Injection Of Luteinizing Hormone Research Articles

Injection of luteinizing hormone or human chorionic gonadotropin increases calcium excretion and serum PTH in males

Animal and human studies have suggested that sex steroids have calciotropic actions, and it has been proposed that follicle-stimulating hormone (FSH) may exert direct effects on bone. Here, we demonstrate the expression of the receptor for Luteinizing hormone (LH) and human choriogonadotropin (hCG), LHCGR, in human kidney tissue, suggesting a potential influence on calcium homeostasis. To investigate the role of LHCGR agonist on calcium homeostasis in vivo, we conducted studies in male mice and human subjects. Male mice were treated with luteinizing hormone (LH), and human extrapolation was achieved by injecting 5000 IU hCG once to healthy men or men with hypergonadotropic or hypogonadotropic hypogonadism. In mice, LH treatment significantly increased urinary calcium excretion and induced a secondary increase in serum parathyroid hormone (PTH). Similarly, hCG treatment in healthy men led to a significant increase in urinary calcium excretion, serum PTH levels, and 1,25 (OH)2D3, while calcitonin, and albumin levels were reduced, possibly to avoid development of persistent hypocalcemia. Still, the rapid initial decline in ionized calcium coincided with a significant prolongation of the cardiac QTc-interval that normalized over time. The observed effects may be attributed to LH/hCG-receptor (LHCGR) activation, considering the presence of LHCGR expression in human kidney tissue, and the increase in sex steroids occurred several hours after the changes in calcium homeostasis. Our translational study shed light on the intricate relationship between gonadotropins, sex hormones and calcium, suggesting that LHCGR may be influencing calcium homeostasis directly or indirectly.

Sex differences in luteinizing hormone aggravates Aβ deposition in APP/PS1 and Aβ1-42-induced mouse models of Alzheimer's disease

Alzheimer's disease (AD) exhibits a higher incidence rate among older women, and dysregulation of the hypothalamic-pituitary-gonadal (HPG) axis during aging is associated with cognitive impairments and the development of dementia. luteinizing hormone (LH) has an important role in CNS function, such as mediating neuronal pregnenolone production, and modulating neuronal plasticity and cognition. The sex differences in LH and its impact on Aβ deposition in AD individuals remain unclear, with no reported specific mechanisms. Here, we show through data mining that LH-related pathways are significantly enriched in female AD patients. Additionally, LH levels are elevated in female AD patients and exhibit a negative correlation with cognitive levels but a positive correlation with AD pathology levels, and females exhibit a greater extent of AD pathology, such as Aβ deposition. In vivo, we observed that the exogenous injection of LH exacerbated behavioral impairments induced by Aβ1-42 in mice. LH injection resulted in worsened neuronal damage and increased Aβ deposition. In SH-SY5Y cells, co-administration of LH with Aβ further exacerbated Aβ-induced neuronal damage. Furthermore, LH can dose-dependently decrease the levels of NEP and LHR proteins while increasing the expression of GFAP and IBA1 in vivo and in vitro. Taken together, these results indicate that LH can exacerbate cognitive impairment and neuronal damage in mice by increasing Aβ deposition. The potential mechanism may involve the reduction of NEP and LHR expression, along with the exacerbation of Aβ-induced inflammation.

The hypothalamic-pituitary-gonadal axis and thyroid hormone regulation interact to influence seasonal breeding in green anole lizards (Anolis carolinensis)

Reproductive physiology and behavior is mainly regulated by the hypothalamus-pituitary-gonad (HPG) axis, although abnormal thyroid hormone (TH) levels alter HPG axis activity. Seasonally breeding animals, such as green anole lizards (Anolis carolinensis), undergo drastic hormonal and behavioral changes between breeding and non-breeding seasons, with increased sex steroid hormones, larger gonads and increased reproductive behaviors during the breeding compared to non-breeding seasons. Relatively less is known regarding the regulation of gonadal TH in seasonal reproduction. We examined whether the gonadal expression of enzymes involved in TH activation are altered in concert with seasonal reproduction. Type 2 deiodinase (Dio2) mRNA, the TH activating enzyme, was upregulated in breeding compared to non-breeding testes, while type 3 deiodinase (Dio3) mRNA, the TH deactivating enzyme, was upregulated in breeding ovaries. To study the association between the HPG axis and local activation of TH, we manipulated the HPG axis during the non-breeding season by subcutaneously injecting luteinizing hormone (LH) and follicle stimulating hormone (FSH) in male lizards. We found that acute LH and FSH injections induced many aspects of breeding, with increased testes size and testosterone levels. Surprisingly, Dio3 was upregulated in the testes after LH and FSH injections, while Dio2 mRNA levels were unchanged. These results suggest that there might be different roles for local TH activation in developing and maintaining fully mature and functional gonads. Our findings continue to support the role for TH in regulating reproduction.

