New concepts in the regulation of hypothalamic gonadotropin releasing hormone (GnRH) secretion

Rasmussen, Dennis D.

doi:10.1007/bf03346958

Cited by 35 publications

(16 citation statements)

References 112 publications

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“…It remains to be defined whether this depends on some residual bursts of GnRH or on some spontaneous activity of the gonadotropes. This last hypothesis might be supported by recent reports (35,36) that demonstrated the presence of an intrinsic pulsatile release of LH from human pituitary in an in vitro perfused system.…”

Section: Discussionmentioning

confidence: 70%

Luteinizing Hormone (LH) Secretory Burst Duration Is Independent from LH, Prolactin, or Gonadal Steroid Plasma Levels in Amenorrheic Women

Genazzani¹,

Petraglia²,

Benatti³

et al. 1991

The Journal of Clinical Endocrinology & Metabolism

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The possible presence of LH pulsatile secretion has been studied in patients with hypothalamic amenorrhea [LH plasma levels, less than 3 (n = 35) or greater than 3 IU/L (n = 18)], amenorrhea associated with hyperandrogenemia (n = 31), or hyperprolactinemia (n = 10). Patients were sampled every 10 min for 4 h, and LH plasma concentrations were determined by the use of an immunofluorimetric assay. The program Detect was used for both pulse detection and data deconvolution, i.e. for instantaneous secretory rate computation, on LH time series. The presence of episodic LH secretion was observed in all patients, and LH pulse frequency ranged between 3.5 +/- 0.3 and 3.8 +/- 0.2 peaks/4 h among the four groups. LH pulse amplitude was significantly reduced in patients affected by hypothalamic amenorrhea with LH plasma levels lower than 3 IU/L (0.7 +/- 0.1 IU/L; P less than 0.01) and significantly increased in patients with hyperandrogenic amenorrhea (6.8 +/- 0.3 IU/L; P less than 0.01) compared to levels in the other groups under study. Instantaneous secretory rate computation permitted the optimal resolution of the secretory events and demonstrated that the duration of gonadotrope secretory bursts ranged from 22.8 +/- 1.4 to 26.8 +/- 2.3 min in amenorrheic patients and did not depend on LH, PRL, or sex steroid plasma levels. In conclusion, the present study shows the presence of significant LH pulsatile release in amenorrheic patients, suggesting that in amenorrheic, as in normally cycling, women the secretory bursts from the gonadotropes have the same duration, despite the plasma LH, PRL, or steroid hormone levels.

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Section: Discussionmentioning

confidence: 70%

Luteinizing Hormone (LH) Secretory Burst Duration Is Independent from LH, Prolactin, or Gonadal Steroid Plasma Levels in Amenorrheic Women

Genazzani¹,

Petraglia²,

Benatti³

et al. 1991

The Journal of Clinical Endocrinology & Metabolism

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“…These studies have demonstrated an increase in pulsatile ACTH secretion, increased adrenal sensitivity to ACTH, and increased cortisol secretion with a normal diurnal rhythm 8–10 . In vitro experiments in rats and humans suggest that CRH inhibits secretion of GnRH from the mediobasal hypothalamus 11–13 . It remains unclear what the overall contribution of each component of these H‐P‐A changes is as a response to perceived endogenous stress resulting in the suppression of the GnRH release.…”

Section: Physiological Changes In Hamentioning

confidence: 92%

Stress‐Associated or Functional Hypothalamic Amenorrhea in the Adolescent

Liu

Bill

2008

Annals of the New York Academy of Sciences

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Stress-associated amenorrhea in the adolescent is likely similar to the disorder found in young reproductive-aged adults and is termed hypothalamic amenorrhea. The key defect is an abnormality in the secretion of gonadotropin-releasing hormone. This review examines the current studies that characterize the disorder and the plausible factor(s) that may account for the disturbances in gonadotropin-releasing hormone, and identifies directions for future research in this group of disorders.

