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PubMed1977

Luteinizing hormone (LH), follicle-stimulating hormone, and testosterone responses to consecutive injections of D-leucine-6-LH-releasing hormone ethylamide in normal men.

Luteinizing hormone (LH), follicle-stimulating hormone (FSH), and testosterone (T) responses to three consecutive intravenous injections of D-Leu-6-LH-releasing hormone ethylamide (D-Leu-6-LH-RH-EA) at 3-hour intervals were studied in six healthy, fertile, male volunteers 34.2+/-1.6 years of age. Each man received three injections of 20 microng of D-Leu-6-LH-RH-EA at 6:00 A.M., 9:00 A.M., and 12:00 noon, respectively. Blood samples were obtained before the first injection and at 1, 2, 3 (before the second injection), 4, 5, 6 (before the third injection), 7, 8 and 9 hours after the beginning of the test. Serum levels of LH, FSH, and T were determined by radioimmunoassay with the double-antibody technique. The response to the first injection of D-Leu-6-LH-RH-EA confirmed the longer duration of the stimulation of LH and FSH release caused by this compound as compared with that caused by LH-RH. Serum T levels rose significantly, almost paralleling the variations experienced with gonadotropins. The second injection caused a slight increase in LH and T responses in relation to the first injection. Two and three hours after administration, the third stimulus resulted in hormone levels lower than those obtained with the first two injections. Possible explanations for this finding might be a reduction of pituitary responsiveness as a result of multiple stimulation with D-Leu-6-LH-RH-EA, or spontaneous circadian variation of the pituitary response, or a combination of factors.

Adult↗
PubMed2000

Age-dependent effect of Freund's adjuvant on 24-hour rhythms in plasma prolactin, growth hormone, thyrotropin, insulin, follicle-stimulating hormone, luteinizing hormone and testosterone in rats.

The effect of Freund's adjuvant administration on 24-hour changes of plasma prolactin, growth hormone (GH), thyrotropin (TSH), insulin, follicle-stimulating hormone (FSH), luteinizing hormone (LH) and testosterone were studied in young (2 months) and aged (18 months) male Wistar rats. Rats were injected s.c. with Freund's adjuvant or adjuvant's vehicle and, 18 days later, they were killed at 6 different time intervals throughout a 24-hour cycle to measure circulating hormone levels by specific RIAs. Young rats receiving adjuvant's vehicle exhibited significant time-of-day-dependent variations in plasma TSH, LH and testosterone, with maximal levels at 1300 h, 0100 h and 1700 h, respectively. Prolactin and insulin levels, analyzed globally in a factorial ANOVA, showed significant time-of-day changes with maximal levels at 1300 - 1700 h and 2100 h, respectively. The daily rhythms in plasma LH and testosterone found in young rats were not longer observed in Freund's adjuvant-injected rats, while as far as TSH, a second peak was observed at 0100 h after Freund's adjuvant administration. Twenty-four hour rhythms in circulating TSH, LH and testosterone were blunted in old rats receiving either Freund's adjuvant or its vehicle. Aged rats exhibited significantly higher circulating levels of prolactin, and lower levels of GH, TSH, FSH and testosterone. The results indicate that secretion of prolactin, GH, TSH, FSH and testosterone are age-dependent, as are the responses of TSH, LH and testosterone to Freund's adjuvant administration.

Aging↗
PubMedDate not supplied

Control of gonadotropin secretion by follicle-stimulating hormone-releasing factor, luteinizing hormone-releasing hormone, and leptin.