Follicle priming by FSH and pre-maturation culture to improve oocyte quality in vivo and in vitro

Nowadays there is strong demand to produce embryos from premium quality cattle, and we can produce embryos using oocytes collected from living premium animals by ovum-pick up (OPU) followed by in vitro fertilization (IVF). However, the developmental competence of IVF oocytes to form blastocysts is variable. The developmental competence of oocytes depends on the size and stages of follicles, and follicle-stimulating hormone priming (FSH-priming) prior to OPU can promote follicular growth and improve the developmental competence of oocytes. Furthermore, following the induction of ovulation using an injection of luteinizing hormone or gonadotropin-releasing hormone after FSH-priming, we can collect in vivo matured oocytes from ovulatory follicles, which show higher developmental competence than oocytes matured in vitro. However, the conventional protocols for FSH-priming consist of multiple FSH injection for 3–4 days, which is stressful for the animal and labor-intensive for the veterinarian. In addition, these techniques cannot be applied to IVF of oocytes collected from bovine ovaries derived from slaughterhouses, which are important sources of oocytes. Here, we review previous research focused on FSH-priming, especially for collecting in vivo matured oocytes and a simplified method for superstimulation using a single injection of FSH. We also introduce the previous achievements using in vitro pre-maturation culture, which can improve the developmental competence of oocytes derived from non-stimulated animals.

Identifying and Treating of Uterine Infection in Cows of Basrah city

The present study was conducted from December 2015 to February 2017 on a local breeds and Holstein Friesian with 88 cows (age 4-12). Metritis was diagnosed by clinical examinations using gloved hand and rectal uterine palpation as well as by bacteriological examinations using swabs. Antibiotic therapy was applied for the treatment of metritis in cow followed by one injection of luteinizing hormone. Examined cows were randomly divided into five groups. In group A (n=15), administration of oxytetracycline was used for one day. Group B (n = 18), received lugols iodine for one day. Group C (n = 22), received penicillin with streptomaycin for one day. Group D (n=7) received intramuscular administration of gentamycin for one day. Finally, group E (n=26) received safapirin for one day . All treatment followed by one injection of luteinizing hormone. Different type of bacteria was isolated from the cow uterus including Escherichia coli (40%), Proteus vulgaris (13.63%), Corynebacterium pyogenes (6.81%), Staphylococcus pyogenes (20.45%), Pseudomonas aeruginosa (5.68%), and Streptococcus spp.(7.95%). E. coli was frequently isolated from the cow uterus (40%). Safapirin and penicillin-streptomaycin were the most effective in treating metritis as they represented 84.61% and 81.81%, respectively. Lugols iodine and oxytetracycline, were also considerably effective in treating metritis as they represented 61.11% and 60.00%, whereas gentamycin intramuscularly accounted about 28.57%.

Identifying and Treating of Uterine Infection in Cows of Basrah city

The present study was conducted from December 2015 to February 2017 on a local breeds and Holstein Friesian with 88 cows (age 4-12). Metritis was diagnosed by clinical examinations using gloved hand and rectal uterine palpation as well as by bacteriological examinations using swabs. Antibiotic therapy was applied for the treatment of metritis in cow followed by one injection of luteinizing hormone. Examined cows were randomly divided into five groups. In group A (n=15), administration of oxytetracycline was used for one day. Group B (n = 18), received lugols iodine for one day. Group C (n = 22), received penicillin with streptomaycin for one day. Group D (n=7) received intramuscular administration of gentamycin for one day. Finally, group E (n=26) received safapirin for one day . All treatment followed by one injection of luteinizing hormone. Different type of bacteria was isolated from the cow uterus including Escherichia coli (40%), Proteus vulgaris (13.63%), Corynebacterium pyogenes (6.81%), Staphylococcus pyogenes (20.45%), Pseudomonas aeruginosa (5.68%), and Streptococcus spp.(7.95%). E. coli was frequently isolated from the cow uterus (40%). Safapirin and penicillin-streptomaycin were the most effective in treating metritis as they represented 84.61% and 81.81%, respectively. Lugols iodine and oxytetracycline, were also considerably effective in treating metritis as they represented 61.11% and 60.00%, whereas gentamycin intramuscularly accounted about 28.57%.

