Immunoreactive LH Research Articles

Alcohol-induced inhibition of LH secretion in intact and gonadectomized male and female rats: possible mechanisms.

Alcohol (EtOH) is reported to decrease gonadotropin secretion, but the mechanisms mediating these changes are not fully understood. The present study examined the ability of acutely or chronically administered EtOH to alter plasma luteinizing hormone (LH) and follicle stimulating hormone (FSH) levels in both male and female rats, and correlated these changes with blood EtOH levels (BALs); investigated possible changes in the pituitary responsiveness of animals exposed to EtOH; and probed the role of the paraventricular nucleus (PVN) of the hypothalamus in mediating alcohol-induced decreases in plasma LH levels. The injection of 0.5 g EtOH/kg was accompanied by significantly higher BALs in females compared with males. This dose of alcohol did not alter rectal temperature, and only significantly (p < or = 0.01) decreased plasma LH levels in female rats. These findings were not altered by removal of gonadal steroids. Administration of 2.0 g EtOH/kg was followed by BALs that were comparable in both groups of rats at the 1- and 2-hr time-points, but were significantly (p < or = 0.01) higher in females 3 hr after treatment. Rectal T measurably decreased in all rats injected with 2 g EtOH/kg, though intact females showed the greatest change. This alcohol treatment also significantly (p < or = 0.01) inhibited immunoreactive LH release in both sexes, but there were no measurable changes in FSH values at any time.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of ethinyl estradiol on semen quality and various hormonal parameters in a eugonadal male

To determine the influence of estrogens on male fertility. A 36-year-old eugonadal male was subjected to two different regimens of treatment with ethinyl estradiol (EE2). Sperm quality, immunoreactive luteinizing hormone (LH) and follicle-stimulating Hormone (FSH), testosterone (T), estrone (E1), estradiol (E2), dehydroepiandrosterone sulfate (DHEAS), prolactin (PRL) and sex hormone-binding globulin were determined at intervals of 2 weeks for 315 days. A gender dysphoria clinic. A transsexual male nurse. It was hypothesized (and confirmed) that by comparing the effects of increasing and constant dose of EE2 on fertility parameters, differences in estrogen-sensitivity would show more clearly. Furthermore, this procedure served to find the minimal dose of EE2 for complete testicular suppression. Low doses of EE2 (20 micrograms/d) had no negative effect on sperm motility and density for a period of approximately 4 weeks, whereas high doses (60 micrograms/d) reduced motility already after a few days and led to a pronounced decrease in sperm density after 2 weeks. After discontinuation of therapy, motility normalized faster than sperm density. Under increasing doses of EE2 there was a constant decrease of FSH that occurred several weeks earlier than that of LH. Under constant dose of EE2 (60 micrograms/d) the decrease of LH was delayed (with respect to FSH) by only a few days. The decrease in T showed a stronger correlation with that of FSH than with that of LH. Volume and fructose content of the seminal fluid correlated with the decrease in T. Rebound effects were observed for FSH, LH, T, and fructose during the therapy-free interval. Ethinyl estradiol therapy had no influence on the serum concentrations of E1, E2, and PRL. Estrone was the dominant estrogen before and after therapy with EE2. Adrenal gland activity was markedly suppressed by EE2, as reflected by the decrease in DHEAS. The suppressive effect of EE2 on FSH and sperm motility was more pronounced and consistent than on LH and sperm density. The T decrease appears to be mainly caused by a direct effect of EE2 on the testes.

