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PubMed1977

The effect of FSH on LH induced testosterone secretion in the immature hypophysectomized male rat.

The effect of gonadotropin pretreatment of hypophysectomized male rats on LH stimulated serum testosterone concentrations was studied. A 5 day pretreatment period began 2 days after hypophysectomy at 21 or 24 days of age. On the day following the pretreatment period the animals received an intraperitoneal injection of saline or LH 60 min before blood collection. Animals pretreated with NIH-FSH-B1, or with doses of LH approximating the amount present in the NIH-FSH, had increased testosterone concentrations after LH stimulation compared to similarly stimulated saline pretreated animals. Pretreatment with more highly purified FSH Ex 199C at a lower dose than the minimum effective dose of NIH-FSH was also effective. There was no synergistic or additive effect when FSH Ex 199C and LH pretreatments were combined. FSH Ex 199C is more potent and contains appreciably less LH contamination than NIH-FSH-B1. The results obtained using FSH Ex 199C indicate that FSH, independent of LH contamination, can increase testes response to LH stimulation.

Animals↗
PubMedDate not supplied

Evidence of different actions of testosterone, estradiol, FSH, and LH on the growth axis.

To study the possible role of sexual hormones, Testosterone (T), Estradiol (E2), follicle-stimulating hormone (FSH), and luteinizing hormone (LH) on the growth axis, we examined the correlations between the sex, growth hormone (GH), insulin-like growth factor-1 (IGF-1), insulin-like growth factor binding protein 3 (IGFBP3), FSH, LH, T and E2, in growth retarded children ranging in age from 7 to 13 yr. All hormones were measured by Radioimmunoassay (RIA) in a pool of aliquots of samples obtained every 20 min over 12 h (overnight) in each child. Multivariate statistical analysis was performed. We have found: a) Thai only FSH concentrations were significantly higher in girls than in boys; b) A positive correlation between T-IGF-1; T-IGFBP3; FSH-LH; FSH-IGF-1; FSH-IGFBP3, LH-IGF-1, LH-IGFBP3 the sex-FSH; and the sex-IGFBP3 c) A high positive correlation between plasmatic E2 and IGF-1/IGFBP3 ratio (an index of free, active IGF-1). We concluded that the sex, FSH, LH, T and E2 influence the growth axis. The sex through IGFBP3; LH, FSH, and T through IGF1 and IGFBP3; E2 through the IGF-1/IGFBP3 ratio, an index of active IGF-1.

Adolescent↗
PubMed2003

Combination of FSH priming and hCG priming for in-vitro maturation of human oocytes.

BACKGROUND: The purpose of this study was to determine if there is any additional benefit from FSH priming in addition to hCG priming on in-vitro maturation (IVM) programmes. METHODS: Sixty women with polycystic ovary syndrome (PCOS) who underwent 68 IVM cycles were randomized by computer-generated numbers to receive FSH stimulation or not. Thirty-five cycles were pretreated with 75 IU rFSH for 6 days, and 33 cycles were not. Every cycle was given hCG 10,000 IU 36 h before oocyte retrieval. Immature oocytes were matured in vitro and fertilized by ICSI, and the resulting embryos were replaced on day 2 or 3. RESULTS: A total of 1528 immature oocytes were recovered. The overall maturation and fertilization rates were 74.2 and 72.8% respectively. After embryo transfer, 23 pregnancies resulted (33.8%). The oocyte numbers and endometrial thickness were similar between FSH-primed and non-FSH-primed groups. Serum estradiol level on the day of hCG injection was significantly higher in the FSH-primed group than in the non-FSH-primed group (377.2 pmol/l versus 143.8 pmol/l, P=0.001). The maturation rate, fertilization rate and pregnancy rate were 76.5, 75.8 and 31.4% respectively for FSH-primed group, and 71.9, 69.5 and 36.4% respectively for non-FSH-primed group (all not significant). CONCLUSIONS: IVM is a feasible treatment for women with PCOS. FSH priming has no additional beneficial effect on IVM.

Adult↗
PubMed2002

Establishment of FSH-responsive cell lines by transfection of pre-ovulatory human granulosa cells with mutated p53 (p53val135) and Ha-ras genes.

