365 days (25 animals). Group 3 – rats that were injected with a solution of triptorelin at the rate of 0.3 mg of the active substance per kg of body weight to simulate central deprivation of the synthesis of luteinizing hormone with the addition of quercitin to the diet using a gastric tube based on the body weight of the animals three times a week (25 animals). Animals were withdrawn from the experiment after 1, 3, 6, 9 and 12 months by overdose with ether anesthesia. A comprehensive study of histological preparations of the myocardium and quantitative calculation of the diameter of the vessels of the microcirculatory bed were carried out using a light microscope with a digital microfilter and software adapted for these studies. Statistical processing of the research results was carried out using the Microsoft Office Excel software and the Real Statistics 2019 extension. When analyzing the index of arteriole diameters in the group of animals that were injected with triptorelin after 1, 3, 6, 9 and 12 months, a significant increase in the diameter of arterioles was established compared to the control group animals, respectively, by 13.9 % – 40.8 % – 102.6 % – 112.6 % – 11.5 %; and in animals to which quercetin was administered against the background of triptorelin administration, it was established that this indicator after 1 month did not reliably differ from the similar one in the control group, and after 3, 6, 9 and 12 months it was reliably higher than in the control respectively by 11.5 % – 136.2 % – 101.1 % – 101.4 %. The analysis of the diameters of the venular link of the hemomicrocirculatory channel in the group of animals administered triptorelin showed a significant increase in the value of this indicator after 3, 6, 9 and 12 months compared to the control group, respectively by 20.0 % – 71.2 % – 57.8 % – 22.9 %; and in animals that were additionally injected with quercetin after 1 month, the diameter of venules was significantly reduced by 8.1% compared to the control, and after 3, 6, 9 and 12 months – respectively by 5.2 % – 87.5 % – 64.0 % – 50.4 % it was significantly greater than in control animals. Analysis of capillary diameters in the group of animals administered triptorelin showed a significant increase in the value of this indicator after 1, 3, 6 and 9 months compared to the control group, respectively by 23.9 % – 49.1 % – 61.8 % – 36.7 %; and in animals that were additionally injected with quercetin, the capillary diameter significantly increased compared to the control after 3, 6, 9, and 12 months – by 22.3 % – 55.3 % – 17.1 % – 25.2 %, respectively. The conducted study showed that the introduction of triptorelin leads to structural and functional changes in the components of the microcirculatory channel of the myocardium of the ventricles of the heart, which are characterized by changes in the diameter of the arterial and venous links with a gradual increase in blood flow, the maximum of which is at the 6th month of the experiment in both experimental groups, but without impaired outflow in the group with the addition of quercitin.

Low concentrations of the food contaminant Deoxynivalenol trigger apoptosis and impair GnRH-induced LH secretion in pituitary gonadotrope-like cells.

AbstractTheFusariummycotoxin deoxynivalenol (DON) is one of the most frequently occurring food contaminants. Nearly all individuals are exposed to DON, due to it widespread presence in grains and grain-based products. Chronic DON poisoning is associated with growth retardation, immunotoxicity as well as impaired reproduction and fetal development. At the molecular level, DON alters intracellular signaling by activating mitogen-activated protein kinases (MAPKs) that modulate cell growth, differentiation, and apoptosis. Of note, these MAPKs are also critical mediators of gonadotrophin-releasing hormone (GnRH)-induced synthesis and secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) by pituitary gonadotrope cells. So far, no research has explored the potential endocrine-disrupting effects of DON on pituitary gonadotropins production. Herein, we show the first evidence that DON affects LH production by the immortalized gonadotrope-like cell line LβT2 in a concentration-dependent manner. Taken together, our experiments demonstrated that low concentrations of DON affect GnRH-induced signaling through a mechanism that, at least in part, involves apoptosis and inhibition of GnRH-induced phosphorylation of ERK-MAPK. Consequently, DON also affects the GnRH-induced expression ofCgaandLhb, two critical genes for LH synthesis and secretion by gonadotrope cells in mammals. This research broadens our knowledge of the toxicity of DON and brings a new depth to the potential neuroendocrine implications for reproduction.Graphical abstract

ZEB1 Inhibits LHβ Subunit Transcription When Overexpressed, but Is Dispensable for LH Synthesis in Mice.

