scholarly journals Erythropoietin-producing hepatocellular receptor A7 restrains estrogen negative feedback of luteinizing hormone via ephrin A5 in the hypothalamus of female rats

2020 ◽  
Vol 319 (1) ◽  
pp. E81-E90 ◽  
Author(s):  
Shang Li ◽  
Junyu Zhai ◽  
Bing Xu ◽  
Jiansheng Liu ◽  
Weiwei Chu ◽  
...  
Keyword(s):  
Luteinizing Hormone ◽  
Negative Feedback ◽  
Female Rats ◽  
Female Rat ◽  
Female Reproduction ◽  
Systemic Injection ◽  
Serum Luteinizing Hormone ◽  
Serum Lh ◽  
17Β Estradiol ◽  
Lh Secretion

We have previously shown that systemic injection of erythropoietin-producing hepatocellular receptor A7 (EPHA7)-Fc raises serum luteinizing hormone (LH) levels before ovulation in female rats, indicating the induction of EPHA7 in ovulation. In this study, we aimed to identify the mechanism and hypothalamus-pituitary-ovary (HPO) axis level underlying the promotion of LH secretion by EPHA7. Using an ovariectomized (OVX) rat model, in conjunction with low-dose 17β-estradiol (E2) treatment, we investigated the association between EPHA7-ephrin (EFN)A5 signaling and E2 negative feedback. Various rat models (OVX, E2-treated OVX, and abarelix treated) were injected with the recombinant EPHA7-Fc protein through the caudal vein to investigate the molecular mechanism underlying the promotion of LH secretion by EPHA7. Efna5 was observed strongly expressed in the arcuate nucleus of the female rat by using RNAscope in situ hybridization. Our results indicated that E2, combined with estrogen receptor (ER)α, but not ERβ, inhibited Efna5 and gonadotropin-releasing hormone 1 ( Gnrh1) expressions in the hypothalamus. In addition, the systemic administration of EPHA7-Fc restrained the inhibition of Efna5 and Gnrh1 by E2, resulting in increased Efna5 and Gnrh1 expressions in the hypothalamus as well as increased serum LH levels. Collectively, our findings demonstrated the involvement of EPHA7-EFNA5 signaling in the regulation of LH and the E2 negative feedback pathway in the hypothalamus, highlighting the functional role of EPHA7 in female reproduction.

INFLUENCE OF AGE ON THE RELEASE OF LUTEINIZING HORMONE INDUCED BY OESTROGEN AND PROGESTERONE IN IMMATURE RATS

1972 ◽  
Vol 55 (1) ◽  
pp. 97-103 ◽  
Author(s):  
L. CALIGARIS ◽  
J. J. ASTRADA ◽  
S. TALEISNIK
Keyword(s):  
Luteinizing Hormone ◽  
Single Injection ◽  
Significant Rise ◽  
Female Rats ◽  
Serum Luteinizing Hormone ◽  
Serum Lh ◽  
Oestradiol Benzoate ◽  
Old Rats ◽  
Lh Secretion ◽  
Phasic Release

SUMMARY In immature female rats serum luteinizing hormone (LH) concentration, as measured by radioimmunoassay, was found to be higher at 10 or 15 days of age than thereafter. Animals ovariectomized soon after birth or at 5 days of age showed a significant rise in serum LH levels 10 days later. A positive feedback effect on LH secretion was observed on the day following a single injection of oestradiol benzoate (OB) in 28-day-old rats but not in younger animals. However, in animals primed with OB a second dose of OB 2 days later resulted in a significant rise in serum LH levels even in rats of 22 days of age. Progesterone (1 mg) injected 3 days after the injection of a single dose of OB induced, a few hours later, a significant rise in serum LH concentration. This effect was observed from the 22nd day of age but not in younger animals. The magnitude of the response to progesterone, as revealed by the serum LH levels, sharply decreased at the time of puberty. It is concluded that the mechanisms responsible for the tonic release of LH are ready to function at the time of birth or shortly thereafter, while those involved in the phasic release mature around 22 days of age.

