Single FSH Research Articles

Expression of biologically active fusion genes encoding the common α subunit and either the CGβ or FSHβ subunits: role of a linker sequence

The gonadotropin/thyrotropin hormone family is characterized by a heterodimeric structure composed of a common α subunit non-covalently linked to a hormone-specific β subunit. The conformation of the heterodimer is essential for controlling secretion, hormone-specific post-translational modifications and signal transduction. Structure-function studies of FSH and the other glycoprotein hormones are often hampered by mutagenesis induced defects in subunit combination. Thus, the ability to overcome the limitation of subunit assembly would expand the range of structure activity relationships that can be performed on these hormones. Here we converted the FSH heterodimer to a single chain by genetically fusing the carboxyl end of the FSHβ subunit to the amino end of the α subunit in the presence or absence of a natural linker sequence. In the absence of the CTP linker, the secretion rate was decreased over three fold. (The CTP sequence is the last 28 amino acids of the CGβ sequence and contains four serine-linked oligosaccharides). Unexpectedly however, receptor binding/signal transduction was unaffected by absence of the linker. Molecular modelling of the tethers lacking the linker sequence show that the alignment of the α β domains in the single chain differ substantially from that seen in the heterodimer. These data show that the single chain FSH was secreted efficiently and is biologically active and that the conformation determinants required for secretion and biologic activity are not the same.

Biological characterization of the isoforms of urinary human follicle-stimulating hormone contained in a purified commercial preparation.

The main physicochemical and biological properties of the several isoforms of urinary follicle-stimulating hormone (uFSH) present in a commercially available uFSH preparation were analysed. Purified urinary FSH was submitted to chromatofocusing and several immunoactive forms of uFSH with isoelectric points (pI) ranging from 5.5 to 3.8 were identified. An additional isoform was detected after passing through the chromatofocusing column a 1.0 M NaCl solution (salt peak). Each uFSH isoform or pool of neighbouring isoforms (pI value 5.5-5.1, pool I, 3.8 +/- 1.0% of total immunoactivity recovered; pI value 5.0-4.6, pool II, 18.4 +/- 3.6% of total; pI value 4.5-4.3, pool III, 14.9 +/- 1.5% of total; pI value 4.1, pool IV, 8.2 +/- 1.4% of total; salt peak, pool V, 51.1 +/- 6.4% of total) eluted as single FSH peaks after Sephadex G-100 exclusion chromatography (apparent M(r) 60,000). Even though FSH present within each pool was recognized by a receptor preparation, the receptor binding activity expressed as the radioreceptor assay/radioimmunoassay (RRA/RIA) activity ratio varied with the pI value of the particular uFSH isoform tested; starting from a pI value of 5.5, the receptor binding activity of FSH decreased from 5.9 +/- 0.39 to 2.4 +/- 0.19, as the pI value of the corresponding isoform declined. A similar trend was observed when the potency of each isoform was assessed by an in-vitro bioassay.(ABSTRACT TRUNCATED AT 250 WORDS)

Superovulatory response in buffaloes following single subcutaneous or multiple intramuscular FSH administration

Superovulatory response in buffaloes following single subcutaneous or multiple intramuscular FSH administration

Endurance training decreases serum testosterone levels in men without change in luteinizing hormone pulsatile release

Cross-sectional studies have suggested that total and bioavailable testosterone levels are reduced in some male athletes. Such changes may be related to loss of body weight, increased serum cortisol, and/or alterations in LH pulsatile release. To determine how endurance training may affect androgen levels, we measured serum total testosterone, sex hormone-binding globulin, free androgen index, LH, FSH, PRL, cortisol, and weight in 15 previously sedentary males. We also examined pulsatile LH release in a subset of 5 subjects. Over 6 months of training, the men increased weekly running mileage to an average of 56 km/week. Total testosterone and free androgen index levels decreased significantly. PRL and cortisol also decreased, while single sample LH and FSH remained unchanged. There was a significant reduction in weight, which did not correlate with changes in serum testosterone levels. LH pulsatile release was not altered by training in the subset of 5 runners. These data confirm previous findings of physiological reduction in serum testosterone and PRL levels and suggest that the testosterone decrease is not related to changes in LH pulsatile release, weight, or increased serum cortisol levels.