Luteinizing hormone (LH), a heterodimeric glycoprotein produced by pituitary gonadotrope cells, regulates gonadal function. Hypothalamic gonadotropin-releasing hormone (GnRH) stimulates LH synthesis and secretion. GnRH induces LHβ subunit (Lhb) expression via the transcription factor, early growth response 1 (EGR1), acting on the Lhb promoter. In contrast, overexpression of zinc finger E-box binding homeobox 1 (ZEB1) represses LH production in mice, but the underlying mechanism was not previously elucidated. Here, we observed that ZEB1 inhibited GnRH-stimulated but not basal Lhb mRNA expression in homologous murine LβT2 cells. Moreover, ZEB1 blocked GnRH and/or EGR1 induction of murine Lhb but not human LHB promoter-reporter activity in these cells. Using chimeric reporters, we mapped the species-specific ZEB1 sensitivity to sequence differences, including in Z- and E-boxes, in the proximal Lhb/LHB promoters, immediately upstream of the transcription start sites. ZEB1 bound to the murine Lhb promoter with higher affinity than to the human LHB promoter in this region. To examine ZEB1's physiological role in LH synthesis, we characterized gonadotrope-specific Zeb1 knockout mice. Loss of ZEB1 in gonadotropes did not affect LH production or secretion. Collectively, the data suggest that ZEB1, when overexpressed, can inhibit GnRH/EGR1 induction of murine Lhb transcription but does not play a necessary role in LH synthesis in mice.

Hyperandrogenemia elevates expression of apelin and apelin receptor protein in the mice pituitary.

Hyperandrogenemia is associated with polycystic ovarian syndrome (PCOS) and imbalances in the pituitary hormones, luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels. Apelin and its receptor, APJ (class A, rhodopsin-like G- protein-coupled receptor), belongs to adipokines, and its expression has been shown in the pituitary. It is also well known that, hyperandrogenism and PCOS have deregulation of different adipokines. Whether hyperandrogenism also deregulates the apelin system in the pituitary has yet to be investigated. Thus, we have investigated the expression and localization of apelin and its receptor, APJ, in the letrozole-induced hyperandrogenised pituitary of female mice. Our results showed that the apelin, APJ and androgen receptor (AR) expression were upregulated in the anterior pituitary. Furthermore, the immunostaining of LH exhibited increased abundance than FSH. The circulating LH was also found to be elevated compared to FSH levels. The increased LH synthesis and secretion coincides with elevated apelin system in the pituitary of hyperandrogenised mice. Recently, a direct role of apelin has also been reported in the female pituitary, where apelin inhibits LH secretion. Thus, apelin could be one of the factors for deregulated gonadotropin secretion in hyperandrogenised conditions. However, more research is needed to fully understand the complex interactions between apelin and androgen regarding gonadotropin secretion in hyperandrogenised conditions.

Electron microscopic changes in interstitial endocrinocytes of rats testicles during administration of triptorellin for 365 days

Triptorelin is a gonadotropin-releasing hormone agonist that is a potent inhibitor of testosterone (in men) and estrogen (in women) synthesis and is used to treat advanced prostate cancer. Studies of the mechanisms of regulation and synthesis of testosterone formation in testicular interstitial cells demonstrate multiple endogenous targets that can increase testosterone biosynthesis, which may moderate the effects of testosterone depletion. Triptorelin, a synthetic analog of the neurohormone gonadoliberin, suppresses the expression of the GnRH receptor in the pituitary gland, but does not change the functioning of the pituitary-testicular complex. The purpose of the work is to study the electron microscopic changes in the interstitial endocrinocytes of the testes of rats after the administration of triptorelin for 365 days. The experiment was conducted on 35 sexually mature male white rats. The rats were divided into 2 groups: the control group (I) was injected with a physiological solution, the II group with central deprivation of the synthesis of luteinizing hormone was injected subcutaneously with triptorelin at a dose of 0.3 mg of the active substance per kg of the rat's body weight. The study of the interstitial space in the testicles of white rats showed that long-term administration of triptorelin causes hormonal dysregulation of the hypothalamus-pituitary-testis system, which leads to quantitative and qualitative changes in the endocrine cells of the interstitial space of the testis, which is confirmed by electron microscopic changes in subcellular structures. The maximum effect of triptorelin is determined from the 180th day of observation, which is characterized by an increase in degenerative changes in endocrinocytes, and the detection of Reinke crystals in the cytoplasm of interstitial endocrinocytes from the 270th day of observation.