Cost-effectiveness analysis on the use of rFSH + rLH for the treatment of anovulation in hypogonadotropic hypogonadal women.

BackgroundHypogonadotropic hypogonadal women are characterized by ovarian functionality deficiency, caused by low concentrations of follicle-stimulating hormone (FSH) and luteinizing hormone (LH). To recover reproduction functionality, recommended therapies for ovarian induction involve injections of FSH and LH medications.ObjectiveSince important differences exist between recombinant and urinary gonadotropin therapies in terms of efficacy and cost, the objective of this study was to develop a cost-effectiveness model to compare recombinant FSH (rFSH) + recombinant LH (rLH) and highly purified human menopausal gonadotropin (HP-HMG).MethodsA Markov model was developed, considering three cycles of therapy; probability of pregnancy and miscarriage were considered, and the efficacy was evaluated in terms of pregnancy occurrence. The perspective of the model was that of the Italian Health Service, so only direct cost (drugs, specialist visits, patient examinations, and hospitalizations) were included.ResultsrFSH + rLH is associated with a higher total cost (€3,453.50) and higher efficacy (0.87) compared with HP-HMG (€2,719.70 and 0.50). rFSH + rLH generated an incremental cost effectiveness ratio equal to €2,007.30 compared to HP-HMG; the average cost per pregnancy is estimated to be €3,990.00 for recombinant strategy and €5,439.80 for urinary strategy. Results of probabilistic sensitivity analysis were consistent with the abovementioned findings.ConclusionDespite the higher acquisition cost in comparison to HP-HMG, rFSH + rLH resulted in a higher pregnancy rate, which makes it the recommended choice when considering cost-effectiveness of LH in supporting FSH-induced follicular gonadotropins in hypogonadotropic hypogonadal women.

Novel In Vivo Evidence That Not Only Androgens But Also Pituitary Gonadotropins and Prolactin Directly Stimulate Murine Bone Marrow Stem Cells – Implications For Potential Treatment Strategies In Aplastic Anemias