Human granulosa cells were immortalized by transfection of the primary cells with a mutated p53 gene in combination with the Harvey-ras oncogene, yielding established cell lines designated HGP53. Here we report that forskolin, 8-Br-cAMP and FSH modulate cell growth and steroidogenesis in HGP53 cells. Low concentrations of 8-Br-cAMP or FSH stimulated cell proliferation, while higher doses attenuated cell proliferation. Progesterone production was already evident at an FSH concentration of 0.3 mIU/ml and was maximally stimulated (50-135-fold) at 50 mIU/ml of FSH. Expression levels of steroidogenic acute regulatory protein (StAR), adrenodoxin and cytochrome P450scc were enhanced 64-, 48- and 3.1-fold respectively by FSH stimulation. Dexamethasone enhanced FSH/cAMP-induced steroidogenesis and this effect involved a marked elevation in the intracellular level of adrenodoxin and P450scc, concomitantly with a marked decrease in StAR. Conversely, basic fibroblast growth factor attenuated FSH-stimulated progesterone production, and this effect involved reductions in adrenodoxin, P450scc and StAR levels. These data suggest that the rate of steroidogenesis may be determined by the ratio of StAR and P450scc, rather than by the level of each protein alone. Whereas FSH at a low dose slightly reduced apoptosis induced by serum withdrawal from HGP53 cells, higher doses enhanced it. Dexamethasone dramatically attenuated FSH- or forskolin-enhanced apoptosis. In conclusion, FSH-dependent mechanisms of differentiation, luteinization and apoptosis can be preserved in human granulosa cells immortalized by mutated p53. Moreover, this system lends itself to studies on cross-talk between the endocrine and paracrine factors that control these processes.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1999

Effects of acute exposure to PCBs 126 and 153 on anterior pituitary and thyroid hormones and FSH isoforms in adult Sprague Dawley male rats.

3,3'4,4',5-Pentachlorobiphenyl (PCB 126) and 2,2',4,4',5,5'-hexachlorobiphenyl (PCB 153) were administered to adult male rats in order to identify sensitive indicators of endocrine disruption. We tested the hypothesis that PCB exposure modifies follicle-stimulating hormone (FSH) pituitary isoforms, as well as the pituitary and serum concentrations of FSH, luteinizing hormone (LH), growth hormone, prolactin, and thyroid-stimulating hormone (TSH). Effects on serum levels of thyroxine (T4) and testosterone (T), and prostate androgen receptor content, were also tested. In one experiment, 5 groups of 8 rats each received two i.p. injections, one day apart, of either corn oil or 6.25, 25, 100 or 400 micrograms/kg/day of PCB 126. Decreases (p < 0.05) in the serum concentrations of T4 and LH started at doses of 25 and 100 micrograms/kg/day, respectively. Serum FSH concentrations were reduced (p = 0.07) in the highest dose group. In contrast, pituitary content of FSH and LH increased with PCB-126 doses (p = 0.004, p = 0.002, respectively). Despite changes in reproductive hormones, PCB-126 had no effect on the androgen receptor content of the prostate. The effect of PCB-126 was tested in the hemicastrated rat, and suggested adverse effects on testosterone secretion. To test the effects of PCB exposure on FSH pituitary isoforms, 4 groups of 10 male rats received two i.p. injections, one day apart, of either corn oil, PCB 153 (25 mg/kg/day), estradiol-17 beta (E2; 20 micrograms/kg/day), or PCB 126 (0.1 mg/kg/day). Serum T4 levels were higher (p < 0.01) in the E2 and PCB 153 groups, and slightly reduced in the PCB 126-treated groups, compared to controls. Simultaneous purification of pituitary FSH and TSH isoforms was performed by HPLC, using two chromatofocusing columns in series. In contrast to TSH isoforms, the distribution of FSH isoforms over the chromatography run differed slightly between treatment groups; the amounts of FSH isoform eluted during the pH gradient were lower (p < 0.05) in E2 and PCB 153-treated rats than in control or PCB 126-treated rats. The similarity between the effects of E2 and PCB 153 on T4 and FSH isoforms supports the contention that PCB 153 possesses estrogenic properties. Serum LH and T4 concentrations were the most sensitive and practical endocrine indicators of PCBs 126 and 153 exposure in male rats.

Animals↗
PubMed1982

Reevaluation of the effect of follicle-stimulating hormone on the steroidogenic capacity of the testis: the effects of neuraminidase-treated FSH preparations.