SERUM LUTEINIZING HORMONE AND FOLLICLE-STIMULATING HORMONE CONCENTRATIONS IN IMMATURE FEMALE RATS TREATED WITH MULTIPLE INJECTIONS AND VARIOUS AMOUNTS OF LUTEINIZING HORMONE RELEASING HORMONE

1975 ◽  
Vol 66 (1) ◽  
pp. 13-20 ◽  
Author(s):  
D. C. JOHNSON ◽  
R. S. MALLAMPATI
Keyword(s):  
Luteinizing Hormone ◽  
Constant Stimulus ◽  
Female Rats ◽  
Intact Female ◽  
Immature Female ◽  
Luteinizing Hormone Releasing Hormone ◽  
Releasing Hormone ◽  
Serum Luteinizing Hormone ◽  
Serum Lh ◽  
Lh Rh

SUMMARY Release of immunoreactive LH and FSH was induced in immature intact female rats by repeated injections of synthetic luteinizing hormone releasing hormone (LH-RH). Altering the dose of LH-RH (5, 10, 20, 50 ng) and the frequency of administration (every 10, 20, 30 or 60 min) over a period of 2 h produced a variety of serum LH and FSH concentrations and ratios. When the dose was a constant 20 ng but the frequency of injections was either 20 or 30 min, a steady state in serum gonadotrophin concentrations was reached within 1 h and the level remained the same during the second hour. When given every 10 min, 20 ng LH-RH produced a much higher concentration of both LH and FSH during the second hour of stimulation. Examination of the gonadotrophin levels after each injection of LH-RH showed that the pituitary response was variable in spite of a constant stimulus.

ANTIFERTILITY PROPERTIES OF BOVINE PINEAL EXTRACTS: REDUCTION OF OVULATION AND PRE-OVULATORY LUTEINIZING HORMONE IN THE RAT

1977 ◽  
Vol 85 (2) ◽  
pp. 225-234 ◽  
Author(s):  
R. J. Orts ◽  
K. M. Kocan ◽  
R. P. Johnson
Keyword(s):  
Luteinizing Hormone ◽  
Female Rats ◽  
Low Molecular Weight ◽  
Moderate Reduction ◽  
Serum Lh ◽  
Bovine Pineal Extracts ◽  
Modifying Effect ◽  
The Mean ◽  
Pineal Extracts ◽  
Lh Secretion

ABSTRACT Bovine pineal glands were extracted with acetic acid and partially purified on Sephadex G-25. Three fractions, F3, F4 and F5, were each administered to cycling female rats for 4, 2 or 1 day prior to ovulation to determine their effects on fertility, ovulation and the pro-oestrous surge of luteinizing hormone (LH). The incidence of pregnancy and the mean number of foetuses were reduced in animals after treatment with F3 or F4 but not in those treated with F5. Each of the F3 and F4 fractions significantly reduced the mean number of ova shed and the pre-ovulatory concentration of serum LH. The F5 fraction caused a moderate reduction of the pro-oestrous rise of serum LH but had no significant effect on ovulation. The data suggest that fertility in rats can be reduced by more than one substance of low molecular weight present in bovine pineal extracts through a modifying effect on LH secretion and subsequent ovulation.

TEMPORAL CHANGES IN THE HYPOTHALAMIC AND SERUM LUTEINIZING HORMONE-RELEASING HORMONE (LH-RH) LEVELS AND THE CIRCULATING OVARIAN STEROIDS DURING THE RAT OESTROUS CYCLE

1977 ◽  
Vol 85 (3) ◽  
pp. 449-455 ◽  
Author(s):  
Pushpa S. Kalra ◽  
Satya P. Kalra
Keyword(s):  
Luteinizing Hormone ◽  
Oestrous Cycle ◽  
Female Rats ◽  
Medial Basal Hypothalamus ◽  
Luteinizing Hormone Releasing Hormone ◽  
Ovarian Steroids ◽  
Serum Luteinizing Hormone ◽  
Serum Lh ◽  
Early Afternoon ◽  
Lh Rh