SAT606 Comparison Of Psychosocial And Immune/Inflammatory Stress On Luteinizing Hormone Pulsatile Secretion

Abstract Disclosure: J. Jang: None. M.J. Kreisman: None. K.M. Breen Church: None. Stress induces a physiological response in the body to return to the homeostatic state. It is recognized that many stress types impair reproduction, but the mechanisms conveying inhibition may be distinct and stressor-dependent. Our research aims to understand how stress inhibits the neuroendocrine mechanisms controlling the pulsatile release of luteinizing hormone (LH). This is especially important because pulsatile LH is pivotal to reproductive health in males and females. Immune/inflammatory stressors such as lipopolysaccharides (LPS) cause an inflammatory response, producing peripheral cytokines that can signal to the brain in distinct ways compared to the neural mechanisms employed in response to psychosocial stress. However, how LPS disrupts the neural mechanisms involved in gonadotropin pulsatility is still unknown. Here, we compared the alteration in LH pulses in response to psychosocial restraint stress or immune/inflammatory LPS stress and sought to understand stress-specific regulation of the upstream targets controlling LH synthesis and secretion. Our initial observations demonstrated, in ovariectomized (OVX) female mice, that restraint stress elicited suppression rapidly, within 30 minutes; yet, the response to LPS was delayed, occurring approximately 90 minutes from injection. Therefore, we investigated the prolonged response of the stressors on LH pulses, observing LH pulse profiles 90 minutes to 180 minutes after the initiation of stress. Restraint stress significantly suppressed mean LH, resulting from a suppression of pulse frequency. LPS injected intraperitoneal (IP, 1.5 ug/g) also significantly suppressed mean LH. In contrast to restraint stress, LPS induced a reduction in both frequency as well as LH pulse amplitude. We conducted two follow-up experiments to investigate the lowered LH pulse amplitude during immune/inflammatory stress. The first study assessed hypothalamic kisspeptin gene expression and pituitary LHβ and GnRH receptor expression, in LPS versus restraint animals, to test whether altered gene transcription in LPS animals resulted in lowered LH secretion. The results of this experiment are still pending. The second study tested the LH response to a single bolus of GnRH or kisspeptin. Interestingly, we found equivalent LH increases, to either agonist, in saline versus LPS-treated animals. Collectively, these data indicate that both restraint and immune/inflammatory stress inhibit LH pulse frequency. However, the endogenous LH pulse profiles suggest an additional stressor-specific mechanism that lowers pulsatile LH during immune/inflammatory stress via LPS. Identification of stress pathways that alter endocrine hormones is critical as it allows for the development of therapeutics and medications to treat endocrine disorders. Presentation: Saturday, June 17, 2023

The effect of quercetin on the morphogenesis of the interstitial space in the testes of rats after 90 days with central blockade of luteinizing hormone

Leydig cells are responsible for the production of testosterone in the male testicles when stimulated by luteinizing hormone (LH). Dysfunction of Leydig cells, which occurs during inflammation or oxidative stress, is one of the main causes of male infertility. The purpose of the study is to determine the effect of quercetin on the microscopic organization of rat testes, nitric oxide production and the intensity of oxidative stress in rat testes on the 90th day of the experiment, during the experimental central deprivation of LH synthesis caused by the administration of triptorelin acetate solution. The experiment was conducted on 20 sexually mature male white rats. Rats were divided into 2 groups of 10 animals in each group: control group (I), group with central deprivation of LH + quercetin synthesis (II). Animals from the group with central blockade of LH synthesis were injected subcutaneously with triptorelin acetate at a dose of 0.3 mg of the active substance per kg and quercetin at 100 mg per kg of body weight 3 times a week, while the control group was injected with saline. Our study of the interstitial space in the testes of white rats showed heterogeneity of macrophage populations and variability of structural and functional parameters. Central blockade of LH synthesis by the administration of treptorelin with the parallel administration of quercitin to the studied animals on the 90th day of the experiment causes changes in the structure of the interstitial space of rat testes, which is characterized by high variability both in the populations of interstitial endocrinocytes and macrophages. Biochemical indicators on the 90th day of the experiment indicate an increase in NO production in conditions of central blocking of the synthesis of luteinizing hormone by more than three times, which is ensured by the activity of the inducible isoform of NOS (iNOS). At the same time, the increase in the activity of iNOS with a decrease in the activity of the arginase pathway leads to the polarization of macrophages according to the pro-inflammatory type. The introduction of quercetin protects the testicular tissue of rats from oxidative damage caused by the administration of triptorelin on the 90th day of the experiment by increasing antioxidant protection and reducing reactive oxygen species in the tissue.