The ability of FSH treatment to increase the amount of androgen produced by the testis in response to maximum LH stimulation may be an effect of the LH contamination of the FSH preparations. To examine this question, 3 FSH preparations of different potencies and degrees of LH contamination or their neuraminidase-treated derivatives were administered to hypophysectomized immature rats for 5 days. The capacity of the testes to produce androgens in vitro was assessed at the end of the treatment period. Neuraminidase treatment reduces the in vivo activity of ovine and bovine FSH but does not alter the activity of ovine or bovine LH. Neuraminidase treatment of one FSH preparation (NH-bFSH-B1) did not reduce the ability of this FSH preparation to increase the response of the testis to LH stimulation in vitro. This suggests that the considerable LH contamination of the NIH-bFSH-B1 may be responsible for its effect. However, neuraminidase treatment of 2 more highly purified FSH preparations (bFSH-199C and NIH-oFSH-S13) abolished or greatly reduced the ability of these preparations to increase testicular weight and the response to LH in vitro. It is concluded that the ability of highly-purified FSH preparations to increase the amount of androgen produced by the testis is due to FSH activity and not the contaminating LH.

Androgens↗
PubMed1990

Bioactive and immunoreactive FSH in serum of normal and oligospermic men.

In men suffering from idiopathic oligospermia and azoospermia the hypothesis was tested that decreased spermatozoa production could be due in part to inadequate hormonal stimulation of spermatogenesis. In 53 healthy male subjects with normal spermatozoa production (n = 10), varying degrees of oligospermia (n = 40), and azoospermia (n = 3), serum immunoreactive LH, testosterone (T), and oestradiol (E2), and immunoreactive and bioactive FSH concentrations were determined. FSH bioactivity was estimated using the rat granulosa cell aromatase bioassay. Mean LH, T, and E2 levels were similar in the control group (spermatozoa concentration greater than 40 x 10(6)/ml) compared with men exhibiting mild (10-20 x 10(6)/ml), moderate (5-10 x 10(6)/ml), or severe oligospermia (1-5 x 10(6)/ml), and in the azoospermia group. An inverse correlation was found between immunoreactive FSH levels and spermatozoa concentration (P less than 0.05), with elevated levels (twofold increase) of FSH in the combined severe oligospermia and azoospermia (P less than 0.01) groups. Moreover, augmented (P less than 0.01) bioactive FSH levels were also observed in this group of patients. The mean bioactive to immunoreactive FSH ratio was also negatively correlated with sperm counts (P less than 0.005). In addition, T/LH ratios were inversely correlated with immunoreactive (P less than 0.05) and bioactive (P less than 0.05) FSH, which may indicate that altered Leydig cell function is involved in the augmented secretion of FSH. The data presented in this study indicate that immunoreactive FSH, as measured in oligospermia and azoospermia, does not exhibit decreased bioactivity.

Estradiol↗
PubMed1994

Increased 17-OH-progesterone levels following hCG stimulation in men with idiopathic oligozoospermia and raised FSH levels.

Leydig cell function was investigated in 71 men with idiopathic oligospermia and compared to 14 fertile controls by assessing the steroidogenic response to GnRH and the repetitive administration of hCG (1500 IU x3). The oligospermic men were divided into two groups according to their basal serum FSH values (FSH < 8, n = 35; FSH > 8, n = 36), this level being defined by the mean + 3 SD of the levels in normal men (3.71 + 4.08 mIU/ml). Oversecretion of LH was supported by the findings of: (a) higher basal LH levels (p < 0.0001) in both oligospermic groups, although still within the normal range; (b) higher Dmax LH and area LH (p < 0.0001) levels in the FSH > 8 group; (c) a strong position correlation (p < 0.001) of the above parameters with the respective levels of FSH. No difference in basal testosterone levels was observed between the three groups, whereas basal levels of 17-OHP were significantly higher (p < 0.05) in the group with FSH > 8. The testosterone/LH ratio was significantly (p < 0.0001) lower in the FSH > 8 group, and was correlated inversely to the basal blood levels of FSH (p < 0.0001) and to the area LH (p < 0.04). After the hCG test, there was no difference in the testosterone and oestradiol response between the groups, whereas the secretion of 17-OHP and the ratio of 17-OHP/testosterone was significantly higher (p < 0.0001) in the group with FSH > 8 compared with the other two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

17-alpha-Hydroxyprogesterone↗
PubMed2005

Repeat ovum pick-up and in vitro embryo production from adult ewes with and without FSH treatment.