GnRH antagonists in men: Development of a male contraceptive

Antagonist analogs of GnRH inhibit pituitary and gonadal function by competing with endogenous GnRH for binding to gonadotropin receptors. Administration of GnRH antagonists to humans induces rapid and sustained pituitary and gonadal suppression. Induction of suppression is potentiated by a decrease in the biological potency of the follicle stimulating hormone (FSH) and luteinizing hormone (LH) molecules. Development of GnRH antagonists however has been slow because of low potency of early prototype analogs and histamine-like side effects caused by more potent analogs. A GnRH antagonist synthesized at the Salk Institute by Drs. J. Rivier and W. Vale. has permitted short and longterm clinical studies because of its high potency and its relative lack of side effects in animal studies. We 1st gave this Nal-Glu antagonist as single doses to normal men and immunoreactive FSH LH and bioactive LH decreased significantly after all doses of the antagonist. Testosterone (T) levels decreased with the same rate after all doses of Nal-Glu by up to 90 9 +or- 2.8%. The duration of T suppression rather than the nadir reached was dose dependent. Then 5 mg Nal-Glu was given daily to normal men for 3 weeks. FSH LH and T progressively decreased and were totally suppressed from day 18 until the end of the study. A higher daily dose of 10 mg in 5 men could inhibit the brief escape seen during the 1st week of Nal-Glu administration; LH and T decreased promptly and remained suppressed throughout the study. In contrast serum free alpha-subunit decreased slowly to a nadir of only 50%. Estradiol also decreased whereas 17-OH-P levels did not change. In order to study the effects of the GnRH antagonist on the pulsatile secretion of LH we gave 5 mg of Nal-Glu to 5 normal men and collected blood samples every 10 min for 24 hours. LH pulse frequency expressed as the interval between pulses remained the same at 119 +or- 16 minutes during baseline and at 134 +or- 11 minutes following antagonist administration. However LH pulse amplitude decreased from 1.8 +or- 0.5 to 0.16 +or- 0.01 U/L. We then studied the effects of combined Nal-Glu antagonist and T administration in men in a protocol simulating a likely male contraceptive regimen. The antagonist 10 mg daily for 20 weeks was given to 8 normal men; T enanthate 25 mg every week was added to this regimen starting at 2 weeks. Sperm counts started declining on week 4 and complete azoospermia was reached in 7 of the 8 subjects. In the 8th man total sperm count was decreased at week 20 to a nadir of 1.4 million and residual sperm showed no motility and viability during the last 6 weeks of treatment. No systemic or significant local side effects were observed other than a small reaction at the injection site. These results indicate that prolonged administration of the Nal-Glu antagonist can effectively suppress pituitary and gonadal function. Furthermore combined administration of a GnRH antagonist and T can result in complete sustained and reversible azoospermia in men without loss of libido. (full text)

Induction of azoospermia in normal men with combined Nal-Glu gonadotropin-releasing hormone antagonist and testosterone enanthate.

The effects of a combined GnRH antagonist and testosterone (T) replacement regimen on gonadotropins and spermatogenesis were examined to assess its potential as a male contraceptive regimen. The potent Nal-Glu GnRH antagonist ([Ac-D2-Nal1,D4-Cl-Phe2,D3-Pal3,Arg5, D4-p-methoxybenzoyl-2-amino butyric acid6,D-Ala10]GnRH) was administered daily (7.5 mg, sc) to eight normal men for 16 weeks. T enanthate was given im starting at week 2 and every 2 weeks thereafter through week 14 of the treatment phase. Serum LH, FSH, T, and estradiol concentrations were measured frequently during the 5-week control period, the 16-week treatment phase, and the 14-week recovery phase. Semen analyses were performed every week during the control phase and every 2 weeks during the treatment and recovery phases. Seven of eight subjects became azoospermic by 6-10 weeks of treatment; the eighth subject, who failed to achieve azoospermia, suppressed his sperm count to 7 million/mL by week 14 (from a mean baseline of 42 million/mL) before treatment was prematurely terminated because of localized swelling at each of his injection sites. Sperm counts returned to baseline 10-14 weeks after the end of Nal-Glu administration. Seven of the eight subjects showed suppression of LH to the limit of assay detection (less than 0.2 U/L), whereas the eighth subject showed incomplete suppression. Serum bioactive and immunoreactive LH concentrations showed concordant responses. Mean serum FSH concentrations were also markedly suppressed. Serum T and estradiol concentrations declined dramatically during the first 2 weeks of Nal-Glu GnRH treatment, but returned to the normal physiological range after T enanthate replacement was initiated. Libido and sexual potency were maintained. No systemic side-effects, other than erythema and induration at injection sites, were observed. These data demonstrate that combined GnRH antagonist plus T treatment can predictably and reversibly induce azoospermia in most men and has potential as a male contraceptive regimen.

Changes in peripheral levels of bioactive and immunoreactive inhibin, estradiol-17 beta, progesterone, luteinizing hormone, and follicle-stimulating hormone associated with follicular development in cows induced to superovulate with equine chorionic gonadotropin.