Fractionation of hypothalamic extracts on a Sephadex G-25 column separates follicle-stimulating hormone-releasing factor (FSHRF) from luteinizing hormone-releasing hormone (LHRH). The FSH-releasing peak contained immunoreactive lamprey gonadotropin-releasing hormone (lGnRH) by radioimmunoassay, and its activity was inactivated by an antiserum specific to lGnRH. The identity of lGnRH-III with FSHRF is supported by studies with over 40 GnRH analogs that revealed that this is the sole analog with preferential FSH-releasing activity. Selective activity appears to require amino acids 5-8 of lGnRH-III. Chicken GnRH-II has slight selective FSH-releasing activity. Using a specific lGnRH-III antiserum, a population of lGnRH-III neurons was visualized in the dorsal and ventral preoptic area with axons projecting to the median eminence in areas shown previously to control FSH secretion based on lesion and stimulation studies. Some lGnRH-III neurons contained only this peptide, others also contained LHRH, and still others contained only LHRH. The differential pulsatile release of FSH and LH and their differential secretion at different times of the estrous cycle may be caused by differential secretion of FSHRF and LHRH. Both FSH and LHRH act by nitric oxide (NO) that generates cyclic guanosine monophosphate. lGnRH-III has very low affinity to the LHRH receptor. Biotinylated lGnRH-III (10(-9) M) labels 80% of FSH gonadotropes and is not displaced by LHRH, providing evidence for the existence of an FSHRF receptor. Leptin has equal potency as LHRH to release gonadotropins by NO. lGnRH-III specifically releases FSH, not only in rats but also in cows.

Animals↗
PubMed2002

Lamprey gonadotropin hormone-releasing hormone-III has no selective follicle-stimulating hormone-releasing effect in rats.

Lamprey gonadotropin releasing-hormone (LGnRH)-III, a hypothalamic neurohormone recently isolated from sea lamprey, was reported to have a selective stimulatory effect on follicle-stimulating hormone (FSH) release in rats and suggested to be the mammalian FSH-releasing factor. In this study, we determined the relative luteinizing hormone (LH)- and FSH-releasing potency of LGnRH-III compared to mammalian gonadotropin-releasing hormone (LHRH) in normal female rats, ovariectomized (OVX) and oestrogen/progesterone substituted rats and the superfused rat-pituitary cell system. The specificity of LGnRH-III for the mammalian LHRH receptor was investigated by blocking the receptor with an LHRH antagonist, MI-1544. In vitro, LGnRH-III dose-dependently stimulated both LH and FSH secretion from rat pituitary cells at 10(-7) to 10(-5) M concentrations, while LHRH stimulated gonadotropin secretion at a 1000-fold lower doses (10(-10) to 10(-8) M). The difference between its LH- and FSH-releasing potency was similar to that of LHRH. LGnRH-III bound to high affinity binding sites on rat pituitary cells with a Kd of 6.7 nM, B(max)=113 +/- 27 fmol/mg protein. In vivo, LGnRH-III also stimulated both LH and FSH secretion in a dose-dependent manner and, similar to LHRH, induced a greater rise in the serum LH than the FSH level. In normal cycling rats, it showed 180-650-fold weaker potency than LHRH in stimulating LH secretion and 70-80-fold weaker effect in stimulating FSH secretion. In OVX rats, LGnRH-III demonstrated a similarly weak effect on both gonadotropins. It was found to be 40-210-fold less potent than LHRH regarding LH release and 50-160-fold weaker regarding FSH release. LHRH-receptor antagonist MI-1544 prevented both the LH- and the FSH-releasing effect of LGnRH-III both in vitro and in vivo. These results do not support the hypothesis that LGnRH-III might be the mammalian FSH-releasing factor but demonstrate that it is a weak agonist for the pituitary LHRH receptor and stimulates both gonadotropins in a dose-dependent fashion.

Animals↗
PubMed1987

Effects of gonadotropin-releasing hormone pulse-frequency modulation on luteinizing hormone, follicle-stimulating hormone and testosterone secretion in hypothalamo/pituitary-disconnected rams.

