Low LH Levels Research Articles

Expression and bioactivity of a single chain recombinant equine luteinizing hormone (reLH)

To study structure–activity relationships and the role of equine gonadotropins in the normal and pathophysiology of equine reproduction, the availability of purified hormones is essential. Previous expression studies in transfected CHO cells showed inefficient assembly of the human and bovine α and β subunits, resulting in low levels of recombinant LH. The ability to express a single chain bearing genetically linked α and β subunits bypasses this rate-limiting assembly step. A chimera was constructed by overlap PCR in which the carboxy terminal end of the eLHβ subunit was genetically fused to the amino end of the α subunit. This gene was transfected into CHO cells and the recombinant product was purified through multiple steps, including a Fractogel resin separation. Serial dilutions of pituitary derived native eLH and the single chain reLH were compared in an eLH radioimmunoassay (RIA); the concentration curves between the single chain recombinant eLH and the native eLH standard were parallel. The biological activity of the analog was determined in vitro and in vivo using homologous equine models. Testicular tissue from five colts was processed for Leydig cell cultures. Increasing doses of reLH were incubated with equine Leydig cells for 24 h in vitro and testosterone production was determined by RIA. Recombinant eLH stimulated a greater than 15-fold increase in testosterone production in a dose-dependent manner. Quarter Horse breeding stallions were treated with either reLH ( n = 5) or saline ( n = 3) and plasma testosterone concentrations were measured by RIA. Recombinant eLH stimulated a four-fold increase in circulating testosterone concentrations compared to the saline control. Therefore, the single chain recombinant will be effective for a variety of structure–function analyses and for breeding management in the horse.

A relative reduction in mid-follicular LH concentrations during GnRH agonist IVF/ICSI cycles leads to lower live birth rates

The effect of early- and mid-follicular LH concentrations on the ovarian response and pregnancy outcomes was evaluated in women receiving pituitary down-regulation with a GnRH agonist and ovarian stimulation with recombinant FSH (rFSH) during IVF/ICSI treatment. Blood samples were collected prospectively from 701 cycles (560 patients) of assisted reproduction and analysed retrospectively. On the basis of LH concentrations on stimulation day 7/8, the patients were divided into two groups: LH<1.2 IU/l (n=179) and LH>or=1.2 IU/l (n=522). Cycle outcomes were also compared on the basis of a ratio of mid- to early-follicular LH concentrations (<or=0.5, n=210; >0.5, n=491). Patients with low LH concentrations were found to have a significant reduction in the late-follicular estradiol concentrations (P<0.001), the number of oocytes retrieved (P<0.01) and the number of usable embryos (P<0.01), and they required significantly more rFSH (430 IU difference, P<0.01). These differences did not translate into a significant change in live birth rates. Conversely, a ratio of <or=0.5 mid- to early-follicular LH concentrations (a reduction of >or=50%) was associated with a significant reduction in live birth rates per embryo transfer and per cycle started (27.3 versus 19.0%, P<0.05 and 22.2 versus 15.8%, P<0.05, respectively). Low mid-follicular levels of LH have a significant impact on ovarian response but not on live birth rates. A fall in LH level of >or=50% from the early- to mid-follicular phase resulted in a lower live birth rate.

Follow-up study of two sisters with type A syndrome of severe insulin resistance gives a new insight into PCOS pathogenesis in relation to puberty and pregnancy outcome: a case report

We report two sisters with profound insulin resistance associated with a novel heterozygous missense mutation in exon 19 (His1130Arg) of the insulin receptor gene. The eldest was seen after puberty at age 15 and she presented a severe form of polycystic ovary syndrome (PCOS) with biological hyperandrogenism (HA) mimicking a virilizing tumour. However, she has been able to ovulate under clomiphene citrate (CC) and to achieve two uneventful pregnancies. The patient had no glucose tolerance abnormality during pregnancies. The outcome of pregnancy was good except for a low birthweight. The youngest sister was seen earlier in life (at age 11) before puberty. First, she developed polycystic ovaries (PCO), seen under ultrasound scan, and later also developed full PCOS. This second finding gave us the opportunity to observe that PCO developed before and at the beginning of puberty despite low LH levels. We postulate that the development of PCO was the consequence of an LH-independent intra-ovarian HA likely induced by the severe hyperinsulinism in the context of genetic abnormalities.