Endurance Training Decreases Serum Testosterone Levels in Men without Change in Luteinizing Hormone Pulsatile Release*

Cross-sectional studies have suggested that total and bioavailable testosterone levels are reduced in some male athletes. Such changes may be related to loss of body weight, increased serum cortisol, and/or alterations in LH pulsatile release. To determine how endurance training may affect androgen levels, we measured serum total testosterone, sex hormone-binding globulin, free androgen index, LH, FSH, PRL, cortisol, and weight in 15 previously sedentary males. We also examined pulsatile LH release in a subset of 5 subjects. Over 6 months of training, the men increased weekly running mileage to an average of 56 km/week. Total testosterone and free androgen index levels decreased significantly. PRL and cortisol also decreased, while single sample LH and FSH remained unchanged. There was a significant reduction in weight, which did not correlate with changes in serum testosterone levels. LH pulsatile release was not altered by training in the subset of 5 runners. These data confirm previous findings of physiological reduction in serum testosterone and PRL levels and suggest that the testosterone decrease is not related to changes in LH pulsatile release, weight, or increased serum cortisol levels.

Gonadotrophins and ovarian steroids in cattle. I. Pulsatile changes of concentrations in the jugular vein throughout the oestrous cycle.

Short-term secretion patterns of LH, FSH, progesterone and oestradiol-17 beta were evaluated throughout complete oestrous cycles of 6 heifers. Frequent blood samples (in 20-min intervals for 12 continuous h) were taken every 3-5 days from indwelling jugular catheters. There was a high incidence of concomitant LH and FSH pulses ranging from 72% at luteolysis to 83-100% during the luteal phase. Almost the same total number of LH and FSH pulses occurred during the early luteal phase (7.0 vs 7.4/12 h, respectively), however, there was an average of one additional FSH pulse in between the synchronous LH/FSH ones during the mid- and late luteal phase (6.9 FSH vs 3.4 LH pulses/12 h). Basal LH and FSH concentrations remained unchanged from the early until the late luteal period. During and after luteolysis frequency of LH and FSH release (14.5 vs 10.5 pulses/12 h) increased considerably as well as basal concentrations and magnitude of LH pulses. Secretion of both gonadotrophins persisted very frequently (13.3 LH and 10.7 FSH pulses/12 h) during pro-oestrus and oestrus when basal FSH concentrations and FSH pulse maxima approached a nadir. During the mid-luteal phase 45% of pulsatile progesterone occurred concomitantly with each coinciding LH/FSH pulse and 44% of pulsatile progesterone happened after additional single FSH pulses. Distinct short-term changes of oestradiol concentrations were not observed in the jugular vein but concentrations fluctuated randomly ranging from 2-6 pg/ml throughout the luteal period. Prior to and during heat mean concentrations of oestradiol were approximately 2-fold higher (P less than 0.05) than during the other periods of the cycle. It is concluded that the frequency of pulsatile LH release is modulated to a much greater extent than FSH by negative feedback of ovarian steroids. Some pulsatile progesterone secretion resulting from the stimulation of FSH (and LH) is still detectable in the jugular vein whereas of oestradiol-17 beta is not. The additional frequent monitoring of FSH might be more appropriate reflecting pituitary and hypothalamic function than only measuring LH.

Endocrine assessment of the subfertile male.