The effects of changes in pulse frequency of exogenously infused gonadotropin-releasing hormone (GnRH) were investigated in 6 adult surgically hypothalamo/pituitary-disconnected (HPD) gonadal-intact rams. Ten-minute sampling in 16 normal animals prior to HPD showed endogenous luteinizing hormone (LH) pulses occurring every 2.3 h with a mean pulse amplitude of 1.11 +/- 0.06 (SEM) ng/ml. Mean testosterone and follicle-stimulating hormone (FSH) concentrations were 3.0 +/- 0.14 ng/ml and 0.85 +/- 0.10 ng/ml, respectively. Before HPD, increasing single doses of GnRH (50-500 ng) elicited a dose-dependent rise of LH, 50 ng producing a response of similar amplitude to those of spontaneous LH pulses. The effects of varying the pulse frequency of a 100-ng GnRH dose weekly was investigated in 6 HPD animals; the pulse intervals explored were those at 1, 2, and 4 h. The pulsatile GnRH treatment was commenced 2-6 days after HPD when plasma testosterone concentrations were in the castrate range (less than 0.5 ng/ml) in all animals. Pulsatile LH and testosterone secretion was reestablished in all animals in the first 7 days by 2-h GnRH pulses, but the maximal pulse amplitudes of both hormones were only 50 and 62%, respectively, of endogenous pulses in the pre-HPD state. The plasma FSH pattern was nonpulsatile and FSH concentrations gradually increased in the first 7 days, although not to the pre-HPD range. Increasing GnRH pulse frequency from 2- to 1-hour immediately increased the LH baseline and pulse amplitude. As testosterone concentrations increased, the LH responses declined in a reciprocal fashion between Days 2 and 7. FSH concentration decreased gradually over the 7 days at the 1-h pulse frequency. Slowing the GnRH pulse to a 4-h frequency produced a progressive fall in testosterone concentrations, even though LH baselines were unchanged and LH pulse amplitudes increased transiently. FSH concentrations were unaltered during the 4-h regime. These results show that 1) the pulsatile pattern of LH and testosterone secretion in HPD rams can be reestablished by exogenous GnRH, 2) the magnitude of LH, FSH, and testosterone secretion were not fully restored to pre-HPD levels by the GnRH dose of 100 ng per pulse, and 3) changes in GnRH pulse frequency alone can influence both gonadotropin and testosterone secretion in the HPD model.

Animals↗
PubMed1990

Growth hormone responses to growth hormone-releasing hormone, clonidine and insulin-induced hypoglycemia in normal weight bulimic women.

The growth hormone (GH) responses to GH-releasing hormone (GHRH; 1 microgram/kg BW in an i.v. bolus), clonidine (150 micrograms in a single oral dose) and insulin (0.15 IU/kg BW in an i.v. bolus) induced hypoglycemia were evaluated in 7 normal weight bulimic women with regular menstrual cycles and in 7 age- and weight-matched normal women. In addition, the effect of thyrotropin-releasing hormone (TRH; 200 micrograms in an i.v. bolus) on serum thyroid-stimulating hormone (TSH) and GH levels was measured in the same subjects. Tests were carried out in random order on the 22nd days of the following menstrual cycles. A control test with the i.v. administration of normal saline instead of drugs was carried out 2 days after the TRH test. Basal GH levels were significantly higher in bulimic women than in normal controls; despite higher GH levels, bulimic women showed normal circulating concentrations of somatomedin-C (Sm-C). Serum GH levels remained unmodified during the control test. In contrast, the administration of GHRH, clonidine or insulin induced significant GH responses in all subjects. Bulimic and normal women showed comparable responses after GHRH, clonidine or hypoglycemia. The hypoglycemic response to insulin was similar in bulimic and control subjects. The administration of TRH was unable to increase the circulating levels of GH in the normal controls, whereas it significantly increased GH concentrations in 5 of 7 bulimic women.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1971

Dose-response relationship of luteinizing hormone to luteinizing hormone--releasing hormone in man.