ABSTRACT Cycling female rats were sacrificed at various times during the 4-day oestrous cycle. LH-RH in the medial basal hypothalamus (MBH) and serum LH-RH, LH, oestradiol (Oe2), and progesterone were analyzed by radioimmunoassays. The MBH LH-RH content was lowest at 19.55–20.15 h during pro-oestrus but increased gradually through oestrus and dioestrus I to significantly higher values at noon of dioestrus II, and then decreased precipitously at 18.00 h. Although serum LH levels remained basal from midnight of pro-oestrus through dioestrus II, serum LH-RH levels were significantly elevated at 12.00 and 21.00 h on oestrus (vs. the midnight prooestrus levels) and declined between 15.00 and 22.00 h of dioestrus I. In conjunction with high Oe2 titres, LH-RH in the MBH and serum declined initially during pro-oestrus between 14.07–14.45 h and then increased abruptly between 14.55–15.55 h; the pre-ovulatory rise in serum LH was observed from 16.05 h onwards. LH-RH activity in the MBH and serum receded gradually to the early afternoon levels by 19.55–24.00 h while the peak in serum LH was observed at 17.05–18.05 h. These studies suggested that the hypersecretion of the MBH LH-RH (synthesis + release) may be responsible for the pre-ovulatory discharge of LH.

Effect of Long-Acting Thyroid Stimulator on Serum Concentration of Luteinizing Hormone in the Rat

1975 ◽  
Vol 48 (3) ◽  
pp. 231-233
Author(s):  
P. Dandona ◽  
D. J. El Kabir ◽  
F. Naftolin ◽  
P. C. B. MacKinnon
Keyword(s):  
Luteinizing Hormone ◽  
Serum Concentration ◽  
Pituitary Gland ◽  
Immunoglobulin G ◽  
Adrenocorticotrophic Hormone ◽  
Serum Concentrations ◽  
Serum Luteinizing Hormone ◽  
Serum Lh ◽  
Long Acting ◽  
Dexamethasone Suppression

1. The effect of long-acting thyroid stimulator (LATS) on the serum luteinizing hormone (LH) levels of the rat in pro-oestrus has been studied. 2. The injection of three out of four LATS-containing immunoglobulin G fractions caused an increase in amounts of serum LH. 3. Adrenalectomy and dexamethasone suppression did not alter this response. 4. Injection of large doses of adrenocorticotrophic hormone did not produce any increase in serum concentrations of LH. 5. It is postulated that LATS may have a direct effect on the release of LH from the pituitary gland.

Effects of valproate-induced alteration of the GABAergic system on pulsatile luteinizing hormone secretion in ovariectomized women

1996 ◽  
Vol 135 (3) ◽  
pp. 293-298 ◽  
Author(s):  
Joaquin Lado-Abeal ◽  
Jose L Liz ◽  
Carlos Rey ◽  
Manuel Febrero ◽  
Jose Cabezas-Cerrato
Keyword(s):  
Luteinizing Hormone ◽  
Sodium Valproate ◽  
Pulse Generator ◽  
Hormone Secretion ◽  
Gabaergic System ◽  
Luteinizing Hormone Secretion ◽  
Serum Lh ◽  
Nutrition Service ◽  
Significant Difference ◽  
Lh Secretion