Sixty-three male (XY) patients attending a subfertility clinic with average sperm density under 40 million/ml were studied by testicular biopsy and multiple basal estimations of plasma LH, FSH, testosterone as well as LHRH (50 micrograms i.v.) stimulation. A further forty patients with similar sperm densities also had testicular biopsy but only single estimations of the three hormones. A single basal FSH was found to be the best discriminator of testicular histologies. Patients with testicular biopsies showing germ cell aplasia in some or all seminiferous tubules (grades 3 and 4) had significantly higher basal FSH than those with hypospermatogenesis, germ cell arrest or normal appearance (grades 1 and 2). Basal FSH also showed a linear trend rising with decreasing sperm density but only rose above the normal range when sperm densities fell below 1 million/ml. When basal FSH, testicular histology and sperm density were considered together in the whole group (n = 100), high levels of FSH accurately indicated the presence of germ cell aplasia in some or all seminiferous tubules in azoo- and oligospermic men with sperm density under 5 million/ml. Normal FSH and azoospermia is diagnostic of obstruction in the excurrent ducts, and further investigation is undertaken if surgical correction of the obstruction is contemplated. Hormone estimations are not helpful in oligospermic patients with average sperm density over 5 million/ml. On the basis of these findings it is suggested that there is little place for the LHRH test in the routine assessment of male subfertility. Testicular biopsy is indicated only in oligospermic patients with average sperm density under 5 million/ml and normal basal FSH.

Prolongation of pseudopregnancy of rats by gonadotropins implanted in the ovarian bursae.

Effects on the duration of pseudopregnancy (PSP) of prolactin, LH, FSH, or various combinations of those hormones were studied in female rats. Hormones were implanted in the ovarian bursae on day 4, 7, or 9 of PSP or consecutively on days 4, 5, and 6. Prolactin, in doses ranging from 3 to 642 μg, and LH or FSH, at 3 μg, had no effect on PSP. However, 17 μg or more of LH implanted on day 4 or 7 significantly (p 80 μg) likewise prolonged PSP, but lower doses (17 or 56 μg) implanted on day 7 were less effective. The effect of consecutive (days 4-6) implantation of LH or FSH was similar to that of a single (day 4) LH or FSH implant. There was no synergism among prolactin, LH, and⁄or FSH when equal amounts of those hormones were implanted simultaneously on day 7 or 9. Neither LH nor FSH, when implanted on day 9, affected PSP. Ova were not found in 15 rats 24 hr after implantation on day 7 of 17 μg or 68 μg of LH or 17 μg of FSH, suggest...

Influence of gonadotrophins and cyclic AMP on carbohydrate and protein metabolism in the immature rat ovary.

ABSTRACT Ovaries from rats varying in age between 5–12 days were incubated in Krebs bicarbonate buffer at 37°C containing 5.5 mmol/l glucose. A 2 h incubation in the presence of 0.01 μg/ml LH (NIH-LH-B6) caused an increase in lactic acid production as compared to controls, and a clear dose-response was demonstrated up to 100 μg/ml. In vitro the addition of 100 μg/ml FSH (NIH-FSH-S5) or 10 mmol/l cyclic AMP also caused stimulatory effects on lactate production. In experiments with ovaries from 8–9 day old rats, incubations were carried out in a medium containing 0.1 mmol/l [14C]AIB (α-aminoisobutyric acid), and the distribution ratios for this model amino acid were determined after 2 h incubation in the absence and presence of LH, FSH or cyclic AMP respectively. No hormonal effects were demonstrated, while cyclic AMP caused a significant increase in the [14C]AIB uptake. In further experiments ovaries from 9 day old rats were incubated in medium containing both [14C]AIB (0.1 mmol/l) and [3H]leucine (0.03 mmol/l). Four hours before the removal and incubation of the ovaries the rats were injected ip with FSH or LH (500 μg/100 g body weight) or saline. The distribution ratios of both [14C]AIB and [3H]leucine were significantly elevated in the FSH injected group while LH was ineffective. In similar experiments with 0.01 mmol/l [3H]proline it was also possible to demonstrate an increased incorporation of this amino acid into ovarian protein after a single FSH injection 2 h before the incubation.