Changes in concentrations of bioactive and immunoreactive (ir-) inhibin, estradiol-17 beta, progesterone, LH, and FSH in peripheral blood were determined in cows induced to superovulate with eCG. The pattern of follicular growth was also characterized by daily ultrasonographic examination. Hormonal profiles and follicular development during the intact estrous cycle of the same animals before eCG treatment served as controls. Equine CG increased the number of follicles of various sizes (small, greater than or equal to 4 less than 7, medium, greater than or equal to 7 less than 10; large, greater than or equal to 10 mm in diameter) by 4 days after administration. The second growth of large follicles occurred within 1 day after superovulation. Inhibin bioactivity in jugular vein blood was detectable 48 h after eCG injection (44 h before LH peak), whereas it was not detected before administration of eCG or during control cycles. Circulating levels of bioactive inhibin further increased during the two waves of growth of large follicles. The highest activity of inhibin was noted at the time of the preovulatory LH peak (0 h). Thereafter, bioactivity of inhibin in peripheral plasma dropped from 0 to 24 h after the LH peak, and the activity increased again at 72 h compared to the value at -44 h. Plasma levels of ir-inhibin showed a pattern similar to changes in bioactive inhibin in the eCG-treated cows. Plasma concentrations of estradiol-17 beta also increased concomitantly with two waves of growth of large follicles. There was no correlation between plasma levels of progesterone and inhibin.(ABSTRACT TRUNCATED AT 250 WORDS)

Bioactive and immunoreactive concentrations of circulating luteinizing hormone during sexual maturation in the bovine.

The characteristics of circulating LH during sexual maturation in cattle were assessed by examining bioactive and immunoreactive LH concentrations, as well as their ratio (B/I ratio). Male and female intact control (CONT), gonadectomized (GNX; at 241 +/- 3 days of age, Day 0 of the study), and gonadectomized animals administered 17 beta-estradiol (GNXE) were evaluated. Serum samples were collected at 15-min intervals for 24 h at 1, 7, 13, 17, 21, 25, 29, 33, 37, and 43 wk subsequent to Day 0. Bioactive LH was assessed with an in vitro bioassay using mouse testicular interstitial cells. In initial experiments, immunoreactive LH was quantified in RIAs using three different antibodies. The two RIAs employing polyclonal antibodies overestimated low LH concentrations, but the absolute values obtained in each of the three assays were highly correlated. Hence, immunoreactive LH was measured in an RIA using monoclonal anti-bovine LH (bLH) (JR-518B7). No significant changes in the B/I ratios were observed during individual pulses of LH secretion. Accordingly, pools consisting of equal volumes of the serial blood samples collected during the 24-h period for each animal at each stage of maturation (pools) were compared. LH B/I ratios for GNX females increased significantly with time (p less than 0.01) and the B/I ratios for GNX males were significantly higher than for GNX females (p less than 0.05). Concentrations of LH in most of the pools for GNXE and CONT animals were extremely low or nondetectable until the later bleeding periods.(ABSTRACT TRUNCATED AT 250 WORDS)

Expression of the genes for alpha inhibin, beta A inhibin and follistatin in the ovaries of Booroola ewes which were homozygotes or non-carriers of the fecundity gene FecB.

Ovine cDNA probes for the alpha and beta A inhibin subunits and for follistatin were used to investigate the mRNA species for these hormones in ovaries obtained during the luteal phase of the oestrous cycle, from Booroola ewes which were homozygous carriers (BB) or non-carriers (++) of the FecB gene. BB ewes had significantly higher concentrations of peripheral FSH and LH immunoreactivity than ++ ewes, but the peripheral inhibin immunoreactivity and ovarian inhibin and progesterone secretion rates were not significantly different between genotypes. No gene-specific differences in the number or size of mRNA transcripts detected by Northern blotting were noted for any of these genes. A single alpha inhibin mRNA species at 1.5 kb was observed in the follicle RNA from ++ and BB ovaries. Low amounts of alpha inhibin hybridization were discerned occasionally in ++ and BB stroma and also in BB, but not in ++, corpora lutea. The beta A inhibin gene was expressed only in the follicles from both ++ and BB ovaries. At least three beta A inhibin transcripts were observed; one at 7.5 kb and at least two between 1.4 and 5.0 kb. The follistatin cDNA probe detected two major transcripts at 2.7 and 1.5 kb and a minor band at 0.5 kb in both follicle and corpora lutea RNA. Densitometry of the Northern blots revealed no significant gene-specific differences in the levels of alpha inhibin and follistatin gene mRNA transcripts.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of nutritional repletion on pituitary and serum follicle-stimulating hormone isoform distribution in growth-retarded lambs.