Ovum pick-up (OPU) was performed three times on adult ewes after synchronization with (n = 4) or without (n = 4) FSH treatment to investigate the effects of FSH treatment on the number of ovarian follicles, oocytes recovered, oocyte quality and development in vitro. FSH treatment increased the number of ovarian follicles (85 vs 162) and oocytes recovered (33 vs 91), although recovery rate was similar for ewes with and without FSH (91/162, 56.2% and 33/85, 38.8% respectively). Of the oocytes recovered, those classified as grades I and II were similar between ewes with (78/91, 85.7%) and without FSH treatment (27/33, 81.8%). The number of ovarian follicles was similar after repeated OPU for ewes treated with FSH, but for ewes not treated with FSH the number of ovarian follicles decreased with repeated OPU. The number of oocytes recovered decreased for FSH-treated ewes only, while the oocyte recovery rate and proportion of oocytes classified as grades I and II were not affected by repeated OPU. Oocyte cleavage (46/78, 58.9% and 19/24, 79.2%) and blastocyst formation (35/46, 76.1% and 12/19, 63.2% respectively) were similar for ewes with and without FSH treatment. The number of ovarian follicles varied between ewes (p < 0.05) although the number of oocytes recovered and oocyte development in vitro were similar between ewes.

Animals↗
PubMed2005

Lamprey GnRH-III stimulates FSH secretion in barrows.

Although studies have indicated that follicle-stimulating hormone (FSH) and luteinizing hormone (LH) release can be dissociated in the pig, the underlying mechanisms are still to be answered. Since it was demonstrated that lamprey gonadotropin-releasing hormone (l-GnRH-III) has preferential FSH-releasing potency in several mammalian species, we have investigated the gonadotropin-releasing activity of l-GnRH-III in barrows. Each of nine barrows (body weight: 85-90 kg; age: 207 days) received 2 ml saline (S-barrow), followed by 150 microg l-GnRH-III (1.6-1.7 microg/kg body weight) dissolved in 2 ml saline intramuscularly 7 days later. Three pre-treatment and 13 post-treatment blood samples were taken at intervals of 30 min to 8 h to assess basal and treatment-associated concentrations of FSH and LH, respectively, by radioimmunoassay. Animals were defined as having responded to treatment if, 2 h post-treatment, plasma FSH and/or LH levels were >3 SD of the respective basal concentrations. There was no treatment-associated FSH response after saline treatment, but a clear FSH response in all l-GnRH-III-injected barrows. On average, the maximum FSH level (205% of the basal concentration) was observed at 1 h post-treatment. Mean FSH values were elevated until 10 h post-treatment. There was no LH response either to saline or to l-GnRH-III. In conclusion, this study demonstrates a selective FSH-releasing activity of 150 microg l-GnRH-III in barrows. Further studies are needed to investigate whether this effect is ubiquitous in the pig and what the physiological relevance is.

Animals↗
PubMed1970

Correlation of serum follicular stimulating hormone (FSH) and luteinizing hormone (LH) as measured by radioimmunoassay in disorders of sexual development.

Serum FSH and LH levels in 104 patients with disorders of sexual development were determined by radioimmunoassay and compared with serum FSH and LH levels in 164 normal individuals.32 of 35 gonadal dysgenesis patients (ages 4.8-18.9 yr) had serum FSH levels which were elevated above the range of normal for chronological age, and 19 had serum LH levels similarly elevated. All patients with elevated serum LH levels were 11 yr of age or older. However, 8 of 10 gonadal dysgenesis patients, ages 4.8-10.9 yr, had serum FSH levels elevated above the normal range. In accord with these observations was the finding that in normal girls, serum FSH levels may increase at an earlier age than do serum LH levels (FSH, 5-8 yr of age; LH, 9-10 yr of age). These data indicate that serum FSH determinations may be helpful in diagnosing gonadal dysgenesis during childhood. Serum gonadotropin levels within the range of normal for chronological age were found in 2 of 18 girls with idiopathic isosexual precocity. The other 16 had serum FSH levels elevated above the range of normal for chronological age, and 8 also had serum LH levels similarly elevated. In all instances serum FSH and LH levels were in the range expected for the stage of sexual development. In 35 boys, ages 13.1-17.8 yr, with delayed adolescence, serum gonadotropin levels correlated with stage of sexual development and, therefore, were often less than those expected for age.8 patients with premature pubarche, 5 patients with premature thelarche, and 3 patients with adolescent gynecomastia had serum gonadotropin levels within the range of normal for chronological age.