BackgroundHematopoietic stem/progenitor cells (HSPCs) are exposed in vivo to several growth factors, cytokines, chemokines, and bioactive lipids in bone marrow (BM) in addition to various sex hormones circulating in peripheral blood (PB). It is known that androgen hormones (e.g., danazol) is employed in the clinic to treat aplastic anemia patients. However, the exact mechanism of action of sex hormones secreted by the pituitary gland or gonads is not well understood. Therefore, we performed a complex series of experiments to address the influence of pregnant mare serum gonadotropin (PMSG), luteinizing hormone (LH), follicle-stimulating hormone (FSH), androgen (danazol) and prolactin (PRL) on murine hematopoiesis. In particular, from a mechanistic view we were interested in whether this effect depends on stimulation of BM-residing stem cells or is mediated through the BM microenvironment. Materials and MethodsTo address this issue, normal 2-month-old C57Bl6 mice were exposed or not to daily injections of PMSG (10 IU/mice/10 days), LH (5 IU/mice/10 days), FSH (5 IU/mice/10 days), danazol (4 mg/kg/10 days) and PRL (1 mg/day/5days). Subsequently, we evaluated changes in the BM number of Sca-1+Lin–CD45– that are precursors of long term repopulating hematopoietic stem cells (LT-HSCs) (Leukemia 2011;25:1278–1285) and bone forming mesenchymal stem cells (Stem Cell & Dev. 2013;22:622-30) and Sca-1+Lin–CD45+ hematopoietic stem/progenitor cells (HSPC) cells by FACS, the number of clonogenic progenitors from all hematopoietic lineages, and changes in peripheral blood (PB) counts. In some of the experiments, mice were exposed to bromodeoxyuridine (BrdU) to evaluate whether sex hormones affect stem cell cycling. By employing RT-PCR, we also evaluated the expression of cell-surface and intracellular receptors for hormones in purified populations of murine BM stem cells. In parallel, we studied whether stimulation by sex hormones activates major signaling pathways (MAPKp42/44 and AKT) in HSPCs and evaluated the effect of sex hormones on the clonogenic potential of murine CFU-Mix, BFU-E, CFU-GM, and CFU-Meg in vitro. We also sublethally irradiated mice and studied whether administration of sex hormones accelerates recovery of peripheral blood parameters. Finally, we determined the influence of sex hormones on the motility of stem cells in direct chemotaxis assays as well as in direct in vivo stem cell mobilization studies. ResultsWe found that 10-day administration of each of the sex hormones evaluated in this study directly stimulated expansion of HSPCs in BM, as measured by an increase in the number of these cells in BM (∼2–3x), and enhanced BrdU incorporation (the percentage of quiescent BrdU+Sca-1+Lin–CD45– cells increased from ∼2% to ∼15–35% and the percentage of BrdU+Sca-1+Lin–CD45+ cells increased from 24% to 43–58%, Figure 1). These increases paralleled an increase in the number of clonogenic progenitors in BM (∼2–3x). We also observed that murine Sca-1+Lin–CD45– and Sca-1+Lin–CD45+ cells express sex hormone receptors and respond by phosphorylation of MAPKp42/44 and AKT in response to exposure to PSMG, LH, FSH, danazol and PRL. We also observed that administration of sex hormones accelerated the recovery of PB cell counts in sublethally irradiated mice and slightly mobilized HSPCs into PB. Finally, in direct in vitro clonogenic experiments on purified murine SKL cells, we observed a stimulatory effect of sex hormones on clonogenic potential in the order: CFU-Mix > BFU-E > CFU-Meg > CFU-GM. ConclusionsOur data indicate for the first time that not only danazol but also several pituitary-secreted sex hormones directly stimulate the expansion of stem cells in BM. This effect seems to be direct, as precursors of LT-HSCs and HSPCs express all the receptors for these hormones and respond to stimulation by phosphorylation of intracellular pathways involved in cell proliferation. These hormones also directly stimulated in vitro proliferation of purified HSPCs. In conclusion, our studies support the possibility that not only danazol but also several other upstream pituitary sex hormones could be employed to treat aplastic disorders and irradiation syndromes. Further dose- and time-optimizing mouse studies and studies with human cells are in progress in our laboratories.▪ Disclosures:No relevant conflicts of interest to declare.

Dynamic testosterone responses to near-physiological LH pulses are determined by the time pattern of prior intravenous LH infusion

The long-lived glycoprotein hormone, human chorionic gonadotropin (hCG), downregulates testosterone (T) biosynthesis in vitro and in vivo in animals and humans. The degree to which short-lived pulses of pituitary luteinizing hormone (LH) do so, particularly at physiological concentrations, is not known. We test the hypothesis that continuous LH infusion compared with bolus injections of LH every 1 h or every 2 h overnight downregulates T secretory responses to a subsequent fixed template of three consecutive intravenous pulses of a physiological amount of recombinant human (rh) LH (triple stimulus). Nineteen healthy men ages 18-49 yr each underwent four separate randomly ordered overnight gonadotropin-releasing hormone-receptor antagonist treatments with superimposed intravenous infusions of saline or rhLH (1-h pulses, 2-h pulses, or continuously). Each 12-h infusion protocol was followed by the triple rhLH-pulse stimulus the next morning. During the triple stimulus, basal (nonpulsatile) as well as total (basal plus pulsatile) T secretion was higher after overnight 2- and 1-h rhLH pulses than after continuous rhLH or saline delivery. Approximate entropy, a probabilistic measure of feedforward-induced irregularity of T concentration time series, was higher after 1-h rhLH pulses than after continuous rhLH. Analytical estimation of pulsatile rhLH-T dose-response measures revealed higher T secretory sensitivity and greater rhLH potency (lower EC₅₀) after exposure to 1-h than 2-h rhLH pulses. Collectively, these data indicate that in vivo dynamics of LH-stimulated T secretion under standardized conditions in men depend on the prior time mode of LH delivery in the bloodstream.