To add or not to add LH: comments on a recent commentary

From a period of time when LH activity supplementation in stimulation protocols for assisted reproductive technology was questioned, recent scientific evidence seems to prove a role of LH activity in optimizing the clinical results of certain subgroups. Until now, apart from the hypogonadotrophic hypogonadal patient, two subgroups of patients have attracted attention: patients over 35 years of age, and normogonadotrophic patients with an initial low response to recombinant FSH (rFSH). However, in a recent paper, another subgroup of patients has been identified: normogonadotrophic patients with high endogenous LH levels (>1.99 IU/l) on day 8 of stimulation after a long GnRH agonist down-regulation. By adding recombinant LH (rLH) from day 8 to the stimulation protocol, this subgroup of patients achieved good implantation rates, similar to those of patients with lower LH levels. Interestingly, the dynamics of the endogenous LH levels during down-regulation in this group of patients differed from those of patients with lower LH levels. The immunoreactivity of the LH molecule does not necessarily reflect the bioactivity, which might explain the beneficial effect of LH activity supplementation in patients with high endogenous LH levels after down-regulation. Future studies should be focused on subgroups to further explore the effect of LH activity supplementation in assisted reproduction techniques.

Are endogenous LH levels during ovarian stimulation for IVF using GnRH analogues associated with the probability of ongoing pregnancy? A systematic review

The aim of this systematic review was to evaluate, among women with normal ovulation or World Health Organization (WHO) II oligoanovulation who undergo ovarian stimulation for IVF using GnRH analogues, whether endogenous LH levels predict the likelihood of ongoing pregnancy beyond 12 weeks. A literature search identified six studies that answered the research question, among which two were prospective studies (one in GnRH agonist and one in GnRH antagonist cycles). None of the retrospective studies suggest that low endogenous LH levels are associated with a significantly decreased probability of ongoing pregnancy beyond 12 weeks in such patients. In the two prospective studies high endogenous LH levels during down-regulation were associated with a decreased probability of ongoing pregnancy beyond 12 weeks. Until further prospective studies modify the existing evidence summarized here, an adverse effect of low endogenous LH levels on the probability of ongoing pregnancy beyond 12 weeks is not a sensible rationale for LH supplementation during ovarian stimulation for IVF using GnRH analogues.

Differential effects of morphine and naltrexone on the in vitro LH secretion from male and female carp pituitary gland

The in vitro effects of morphine (10 − 10 , 10 − 8 , 10 − 6 or 10 − 5 M) or/and naltrexone (10 − 6 or 10 − 8 M) on LH release from male and female carp ( Cyprinus carpio L.) dispersed pituitary cells (obtained from fish at the time of late gonad recrudescence) were investigated. Morphine alone at the lowest tested concentration (10 − 10 M) increased LH secretion from the cells of males. On the contrary, in female cell incubations the highest concentrations of morphine (10 − 6 or 10 − 5 M) significantly lowered LH levels. Naltrexone alone (at both tested concentrations) had no influence on LH secretion, neither in males nor in females. However in the incubations of female cells it antagonised the influence of morphine at 10 − 10 or 10 − 8 M. In male cell incubations naltrexone abolished the stimulatory action of morphine at 10 − 10 M. The results suggest that in the in vitro culture of carp pituitary cells LH secretion is modulated by the opioids which affect the release of this gonadotropin through the typical opioid receptors and that the μ type of these receptors is involved in this process. The effects of opioid agonist and antagonist depend on the stage of gonadal maturity and the sex of fish i.e. the actual level of sex steroids.

IVF/ICSI outcome and serum LH concentration on day 1 of ovarian stimulation with recombinant FSH under pituitary suppression

Down-regulation with GnRH agonist has been suggested to result in a profound suppression of LH bioactivity, reduced estradiol synthesis, and thus impaired IVF and pregnancy outcome. The aims of this study were: (i) to assess the usefulness of serum LH measurement on stimulation day 1 as a predictor of ovarian response, conception and pregnancy outcome in patients treated with long-term down-regulation with GnRH agonist and recombinant FSH, and (ii) to define the best threshold LH value, if any, to discriminate between women with different outcomes of IVF. Records of 2625 cycles in 1652 infertile women undergoing IVF (n = 1856) and/or ICSI (n = 769) treatment were reviewed. The range of LH concentrations on stimulation day 1 overlapped among non-conception cycles, conception cycles, ongoing pregnancies and early pregnancy losses. Receiver operating characteristic (ROC) analysis showed that serum LH concentrations on stimulation day 1 were unable to discriminate between conception and non-conception cycles (AUC(ROC) = 0.51; 95% CI: 0.49-0.54) or ongoing pregnancies versus early pregnancy loss groups (AUC(ROC) = 0.52; 95% CI: 0.47-0.57). Stratification for various low serum levels of LH did not reveal significant differences with respect to conception or pregnancy outcome among different LH levels on stimulation day 1. Serum LH concentration on stimulation day 1 cannot predict ovarian response, conception and pregnancy outcome in women receiving long-term down-regulation during assisted reproduction treatment.