Using nutritionally restricted ovariectomized lambs, we tested the hypothesis that nutritionally regulated endogenous increases in GnRH secretion (as assessed by LH pulsatility) not only alter the quantity of FSH present in the pituitary and serum, but also alter the pituitary and serum FSH isoform distribution. Eleven lambs were nutritionally restricted from weaning and ovariectomized at 12 wk of age. Beginning at 56 wk, 6 were fed ad libitum for 14 days, and the other 5 were continued on the restricted diet. Jugular blood samples were collected frequently (12-min interval) for 4 h prior to pituitary removal. Immunoreactive ovine LH (I-oLH) and immunoreactive ovine FSH (I-oFSH) concentrations were measured in sera and pituitary extracts. Bioactive (B) oFSH and I-oFSH isoform distribution patterns were determined in serum pools and pituitary extracts. Ad libitum feeding increased I-oLH pulsatility and mean concentrations of pituitary and serum I-oFSH and B-oFSH. The I-oFSH isoform distribution patterns in the pituitaries from the nutritionally restricted animals were not different from those of repleted lambs; in both, the predominant FSH peak eluted in the pH range of 3.5-5.6. A similar predominance of I-oFSH isoforms was also evident in the serum of ad libitum-fed animals. This predominance was not demonstrable in 3 of the restricted-fed animals due to low circulating concentrations of FSH (less than 2.5 ng/ml). Subsequent studies, utilizing serum from 4 additional restricted-fed lambs with circulating I-oFSH concentrations in the range of 4-14 ng/ml (but no detectable LH pulses) revealed similar predominance of oFSH isoforms in the pH 3.5-5.6 range.(ABSTRACT TRUNCATED AT 250 WORDS)

Age related changes in follicle stimulating hormone, luteinizing hormone, oestradiol and immunoreactive inhibin in women of reproductive age.

In women over the age of 45 years with continuing regular menstrual cycles, follicular phase FSH levels rise without an accompanying change in LH. We determined the effect of increasing age in women with regular cycles on the serum levels of FSH, LH, immunoreactive inhibin, progesterone and oestradiol. Single blood samples were taken during the early follicular phase (days 4-7) and again in the midluteal phase (3-12 days before the next menses) of the menstrual cycle. Regularly cycling women aged 21-49 years participated in the study (and were grouped into four groups: 20-29, 30-39, 40-44 and 45-49 years in the follicular phase and three groups: 20-29, 30-39 and 40-49 years in the luteal phase. Serum levels of FSH, LH, oestradiol, progesterone and immunoreactive inhibin were measured from the blood samples obtained. Follicular phase Mean follicular phase levels of immunoreactive inhibin were significantly lower in the 45-49 year age group (P less than 0.05) than in the younger age groups (128 U/l in the 45-49 year age group vs 239, 235 and 207 U/l in the 20-29, 30-39, 40-44 year age groups respectively), while mean FSH levels were significantly higher in the 45-49 year age group (P less than 0.05, 13.0 IU/l in the 45-49, 4.9, 5.5 and 5.2 IU/l in the 20-29, 30-39 and 40-44 year age groups respectively). Mean oestradiol levels in the 45-49 year age group were significantly lower only when compared to age group 30-39 years (P less than 0.05, 130 vs 210 pmol/l). There was no significant difference in oestradiol levels between the 45-49 year age group and the 20-29 and 40-44 year age groups. LH levels did not differ significantly across age groups. There was also a significant negative correlation between serum immunoreactive inhibin and FSH (r = -0.45, P less than 0.05) and between oestradiol and FSH (r = -0.35, P less than 0.05). There was a significant negative relationship between immunoreactive inhibin and age (r = -0.46, P less than 0.05). For every 10-year increase in age, average immunoreactive inhibin decreased by an estimated 49.3 U/l. As age increased, average FSH levels exhibited a two-phase linear increase with the change-point estimated at 42.97 (1.42) (estimate (SE)) years. Prior to 42.97 years, FSH barely changed; after 42.97 years there was a significant (P less than 0.05) increase in FSH as age increased. Oestradiol levels did not change significantly until an estimated 37.9 years of age, but then decreased significantly (P less than 0.05) with increasing age. Luteal phase Levels of FSH, LH, serum immunoreactive inhibin, oestradiol and progesterone fell slowly with increasing age. There was a significant correlation between serum immunoreactive inhibin with progesterone (r = 0.41, P less than 0.05) but there was no correlation between serum immunoreactive inhibin LH or FSH. The results are consistent with a role for serum immunoreactive inhibin, in addition to oestradiol, in the regulation of FSH during the follicular phase of the menstrual cycle as a function of increasing age. This is postulated to reflect diminished folliculogenesis as age progresses with the known decline in the numbers of primordial follicles in the ovary as the menopause approaches.

Immunoreactive plasma inhibin levels in men after polyvalent chemotherapy of germinal cell cancer.