Dynamics of CD68 receptor expression in macrophages of the interstitial space of the rat testis under triptorelin prolonged administration

Testosterone, the production of which is stimulated by the release of luteinizing hormone (LH) has a remarkable anti-inflammatory and immunomodulatory effect, and in conditions of testosterone deficiency tissue damage can occur due to excessive differentiation of macrophages into a pro-inflammatory M1 phenotype. The aim of this study was to determine the spread of CD68 receptorn as the marker of inflammation on the cells in the interstitial space and testicular vessels under LH synthesis blockade with tryptorelin. Sexually mature white male rats were randomly divided into control (10 animals) and experimental (25 animals) groups. Animals in the experimental group were injected with a tryptorelin acetate solution (0.3 mg/kg). Immunochemical analysis of CD68+ expression was estimated at Olympus FV10i-LIV laser scanning confocal microscope using fluorescent labeling dye hilyte flour 488. It was shown that luteinizing hormone deprivation led to an increase in the distribution of the CD68 receptor in the interstitial space and in the testicular vessels from day 30 to 180 of the experiment, associated with the increase of inducible NO synthase activity in testis tissue. Keywords: CD68, luteinizing hormone, macrophage M1 phenotype, testis, testosterone, tryptorelin

Percentage Fertility of Female Wistar Rats Treated with Extracts of Persea americana

The purpose of this research study was to investigate the effects of ethanolic stem bark extract of Persea americana on some reproductive parameters of female Wistar rats. In this study, female Wistar rats were randomly assigned into three (3) groups of 5 rats each. The control group (Group 1) was given distilled water. Group 2 received 200mg/kg of the extract and group 3 received 400mg/kg of the extract daily for a period of 21 days following acclimatization. The female rats were cohabited with males in the ratio 2:1 (M:F) for 10 days. Blood samples were collected and some tissues harvested at sacrifice. The statistical analysis was done using Statistical Package for Social Sciences (SPSS). One-way analysis of variance (ANOVA) test was used to compare groups followed by post-hoc testing to determine whether there were significant differences between the control and treatment groups. P-value less than 0.05 was considered significant and result presented as Mean±SEM. The result showed that the extract of Persea americana caused stimulatory effect on anterior pituitary synthesis of luteinizing hormone (LH) and follicle stimulating hormone (FSH) and may have also caused changes in the gonads leading to decreased gonadal hormone synthesis (estrogen and progesterone). The percentage fertility of the female Wistar rats was significantly reduced suggesting that the stem bark extract of Persea americana possess antifertility effects.

Pituitary luteinizing hormone synthesis starts in aromatase (cyp19a1b)-positive cells expressing esr1 and esr2b at the onset of puberty in Takifugu rubripes (fugu)

Unlike mammals, teleost fish have high aromatase activity (AA) in the pituitary. However, the cells responsible for oestradiol synthesis and the local physiological roles of this hormone remain unclear. Hence, we investigated the effects of age and development on steroidogenic activity, mRNA expression, and cyp19a1b localization in the pituitary gland of the Japanese pufferfish Takifugu rubripes. Under aquaculture conditions, AA was highest after puberty, and the mRNA expression levels of cyp19a1b and the oestrogen receptors esr1 and 2b and the level of serum testosterone (T) were significantly increased after puberty compared with the other developmental stages in male and female pufferfish. Immunohistochemistry using multiple antibodies and in situ hybridization analysis revealed that Cyp19a1b colocalizes with luteinizing hormone (LH) in pituitary cells. Furthermore, Esr1 was localized in the nuclei of all hormone-producing cells, whereas Esr2b was localized only in the nuclei of Cyp19- and LH-positive cells. The administration of an aromatizable androgen (T) or oestrogen (E2) to reproductively inactive females induced LH synthesis in vivo. We prepared spheroids from pituitary cells to investigate the role of local E2 in LH synthesis in vitro. Immunohistochemical analysis of spheroids showed that T-induced LH synthesis could be blocked by an aromatase inhibitor and/or an ER antagonist but not an AR antagonist. Taken together, these findings suggest that LH synthesis is initiated in cyp19a1b-, esr1-, and esr2b-expressing cells at the onset of puberty under the control of steroidal feedback, and both feedback and local oestrogen may be involved in controlling LH synthesis in these cells.

Chronic exposure to aquacultural stressors affects pituitary-testis axis in the Mozambique tilapia Oreochromis mossambicus.

