Two days of pulsatile GnRH infusion beginning 4 days before weaning in sows initiates a wave of follicular growth that is not sustained after weaning

ABSTRACT Experiments were conducted in ovariectomized ewes after hypothalamo-pituitary disconnection (HPD) (a) to examine LH and FSH secretion during constant infusion of gonadotrophin-releasing hormone (GnRH) or physiological saline and (b) to determine whether or not a constant GnRH background enhances or diminishes pituitary responsiveness to GnRH pulses. Whereas pulsatile GnRH infusions maintained LH and FSH secretion, constant infusions (125 or 250 ng/h) led to the complete cessation of LH secretion and reduced FSH secretion. The rate of decline of plasma FSH concentrations was significantly (P<0·01) greater in animals receiving 250 ng GnRH/h than in saline-treated animals, whereas that in animals receiving 125 ng/h was not significantly different. When GnRH pulses were administered during constant GnRH infusion, the plasma LH pulse amplitudes were similar to those seen without the GnRH background. These data show that, in ovariectomized-HPD ewes (a) FSH secretion does not require GnRH pulses and may merely reflect ongoing FSH synthesis and (b) a constant low background of GnRH does not affect pituitary responsiveness to GnRH pulses. J. Endocr. (1986) 111, 43–49

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The effects of pulsatile GnRH infusion upon the diurnal variations in serum LH and testosterone in pre-pubertal and pubertal boys

Acta Endocrinologica ◽

10.1530/acta.0.1210241 ◽

1989 ◽

Vol 121 (2) ◽

pp. 241-245 ◽

Cited By ~ 2

Author(s):

Derek Gordon ◽

Christina E. Gray ◽

Graham H. Beastall ◽

John A. Thomson

Keyword(s):

Serum Testosterone ◽

Diurnal Variations ◽

Early Puberty ◽

Testosterone Secretion ◽

Pulsatile Gnrh ◽

Serum Lh ◽

Median Serum ◽

Pubertal Boys ◽

Pre Treatment ◽

Gnrh Infusion

Abstract. The aim of the present study was to determine the effects of exogenous GnRH pulsatile infusions on the diurnal variations of LH and testosterone secretion which occur in late pre-puberty and early puberty. GnRH infusions were administered to 12 short stature males in pre-puberty or early puberty, over 6-day periods. In 6 patients, GnRH doses of 2.5, 7.5 and 15 μg/pulse were used and 24-h profiles of serum LH and testosterone were measured before and at the end of the infusions. In the remaining 6 patients GnRH was administered at a dose of 7.5 μg/pulse and profiles between 21.00 and 06.00 h the following day were determined. Pre-infusion profiles demonstrated nocturnal LH and testosterone rises in all patients. Median pre-infusion serum LH prior to midnight was 2.2 U/l (range 1.0–5.4) rising to 3.7 U/l (range 1.9–10.7) during GnRH administration (p < 0.005). After midnight, median pre-treatment serum LH concentration was 4.3 U/l (range 2.7–7.5) which remained unaltered by GnRH administration (median 4.8 U/l, range 2.9–7.9, p > 0.05). Median pre-therapy serum testosterone before midnight was 0.8 nmol/l (range 0.1−7.1) rising significantly (p < 0.05) to 4.1 nmol/l (range 0.2–8.0). Following therapy, post-midnight median serum testosterone rose from 4.8 (range 0.4–9.4) to 7.0 nmol/l (range 0.5–13.9, p > 0.05). Diurnal variation in LH and testosterone secretion, therefore, is maintained during exogenous GnRH administration to pre-pubertal and pubertal boys. Response to exogenous GnRH pulses may be significantly influenced by endogenous GnRH.

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NEW DATA CONCERNING THE ROLE PLAYED BY PROGESTERONE IN THE CONTROL OF FOLLICULAR GROWTH IN THE RAT

Acta Endocrinologica ◽

10.1530/acta.0.0750569 ◽

1974 ◽

Vol 75 (3) ◽

pp. 569-578 ◽

Cited By ~ 29

Author(s):

G. Buffler ◽

S. Roser

Keyword(s):

Wistar Rats ◽

Venous Blood ◽

Oestrous Cycle ◽

Female Rats ◽

Cycle Duration ◽

Follicular Growth ◽

The Third ◽

Female Wistar Rats

ABSTRACT The mechanisms involved in the prolongation of the oestrous cycle following LH administration were studied in 4-day cyclic female Wistar rats. In females injected with LH on the morning of dioestrus I there was an increase in ovarian venous blood progesterone as compared with non-injected animals. In both LH-treated females, and those injected with progesterone on the morning of dioestrus I, a slowing up in follicular growth was observed from the afternoon of dioestrus I. The size of follicles greater than 400 urn present in LH or progesterone injected animals on the third day of cycle was similar to the size reached by the same range of follicles in non-injected animals on the second day of the cycle. Hence, the increase in endogenous ovarian progesterone elicited by LH was considered as the cause of the slowing up of follicular growth and therefore of the lengthening of the oestrous cycle duration in female rats injected with LH at the beginning of 4-day cycle.

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Pulsatile GnRH administration is attended by decreased plasma melatonin in patients suffering from GnRH deficiency

Acta Endocrinologica ◽

10.1530/acta.0.120s050 ◽

1989 ◽

Vol 120 (3_Suppl) ◽

pp. S50-S51

Author(s):

R. P. WILLIG ◽

J. C. COMMENTZ ◽

N. STAHNKE

Keyword(s):

Plasma Melatonin ◽

Pulsatile Gnrh

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The gonadotroph natriuretic peptide system is sensitive to pulsatile GnRH stimulation: insights into CNP/GC-B signalling in gonadotroph function

Endocrine Abstracts ◽

10.1530/endoabs.34.p286 ◽

2014 ◽

Author(s):

Samantha Mirczuk ◽

Alice Catterick ◽

Andrew Lessey ◽

Rebecca Perrett ◽

Craig McArdle ◽

...

Keyword(s):

Natriuretic Peptide ◽

Pulsatile Gnrh ◽

Peptide System ◽

Natriuretic Peptide System

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Pulsatile GnRH secretion from primary cultures of sheep olfactory placode explants

Reproduction ◽

10.1530/reprod/120.2.391 ◽

2000 ◽

pp. 391-396 ◽

Cited By ~ 11

Author(s):

AH Duittoz ◽

M Batailler

Keyword(s):

Culture Medium ◽

Primary Cultures ◽

Pulsatile Secretion ◽

Olfactory Placode ◽

Gnrh Secretion ◽

Individual Culture ◽

Pulsatile Gnrh

The aim of this study was to investigate the development of pulsatile GnRH secretion by GnRH neurones in primary cultures of olfactory placodes from ovine embryos. Culture medium was collected every 10 min for 8 h to detect pulsatile secretion. In the first experiment, pulsatile secretion was studied in two different sets of cultures after 17 and 24 days in vitro. In the second experiment, a set of cultures was tested after 10, 17 and 24 days in vitro to investigate the development of pulsatile GnRH secretion in each individual culture. This study demonstrated that (i) primary cultures of GnRH neurones from olfactory explants secreted GnRH in a pulsatile manner and that the frequency and mean interpulse duration were similar to those reported in castrated ewes, and (ii) pulsatile secretion was not present at the beginning of the culture but was observed between 17 and 24 days in vitro, indicating the maturation of individual neurones and the development of their synchronization.

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