In vitro studies have shown that the Sertoli cell is the primary source of inhibin in the male. We measured immunoreactive inhibin with a new two-site immunoenzymatic assay in the plasma of 92 men: 40 normal men, 7 patients with germinal cell cancer after unilateral orchidectomy and 45 patients with the same disease following unilateral orchidectomy and subsequent chemotherapy based on cisplatin. Normal men had inhibin levels of 1.77 +/- 0.09 U/l x 10(-3) (mean +/- SEM). Seven patients after unilateral orchidectomy had inhibin concentrations within the lower normal range (1.23 +/- 0.22 U/l x 10(-3)). Forty-five patients were investigated in a cross-sectional study up to 102 months after completion of chemotherapy. Inhibin levels were within the normal range in 25 patients (1.76 +/- 0.14 U/l x 10(-3)); 18 patients had significantly lower inhibin levels (0.48 +/- 0.05 U/l x 10(-3), p less than 0.005) when compared to patients after unilateral orchidectomy. Two patients had elevated inhibin levels (4.4 and 5.6 U/l x 10(-3)). The proportion of patients with normal and subnormal inhibin was not dependent on the time that elapsed after completion of chemotherapy or on the chemotherapy combination. There was no correlation between immunoreactive plasma inhibin and LH, FSH, testosterone or sperm count. The decrease in inhibin concentrations after chemotherapy may indicate long-term damage to Sertoli cells in some of the patients.

A similar distribution of gonadotropin isohormones is maintained in the pituitary throughout sexual maturation in the heifer.

Our working hypotheses for this study were that 1) the profile of intrapituitary LH and FSH isoforms would be shifted toward acidic forms as sexual maturation progresses in the bovine female; and 2) concentration of 17 beta-estradiol (E2) in circulation during sexual maturation would be a major factor modulating the percentage of the more acidic isoforms. In addition, the biological-immunoreactive (B:I) ratios of each isoform of LH were evaluated at selected stages of sexual maturation. Heifers (7 mo of age) were assigned to one of three treatment groups: 1) ovariectomized (OVX; n = 16); 2) OVX and administered E2 (OVXE; n = 16); or 3) ovary-intact (INTACT; n = 14). Pituitaries were collected from heifers in each group at an estimated 120 days (prepubertal) of 25 days before puberty (peripubertal). A fourth group of 6 heifers remained intact (postpubertal INTACT) to determine time of puberty during the experimental period. Pituitaries of heifers assigned to the postpubertal INTACT group were collected during the follicular phase of the first or second estrous cycle postpuberty. Pituitaries were used for determination of relative amounts of gonadotropin isohormones. Tissue extracts of the pituitaries were chromatofocused on pH 10.5-4.0 gradients. The LH of all pituitaries resolved into thirteen isoforms that were designated isoforms A-L, and S, with isoform A the most basic form. Isoforms F and G (basic pH range) were the predominant isoforms of each chromatofocusing profile and comprised 50-60% of the immunoreactive LH. Isoforms J and K were the major isoforms eluting in the acidic pH range.(ABSTRACT TRUNCATED AT 250 WORDS)

Concordant suppression of serum immunoreactive luteinizing hormone (LH), follicle-stimulating hormone, alpha subunit, bioactive LH, and testosterone in postmenopausal women by a potent gonadotropin releasing hormone antagonist (detirelix)

Concordant suppression of serum immunoreactive luteinizing hormone (LH), follicle-stimulating hormone, alpha subunit, bioactive LH, and testosterone in postmenopausal women by a potent gonadotropin releasing hormone antagonist (detirelix)

Is an immunoassay available for the measurement of bioactive LH in serum?

An in vitro bioassay for luteinizing hormone (LH) is in our opinion the "gold standard" bioassay. The rodent interstitial cell testosterone assay (RICT) is specific for bioactive LH and very sensitive, accurate, and reproducible. Diverse LH standards consistently display parallel dose-response characteristics. Sera also manifest parallel dose-response characteristics throughout reproductive life, with the exception of basal samples from prepubertal children. This indicates that all known hormones with LH bioactivity have a similar bioactive site. The in vivo bioassays for LH used for calibration of World Health Organization standards are more cumbersome and less precise and accurate than the in vitro bioassay. The ovarian ascorbic acid depletion assay corresponds better than the seminal vesicle weight assay with in vitro bioassay. Variation in the ratio of bioactive to immunoreactive LH (B/I) principally reflects variation in LH immunoassay dose-response characteristics, rather than a change in the bioactive moiety of LH. The varying B/I ratio is due to molecular heterogeneity at multiple levels. Different LH standards contain different proportions of nonbioactive but immunoreactive material. The immunoreactive LH isoforms in serum contain different proportions of bioactive material and the isoform distribution differs with reproductive status. Furthermore, the antibodies comprising the various immunoassay systems detect heterogeneous epitopes on LH, which are not necessarily bioactive. B/I ratio disparities indicate lack of specificity of immunoassays for bioactive LH. Polyclonal antibody-based radioimmunoassay requires the use of purified reagents, including a bioactive tracer, in order to achieve high specificity for bioactive LH. The new generation of monoclonal antibody-based immunometric assays yields results that are lower than, but correlate with, LH measured by the in vitro bioassay. The purest of standards, even a recombinant standard, yields results that differ up to 50% or more from one immunoassay to another. Serum LH levels also differ up to two-fold among assays. The immunometric assays have the advantage of being more sensitive and more specific for low levels of LH in serum than radioimmunoassays, but B/I ratio discrepancies remain great. An immunoassay specific for the bioactive "docking site" of human LH isoforms is still needed.

