Differential Suppression of FSH and LH Secretion by Follicular Fluid in the Presence or Absence of GnRH

Charlesworth, M. Cristine; Grady, Rosemary R.; Shin, Lisa M.; Vale, Wylie; Rivier, Catherine; Rivier, J.; Schwartz, Neena B.

doi:10.1159/000123891

Cited by 26 publications

(10 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Judging from the LH concentrations found at 5 and 8 h after unilateral or bilateral ovariec¬ tomy performed at various ages, which, with the excep¬ tion of results at 28 days of age, showed no changes compared with control rats, it seems justified to conclude that ILA plays a specific role in the regulation of FSH secretion only, in agreement with the results of others (e.g. Charlesworth, Grady, Shin et al 1984). The differences in LH concentrations seen at 28 days of age between some experimental and control groups are most easily explained by the high variability in LH levels generally found, as clearly illustrated by the LH concentrations in control groups at this age.…”

Section: Discussionsupporting

confidence: 88%

Inhibin-like activity in ovarian homogenates of prepubertal female rats and its physiological significance

Sander¹,

Meijs-Roelofs²,

Kramer³

et al. 1985

Journal of Endocrinology

View full text Add to dashboard Cite

The presence and physiological significance of ovarian inhibin-like activity (ILA) in immature rats was studied by measuring ILA in ovarian homogenates and by studying the short-term changes in serum concentrations of FSH and LH after unilateral or bilateral ovariectomy. Inhibin-like activity in ovarian homogenates was estimated using an in-vitro bioassay system with dispersed rat anterior pituitary cells and subsequent measurement of FSH and LH levels in the spent pituitary cell medium. Inhibin-like activity, expressed in units/ovary, was undetectable in 13-day-old ovaries, was present in 18-day-old ovaries (5.8 units/ovary) and rose significantly to a value of 29.1 units/ovary on day 23. Another significant rise was seen between 28 and 33 days of age, with ILA reaching a value of 66.4 units/ovary, a value still well below that found in adult dioestrous ovaries (155.6 units/ovary). In the bioassay no systematic dose-dependent influence on LH secretion was found. Serum concentrations of FSH after unilateral or bilateral ovariectomy at 18 days of age showed no change at 5h and a significant (P less than 0.05) increase compared with sham-operated controls at 24 h after operation. At 23, 28 and 33 days of age significant increases in FSH concentration were seen at 5 and 8 h after both unilateral and bilateral ovariectomy. At 24 h after unilateral ovariectomy, FSH had returned to the control values in these rats, whereas after bilateral ovariectomy a further increase in FSH was seen.(ABSTRACT TRUNCATED AT 250 WORDS)

show abstract

Section: Discussionsupporting

confidence: 88%

Inhibin-like activity in ovarian homogenates of prepubertal female rats and its physiological significance

Sander¹,

Meijs-Roelofs²,

Kramer³

et al. 1985

Journal of Endocrinology

View full text Add to dashboard Cite

show abstract

“…These observations support the contention that FSH secretion may be less dependent on GnRH than LH, utilizing evidence that GnRH antagonists in vivo lower serum LH more than FSH, whether given to gonadectomized rats or intact rats at metestrus and proestrus [23,24]. In dispersed cell cultures the effect of Antag on LH and FSH is equal when given against a back ground of GnRH stimulation [8], but others have seen discre pancies using pituitary fragments [10], A GnRH antagonist si milar to the one used in the present experiments causes a drop in bioassayable FSH when given to male patients [25], while immunoassayable FSH shows the minor drop we have seen in rats [8,23]. Since we did not measure bioassayable FSH we do not know whether the differences in FSH:LH ratios seen in this study as a function of Antag are partly due to failure of the RIA to pick up changes in bioactive FSH.…”

Section: Discussionsupporting

confidence: 76%

Suppression of Basal and GnRH-Stimulated Gonadotropin Secretion Rate in vitro by GnRH Antagonist: Differential Effects on Metestrous and Proestrous Pituitaries