SPERMATOZOAL VELOCITY AND MOTILITYAND ITS RELATIONSHIP TO FERTILITY IN THE RABBIT INSEMINATED WITH LOW SPERM NUMBERS

The objective of this study was to examine the relationship between velocity and fertility of rabbit sperm, using low sperm numbers per insemination. Semen was collected weekly for 5 weeks from two fertile males. To study the effect of high dilution of sperm in media without macromolecules, each semen sample was split with one portion retained as whole semen, and the remainder was centrifuged and washed with saline. The washed sperm were resuspended with seminal plasma (SP), phosphate­buffered saline (PBS), or PBS containing 1 % (wt/vol) of bovine serum albumin (BSA). Each week two non-lactating does per buck were each inseminated at the cervix with 0.5 X 106 total sperm, for a total of 80 does inseminated. This was followed immediately with injection of luteinizing hormone. Sperm were video taped at this time. The velocity of 25 sperm from each semen sample was determined by each of two observers (50 sperm total). The two observers also estimated the percentage of motile sperm. Fertilized and unfertilized oocytes (1635 total) were recovered from the oviducts 42 hours after insemination. Both the percentage of motile sperm and their velocity were greatly affected by the washing and diluting fluid used. The ranges for these two variables, respectively, were 1 to 50% and 11 to 100 Fm/second. The percentage of motile sperm and velocity were highly correlated (P<0.05) in the different treatments (BSA=0. 77; SP=0.59; PBS=0.81; WS=0.86). Fertility ranged from 42 to 85%. Velocity was not more useful than the percentage of motile sperm in predicting fertility. The importance of including macromolecules in the diluting fluids to maintain motility of highly diluted sperm was obvious from the five-fold or greater improvement in motility and velocity of sperm by adding BSA. Good fertility was obtained with low sperm numbers inseminated on the cervix in media containing macromolecules, even following extensive washing and storage.

Effect of dose of equine chorionic gonadotrophin on the estrus responses of gilts and weaned sows and effect of the interval between equine chorionic gonadotrophin and luteinizing hormone injections on sow performance

Objectives: To determine estrus and ovulation responses of gilts and sows to different doses of equine chorionic gonadotrophin (eCG), with different intervals between eCG and luteinizing hormone (pLH) injections. Materials and methods: Experiment One: gilts received 0 (Control; n = 20), 600 (n = 42), or 900 (n = 42) IU eCG, then were exposed to a boar daily for estrus detection. Experiment Two: weaned primiparous sows received 600 (n = 56) or 900 (n = 59) IU eCG, 2.5 mg pLH 80 hours later, and a single insemination 36 hours after pLH. Controls (n = 43) received no hormones and were inseminated at estrus detection and 24 hours later. Experiment Three: weaned mixed-parity sows received 600 IU eCG at weaning and 2.5 mg pLH 72 (n = 107) or 80 hours (n = 116) later, or served as Controls (n = 66). Sows were inseminated as for Experiment Two. Results: Experiment One: rate of ovulation was greater at the higher eCG dose (P &lt; .05). Experiment Two: sows receiving 900 IU eCG had a higher farrowing rate than controls (P = .03), with sows receiving 600 IU eCG being intermediate. Litter sizes were unaffected. Experiment Three: farrowing rates were higher for the eCG treatment than for Controls (P &lt; .05). Litter sizes were unaffected. Implications: These data suggest that the dose of eCG should be 900 IU for induction of estrus in young females. For controlled ovulation, the eCG-pLH interval can be reduced to 72 hours without affecting reproduction.