Recruitment and maturation of small subsets of luteinizing hormone gonadotropes during the estrous cycle.

Small and medium-sized gonadotropes may enlarge and produce more LH in order to contribute to the proestrous surge. To test this hypothesis, dispersed pituitary cells from cycling female rats were separated by centrifugal elutriation into small, medium, and large fractions and labeled for LH beta antigens or mRNA (by in situ hybridization with a biotinylated oligonucleotide probe complementary to sequences encoding amino acids 28-40). The percentage of cells bearing LH beta mRNA in the pituitary cell population increased from 6 +/- 0.4% in the evening of diestrous day 2 to 16 +/- 0.7% in the morning of estrus (average +/- SEM). Over 80% of these labeled cells were large or small subtypes. The proportion of small gonadotropes labeled with LH beta mRNA declined from 43 +/- 3% at metestrus to 29 +/- 1% on the evening of proestrus as the proportion of medium-sized gonadotropes labeled for LH beta antigens (15 +/- 1%) or mRNA (17 +/- 1%) increased to 25 +/- 2% or 38 +/- 2%, respectively. Because the overall percentage of immunoreactive LH cells did not change after diestrus, small LH cells may have enlarged or increased their density to join the medium-sized pool. During proestrus, the proportion of large immunoreactive LH gonadotropes increased from 41 +/- 2% to 65 +/- 2% (by the morning of estrus) as the proportion of small or medium-sized LH cells declined to 17-18 +/- 1%, suggesting further increases in size or density. These data suggest that small or medium-sized gonadotropes are activated during early diestrus to enlarge and produce LH beta. They contribute to the increased number of cells in medium-sized and large fractions in proestrous or estrous rats. The predominance of the smaller subtypes during metestrus and diestrus suggests that LH gonadotropes may revert to a smaller or lighter subset to await activation during the next cycle.

An immunologically anomalous luteinizing hormone variant in a healthy woman.

An investigation was undertaken to characterize an immunological LH variant in a 31-yr-old healthy woman whose serum LH was either poorly or not at all recognized by two monoclonal antibodies. The two antibodies recognize epitopes present on the intact LH dimer, but not on the free subunits. It was found that the immunologically aberrant LH of the subject was bioactive, as evidenced by an in vitro bioassay for LH. Nothing in the personal history of the subject or in the results from a number of hormone analyses revealed any endocrine abnormalities. In a GnRH stimulation test, the increase in immunoreactive LH using two reference immunometric assays for LH was less than 10% of the mean response of five control subjects. In relative terms, the maximal increase in LH in the subject was only 60-100%, in contrast to 340-560% for the control subjects. The bio/immuno ratio of the LH in the subject was high and was further increased in the GnRH stimulation test. A low proportion of acid LH isoforms in basal and stimulated samples from the subject was in agreement with the high bio/immuno ratio. Gel filtration studies showed the presence of molecular species of apparently lower molecular size than the intact LH, but different from the free beta-subunit. The results suggest the presence of fragments of the alpha-beta-dimer where at least part of the beta-subunit has been lost. A pedigree analysis involving the parents, siblings, and children of the subject strongly suggests a genetic origin of the LH variant described with an autosomal mode of inheritance. This report on an immunological variant of LH illustrates the potential dangers of using monoclonal based immunoassays where a protein hormone with fully maintained biopotency may be partially or totally missed due to the monospecificity of the immunoreagent. This possibility should be kept in mind when inappropriately low levels of gonadotropins are detected in diagnostic routine.