Adolescent↗
PubMed2006

Recombinant versus highly-purified, urinary follicle-stimulating hormone (r-FSH vs. HP-uFSH) in ovulation induction: a prospective, randomized study with cost-minimization analysis.

BACKGROUND: Both recombinant FSH (r-FSH) and highly-purified, urinary FSH (HP-uFSH) are frequently used in ovulation induction associated with timed sexual intercourse. Their effectiveness is reported to be similar, and therefore the costs of treatment represent a major issue to be considered. Although several studies about costs in IVF have been published, data obtained in low-technology infertility treatments are still scarce. METHODS: Two hundred and sixty infertile women (184 with unexplained infertility, 76 with CC-resistant polycystic ovary syndrome) at their first treatment cycle were randomized and included in the study. Ovulation induction was accomplished by daily administration of rFSH or HP-uFSH according to a low-dose, step-up regimen aimed to obtain a monofollicular ovulation. A bi- or tri-follicular ovulation was anyway accepted, whereas hCG was withdrawn and the cycle cancelled when more than three follicles greater than or equal to 18 mm diameter were seen at ultrasound. The primary outcome measure was the cost of therapy per delivered baby, estimated according to a cost-minimization analysis. Secondary outcomes were the following: monofollicular ovulation rate, total FSH dose, cycle cancellation rate, length of the follicular phase, number of developing follicles (>12 mm diameter), endometrial thickness at hCG, incidence of twinning and ovarian hyperstimulation syndrome, delivery rate. RESULTS: The overall FSH dose needed to achieve ovulation was significantly lower with r-FSH, whereas all the other studied variables did not significantly differ with either treatments. However, a trend toward a higher delivery rate with r-FSH was observed in the whole group and also when results were considered subgrouping patients according to the indication to treatment. CONCLUSION: Considering the significantly lower number of vials/patient and the slight (although non-significant) increase in the delivery rate with r-FSH, the cost-minimization analysis showed a 9.4% reduction in the overall therapy cost per born baby in favor of r-FSH.

Adult↗
PubMed1975

FSH stimulation of testicular androgen binding protein (ABP): comparison of ABP response and ovarian augmentation.

Production of testicular androgen binding protein (ABP), ceases following hypophysectomy and can be stimulated by FSH. Within 24 h after the administration of FSH, ABP can be measured in caput epididymis supernatant and by 4 days after FSH treatment, the concentration of ABP reaches a plateau. In a 3-day assay, ABP production in immature hypophysectomized rats was stimulated by 31 mug NIH-FSH-P1 per day (0.08 U NIH-FSH-P1 per 3 days) which is comparable to the sensitivity of the ovarian weight augmentation test in hypophysectomized rats. The relative ovarian weight augmenting and ABP stimulating activities of various FSH preparations were in agreement, suggesting that the biological stimulus of the ABP response is, in fact, FSH. The ABP response to FSH could become a useful testicular bioassay for FSH. Such an assay would be more practicle if ABP could be measured by a radioimmunoassay.

Animals↗
PubMed1997

Serum FSH levels in women with polycystic ovary syndrome during ovulation induction using down-regulation and urofollitropin.