The Impact of Low Luteinizing Hormone Levels on Implantation and Pregnancy Rates in IVF-ET Cycles Using Recombinant FSH and Ganirelix Acetate®

Background and Significance: GnRH antagonists prevent premature luteinization by causing a rapid inhibition of endogenous LH. Low levels of LH may have a negative impact on follicular growth and oocyte development. Recent evidence suggests that GnRH antagonist cycles supplemented with hCG or recombinant LH provide comparable or improved pregnancy rates compared to r-FSH alone.

Hypogonadism in Hereditary Hemochromatosis

Hypogonadism, usually hypogonadotropic in origin, is the most common nondiabetic endocrinopathy in hereditary hemochromatosis (HH). Early studies, usually evaluating small numbers of patients with advanced HH, report prevalence rates of 10-100%. The clinical presentation of HH has changed in recent years as a result of increased awareness and screening. We assessed the prevalence of hypogonadism in a large group of patients with HH diagnosed in a single center over the past 20 yr, the period of follow-up spanning the time before and after widespread screening was introduced and the HFE gene was recognized. Abnormally low plasma testosterone levels, with low LH and FSH levels, were found in nine of 141 (6.4%) male patients tested. Eight of nine (89%) had associated hepatic cirrhosis; three of nine (33%) had diabetes. Inappropriately low LH and FSH levels were found in two of 38 females (5.2%) in whom the pituitary-gonadal axis could be assessed. This is the largest detailed study of hypogonadism reported in HH. The lower prevalence of hypogonadism compared with other reported series reflects the earlier diagnosis of HH in an unselected group of patients attending a single center. Patients with lesser degrees of hepatic siderosis at diagnosis are unlikely to develop hypogonadism.

New insights in the genetics of isolated hypogonadotropic hypogonadism

Isolated gonadotropic deficiency or isolated hypogonadotropic hypogonadism is defined as a low sexual hormone secretion by the gonads associated with low LH and FSH plasma levels. Kallmann syndrome is defined as a congenital isolated gonadotropic deficiency associated with anosmia whereas the phenotype of the idiopathic form is limited to the gonadotropic axis. For several years, it has been known that mutations of the KAL-1 gene or loss-of-function mutations of GnRH receptor did not explain all familial cases of isolated gonadotropic deficiency with or without anosmia. Thus the existence of other genes playing a major role in the physiology of the gonadotropic axis was highly suggested. In 2003, fibroblast growth factor receptor 1 (FGFR1) and GPR54 were shown to be two of these genes. FGFR1 loss-of-function mutations were reported in Kallmann syndrome whereas inactivating mutations of GPR54 were described in the idiopathic form of the gonadotropic deficiency. These genetic studies have opened up a new chapter in the physiology and the pharmacology of the gonadotropic axis.

Eating disorders from a gynecologic and endocrinologic view: hormonal changes

Infertile women with clinical and subclinical bulimia nervosa have pathologically low FSH and LH levels, suggesting that improper nutrition has an important role in hormonal dysfunction.

Testosterone replacement therapy.