In previous clinical studies with highly purified porcine luteinizing hormone-releasing hormone (LH-RH), administration of the somewhat arbitrarily chosen doses of 700-1500 mug resulted in increased serum levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH). The present study determined the minimum effective dose as well as the relationship of the response of serum LH and FSH to the dose of LH-RH administered. Three normal men received i.v. injections of 1.1-810 mug of LH-RH. A dose of 10 mug of LH-RH caused a statistically significant elevation in serum LH. 30 mug of LH-RH significantly increased serum FSH levels. A highly significant linear trend was observed in the log dose-response curve. The results indicate that both LH and FSH release occurs in man with doses of LH-RH much lower than previously used and that a linear log dose-response relationship can be obtained.

Adult↗
PubMed1994

Long-term effects of human growth hormone-releasing hormone and photoperiod on hormone release and puberty in dairy heifers.

Forty-eight Holstein dairy heifers (98.9 kg BW; 3 mo old) were subjected for 246 d to twice-daily s.c. injections of saline (CTL) or human growth hormone-releasing hormone (GRH; 5 micrograms/kg BW) and to photoperiods of 8 h of light (L): 16 h of dark (D) or 16L:8D according to a 2 x 2 factorial arrangement of treatments. Jugular blood samples were collected from 16 heifers at 3, 4, 8, and 11 mo of age to monitor prolactin, growth hormone, and estradiol-17 beta. Plasma progesterone concentrations were monitored weekly in all heifers as an index of puberty (> 1 ng/mL). Growth hormone release was induced by GRH (P < .001) throughout the trial; area under the GH curve (AUC) averaged 1,582 vs 3,643 ng.min-1.mL-1 in CTL vs GRH heifers. However, GRH-induced GH response was less (P < .05) after the second daily injection. There was also an interaction (P = .08) between GRH, photoperiod, and days of treatment on GRH-induced GH response; AUC was greater in GRH-16L:8D than in GRH-8L:16D heifers at 3 mo but less at 8 mo of age. The PRL concentrations were similar for both photoperiods at 3 mo (36.4 vs 41.7 ng/mL) and 8 mo (16.2 vs 12.8 ng/mL) of age but were greater in 16L:8D vs 8L:16D heifers at 4 mo (18.4 vs 39.3 ng/mL) and 11 mo (26.3 vs 44.1 ng/mL) of age (photoperiod x day interaction, P < .001). Photoperiod of 16L:8D vs 8L:16D reduced (P < .01) weight at puberty in CTL heifers (251 vs 303 kg BW) and to a lesser extent in GRH-treated heifers (271 vs 284 kg BW; GRH x photoperiod interaction, P = .10). In conclusion, GH response is maintained throughout 8 mo of GRH treatment, and a 16L:8D photoperiod will reduce age and weight at puberty in heifers. Furthermore, refractoriness to photoperiod-induced PRL changes was detected.

Aging↗
PubMed1992

Pubertal development in the male pig: effects of treatment with a long-acting gonadotropin-releasing hormone agonist on plasma luteinizing hormone, follicle stimulating hormone and testosterone.

The effects of a long-acting gonadotropin-releasing hormone (GnRH) agonist, [D-Trp6]-GnRH (GnRH-A) on developmental profiles of plasma luteinizing hormone (LH), follicle stimulation hormone (FSH) and testosterone (T), and pituitary responsiveness to exogenous GnRH were studied in male Dutch Landrace x Large White crossbred pigs from 1 to 30 wk of age. Group 1 control animals (control; n = 12) were injected subcutaneously in the neck with vehicle at 1 and 16 wk of age. Group 2 animals (early treatment; n = 10) were injected with 600 micrograms [D-Trp6]-GnRH at 1 wk and with vehicle at 16 wk. Group 3 animals (late treatment; n = 8) were injected with vehicle and 3 mg GnRH-A at 1 and 16 wk, respectively. Group 4 animals (early plus late treatment; n = 9) were injected at both 1 and 16 wk with GnRH-A. Blood was collected by brachiocephalic puncture at weekly or biweekly intervals, and through brachiocephalic cannulae, to determine longitudinal profiles of LH, FSH and T, and plasma gonadotropin responses to intravenous injection of GnRH (0.1 microgram/kg), respectively. In control animals, LH and FSH declined over the first 5 wk of postnatal life and peaked again at 10-14 wk. Levels of both hormones were basal from 18 to 30 wk. Plasma T was high in the first week, declined progressively over the next few weeks and remained low until 24 wk when a transient increment was noted. The LH and FSH responses to acute GnRH stimulation were similar at 7 and 14 wk and declined significantly at 23 wk of age.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Alcohol effects on luteinizing hormone releasing hormone-stimulated anterior pituitary and gonadal hormones in women.