Inhibin A Production after Gonadotropin Stimulus: A New Method to Detect Ovarian Tissue in Ovotesticular Disorder of Sex Development

Background/Aims: While laboratory methods for the detection of testicular tissue are well standardized, currently there is no available test to demonstrate the presence of ovarian tissue. We evaluated the effectiveness of gonadal stimulation with luteinizing hormone (LH)/follicle-stimulating hormone (FSH) for the detection of ovarian tissue in patients with disorders of sex development (DSD). Methods: Ten patients with congenital adrenal hyperplasia (CAH) as ovarian-positive controls, 10 with cryptorchidism (ovarian-negative controls), 13 patients with DSD of no defined etiology and 7 patients with ovotesticular DSD (true hermaphroditism, TH) were included in the study. They underwent a daily injection of both LH and FSH on 3 consecutive days. LH, FSH, estradiol, testosterone and inhibin A were measured before treatment, 24 h after the 1st dose and 24 h after the 3rd dose. Results: Estradiol increased in all CAH and TH patients, with a median value of 155.1 and 92.6 pg/ml, respectively, after the 3rd injection. Inhibin A also increased in all CAH and TH patients, with a median value of 70.4 and 32.2 pg/ml, respectively, after the 3rd injection. There was no change in these hormones in the other groups. Conclusion: The LH/FSH stimulation test might be a useful method to detect the presence of ovarian tissue.

Suppression of fetal testicular cytochrome P450 17 by maternal exposure to 2,3,7,8-tetrachlorodibenzo- p-dioxin: A mechanism involving an initial effect on gonadotropin synthesis in the pituitary

The effect of 2,3,7,8-tetrachlorodibenzo- p-dioxin (TCDD) on the fetal expression of testicular cytochrome P450 17 (CYP17), one of the enzymes necessary for sex steroid synthesis, was studied in Wistar rats. Fetal testicular CYP17 exhibited reduced mRNA and protein levels following exposure of the dams at gestational day 15 to 1 μg/kg TCDD. In support of this, CYP17 activity catalyzed by fetal testis homogenate was also reduced by maternal exposure to TCDD. The reduction in CYP17 expression seemed to be specific for fetal stages, because 7 day-old pups born from TCDD-treated dams did not exhibit any reduction in CYP17. In sharp contrast to the in vivo observations, TCDD failed to reduce CYP17 expression in cultured fetal testis, although CYP17 could be induced by activating cAMP-dependent signaling. To assess the role of pituitary luteinizing hormone (LH) on TCDD-induced reduction in fetal testicular CYP17, a further investigation was performed to examine whether the direct injection of LH into fetuses restores the altered CYP17 expression. The results showed that in utero injection of equine chorionic gonadotropin, an LH-mimicking hormone, completely abolishes the TCDD-produced reduction in fetal CYP17. However, neither the α- nor β-subunits of LH in cultured fetal pituitary was reduced by TCDD. These results suggest that 1) maternal exposure to TCDD impairs the expression of testicular CYP17 in a fetal stage-specific manner; 2) this effect is due, at least partially, to a TCDD-produced reduction in circulating LH; and 3) TCDD exerts such an effect by affecting the upstream mechanism regulating the pituitary synthesis of LH.

The effects of equine somatotropin on pituitary and testicular function in the stallion during the nonbreeding season

An experiment was conducted to determine the effects of equine somatotropin on the reproductive axis of the stallion during the nonbreeding season. Adult stallions were treated with equine somatotropin (20 μg/kg body weight [BW]; n = 5) or saline (n = 4) daily for 21 days starting in January. During the last week of treatment, stallions were subjected to low- and high-dose injections of luteinizing hormone (LH), as well as low- and high-dose injections of gonadotropin-releasing hormone (GnRH) and thyrotropin-releasing hormone (TRH). Two months after the onset of somatotropin treatment, semen was collected from all stallions every other day for 14 days. Treatment with equine somatotropin increased ( P < .001) daily IGF-1 concentrations but had no effect ( P > .1) on concentrations of LH, follicle-stimulating hormone (FSH), or testosterone. The testosterone responses to injections of LH were similar ( P > .1) between treatments. Likewise, the LH, FSH, prolactin, and testosterone responses to the injections of GnRH/TRH were similar ( P > .1) between groups. At seminal collections, stallions treated with somatotropin exhibited greater volumes of gel-free semen ( P < .01) and gel ( P < .05) and had decreased time until ejaculation ( P < .05). In conclusion, somatotropin treatment for 21 days may alter the long-term accessory gland contribution to seminal volume but does not appear to alter pituitary gonadotrope function or testicular testosterone secretion.