LH pulsatility and in vitro bioactivity in women with anorexia nervosa-related hypothalamic amenorrhea

LH nocturnal pulsatility and bioactivity to immunoreactivity (B/I) ratio were determined in 16 patients with anorexia nervosa-related hypothalamic amenorrhea and low sex steroid levels, and in 12 normal women in the midfollicular phase. The patients were subdivided into 2 groups: IA (N = 7) without, and IB (N = 9) with documented recent weight gain. Blood samples were taken from each subject at 10-min intervals from 00.00 to 06.00 h. Immunoreactive LH data were analysed with cluster analysis algorithm. A pool of aliquots from all the samples was used to evaluate bioactive LH, immunoreactive LH and LH B/I ratio in each subject. LH pulse frequency was lower in Group IA than in controls, whereas it did not differ significantly between Group IB and controls. LH pulse amplitude was lower in Group IA, and higher in Group IB than in controls. LH B/I ratio was below the control range in 3/16 patients. In conclusion, persistent hypothalamic amenorrhea does not require a permanent inhibition of the GnRH pulse generator; transient inhibition of pulsatility and qualitative abnormalities of gonadotropins could be involved in the mechanism, at least in some patients.

Clinical Features and Circulating Gonadotropin, Insulin, and Androgen Interactions in Women with Polycystic Ovarian Disease

Objective To investigate the interactions of hyperinsulinemia and inappropriate gonadotropin secretion in women with polycystic ovarian disease (PCOD). Design Comparative study of endocrinologic parameters in subjects with PCOD. Setting Open patient clinic of reproductive endocrinology at University Central Hospital of Turku, Finland. Patients Fourteen nonobese and 10 obese patients with PCOD. Seven healthy women for reference data collection. Normal thyroid function, serum prolactin concentration, normal diurnal cortisol variation, euglycemia in all subjects. Main Outcome Measures Serum concentrations of insulin, testosterone, androstenedione, dehydroepiandrosterone sulfate, sex hormone-binding globulin, immunoreactive luteinizing hormone (LH), bioactive LH, and follicle-stimulating hormone (FSH). Results The concentration of insulin was higher and that of bioactive LH was lower in obese than in nonobese PCOD women in whom the levels were also above the upper reference value. There was a negative correlation between insulin and bioactive LH levels (r = —0.57). Bioactive LH correlated inversely with the body mass index (BMI) (r = —0.50). After eliminating the effect of the BMI, the correlation between bioactive LH and insulin was no longer significant (r = —0.37). The bioactive LH and immunoreactive LH/FSH ratio correlated significantly (r = 0.68). Conclusions These data demonstrate that hyperandrogenic women can be divided into two subgroups: those with insulin resistance, normal or minimally elevated LH, and markedly elevated insulin levels; and those with elevated LH levels, no insulin resistance, and normal insulin concentrations. Obesity is associated with the former, and high bioactive LH levels with the latter subgroup.

Serum Bioactive and Immunoreactive Luteinizing Hormone and Follicle-Stimulating Hormone Levels in Women with Cycle Abnormalities, with or without Polycystic Ovarian Disease*

Serum steroid, gonadotropin, and alpha-subunit levels were assessed in 35 women with cycle abnormalities [11 with and 24 without polycystic ovarian disease (PCOD) according to strict clinical and biochemical criteria] and 8 regularly cycling women in the early (cycle day 3 or 4) and mid (cycle day 7 or 8) follicular phase. LH and FSH levels were estimated using two immunological techniques [RIA and immunoradiometric assay (IRMA)] and in vitro bioassays (BIO), using mouse Leydig cells and rat granulosa cells, respectively. In PCOD patients mean alpha-subunit, free androgen index [FAI; testosterone x 100/sex hormone-binding globulin (SHBG)], androstenedione, estrone, and estradiol (E2) were significantly elevated compared to levels in the early follicular phase of control cycles and non-PCOD patients. In addition, in PCOD patients mean IRMA-LH and RIA-LH levels were distinctly increased (2.8- to 3.6 fold, respectively; both comparisons, P less than 0.001) compared to control values, but in the same order of magnitude (1.3- to 1.4-fold increments) as that in non-PCOD patients. However, the median BIO-LH level in PCOD patients was 5.9-fold higher than that in non-PCOD patients and 4.0-fold higher than the BIO-LH in the early follicular phase of control women. Consequently, the median BIO/IRMA-LH ratio was 4.8-fold higher in PCOD patients compared to non-PCOD patients. In women with cycle abnormalities, individual BIO/IRMA-LH ratios correlated with BIO-LH (rs = 0.48), FAI (rs = 0.39), free estrogens (E2/SHBG ratios; rs = 0 0.47), and dehydroepiandrosterone sulfate (rs = 0.60) concentrations. Mean IRMA-, RIA-, and BIO-FSH levels and BIO/IRMA-FSH ratios were not significantly different when various groups were compared. Although RIA- and IRMA-LH levels showed good correlation (rs = 0.88), RIA-LH levels were consistently higher, resulting in distinctly higher RIA-LH/FSH ratios (mean, 4.5) compared to IRMA-LH/FSH ratios (median, 1.8) in PCOD patients.(ABSTRACT TRUNCATED AT 400 WORDS)