Plasma luteinizing hormone (LH), follicle stimulating hormone (FSH), prolactin, estradiol (E2) and progesterone were measured in 24 normal, adult women before and after i.v. administration of 100 micrograms luteinizing hormone releasing hormone (LHRH; Factrel) and p.o. ingestion of an alcohol (0.694 g of alcohol per kg b.wt.) or placebo solution. Twelve subjects were studied during the early follicular phase of the menstrual cycle and 12 subjects were studied during the midluteal phase of the menstrual cycle. During each menstrual cycle phase, six subjects received placebo solution and six subjects received alcohol solution administered under double-blind conditions. Mean peak blood alcohol levels of 113 to 122 mg/dl were measured 45 to 60 min after initiation of alcohol intake. LHRH stimulated a significant increase in LH after both alcohol (P less than .0001) and placebo (P less than .0001) administration, and this LH increase was equivalent during the follicular and the luteal phases of the menstrual cycle. LHRH also stimulated a significant increase in FSH levels after both alcohol and placebo intake during the follicular and luteal phases of the menstrual cycle (P less than .0001). There were no significant differences in LHRH-stimulated FSH between the alcohol and placebo conditions. Plasma prolactin levels also increased significantly after LHRH administration during the follicular and luteal phases of the menstrual cycle (P less than .0001). There were no significant differences in prolactin response to LHRH administration between the alcohol or placebo conditions during the follicular and luteal phases of the menstrual cycle. Plasma E2 levels did not increase significantly after LHRH administration and placebo alcohol during the follicular phase of the menstrual cycle.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Effects of zeranol on reproduction in beef bulls: luteinizing hormone, follicle-stimulating hormone, and testosterone secretion in response to gonadotropin-releasing hormone and human chorionic gonadotropin.

Effects of zeranol on the maturation of the adenohypophyseal-gonadal axis were studied in beef bulls. Calves were implanted with 36 mg of zeranol at 3-month intervals from birth through 6 months of age (group 2, n = 10) or were not treated (control group 1, n = 10). After 9 months, group-2 calves were given implants of 36 mg of zeranol at 3-month intervals through 18 months of age (group 2B, n = 5) or were not reimplanted (group 2A, n = 5). Areas under the curves outlined by concentrations of luteinizing hormone (LH), follicle-stimulating hormone (FSH), and testosterone for 6 hours after the administration of 100 micrograms of gonadotropin-releasing hormone (GnRH) were calculated. Gonadotropin-releasing hormone was administered at 3-month intervals from 1.5 through 19.5 months of age. Areas under the curves for concentrations of testosterone for 4 hours after the administration of 10,000 IU of human chorionic gonadotropin (HCG) at 4.5, 7.5, and 10.5 months or 1,000 IU at 13.5 and 16.5 months of age also were calculated. The amount of FSH released was greater (P less than 0.05) for group-2 than for group-1 calves at 4.5 and 7.5 months of age. The amount of FSH released in groups 2A and 2B tended (P less than 0.10) to be greater than that for group 1. Significant differences between groups 2A and 2B were not observed. The amount of LH released at 7.5 months of age was less for groups 1 and 2 than that at earlier ages, and the decrease was greater (P less than 0.05) for group 2.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1977

Germinal cell aplasia: response of luteinizing hormone (LH), follicle-stimulating hormone (FSH), and testosterone to LH/FSH-releasing hormone with histopathologic correlation.