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“…These apparently conflict¬ ing responses to DA may be explained by the acti¬ vation of physiologically distinct neuronal popula¬ tions (25) or stimulations of pharmacologically dis¬ tinct receptor subgroups with contrasting effects on GnRH release (26). Moreover, in an in vivo ex¬ periment similar to ours, potential interactions with other neurotransmitters on hypothalamic and/or pituitary sites cannot be excluded and determine the physiological manifestation (27). In this light, these confounding factors determine the ultimate response to DA blockade and should also be considered.…”

Section: Discussionmentioning

confidence: 59%

Does prolonged dopaminergic blockade alter the LH pulsatile secretion in normal cycling and postmenopausal women?

Rossmanith

Wirth²,

Yen³

1989

Acta Endocrinologica

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To investigate effects of prolonged dopaminergic antagonism on LH pulsatile secretion, 22 normal cycling women (10 in the early follicular phase (days 3 and 4), 6 in the late follicular phase (days 10 to 13), 6 in the midluteal phase (days 6 to 8 after ovulations)) and 8 postmenopausal women were studied before and during 8-h dopamine receptor blockade imposed by metoclopramide. Sequential 8-h infusions of either saline (50 ml/ h) or metoclopramide (30 \ g=m\ g \ m=. \ kg\m=-\1 \ m=. \ h\m=-\1) were conducted on two consecutive days. LH pulsatile activity was assessed in blood samples obtained at 15 min intervals during these 8-h infusion periods. Basal estradiol and progesterone concentrations were lowest (p <0.001) in postmenopausal and highest (p <0.001) in the midluteal phase women, 8-h metoclopramide infusions evoked prompt (within 90 min, p <0.001) and sustained (> 70 \ g=m\ g/ 1, p < 0.001) increases of PRL, similar (p = 0.78)) in magnitude for normal cycling and postmenopausal women. Metoclopramide infusions failed to significantly modify the LH pulsatile acitivity during the menstrual cycles and in hypogonadal women. These observations suggest that even in the presence of high circulating estradiol and progesterone concentrations the dopaminergic inhibition may not be operating. However, any possible stimulatory effect on LH secretion by dopamine receptor blockade may be confounded by the concomitant metoclopramide-induced hyperprolactinemia.The role of dopamine (DA) in the regulation of GnRH-LH secretion remains controversial. The administrations of DA and its agonists consistently inhibit LH secretion in women during all phases of the menstrual cycle (1-3). This inhibitory effect of DA becomes most pronounced during periods of high serum estrogen and estrogen-progesterone concentrations, as observed in the late follicular and luteal phases of the cycle. Conversely, experi¬ ments using short-term DA receptor blockade im¬ posed by intravenous injections of DA receptor blockers have demonstrated that acute DA anta¬ gonism does not alter the serum gonadotropin le¬ vels in women during the menstrual cycle (4-6). Consequently, the endogenous DA inhibition of GnRH-LH secretion may not be activated during the normal menstrual cycle, even though DA infu¬ sions inhibit GnRH-LH secretion, most evident in the follicular and luteal phases. Thus, the relative contribution of the dopaminergic system to the neuroendocrine control of GnRH-LH release re¬ mains to be defined.Previous studies investigating the DA regulation of GnRH-LH secretion have utilized a short-term DA antagonism by means of intravenous bolus in¬ jections of DA blockers, such as metoclopramide. However, any DA regulation of the episodic LH re¬ lease and its possible dependency from the circu¬ lating serum sex steroid concentrations can only be estimated by a more prolonged DA blockade. Accordingly, we studied the LH pulsatile activity in eugonadal women during their normal cycles and in hypogonadal women after the natural meno¬ pause before and duri...

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New concepts in the regulation of hypothalamic gonadotropin releasing hormone (GnRH) secretion

Cited by 35 publications

References 112 publications

Luteinizing Hormone (LH) Secretory Burst Duration Is Independent from LH, Prolactin, or Gonadal Steroid Plasma Levels in Amenorrheic Women

Luteinizing Hormone (LH) Secretory Burst Duration Is Independent from LH, Prolactin, or Gonadal Steroid Plasma Levels in Amenorrheic Women

Stress‐Associated or Functional Hypothalamic Amenorrhea in the Adolescent

Does prolonged dopaminergic blockade alter the LH pulsatile secretion in normal cycling and postmenopausal women?

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