OBJECTIVE: To evaluate retrospectively the use of serum FSH levels and to correlate them with follicular growth in a clinical ovulation induction program. METHODS: Twenty women with infertility due to anovulation associated with polycystic ovary syndrome (PCOS) were studied. The patients were down-regulated with a long GnRH agonist protocol and stimulated with purified urofollitropin, using a low-dose step-up regimen. Repeated serum samples were drawn and transvaginal ultrasound scans were-performed. During the exogenous FSH therapy serum FSH levels resulting in continuous follicular growth were analyzed, as well as the rates of ovulation, pregnancy, cancellation and conversion to in vitro fertilization (JVF). RESULTS: Thirty-two out of fifty treatment cycles led to ovulation, resulting in five term pregnancies. Eight cycles were converted to IVF/embryo transfer due to multiple follicular growth. They resulted in two pregnancies. Ten cycles were cancelled because of impaired follicular growth. The serum FSH levels (median 6 IU/I) resulting in continuous growth of the follicles were relatively stable within patients (variation 15%) but varied considerably between patients (45%). The relationship between FSH dose and serum level was different for lean and obese PCOS patients after subcutaneously injected urofollitropin CONCLUSIONS: There seems to be a difference in resorption/metabolism between lean and obese PCOS patients with regard to s.c. injected FSH. The intra-patient coefficient of variation (C.V.) of the serum FSH response level was quite low, as was the C.V. of the FSH dose at the response level. This allowed a more rapid dose adjustment in subsequent cycles. Analysis of serum FSH during induction of ovulation with gonadotropins seems to be of limited value in clinical programs.

Adult↗
PubMed1989

Differences in the plasma concentrations of FSH and LH in ovariectomized Booroola FF and ++ ewes.

During 12 sampling days before ovariectomy the mean plasma FSH but not LH concentrations in FF ewes were higher (P less than 0.01) than those in ++ ewes (16 ewes/genotype). After ovariectomy increases in the concentrations of FSH and LH were noted for ewes of both genotypes within 3-4 h and the rates of increase of FSH and LH were 0.18 ng ml-1 h-1 and 0.09 ng ml-1 h-1 respectively for the first 15 h. From Days 1 to 12 after ovariectomy, the overall mean +/- s.e.m. concentrations for FSH in the FF and ++ ewes were 8.1 +/- 0.6 and 7.1 +/- 0.4 ng/ml respectively and for LH they were 2.7 +/- 0.3 and 2.1 +/- 0.2 ng/ml: these differences were not statistically significant (P = 0.09 for both FSH and LH; Student's t test). However, when the frequencies of high FSH or LH values after ovariectomy were compared with respect to genotype over time, significant F gene-specific differences were noted (P less than 0.01 for both FSH and LH; median test). In Exp. 2 another 21 ewes/genotype were blood sampled every 2nd day from Days 2 to 60 after ovariectomy and the plasma concentrations of FSH and LH were more frequently higher in FF than in ++ ewes (P less than 0.01 for FSH and LH). The F gene-specific differences in LH concentration, observed at 21-36 days after ovariectomy were due to higher mean LH amplitudes (P less than 0.025) but not LH peak frequency in FF than in ++ ewes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Effect of an increase in FSH on the production of gonadotrophin-surge-attenuating factor in women.

Gonadotrophin-surge-attenuating factor (GnSAF) is a putative nonsteroidal ovarian factor that is produced by FSH and that attenuates the LH surge in superovulated women. To study further the role of FSH in the production of GnSAF, 12 normally ovulating women were divided into two groups and investigated during two cycles: a cycle treated with placebo (control) and a cycle treated with FSH. In group 1 (n = 6), placebo (2 ml 0.9% normal saline) or FSH (450 iu) was injected i.m. on day 2 of the cycle (09:00 h). In group 2 (n = 6), placebo (2 ml 0.9% normal saline) or FSH (225 iu) was injected on the day (09:00 h) on which the dominant follicle was 14-15 mm in diameter, as measured by ultrasound (i.e. after the pituitary had been primed by endogenous oestrogen for several days). The response of LH over 30 min (delta LH) to an injection of 10 micrograms LHRH i.v. (bioassay for GnSAF in vivo) was investigated once a day in group 1, and 4, 8, 12 and 24 h after the injection of placebo or FSH in group 2. In group 1, delta LH was significantly attenuated 12 h after treatment with FSH compared with the control cycles, while serum oestradiol concentrations increased 24 h after the injection of FSH. The decrease in delta LH lasted for the period when the FSH concentration was increased (3 days). A significant decrease in the basal concentration of LH was correlated with the increase in the oestradiol concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Estradiol↗
PubMed1998

Testosterone, LH and FSH episodic secretory patterns in GnRH-immunized bulls.