Five male patients with infertility due to biopsy-proven germinal cell aplasia were given a 100-microng bolus of luteinizing hormone (LH)/follicle-stimulating hormone (FSH)-releasing hormone (LRH), and the resultant LH, FSH, and testosterone responses were correlated with their histologic patterns on testicular biopsy. The basal and stimulated FSH values were elevated in four of five patients. Basal LH values were elevated in three patients, while two clearly had exaggerated LH and testosterone responses to LRH. Although there was little correlation between various parameters, elevated basal LH values were associated with Leydig cell hyperplasia. Higher basal FSH levels were present when fibrosis and complete aplasia of germinal elements were found in the same biopsy specimen, and the magnitude of the FSH response to LRH correlated positively with the basal concentration. The findings of elevated basal LH values, an exaggerated LH response to LRH, lack of testosterone response, and Leydig cell hyperplasia indicate a definite disturbance of the LH-testosterone axis in many patients with germinal cell aplasia. Therefore, the regulation of secretion of both gonadotropins appears to be abnormal in this disorder.

Adult↗
PubMed2004

Randomised phase III study of intravenous vinorelbine plus hormone therapy versus hormone therapy alone in hormone-refractory prostate cancer.

BACKGROUND: Vinorelbine (VRL) has been shown to be active in hormone-refractory prostate cancer (HRPC) in phase II studies, alone or in combination. Its moderate toxicity profile is well tolerated in elderly patients. PATIENTS AND METHODS: Patients with metastatic prostate cancer, progressive after primary hormonal therapy, were randomised to receive intravenous VRL 30 mg/m2 on days 1 and 8 every 3 weeks, and hydrocortisone 40 mg/day or hydrocortisone alone until disease progression. Centres could choose to add aminoglutethimide 1000 mg/day to hydrocortisone as second-line hormone therapy (HT) for all their patients. Randomisation was stratified by centre. Further chemotherapy was allowed after progression. The primary end point was progression-free survival (PFS). The final analysis was performed on a total of 414 patients. Reported results were all based on intention-to-treat analyses. All progressions and responses were reviewed by an independent panel. RESULTS: PFS was significantly prolonged in the VRL plus HT arm compared with the HT alone arm, according to the statistical hypothesis of the protocol (P=0.055 in the two-sided log-rank test with a pre-specified significance level of 10%). The 6-month PFS rates were 33.2% versus 22.8%, and the median durations of PFS were 3.7 versus 2.8 months. In the multivariate Cox analysis, which included age, Karnofsky performance status (PS), haemoglobin, alkaline phosphatase at study entry and number of prior hormonal treatments, the P value was decreased to 0.005. The prostate-specific antigen (PSA) response rate (> or =50% decline sustained for at least 6 weeks) was significantly higher for VRL plus HT compared with HT (30.1% versus 19.2%; P=0.01). Clinical benefit, defined as a decrease in pain intensity or analgesic consumption or an improvement of Karnofsky PS for at least 9 weeks, and at least stable assessment in the other two, was also more frequently observed in patients who received VRL plus HT versus HT alone (30.6% and 19.2%; P=0.008). There was no statistical difference in overall survival. Forty-three per cent of patients in the HT arm received at least one line of further chemotherapy after progression, compared with 28% of patients in the VRL-based arm. Aminoglutethimide did not seem to result in better efficacy for either arm. VRL plus HT was well tolerated, with a median administered relative dose intensity of 90%; grade 4 neutropenia occurred in 6.5% of patients and non-haematological toxicity was rare. CONCLUSIONS: The combination of VRL and hydrocortisone compared with hydrocortisone alone resulted in improved clinical benefit, PFS and PSA response rate. This therapeutic gain is similar to that previously reported with mitoxantrone in combination with low-dose corticosteroids. There was no gain in survival; however, the combination is well tolerated in this elderly group of patients, who often present cardiac co-morbidities, and therefore offers an active and safe therapeutic option for patients with hormone-refractory prostate cancer.