Reproduction in fish is modulated by several factors that include environmental and endocrine components. The aim of this study was to elucidate the effect of aquacultural stressors along the pituitary-testis axis in a continuously breeding cichlid fish Oreochromis mossambicus. The fish (35.05 ± 2.20g) were divided into three groups (n = 10 in each group, n = 5 in each replicate), namely initial controls (euthanized on the day of initiation of experiment), time-matched controls (kept undisturbed), and stressed fish, which were subjected to different kinds of randomized aquacultural stressors such as handling, chasing, frequent netting, and low water levels, daily for a period of 21days. Although the gonadosomatic index and the mean numbers of spermatogonia-A and spermatogonia-B did not differ significantly among different experimental groups, significant decrease was observed in the mean numbers of primary spermatocytes, secondary spermatocytes, early spermatids, and late spermatids in fish exposed to stressors compared to those of initial controls and time-matched controls. While the diameter of the seminiferous lobule was significantly lower, the size of the lumen and the serum levels of cortisol were significantly increased in stressed fish compared with initial controls and time-matched controls. Furthermore, weak androgen receptor immunoreactivity was observed in the Sertoli cells of the testis in contrast to the strongly immunoreactive androgen receptors in initial controls and time-matched controls. Concomitant with this, there was a significant decrease in the percent area and the intensity of luteinizing hormone (LH) immunoreactive content in the proximal pars distalis (PPD) region of the pituitary gland in stressed fish compared with initial controls and time-matched controls. Overall, these results suggest that exposure to chronic aquacultural stressors causes suppression of LH synthesis in the pituitary gland concomitant with decreased androgen receptor expression and blockade of recruitment of germline cells at the meiosis stage. This inhibition appears to be mediated through the hypothalamic-pituitary-interrenal axis in the tilapia O. mossambicus.

Effects of melatonin on the production of GnRH and LH in luteal cells of pregnant sows.

Effects of melatonin on the release and synthesis of gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH) at the hypothalamus and pituitary levels have been explored in some species, but a similar study in the corpora lutea (CL) has not yet been conducted. In this study, the immunostaining for GnRH and LH was observed in luteal cells of porcine CL during pregnancy, and a significant effect of pregnant stage on the level of GnRH and LH was found; higher values for GnRH and LH immunostaining and mRNA were detected in the early and mid-stages CL than in the later-stage CL (P < 0.01). Furthermore, the patterns of melatonin membrane receptors (MT1 and MT2) expression were consistent with those of GnRH and LH expression in the CL of pregnant sows; the relative levels of MT1 and MT2 in the early and mid-stages were significantly higher than those in the later-stage (P < 0.01). In luteal cells, melatonin dose-dependently increased in GnRH and LH secretion and mRNA expression. Melatonin also increased the GnRH-induced accumulation of LH and the LH-induced secretion of P4 in luteal cells. Additionally, the effects of melatonin on luteal GnRH and LH production were blocked by luzindole, a non-selective MT1 and MT2 receptor antagonist. Our results demonstrate the stimulatory effects of melatonin on GnRH and LH production in luteal cells of pregnant sows, suggesting a potential role for melatonin in luteal function through regulating the release and synthesis of GnRH and LH in luteal cells.

CORRELATIONS BETWEEN CD68 RECEPTOR EXPRESSION AND ACTIVITY OF MACROPHAGE POLARIZATION MARKER ENZYMES IN RAT TESTES DURING PROLONGED BLOCKADE OF LUTEINIZING HORMONE SYNTHESIS BY TRIPTORELIN