SUMMARY Testosterone is the primary androgenic hormone and is responsible for normal growth and development of male sex organs and maintenance of secondary sex characteristics. Pre-pubertal hypogonadism is generally characterized by infantile genitalia and lack of virilization, while the development of hypogonadism after puberty frequently results in complaints such as diminished libido, erectile dysfunction, infertility, gynecomastia, impaired masculinization, changes in body composition, reductions in body and facial hair, and osteoporosis. Hypogonadal men also report levels of anger, confusion, depression, and fatigue that are significantly higher than those reported in eugonadal men. Evaluation of potential candidates for testosterone replacement therapy should include a complete medical history and hormonal screening. Total serum testosterone should be measured in the morning. When the serum testosterone level is low and LH is elevated, testosterone replacement therapy is warranted. Patients with low serum LH and testosterone levels need an imaging study of their pituitary and may need endocrinologic consultation. Testosterone replacement should in theory approximate natural, endogenous production of the hormone. The clinical rationale for treatment of testosterone deficiency may include: stabilizing or increasing bone density; enhancing body composition by increasing muscle strength and reducing adipose tissue; improving energy and mood; and maintaining or restoring secondary sexual characteristics, libido, and erectile function. Several different types of testosterone replacement are currently marketed, including tablets, injectables, and transdermal systems. Oral testosterone is associated with elevations in liver function tests and abnormalities at liver scan and biopsy. While injectable testosterone is considered safe, fluctuations in testosterone levels may yield variations in libido, sexual function, energy, and mood, and patients may be inconvenienced by the need for frequent testosterone injections. Transdermal systems offer a convenient, though more costly, means of testosterone replacement and have demonstrated safety and efficacy in a number of clinical trials. The physician prescribing testosterone replacement should evaluate any changes in the clinical symptoms and signs of testosterone deficiency and should assess the patient by performing a DRE and checking serum testosterone levels, PSA, and hematocrit at baseline and at prescribed intervals during treatment. Although testosterone replacement is contraindicated in men with carcinoma of the breast or known or suspected carcinoma of the prostate, in general, therapy appears to be safe for the vast majority of hypogonadal men. There is no apparent association between testosterone replacement therapy and the development of prostate cancer. The administration of exogenous testosterone is not a means of reversing the aging process in men with normal testosterone levels, but it may offer considerable benefit for men suffering from hypogonadism.

High dose of rec-LH overcomes the deleterious effect of high dose GnRH antagonist on embryonic implantation

High dose of rec-LH overcomes the deleterious effect of high dose GnRH antagonist on embryonic implantation

Effect of human chorionic gonadotropin on luteal luteinizing hormone concentrations in natural cycles

Effect of human chorionic gonadotropin on luteal luteinizing hormone concentrations in natural cycles

Profound luteinizing hormone suppression induces a deleterious follicular environment during assisted reproduction technology

The exact amount of LH that is required for optimal follicular and oocyte maturation in women undergoing assisted reproduction technology cycles has been the object of debate. A recent study (1) suggested that the mechanism underlying the detrimental effect of low endogenous LH levels could be explained by reduction of the intrafollicular androgen substrate for E2 synthesis, which is suboptimal for oocyte maturation during the follicular phase. However, further studies are needed for a more accurate explanation of the deleterious follicular environment.

Performance of male pigs immunized against GnRH is related to the time of onset of biological response.

In this study, the performance of male pigs immunized against GnRH was determined in relation to the onset of their biological response to the immunization. Pigs were immunized at 9 and 17 wk of age and were housed in a pen together with both a surgically castrated and an intact boar littermate. Feed intake was restricted to 2.8 to 3.2 times maintenance requirement for energy. Animals were weighed weekly and slaughtered at 108 kg BW. Depending on the time of onset of the response after immunization in terms of biological effects, immunized pigs were retrospectively grouped into two categories. One category consisted of the immunized pigs, which had undetectable or low levels of LH and testosterone at the time of booster immunization-known as "early" responding immunocastrates (E-IM, n = 8), whereas the "late" responding immunocastrates (L-IM, n = 7) had substantial LH and testosterone levels at that time. This dichotomy of the response to immunization also was reflected in testis weight, with 17 g and 40 g for E-IM and L-IM pigs, respectively. At slaughter, testis size and weight were reduced (P < 0.001) in the immunocastrated pigs as compared to the intact boars. Androstenone concentrations in backfat of all immunocastrated pigs were undetectable. Growth performance (i.e., ADG and feed efficiency [FE, g gain/kg feed]), was better in boars and L-IM pigs than in surgical castrates and E-IM pigs (P < 0.05). Average daily gain and FE did not differ between E-IM pigs and the surgical castrates, but intact boars performed better than L-IM (P < 0.02). There were no significant differences in carcass quality (backfat thickness and meat percentage) between boars and surgical castrates at slaughter. However, for both characteristics L-IM pigs and intact boars performed better (P < 0.03) than E-IM pigs. Thus, growth performance in L-IM is better than in either E-IM or surgical castrates.

Seasonal short-term effects of naltrexone on LH secretion in male carp ( Cyprinus carpio L.)