Luteinizing hormone depletes ascorbic acid in preovulatory follicles

Objective: The objective of the present studies was to determine whether luteinizing hormone (LH) depletes ascorbic acid in the preovulatory follicle. Design: Controlled, prospective experimental study. Setting: University-based research center. Animal(s): Sprague-Dawley female rats. Intervention(s): Follicular growth and ovulation were induced in immature rats by gonadotropin treatment. Main Outcome Measure(s): Analysis of ovary, follicle, and oocyte levels of ascorbic acid by colorimetric analysis and high-pressure liquid chromatography. Result(s) : Ovarian ascorbic acid was maximally depleted (50%) within 2 h of LH treatment and was sustained for 8 h. Follicle ascorbic acid levels were unchanged 1 h after LH injection but were significantly reduced within 2 h (40%). Incubation of isolated preovulatory follicles for 3 h with hCG or with menadione (a generator of oxygen radicals) reduced ascorbic acid levels. Isolation of cumulus-enclosed or denuded oocytes depleted ascorbic acid to undetectable levels, but follicular ascorbic acid levels were only moderately depleted by isolation and incubation. Accumulation of ascorbic acid by oocytes was significantly enhanced by the presence of intact cumulus cells. Conclusion(s): Elevation of LH and the production of oxygen radicals deplete ascorbic acid in the preovulatory follicle.

Le rôle de l’hormone lutéinisante dans la physiologie du follicule et du corps jaune

Luteinizing hormone (LH) is an hypophyseal glycoprotein involved in both follicular maturation and corpus luteum function. During the follicular phase, effects of LH must be considered according to the stages of follicular development: in the early follicular phase, LH acts through specific receptors, constitutively present on thecal cells, for stimulating androgen production. Androgens seem to be positively involved in the folliculogenesis in primates. Indeed, a positive correlation has been recently established between androgen receptor expression and follicular cell proliferation. Furthermore, androgens are active through a conversion to estrogens in granulosa cells. Estrogens are needed for achieving pregnancy. Thus, a question remains: what in the minimal amount of endogenous LH required for an optimal production of oestradiol? Several models have been investigated in clinical situations with hypogonadotrophic hypogonadism: WHO type I anovulation or GnRH analog-induced hypogonadisms. A large majority of these studies conclude that the minimal amount of LH needed during the follicular phase is probably low (<1.5 IU/L of plasma LH level). Recent availability of GnRH antagonist will give a new opportunity for evaluating this minimal LH threshold. During the late follicular phase, LH plays a biphasic role, with a positive effect on steroidogenesis but a negative effect on cell proliferation. As suggested by S. Hillier, this negative effect on cell proliferation may be relevant to control the rate of follicular growth. One study, performed in WHO type I anovulatory patients, seems to confirm this assumption but further evaluation is needed to give support to this concept. Finally, LH is also involved in corpus luteum function. Due to the short half-life of LH as compared to hCG, the role of LH must be evaluted according to the adjunct therapies. For example, following a long-term GnRH agonist administration that constantly induces a profound hypophyseal desensitization, LH administration must be repeated to adequately sustain the corpus luteum function. This conclusion must be reconsidered with the recent introduction of GnRH antagonists. Indeed, according to their short-term effects on LH secretion, it may be presumed that a single injection of LH may be effective to maintain an adequate corpus luteum function.

Effect of luteinizing hormone on follicle stimulating hormone-activated paracrine signalling in rat ovary.

'Pure' follicle stimulating hormone (FSH) and luteinizing hormone (LH) are expected shortly to become available for pharmaceutical use in the clinical setting. To test the contribution of LH to optimal ovarian responsiveness to FSH, 21-day-old hypophysectomized, immature, female rats received four s.c. injections of recombinant human LH (rhLH; total dose 1-10 IU) and/or rhFSH (total dose 30-72 IU) given at 12-hourly intervals. At 48 h after the first injection, ovaries were removed, weighed and used to isolate granulosa and thecal/interstitial cells for assessment of basal and gonadotrophin-responsive steroidogenesis in vitro, or homogenized to extract total RNA for Northern analysis of 17-hydroxylase/C17-20-lyase (cytochrome P-450c17 alpha) mRNA. Serum oestradiol and uterine weight were measured as indices of ovarian oestrogen production; androstenedione was measured to reflect ovarian androgen production. Consistent with the two-cell, two-gonadotrophin model of oestrogen synthesis, increased ovarian oestrogen secretion only occurred if both rhFSH and rhLH were given simultaneously. Treatment with rhFSH alone stimulated ovarian weight gain and granulosa cell aromatase activity without oestrogen secretion, whereas rhLH alone stimulated thecal androgen synthesis and androgen secretion. When the total rhLH dose was fixed at 1 IU, giving rise to an unmeasurably low serum concentration of rhLH, additional treatment with rhFSH (30-72 IU) dose-dependently stimulated serum androgen concentrations as well as oestrogen concentrations. The approximately 2.0 kb-sized P-450c17 alpha mRNA transcript was undetectable in the ovaries of untreated control animals but was abundant in the ovaries of positive controls treated with 15 IU of pregnant mare serum gonadotrophin.(ABSTRACT TRUNCATED AT 250 WORDS)