Luteinizing hormone and testosterone have a significant effect on the polarization of macrophages. Changing the polarization of macrophages can cause morphological and metabolic changes in various organs and tissues. The CD68 receptor is associated with proinflammatory polarization of macrophages. Currently, the scientific literature provides limited data on the relationship between the expression of the CD68 receptor on testicular macrophages and the activity of markers of macrophage polarization enzymes during long-term deprivation of luteinizing hormone synthesis. The aim of this study was to establish correlations between the number of CD68+ cells in the interstitial space and testicular vessels and the activity of inducible NO synthase, arginase and superoxide anion radical production after 270 and 365 days of central blockade of luteinizing hormone synthesis by triptorelin. Materials and methods. The study was performed on 15 adult male Wistar rats. Animals were randomly divided into 2 groups: control (5 animals) and experimental (10 animals). Animals of the experimental group were injected with a solution of triptorelin acetate at the rate of 0.3 mg of active substance per kg of animal weight to model the central derivation of luteinizing hormone synthesis. Animals from the experimental group were removed from the experiment on days 270 and 365 of the simulation of central derivation of luteinizing hormone synthesis. Histological examination of the testes was performed after preparation of paraffin sections. To perform immunohistochemical study of testicular macrophages for the presence of CD68 receptors we performed, after the manufacture of paraffin blocks, deparaffinization of sections was with subsequent unmasking of antigens. Inducible NO synthase activity, arginase and superoxide anion radical production were determined in 10% of testicular homogenates. Quantitative distribution of the CD68 receptor in the interstitium and testicular blood vessels was also determined. After determining the distribution of the studied parameters, a correlation analysis was performed by the Spearman method and the correlation of the ranks of the studied parameters and its statistical significance were determined. Results. The production of superoxide anion radical is directly proportionally strongly correlated with the expression of CD68 on interstitial and vascular macrophages. There were no statistically significant correlations between the prevalence of CD68 receptor in the interstitium and vascular vessels and the activity of inducible NO synthase and arginase on day 270 of central deprivation of luteinizing hormone synthesis by triptorelin. The production of superoxide anion radical, inducible NO synthase and arginase activity, and the prevalence of the CD68 receptor in the interstitium and blood vessels of testes on day 365 of central deprivation of luteinizing hormone synthesis do not have statistically significant correlations. Conclusions. Expression of the CD68 receptor on interstitial and parietal testicular macrophages leads to hyperproduction of superoxide anion radical on day 270 of central deprivation of luteinizing hormone synthesis by triptorelin. The prevalence of CD68 on day 360 of central deprivation of luteinizing hormone synthesis by triptorelin does not affect the activity of macrophage polarization marker enzymes.

MORPHOLOGICAL CHANGES AND OXIDATIVE HOMEOSTASIS IN THE LIVER TISSUES DURING LONG CENTRAL DEPRIVATION OF LUTEINIZING HORMONE SYNTHESIS BY TRIPTORELIN

In recent years, researchers have focused on the problem of the dependence of the functioning of various organs and systems on the level of androgens. The effect of long inhibition of testosterone synthesis by triptorelin on liver tissue is poorly understood. The aim of this research was to establish the microscopic organization of rat livers, production of nitric oxide and the intensity of oxidative stress in the rat livers during experimental central deprivation of luteinizing hormone synthesis by diphereline injection on the 270-360th day of the experiment. The experiments were carried out on 30 sexually mature male white rats of the Wistar line. Rats were divided into 2 groups: the control group (10) and the experimental group (20). Animals from the experimental group were subcutaneously injected triptorelin at a dose of 0.3 mg of the active substance/ per kg of body weight for 360 days, while the control group received an injection of saline. It was found that oxidative stress develops in hepatocytes, which is morphologically confirmed by karyopyknosis of the nuclei, oxyphilia of the cytoplasm with the appearance of a significant number of vacuoles in it. The vessels of the microcirculatory bed react with stasis. An increase in the production of superoxide radical anion in rat liver may be due to the absence of an inhibitory effect of testosterone on macrophages and liver mitochondria, which is accompanied by depletion of antioxidant enzymes and the development of oxidative stress. The intensity of biochemical markers of oxidative stress on the 360th day is lower than on the 270th day, which is due to an increase in the activity of antioxidant enzymes and a decrease in the production of reactive oxygen species.

Influence of quercetin on morphological changes in rats testes after 180 days during central deprivation of luteinizing hormone