In order to evaluate the influence of the season (the stage of gonad maturity) on the modulatory role of endogenous opioid peptides in LH secretion in fish, sexually mature male carp ( Cyprinus carpio L.) were intravenously injected with naltrexone–opioid receptor antagonist (5 or 50 μg kg −1) in the period of natural spawning (June) or gonad recrudescence (December). Moreover, the possible involvement of the dopaminergic system was studied in fish pre-treated with pimozide (dopamine receptor antagonist) and in intact fish. Blood samples were taken every minute, up to 10 min after naltrexone injection. In June, naltrexone significantly lowered LH levels in comparison to saline injected males. In December, there were no differences between saline and naltrexone-injected carps. In fish pre-treated with pimozide, neither in June nor in December were any significant differences in LH levels between control group and the groups injected with naltrexone found. The results showed that, in male carp, LH secretion under the influence of naltrexone depends on the stage of gonad maturity what suggests that the feedback of gonadal steroids on LH release could be mediated by the endogenous opioids. The role of dopamine in these processes is also discussed.

Changes in sex steroids, gonadotropins, prolactin, and inhibin in pregnant and nonpregnant Japanese black bears (Ursus thibetanus japonicus).

We examined changes in the concentrations of serum progesterone (P4), estradiol-17beta (E2), FSH, LH, prolactin (PRL), and inhibin to determine their interaction and their effect on the reproductive endocrine controls of pregnant and nonpregnant female Japanese black bears. Fourteen female bears were used in this study over a 2-yr period. In the first year, six of the bears were divided into two groups; a pseudopregnant group and a nonpregnant group. In the second year, the remaining eight bears were also divided into two groups; a pregnant group and a nonpregnant group. Pregnant and pseudopregnant bears had similar P4 trends with both groups exhibiting a significant increase in December, which is the suspected time of implantation in pregnant bears. These trends correlated with an increase in PRL levels, whereas low levels of LH were maintained throughout the year. Nonpregnant bears maintained low concentrations of P4, and compared with pregnant and pseudopregnant bears, they also exhibited a delayed elevation in PRL. Luteinizing hormone activity varied among individual animals, but regardless of reproductive status, fluctuation patterns of E2, FSH, and inhibin did not differ among bears. Our results suggest that PRL may play a luteotropic role in both pregnant and pseudopregnant bears, and is possibly responsible for inducing reactivation of the dormant corpus luteum that precedes implantation in the Japanese black bear.

Ovulation induction disrupts luteal phase function.

Abnormalities in the luteal phase have been detected in virtually all the stimulation protocols used in in vitro fertilization, on both the hormonal and endometrial levels. Supraphysiological follicular or luteal sex steroid serum concentrations, altered estradiol: progesterone (E2/P) ratio, and disturbed luteinizing hormone pituitary secretion leading to corpus luteum insufficiency or a direct drug effect have been postulated as the main etiologic factors. Luteinizing hormone supports corpus luteum function, and low LH levels have been described after human menopausal gonadotropin treatment, after gonadotropin-releasing hormone (GnRH)-agonist treatment, or after GnRH-antagonist treatment. These low luteal LH levels may lead to an insufficient corpus luteum function and consequently to a shortened luteal phase or to the low luteal progesterone concentrations frequently described after ovulation induction. A direct effect of the GnRH agonist or GnRH antagonist on human corpus luteum or on human endometrium and thus on endometrial receptivity cannot be excluded, as GnRH receptors have been described in both compartments. Endometrial histology has revealed a wide range of abnormalities during the various stimulation protocols. In GnRH-agonist cycles, mid-luteal biopsies have revealed increased glandulo-stromal dyssynchrony and delay in endometrial development, strong positivity of endometrial glands for progesterone receptors, decreased alphavbeta3-integrin subunit expression, and earlier appearance of surface epithelium pinopodes. These factors suggest a shift forwards of the implantation window. Progesterone supplementation improves endometrial histology, and its necessity has been well established, at least in cycles using GnRH agonists.

Beneficial effects of residual LH levels after GnRH agonist on ovarian response to rFSH, embryo quality, and IVF-ET outcome.

Objective: By the mid-follicular phase of the menstrual cycle, progressive LH secretion parallels the acquisition of LH receptors by the granulosa cells, a phenomenon that may assist final oocyte-follicular maturation and ovulation. In COH, GnRH agonist pretreatment often leads to extensive suppression of endogenous LH activity. By definition, defective LH activity is not subsequently compensated by FSH-only recombinant preparations and such an unbalanced endocrine milieu may alter oocyte-follicular quality. Yet, previous studies addressing this issue have led to divergent conclusions (Scott Sills et al., Hum Reprod, 1999; Fleming et al., Hum Reprod, 1998). Hence, to clarify this point, we assessed possible differences in ovarian response to COH, embryology data, and IVF-ET outcome in women having consistently low or high residual LH levels after pretreatment with GnRH agonist.