Number and state of rat ovarian mast cells after exogenous administration of luteinizing hormone

Diestrous rats were treated with an injection of luteinizing hormone (LH), and their ovaries were examined for mast cell number and stage of degranulation at 2 and 4 hr post-injection. LH tripled the number of medullary mast cells at 2 hr. The source or origin of the additional mast cells is unknown. Comparison of the present results with other studies of rat ovarian mast cell dynamics suggests the occurrence of a reduction in mast cell number in early to mid-proestrus followed by an LH-induced increase in late proestrus.

Secretion of pregnane compounds from follicular and luteal ovaries in rats.

Differences during the follicular and luteal phases in the secretion of pregnane compounds by rat ovaries were studied. Daily s.c. injections of 2 mg of progesterone that began at early diestrus prolonged the diestrus stage for the duration of the treatment. In the follicular phase, normal proestrus and proestrus delayed by progesterone treatment were examined. In the luteal phase, day 6 of pseudopregnancy was examined. 20 alpha-hydroxy-4-pregnen-3-one accounted for most of total amount of pregnane compounds secreted from ovaries in the follicular phase, and progesterone and 20 alpha-hydroxy-4-pregnen-3-one for most at the luteal phase. The levels of 5 alpha-pregnane compounds were low in both phases. Injection of 2 micrograms of luteinizing hormone (LH) before sample collection increased the secretion of progesterone in the follicular phase, but not in the luteal phase. The secretion of 5 alpha-pregnane-3,20-dione and 3 alpha-hydroxy-5 alpha-pregnan-20-one was increased by the injection of LH in either phase, but the ability of the ovaries to produce these steroids was low, suggesting that there was low 5 alpha-reductase activity in the ovaries of rats with delayed proestrus and pseudopregnant rats.

Ovarian 3'5'-cyclic adenosine monophosphate and prostaglandins: a sequential comparison of gonadotropin-stimulated events in small and large ovine follicles.

Luteinizing hormone (LH) stimulates a cascade of ovarian hormonal events that culminate in ovulation. This study was designed to investigate, in sheep, sequential changes in prostaglandin (PG) E2, PGF2 alpha, 6-keto-PGF1 alpha, and cyclic adenosine monophosphate (cAMP) in the theca, granulosa and follicular fluid of large preovulatory follicles and small nonovulatory follicles in response to LH. On d 15 postestrus, preovulatory or nonovulatory follicles were injected intrafollicularly with saline or LH. Ewes were then ovariectomized at 0, 2, 4, or 8 h postinjection. Injected follicles were excised; theca, granulosa and fluid were separated, weighed and assayed for cAMP and PG. Contents of cAMP in the theca, granulosa and fluid of preovulatory follicles increased (P less than .01) 2 to 4 h after injection of LH. Increases (P less than .05) in contents of PGE2 and PGF2 alpha in the theca and fluid of preovulatory follicles were observed between 4 and 8 h after injection of LH. The time courses of LH-induced synthesis of PGE2 and PGF2 alpha in preovulatory follicles were parallel. Luteinizing hormone had no effect on PGE2, PGF2 alpha or cAMP in any compartment of small follicles. Contents of 6-keto-PGF1 alpha varied with time in both theca and granulosa of large and small, saline- and LH-injected follicles. Although specific increases in cAMP and PG followed an injection of LH only in large follicles, the parallel temporal relationship of PGE2 and PGF2 alpha did not explain the dichotomous functions ascribed to PGE2 and PGF2 alpha during the periovulatory period.