A relevant and popular area of research is the protective effect of the bioflavonoid quercetin, which makes it possible to use it to correct testicular dysfunction of various origins. The aim of the study was to determine the effect of quercetin on the microscopic organization of rat testicles, nitric oxide production and the intensity of oxidative stress in rat testicles on the 180th day of the experiment, during experimental central deprivation of luteinizing hormone synthesis caused by triptorelin solution. The experiment was performed on 20 adult male white rats. Rats were divided into 2 groups of 10 animals in each group: control group (I), group with central deprivation of LH synthesis + quercetin (II). Animals from the group with central deprivation of LH synthesis were injected subcutaneously with triptorelin acetate at a dose of 0.3 mg of active substance per kg and quercetin 100 mg per kg of body weight 3 times a week, while the control group was injected with saline. Ultrathin sections made by ultramicrotome were contrasted with 1 % aqueous uranyl acetate and lead citrate according to the Reynolds method and examined by electron microscopy. According to standard methods, the material was poured into paraffin blocks, from which sections with a thickness of 4 μm were made and stained with hematoxylin and eosin. Histological specimens were examined using a Вiorex 3 light microscope with a digital microfilter with software adapted for these studies. All biochemical studies were performed in 10 % of testicular tissue homogenate using a Ulab 101 spectrophotometer. Statistical processing of the study results was performed using Microsoft Office Excel software and Real Statistics 2019 extension. The nonparametric Mann-Whitney test was used to determine the statistical significance of differences between groups. Our study of the interstitial space in the testes of white rats showed the heterogeneity of populations of endocrinocytes and macrophages and the variability of structural and functional parameters. In the tissues of the testes in conditions of prolonged central deprivation of testosterone synthesis develops oxidative stress, which on the 180th day of the experiment leads to the development of edema of the interstitial space, followed by tissue fibrosis. Changes in the polarization of macrophages in our opinion may cause oxidative stress in the testes, as evidenced by increased iNOS activity and decreased arginase activity, but use of quercetin protects rat testicular tissue from oxidative damage caused by triptorelin by increasing direct antioxidant system and effects on the lipoxygenase pathway of arachidonic acid metabolism.

Reproductive Regulation of PrRPs in Teleost: The Link Between Feeding and Reproduction.

Prolactin-releasing peptide (PrRP), a sort of vital hypothalamic neuropeptide, has been found to exert an enormous function on the food intake of mammals. However, little is known about the functional role of PrRP in teleost. In the present study, two PrRP isoforms and four PrRP receptors were isolated from grass carp. Ligand-receptor selectivity displayed that PrRP1 preferentially binds with PrRP-R1a and PrRP-R1b, while PrRP-R2a and PrRP-R2b were special receptors for PrRP2. Tissue distribution indicated that both PrRPs and PrRP-Rs were highly expressed in the hypothalamus-pituitary-gonad axis and intestine, suggesting a latent function on food intake and reproduction. Using grass carp as a model, we found that food intake could significantly induce hypothalamus PrRP mRNA expression, which suggested that PrRP should be also an anorexigenic peptide in teleost. Interestingly, intraperitoneal (IP) injection of PrRPs could significantly induce serum luteinizing hormone (LH) secretion and pituitary LHβ and GtHα mRNA expression in grass carp. Moreover, using primary culture grass carp pituitary cells as a model, we further found that PrRPs could directly induce pituitary LH secretion and synthesis mediated by AC/PKA, PLC/IP3/PKC, and Ca2+/CaM/CaMK-II pathways. Finally, estrogen treatment of prepubertal fish elicited increases in PrRPs and PrPR receptors expression in primary cultured grass carp hypothalamus cells, which further confirmed that the PrRP/PrRPR system may participate in the neuroendocrine control of fish reproduction. These results, taken together, suggest that PrRPs might act as a coupling factor in feeding metabolism and reproductive activities in teleost.

Pituitary P62 deficiency leads to female infertility by impairing luteinizing hormone production

P62 is a protein adaptor for various metabolic processes. Mice that lack p62 develop adult-onset obesity. However, investigations on p62 in reproductive dysfunction are rare. In the present study, we explored the effect of p62 on the reproductive system. P62 deficiency-induced reproductive dysfunction occurred at a young age (8 week old). Young systemic p62 knockout (p62-/-) and pituitary-specific p62 knockout (p62flox/flox αGSUcre) mice both presented a normal metabolic state, whereas they displayed infertility phenotypes (attenuated breeding success rates, impaired folliculogenesis and ovulation, etc.) with decreased luteinizing hormone (LH) expression and production. Consistently, in an infertility model of polycystic ovary syndrome (PCOS), pituitary p62 mRNA was positively correlated with LH levels. Mechanistically, p62-/- pituitary RNA sequencing showed a significant downregulation of the mitochondrial oxidative phosphorylation (OXPHOS) pathway. In vitro experiments using the pituitary gonadotroph cell line LβT2 and siRNA/shRNA/plasmid confirmed that p62 modulated LH synthesis and secretion via mitochondrial OXPHOS function, especially Ndufa2, a component molecule of mitochondrial complex I, as verified by Seahorse and rescue tests. After screening OXPHOS markers, Ndufa2 was found to positively regulate LH production in LβT2 cells. Furthermore, the gonadotropin-releasing hormone (GnRH)-stimulating test in p62flox/flox αGSUcre mice and LβT2 cells illustrated that p62 is a modulator of the GnRH-LH axis, which is dependent on intracellular calcium and ATP. These findings demonstrated that p62 deficiency in the pituitary impaired LH production via mitochondrial OXPHOS signaling and led to female infertility, thus providing the GnRH-p62-OXPHOS(Ndufa2)-Ca2+/ATP-LH pathway in gonadotropic cells as a new theoretical basis for investigating female reproductive dysfunction.