Hiatt¹,

Schwartz²

1989

Neuroendocrinology

Self Cite

View full text Add to dashboard Cite

LH and FSH basal secretion rates (BSR) in vitro of pituitary fragments from female rats at metestrus or following ovariectomy parallel changes seen in serum gonadotropins. These findings led us to suspect that in vitro BSR of fragments depended on prior exposure to GnRH or lingering GnRH in the culture. We compared pituitaries removed from rats in two cycle stages, proestrus (PRO) and metestrus (MET). Rats were given a single injection of a potent GnRH antagonist, Antag – WY 45760 -[Ac-β(2)-D-Nal¹, 4-F-D-Phe², D-Trp³, D-Arg⁶]-LHRH, or oil prior to sacrifice at 09.00 h on PRO or MET. Pituitary fragments were perifused for 8 h. To test the effects of Antag in vitro some pituitaries from oil-injected rats were perifused with medium containing 1 µM Antag for the first 4 h. Starting at 5 hall chambers received hourly 10-min pulses of 1 µM GnRH. In PRO rats Antag injection in vivo lowered LH BSR to 50% and FSH to 70% of oil-treated controls. Surprisingly, Antag administered in vitro suppressed LH BSR to 30% and FSH to 55% of controls. In pituitaries from MET rats, BSR of LH and FSH were 20 and 70% of control PRO values and were unaffected by Antag treatment in vivo or in vitro. In PRO pituitaries LH and FSH responses to the first GnRH pulse were blunted by Antag in vivo but responses to subsequent pulses were unaffected; MET responses were not different from controls. In vitro Antag suppressed GnRH-stimulated release to 10–20% of controls at both cycle stages. The lower effectiveness of Antag in suppressing FSH has not been shown previously in vitro, but is consistent with in vivo studies in this laboratory. The relative ineffectiveness of the Antag in lowering BSR in MET compared to PRO pituitary fragments suggests that there is less GnRH present, consonant with data showing lower in vivo GnRH release and pituitary receptor levels in MET rats. Our findings suggest that pituitary fragments retain an appreciable amount of endogenous GnRH that stimulates apparent ‘basal’ gonadotropin secretion and that the concept of basal in vitro secretion rate in fragments needs reexamination.

show abstract

“…The variable patterns of the LH responses to oFF (1 sheep showed an increased amplitude) indicate the fickle nature of the LH secretory mechanisms with regard to follicular fluid proteins. Similarly inconsistent results have been achieved in rats by Charlesworth et al (1984), who explained their results in terms of varying backgrounds of GnRH stimulation.…”

Section: Discussionmentioning

confidence: 87%

Effects of ovine follicular fluid on plasma LH and FSH secretion in ovariectomized ewes to indicate the site of action of inhibin

Clarke¹,

Findlay²,

Cummins³

et al. 1986

Reproduction

View full text Add to dashboard Cite

Ovariectomized ewes were given 2 ml s.c. injections of ovine follicular fluid (oFF) (N = 3) or serum (N = 3) and blood samples were collected each day for 3 days. Follicular fluid caused a significant (P < 0\m=.\005) reduction in FSH within 1 day, but did not affect mean LH values. Two groups of 3 ewes were treated as above but sampled intensively (each 10 min for 6h) on Days 1 (before treatment) and 4; mean plasma FSH concentration and plasma LH pulse frequency and amplitude were ascertained. Significant (P < 0\m=.\005) reduction of FSH concentration was seen in the oFF-treated ewes. A non-specific reduction in LH pulse amplitude, but not pulse frequency, was noted in the control ewes. This experiment was repeated with 2 groups of 4 ewes that were conditioned to the experimental environment and effects on LH secretion were not observed in the controls given serum. Treatment with oFF caused a 70% reduction (P < 0\m=.\005) in plasma FSH and a small (30%) but significant (P < 0\m=.\005) reduction in mean LH concentrations. The latter was probably associated with a reduction in LH pulse amplitude in 3/4 animals (N.S.) with no change in LH pulse frequency. Treatment with oFF, as in Exp. 1, caused a 95% reduction in FSH values and significant (P < 0\m=.\01) reduction (32%) of LH pulse amplitude in ovariectomized ewes that had been subjected to hypothalamo-pituitary disconnection and in which gonadotrophin secretion was reinstated with pulses of 250 ng GnRH every 2 h.These results suggest that proteins from the sheep follicular fluid, including inhibin, act at the pituitary level to inhibit FSH secretion and may have some effects on LH pulse amplitude.

show abstract

Differential Suppression of FSH and LH Secretion by Follicular Fluid in the Presence or Absence of GnRH

Cited by 26 publications

References 24 publications

Inhibin-like activity in ovarian homogenates of prepubertal female rats and its physiological significance

Inhibin-like activity in ovarian homogenates of prepubertal female rats and its physiological significance

Suppression of Basal and GnRH-Stimulated Gonadotropin Secretion Rate in vitro by GnRH Antagonist: Differential Effects on Metestrous and Proestrous Pituitaries

Effects of ovine follicular fluid on plasma LH and FSH secretion in ovariectomized ewes to indicate the site of action of inhibin

Contact Info

Product

Resources

About