Lado-Abeal J, Liz JL, Rey C, Febrero M, Cabezas-Cerrato J. Effects of valproate-induced alteration of the GABAergic system on pulsatile luteinizing hormone secretion in ovariectomized women. Eur J Endocrinol 1996;135:293–8. ISSN 0804–4643 It is well established that valproate increases hypothalamic concentrations of γ-aminobutyric acid (GABA). Although little research has been done on the role of GABA in the control of pulsatile luteinizing hormone (LH) secretion in humans, our group recently found that administration of valproate had no significant effect on pulsatile LH secretion in late follicular and mid-late luteal phase normal women. However, the results of several studies of rats suggest that GABAergic regulation of LH secretion may depend on steroid levels. The objective of this work was to determine whether regular administration of sodium valproate inhibits pulsatile LH secretion in ovariectomized women. Twelve women who had undergone ovariectomy for causes other than malignant tumors were each studied in two 8 h sessions, in each of which blood samples were taken every 5 min. The first session was the control; for the second, 400 mg of sodium valproate was administered every 8 h during the seven preceding days and at 08.00 h and 14.00 h on the day of the study session. Serum valproate was determined by repolarization fluorescence spectrophotometry, and LH, estradiol and progesterone by radioimmunoassay. The serum LH series were subjected to a deconvolution procedure to reconstruct the pattern of pituitary LH secretion. Luteinizing hormone pulses were identified by the authors' nonparametric method. Control and post-valproate results were compared with regard to number of pulses, pulse duration, the quantity of LH secreted in each pulse, interpulse interval and mean serum LH level. There was no statistically significant difference between control and post-valproate results for any of the variables considered. It is concluded that sustained serum valproate levels do not alter pulsatile secretion of LH in ovariectomized women. This implies that, in humans, GABA is probably not a decisive factor in the regulation of the GnRH pulse generator. J Cabezas-Cerrato, Endocrinology and Nutrition Service, General Hospital of Galicia, c/Galeras s/n 15705, Santiago de Compostela, La Coruña, Spain

scholarly journals Beta-endorphin/beta-lipotropin release and gonadotropin secretion after acute exercise in normal males

1986 ◽  
Vol 61 (6) ◽  
pp. 2045-2049 ◽  
Author(s):  
A. N. Elias ◽  
K. Iyer ◽  
M. R. Pandian ◽  
P. Weathersbee ◽  
S. Stone ◽  
...  
Keyword(s):  
Luteinizing Hormone ◽  
Acute Exercise ◽  
Suppressive Effect ◽  
Normal Male ◽  
Base Line ◽  
Gonadotropin Secretion ◽  
Beta Endorphin ◽  
Serum Lh ◽  
Normal Males ◽  
Lh Secretion

The plasma beta-endorphin (beta-EP) and beta-lipotropin (beta-LPH) response to acute exercise and the relationship of these opioid peptides to basal and luteinizing hormone-releasing hormone (LRH)-stimulated luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secretion was studied in eight normal male volunteers. Acute exercise resulted in a rise in plasma beta-LPH levels that returned to base line when measured 60 min after exercise. Plasma beta-EP levels did not demonstrate any rise when measured immediately after 20 min of exercise or at 60 min after exercise. Serum LH concentrations in individual volunteers declined to nadir values 60–180 min after exercise after which they showed a rebound to levels higher than the preexercise values in three of five volunteers in whom nadir LH levels were attained before the final (180 min) measurement. Serum FSH concentrations were unaltered by exercise. Acute exercise similarly did not alter the LH/FSH response to exogenous LRH stimulation. Pretreatment of the volunteers with the narcotic antagonist, naloxone, failed to alter the postexercise or LRH-stimulated LH and FSH release. The data suggest that beta-EP does not exert a suppressive effect on LH secretion after acute exercise in normal human males. Whether the suppression of LH secretion after acute exercise in unconditioned males is due to factor(s) cosecreted with beta-LPH, an increase in brain beta-EP or to alternate mechanisms such as alteration in central dopaminergic or GABAergic tone remains to be established.

RESTORATION OF OESTROGEN POSITIVE FEEDBACK EFFECT ON LH RELEASE BY BROMOCRIPTINE IN HYPERPROLACTINAEMIC PATIENTS WITH GALACTORRHOEA-AMENORRHOEA

1979 ◽  
Vol 91 (3) ◽  
pp. 591-600 ◽  
Author(s):  
Toshihiro Aono ◽  
Akira Miyake ◽  
Takenori Shioji Motoi Yasuda ◽  
Koji Koike ◽  
Keiichi Kurachi
Keyword(s):  
Luteinizing Hormone ◽  
Follicle Stimulating Hormone ◽  
Serum Prolactin ◽  
Serum Luteinizing Hormone ◽  
Serum Lh ◽  
Lh Release ◽  
The Mean ◽  
Lh Rh ◽  
Lh Releasing Hormone ◽  
Positive Feedback Effect