The objective was to determine: (i) the secretory patterns of LH, FSH and testosterone in bulls, and the temporal relationships between the pulses of these hormones; and (ii) the effect of GnRH immunization on these parameters. Friesian bulls (n = 72) were given a primary immunization on day 0 (10-week-old) and a booster immunization on either day 28 (n = 36) or day 56 (n = 36) against either a GnRH-human serum albumin (HSA) conjugate (n = 48) or HSA (n = 24; control). On the basis of GnRH antibody titres at a plasma dilution of 1:160, 1 week after booster immunization, 12 GnRH-immunized and six control bulls from each booster-immunized group were selected and allocated to one of three groups: control bulls and bulls with medium and high antibody titres (0.3, 32 and 51% binding, respectively; pooled SED 4.3%). Blood samples were taken from these animals (n = 36) every 15 min for 8 h on three occasions: (i) 2 weeks after booster immunization when bulls were 4-5 months of age (prepubertal); (ii) at 7 months of age (peripubertal); and (iii) at 11 months of age (post-pubertal). Data were analysed by PULSAR, ANOVA and chi-squared test. The mean antibody titre of the high antibody titre group was greater (P < 0.05) than that of the medium antibody titre group in prepubertal bulls only, but the mean antibody titres of both antibody titre groups were greater (P < 0.05) than that of the control bulls at all times. The frequency and amplitude of LH and FSH pulses in the control bulls were greater (P < 0.05) during prepuberty than after puberty. The frequency, amplitude and duration of LH pulses were greater (P < 0.05) in control bulls than those in medium and high antibody titre bulls at prepuberty. The mean and basal concentrations of FSH and the amplitude and duration of FSH pulses were greater (P < 0.05) in the control bulls than in the high antibody titre bulls at prepuberty. The frequency of testosterone pulses was greater (P < 0.05) in the control bulls than in the medium and high antibody titre bulls at peripuberty. The mean and basal concentrations and pulse amplitude of testosterone were greater (P < 0.05) in high antibody titre bulls than in control bulls after puberty. There was a close temporal relationship between LH and FSH (62.5% of LH pulses were followed by FSH pulses within 75 min) at prepuberty in the control bulls but there was no relationship after puberty. The opposite trend occurred in the high antibody titre bulls, that is, there was no relationship between LH and FSH at prepuberty but there was a close temporal relationship after puberty. The temporal relationship between LH and testosterone was closest at peripuberty (86.7%) in the control bulls, but increased in the high antibody titre bulls from 0% at prepuberty to 57.1% after puberty. In summary, there was an age-related decrease in LH and FSH pulse frequency and amplitude and also in the temporal relationships between these hormones in control bulls. Prepubertal GnRH immunization had a suppressing effect on the pulsatile release of LH, FSH and testosterone before but not after puberty. The presence of high amplitude testosterone pulses in the GnRH-immunized bulls after puberty indicates that the long-term tonic release of LH may be sufficient to initiate a late pubertal-type increase in testosterone concentrations.

Analysis of Variance↗
PubMed1989

Treatment of ovariectomized heifers with bovine follicular fluid specifically suppresses pituitary levels of FSH-beta mRNA.

To investigate the inhibin-induced suppression of FSH secretion by the anterior pituitary, chronically ovariectomized heifers (three per group) were treated for 56-58 h with either steroid-free bovine follicular fluid (bFF; 8 ml i.v. every 8 h) or 0.9% (w/v) NaCl (8 ml i.v. every 8 h). Blood was withdrawn at 8-h intervals for analysis of plasma concentrations of FSH and LH by radioimmunoassay. At the end of the treatment period, heifers were slaughtered and pituitary glands recovered for determination of gonadotrophin contents and levels of mRNA encoding FSH-beta, LH-beta, TSH-beta and common alpha glycoprotein hormone subunits using [32P]cDNA probes in total RNA dot and Northern blot assays. Treatment with bFF markedly suppressed plasma FSH by 85% (P less than 0.001 compared with pretreatment period), but did not affect plasma LH concentrations. Plasma FSH and LH concentrations did not vary significantly in the saline-injected control heifers. The level of FSH-beta subunit mRNA was reduced by 60% (P less than 0.001) in heifers treated with bFF, whereas no significant differences between control and bFF-treated heifers were observed in the levels of mRNA encoding LH-beta, TSH-beta or common alpha subunits. Treatments with bFF, however, did not affect pituitary content of either FSH or LH. These results support the conclusion that inhibin exerts its selective suppressive effect on the secretion of FSH by the bovine pituitary, at least in part, by directly inhibiting expression of the gene encoding the FSH-beta subunit.

Animals↗