Plasticity of Anterior Pituitary Gonadotrope Cells Facilitates the Pre-Ovulatory LH Surge.

Gonadotropes cells located in the anterior pituitary gland are critical for reproductive fitness. A rapid surge in the serum concentration of luteinizing hormone (LH) secreted by anterior pituitary gonadotropes is essential for stimulating ovulation and is thus required for a successful pregnancy. To meet the requirements to mount the LH surge, gonadotrope cells display plasticity at the cellular, molecular and morphological level. First, gonadotrope cells heighten their sensitivity to an increasing frequency of hypothalamic GnRH pulses by dynamically elevating the expression of the GnRH receptor (GnRHR). Following ligand binding, GnRH initiates highly organized intracellular signaling cascades that ultimately promote the synthesis of LH and the trafficking of LH vesicles to the cell periphery. Lastly, gonadotrope cells display morphological plasticity, where there is directed mobilization of cytoskeletal processes towards vascular elements to facilitate rapid LH secretion into peripheral circulation. This mini review discusses the functional and organizational plasticity in gonadotrope cells including changes in sensitivity to GnRH, composition of the GnRHR signaling platform within the plasma membrane, and changes in cellular morphology. Ultimately, multimodal plasticity changes elicited by gonadotropes are critical for the generation of the LH surge, which is required for ovulation.

Hormonal Characteristics of Androgen Status in Males of Different Age Groups

Males (n = 374) aged 20–69 years were divided into five age groups and examined: first group was aged 20–29 years; the second, 30–39 years; the third, 40–49 years; the fourth, 50–59 years; and the fifth, 60–69 years. The average content of total testosterone in the blood serum in all males was 16.1 ± 7 nmol/L. Hormonal traits of androgen deficiency, the frequency of which increased with age, were detected in males of the second group as compared with those of the first group. The frequency of androgen deficiency (total testosterone level <12.1 nmol/L) in the first group was 26.9%; it did not differ in the second, third, and fourth groups (30.6–33.9%). The frequency of androgen deficiency in the fifth group was 44%. The frequency of hormonal traits of hypogonadism (total testosterone level <8 nmol/L) did not differ significantly in groups 1–4 (6.2–9.3%) and increased only in the fifth group (28%). The age-related androgen deficiency was associated in males with a decrease in the androgen function of not only gonads but also adrenal glands, an increase in the level of sex steroid-binding globulin in the blood, and an increase in the metabolism of testosterone to estradiol, and it was accompanied by a compensatory increase in the synthesis of luteinizing hormone in the pituitary gland.

MiR-7 mediates the signaling pathway of NE affecting FSH and LH synthesis in pig pituitary.

MicroRNA-7 (miR-7) is an important modulator of a plenty of gene expressions and the interrelated biological processes, highly expressed in porcine pituitary. Norepinephrine (NE), acting as an important neurotransmitter or/and a hormone secreted excessively under stress, affects the synthesis and secretion of various hormones, including pituitary follicle-stimulating hormone (FSH) and luteinizing hormone (LH), which are the key hormones which regulate sexual maturation and reproductive functions. However, the relationship among NE, miR-7 and gonadotropin needs to be elucidated. The aim of this study was to identify whether miR-7 involved in the NE-adrenoceptor signaling pathway affects the synthesis and secretion of FSH and LH in porcine pituitary. Our results showed that the NE intracerebroventricular injection increased pituitary miR-7 level and the synthesis and secretion of FSH and LH in porcine, whereas the inhibition of either endogenous miR-7 or β-adrenergic receptors hindered the rise of FSH and LH synthesis induced by NE in cultured primary porcine anterior pituitary cells. Further, we identified the molecular type of β-adrenergic receptors and the signaling pathway in porcine pituitary, and we found that NE played its roles relying on adrenoceptor beta 2 (β2AR) and the RAF/MEK/ERK1/2 signaling pathway. The phosphorylation of ERK1/2 upregulated miR-7 level which subsequently enhanced FSH and LH synthesis by targeting to Golgi glycoprotein 1 (GLG1). These suggest that miR-7 mediates NE's effect on promoting FSH and LH synthesis in porcine pituitary.