Aged↗
PubMed1987

Neuropeptide Y stimulates the release of luteinizing hormone-releasing hormone from medial basal hypothalamus in vitro: modulation by ovarian hormones.

These studies investigated the effects of neuropeptide Y (NPY) on in vitro release of luteinizing hormone-releasing hormone (LHRH) from the medial basal hypothalmus (MBH) and tested whether ovarian steroids modulate the LHRH response to NPY. Ovariectomized rats were implanted with 20-mm-long Silastic capsules containing a low concentration of estradiol (E2) (150 micrograms/ml oil), a high concentration of E2 (250 micrograms/ml oil), or sesame oil vehicle. Additional animals received high-dose E2 capsules plus an injection of progesterone (15 mg) concomitantly. Two days later, individual MBH fragments were incubated in medium alone for a 30-min period to obtain the basal rate of LHRH release, followed by a second 30-min period in medium containing NPY or saline. Exposure to NPY (10(-6) M) increased the release of LHRH from MBH of ovarian hormone-treated, but not from hormonally untreated rats. The LHRH response was most pronounced from the MBH of rats treated with either high-dose E2 or E2 plus progesterone. The increase in LHRH release was also elicited by 10(-7) M, but not by 10(-8) M NPY concentrations, using MBH from E2 plus progesterone-treated rats. In addition, NPY markedly potentiated the KCl-evoked release of LHRH from MBH of ovariectomized, hormonally untreated or low-dose E2-treated rats, under conditions when there was little or no effect of NPY on the basal LHRH release. Further, the release of LHRH stimulated by NPY was not accompanied by increase in the release of norepinephrine or of dopamine.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1982

Somatic cell hybridization of growth hormone-producing rat pituitary cells and mouse fibroblasts results in extinction of growth hormone expression via a defect in growth hormone RNA production.

In the GH3 line of pituitary cells, growth hormone (GH) production is stimulated by thyroid and glucocorticoid hormones, yet non-pituitary cells, for example mouse fibroblast cells, which also contain receptors for these hormones do not produce GH. We have chosen to study both types of control over GH production in GH3 rat pituitary x GH nonexpressing LB82 mouse fibroblast hybrid cells. Most hybrid cells fail to produce GH in either the absence or presence of the inducers triiodothyronine and dexamethasone although these hormone receptors are present. Rat and mouse GH genes were detected in the hybrid cells' DNA by Southern hybridization following restriction enzyme digestion and gel electrophoresis. The probe was a cloned, full length rat GH cDNA which cross-hybridizes with the mouse GH gene. Analyses with multiple restriction enzymes that cut inside and outside the rat and mouse GH coding sequences were performed. We conclude that 1) both rat and mouse GH genes are present in the hybrid cells in copy number equivalent to those in the parental cell lines, and 2) the rat GH structural gene and flanking sequences are identical in the GH3 and hybrid cell DNA at the level of sensitivity afforded by restriction enzyme analyses. GH mRNA was not detected in total cell or poly(A+) RNA isolated from control or hormone-treated hybrid cells assayed by translation in 2 in vitro systems or by Northern hybridization analyzes. The latter experiments showed that no hybridizable GH mRNA sequences were present in the hybrids as either incomplete transcripts, mature mRNA, or unprocessed high molecular weight precursors. We conclude that extinction of GH in these hybrid cells results from a transcriptional block and/or rapid transcript degradation.