ABSTRACT Five mg of bromocriptine was administered for 3 weeks to 8 hyperprolactinaemic women with galactorrhoea-amernorrhoea, in whom the response of serum luteinizing hormone (LH) and follicle-stimulating hormone (FSH) to 100 μg of iv LH-releasing hormone (LH-RH) had been evaluated. Twenty mg of conjugated oestrogen (Premarin®) was injected iv any day between the 10th and 12th day from the initiation of the treatment, and serum LH levels were serially determined for 120 h. Hyperresponse of LH with normal FSH response to LH-RH was observed in most patients. Bromocriptine treatment for 10 to 12 days significantly suppressed mean (± se) serum prolactin (PRL) levels from 65.1 ± 23.0 to 10.4 ± 2.0 ng/ml, while LH (12.6 ± 2.1 to 24.8 ± 5.9 mIU/ml) and oestradiol (40.1 ± 7.6 to 111.4 ± 20.8 pg/ml) levels increased significantly. Patients on bromocriptine treatment showed LH release with a peak at 48 h after the injection of Premarin. The mean per cent increases in LH were significantly higher than those in untreated patients with galactorrhoea-amenorrhoea between 32 and 96 h after the injection. The present results seem to suggest that the restoration of LH-releasing response to oestrogen following suppression of PRL by bromocriptine may play an important role in induction of ovulation in hyperprolactinaemic patients with galactorrhoea-amenorrhoea.

scholarly journals Effect of androgen on Kiss1 expression and luteinizing hormone release in female rats

2017 ◽  
Vol 233 (3) ◽  
pp. 281-292 ◽  
Author(s):  
Kinuyo Iwata ◽  
Yuyu Kunimura ◽  
Keisuke Matsumoto ◽  
Hitoshi Ozawa
Keyword(s):  
Luteinizing Hormone ◽  
Arcuate Nucleus ◽  
Female Rats ◽  
Hormone Release ◽  
Lh Surge ◽  
Continuous Release ◽  
Ovulatory Dysfunction ◽  
Lh Release ◽  
Gonadotrophin Releasing Hormone ◽  
Lh Secretion

Hyperandrogenic women have various grades of ovulatory dysfunction, which lead to infertility. The purpose of this study was to determine whether chronic exposure to androgen affects the expression of kisspeptin (ovulation and follicle development regulator) or release of luteinizing hormone (LH) in female rats. Weaned females were subcutaneously implanted with 90-day continuous-release pellets of 5α-dihydrotestosterone (DHT) and studied after 10 weeks of age. Number of Kiss1-expressing cells in both the anteroventral periventricular nucleus (AVPV) and arcuate nucleus (ARC) was significantly decreased in ovary-intact DHT rats. Further, an estradiol-induced LH surge was not detected in DHT rats, even though significant differences were not observed between DHT and non-DHT rats with regard to number of AVPV Kiss1-expressing cells or gonadotrophin-releasing hormone (GnRH)-immunoreactive (ir) cells in the presence of high estradiol. Kiss1-expressing and neurokinin B-ir cells were significantly decreased in the ARC of ovariectomized (OVX) DHT rats compared with OVX non-DHT rats; pulsatile LH secretion was also suppressed in these animals. Central injection of kisspeptin-10 or intravenous injection of a GnRH agonist did not affect the LH release in DHT rats. Notably, ARC Kiss1-expressing cells expressed androgen receptors (ARs) in female rats, whereas only a few Kiss1-expressing cells expressed ARs in the AVPV. Collectively, our results suggest excessive androgen suppresses LH surge and pulsatile LH secretion by inhibiting kisspeptin expression in the ARC and disruption at the pituitary level, whereas AVPV kisspeptin neurons appear to be directly unaffected by androgen. Hence, hyperandrogenemia may adversely affect ARC kisspeptin neurons, resulting in anovulation and menstrual irregularities.

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