Pattern of secretion of bioactive and immunoreactive gonadotrophins in normal pubertal children

The aim was to investigate the relationship between the nocturnal pulsatile secretory patterns of immunoreactive and bioactive luteinizing hormone in normal children at various stages of puberty. Blood samples were taken at 15-minute intervals from 2000 hours to 0800 hours. Pubertal stage was assessed by the method of Tanner (1962). Thirty-four healthy siblings (17 males, 17 females) of diabetic children were recruited (median age 13.1, range 9.1-20.9 years). They were of normal height, non-obese, and covered the range of puberty. Follicle stimulating and luteinizing hormone levels were measured by radioimmunoassay in all 34 subjects; bioactive LH (B-LH) was assayed in a subgroup of 13 subjects selected to encompass the range of normal puberty. Oestradiol (girls) and testosterone (boys) were also measured at hourly intervals. Immunoreactive luteinizing and follicle stimulating hormone concentrations showed a progressive rise during puberty in both sexes. FSH concentrations were significantly higher in females than in males at all stages of puberty. Overnight mean bioactive luteinizing hormone concentrations were higher than immunoreactive luteinizing hormone levels in all the girls studied (n = 7). Although the number of bioactive luteinizing hormone pulses (31) was greater than immunoreactive pulses (27), the profiles were generally very similar. In the early pubertal girls an increase in the bioactive: immunoreactive ratio was observed during the middle of the night with the onset of pulsatility. Oestrogen was detected in the girls in breast stage 4-5 but not in two of the early pubertal girls, despite pulses of immunoreactive and bioactive luteinizing hormone. The boys had higher mean bioactive than immunoreactive luteinizing hormone levels and overall bioactive and immunoreactive luteinizing hormone and testosterone concentrations increased with puberty stage. Concordance between bioactive and immunoreactive hormone pulses was good although more immunoreactive pulses (16) were seen than bioactive pulses (14). As in the girls, an increase in the bioactive: immunoreactive ratio was observed in the middle of the night with the onset of pulsatility at genital stage 2 but, in contrast to the oestrogen data in the girls, testosterone secretion always followed luteinizing hormone pulsatility overnight. We conclude that mean overnight immunoreactive luteinizing and follicle stimulating hormone concentrations increase during puberty in both sexes. Bioactive luteinizing hormone levels are two to three times higher than immunoreactive luteinizing hormone in both sexes, but there is very little discordance between immunoreactive and bioactive luteinizing hormone pulsatility. The bioactive: immunoreactive ratio increases with the occurrence of pulsatility overnight in early pubertal children. The relationship between these changes in bioactive and immunoreactive luteinizing hormone and sex steroids is clearest in boys where the nocturnal testosterone rise always follows pulsatile LH secretion.

Plasma progesterone and luteinizing hormone concentrations and the role of the corpus luteum and LH gonadotrophs in the control of delayed implantation in Schreibers' long-fingered bat (Miniopterus schreibersii)

In Schreibers' long-fingered bat from South Africa (approximately 33 degrees S) copulation, ovulation and fertilization occurred in April and May, implantation was delayed until August, and parturition occurred in December. Delayed implantation coincided with winter, during which the bats remained active, only entering prolonged periods of torpor during particularly cold spells. Plasma progesterone concentration was low during non-pregnancy (1.54 ng/ml) and during delayed implantation (1.67 ng/ml), and thereafter increased to reach a peak mean of 64.82 ng/ml in late pregnancy. Changes in size and ultrastructure of the luteal cells indicated periods of steroidogenesis just after formation of the corpus luteum, and for about 2 months after implantation; reduced steroidogenic activity during delayed implantation; and luteolysis in the last 2 months of pregnancy. Plasma luteinizing hormone (LH) concentration and pituitary LH-beta immunoreactivity were highest during follicular development and peaked just before ovulation. During early delayed implantation, plasma LH concentration was low, and both plasma LH and pituitary LH-beta immunoreactivity increased from July, reaching peaks in late pregnancy. LH may be required to activate the corpus luteum and terminate delayed implantation, or, as in some small carnivores, it may be required for luteal maintenance.