Animals↗
PubMed1985

Glycoprotein hormone alpha-subunit response to growth hormone (GH)-releasing hormone in patients with active acromegaly. Evidence for alpha-subunit and GH coexistence in the same tumoral cell.

Basal serum concentrations of glycoprotein hormone alpha-subunit and its response to GH-releasing hormone (GHRH) were studied in 22 acromegalic patients and in normal subjects. Four out of 22 patients had a basal alpha-subunit concentration (1.2-3.5 ng/ml) clearly above the upper limit of the normal range. GHRH injection (1 microgram/kg body weight, bolus dose iv) produced a clear alpha-subunit response [mean % increase: 120 +/- 37 (SD)] in the 4 patients with elevated basal alpha-subunit levels. No increase in serum glycoprotein hormones (TSH, LH, and FSH) occurred. Selective adenomectomy in 2 patients resulted in normalization of both serum GH and alpha-subunit levels, as well as disappearance of the abnormal alpha-subunit response to GHRH. In in vitro studies, only these 2 adenomas secreted alpha-subunit in large amounts (534 and 388 ng/mg protein . 30 min) and was it further stimulated by GHRH (% increase: 83 and 126). Morphological studies done with protein A-gold particle immunotechnique demonstrated that in these adenomas the great majority of the cells contained secretory granules positive for both GH and alpha-subunit. We conclude that: 1) alpha-subunit hypersecretion is present in some acromegalic patients (about 20%), 2) GHRH stimulates alpha-subunit release both in vivo and in vitro only in patients with elevated basal alpha-subunit levels, and 3) in these patients alpha-subunit derives from a common adenomatous cell secreting both alpha-subunit and GH molecules.

Acromegaly↗
PubMed1985

Plasma follicle-stimulating hormone, luteinizing hormone, and sex hormones in patients with gout.

Plasma levels of follicle-stimulating hormone, luteinizing hormone, testosterone, progesterone, 17 beta-estradiol, and cortisol were examined in normal subjects and gout patients under baseline conditions and after clomiphene stimulation. A significant decrease in follicle-stimulating hormone, luteinizing hormone, and 17 beta-estradiol was observed both in male and female gout patients; in the same patients, the plasma testosterone: 17 beta-estradiol ratio was found to be significantly higher than in control subjects. The changes observed suggest a possible role played by 17 beta-estradiol in the regulation of purine biosynthesis and uric acid metabolism.

Adult↗
PubMed2006

Time course of serum testosterone and luteinizing hormone levels after cessation of long-term luteinizing hormone-releasing hormone agonist treatment in patients with prostate cancer.

INTRODUCTION: In order to elucidate the influence of hormone-releasing hormone (LH-RH) agonist therapy cessation on pituitary/testicular function and its clinical implications, we investigated prospectively hormonal (luteinizing hormone: LH; testosterone: T) responses in patients with prostate cancer who received long-term LH-RH 10 agonist therapy. PATIENTS AND METHODS: A consecutive 32 patients who had received LH-RH agonist therapy over 24 months were enrolled. As a baseline, T and LH were measured at the time of LH-RH agonist therapy cessation, monthly for 3 months, and subsequently, every 3 months. RESULTS: The median duration of LH-RH agonist therapy was 30 months (24-87 months) with median follow-up duration of 24 months following cessation. All patients had castrated T levels and suppressed LH levels at baseline. Median duration of castrated T levels following cessation was 6 months. Median time to normalization of T levels was 24 months. LH levels returned to normal within 3 months in all cases. Patients who received androgen deprivation therapy for 30 months or longer required a longer time for recovery of T levels. Patients over 65 years of age showed a statistically significant longer time for recovery of T levels (P=0.0167). CONCLUSIONS: Long-term LH-RH agonist therapy has remarkable effects on serum T level that last for a significant time after cessation, a fact that should be applied to the interpretation of both PSA and serum T levels after cessation of androgen deprivation therapy.

Aged↗