Time-Related Secretion of Gonadotrophins After a Single Injection of Steroid-Free Bovine Follicular Fluid in Prepubertal and Adult Female Rats

Hermans, W. P.; Debets, M. H. M.; Leeuwen, E. C. M. van; Jong, Frank H. de

doi:10.1677/joe.0.0900069

Cited by 20 publications

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“…1B), and the enhancement or suppression of LH at one dose of pFF and GnRH in experiment 3 ( fig. 5C, F) are reminiscent of other occasional reports of LH enhancement or suppression with pFF in vivo [1,10,14,21,23,27], The lack of consistent findings, and the generally high dose of FF necessary to elicit LH changes, suggest that the LH effect is independent of the FSH effect. This impression is supported by in vitro studies.…”

Section: Discussionmentioning

confidence: 69%

“…In vitro, FF does not alter luteinizing hormone (LH) secretion under basal conditions: however, when cultures are challenged with gonadotropin releasing hormone (GnRH), LH secre tion may be suppressed or enhanced [8,16]. Most in vivo studies with FF demonstrate highly specific FSH suppres sion, with no alteration of LH [2,15,17,20], However, occasional reports of LH suppression [ 10,23,27] or enhance ment [1,14,21] after FF injection in vivo have provided confusing evidence regarding the specificity of FSH supReceived: May 13,1983 Accepted after revision: August 11,1983 pression by such fluid. When they occur, these effects on LH in vivo appear to be associated with the highest doses of FF and with high endogenous GnRH secretion [12], We and others have proposed that the FSH suppressing factor in FF named 'folliculostatin' or 'ovarian inhibin', is a hormone of the ovary which provides the crucial negative feedback signal which selectively maintains FSH levels low in the presence of ovaries.…”

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confidence: 99%

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

Charlesworth¹,

Grady²,

Shin³

et al. 1984

Neuroendocrinology

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The differential role of porcine follicular fluid (pFF) in regulating follicle-stimulating hormone (FSH) and luteinizing hormone (LH) release in vivo in situations of different gonadotropin releasing hormone (GnRH) backgrounds was studied. In experiment 1, 2-week ovariectomized rats injected intravenously with 4, 16 or 64 mg of protein from pFF, showed a dose-dependent suppression of FSH over time, with a maximal suppression to 40% of control values by 10 h. LH levels were slightly, but significantly, elevated by the two lower doses, but not by the highest dose of pFF. In experiment 2,64 mg pFF was superimposed (i.v. injection) in ovariectomized rats injected subcutaneously with a high dose of GnRH antagonist (500 µg) 24 h earlier. The pFF suppressed FSH 35% below the level achieved in the absence of GnRH stimulation, with no effect on LH. In experiment 3, the rise in FSH secretion in acutely ovariectomized rats was shown to be inhibited by 8 or 32 mg pFF administered intravenously 3.5 h after surgery. Injection of GnRH (250 or 1,000 ng) 4.5 h after pFF could not overcome the inhibitory action of pFF on FSH, although non-pFF-treated controls responded in a dose-dependent fashion to GnRH stimulation. The expected LH response to GnRH was not affected by pFF, except in the group receiving 1,000 ng GnRH and 8 mg pFF. In these rats, LH was enhanced in one trial, but suppressed in a replicate trial, illustrating the inconsistent effects of pFF on LH under conditions of high GnRH stimulation. These results demonstrate the existence of a component of FSH secretion which is independent of GnRH, but sensitive to the inhibitory effect of pFF, suggesting a site of action of the putative peptide hormone, folliculostatin, distal to the GnRH receptor. Also, pFF always suppresses FSH (due to the action of folliculostatin); its effect on LH depends on the dose and the state of GnRH stimulation, and is probably not a function of folliculostatin per se.

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Section: Discussionmentioning

confidence: 69%

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confidence: 99%

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

Charlesworth¹,

Grady²,

Shin³

et al. 1984

Neuroendocrinology

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“…It is unlikely that this efTect can be attributed to inhibin since the onset of the suppressive action of this hormone on FSH release has a relatively long latency, in the order of 3-4 h in vivo [20). This would account for the fact that a significant reduction in GnRH-induced FSH secretion in the presence of 50 ng inhibin/ml was only observed when the perifusing period was extended to 240 min ( fig.…”

Section: Discussionmentioning

confidence: 99%

Non-Steroidal Follicular Factors Attenuate the Self-Priming Action of Gonadotropin-Releasing Hormone on the Pituitary Gonadotroph

Busbridge

Chamberlain²,

Griffiths³

et al. 1990

Neuroendocrinology

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Pituitary glands of pro-oestrous and oestrous rats were perifused in series with isolated ovarian follicles and the luteinizing hormone (LH) and follicle-stimulating hormone (FSH) responses to gonadotropin-releasing hormone (GnRH) were measured. Pituitary glands from pro-oestrous rats, perifused with the effluent medium from isolated preovulatory follicles, showed a significant reduction in the self-priming effect of GnRH as observed from the typical biphasic LH response to a continuous GnRH challenge. The initial FSH response to GnRH was also reduced. A similar trend was seen in the LH responses of pituitary glands from oestrous rats but results were not significant; there was no parallel reduction in FSH release. It is unlikely that the attenuation of GnRH self-priming was due to the steroids released by the isolated follicles. LH responses of pro-oestrous pituitaries, perifused with medium containing 200 pg oestradiol/ml, 5 ng progesterone/ml or 200 pg testosterone/ml were similar to paired controls as were the responses when all three steroids were added to the perifusing media at identical concentrations. Furthermore, when steroids were charcoal extracted from the effluent medium of perifused isolated follicles the biological activity of this medium in attenuating GnRH self-priming was not destroyed. Finally, the effects of purified bovine inhibin and steroid-free human follicular fluid (hFF) on LH responses were compared. Purified inhibin at a concentration of 20 or 50 ng/ml perifusing medium had no effect on GnRH-stimulated LH release although GnRH-stimulated FSH secretion was significantly reduced toward the end of an extended perifusing period. In contrast, hFF at a dilution of 1:50 in the perifusate, caused a marked attenuation of the primed LH response. We conclude that preovulatory follicles and hFF contain a non-steroidal substance, distinct from inhibin, which can attenuate the self-priming effect of GnRH on the pituitary gonadotroph.

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“…The present study was undertaken to determine whether there is not only an initial suppression but also a later rebound of concentrations of FSH after a single injection of bFF in intact female rats on dioestrus-2, dioestrus-3, pro-oestrus and oestrus, thereby extending a previous study which used a similar treatment on dioestrus-1 (Hermans et al 1981). …”

Section: Introductionmentioning

confidence: 93%

“…These results could be due to levels of FSH after bFF injection insufficiently decreased to affect follicular development on different days of the cycle. Alternatively, this observation may be explained from the results of recent studies showing that after a single injection of porcine FF (pFF) on pro-oestrus (DePaolo, Hirshfield, Anderson, Barraclough & Channing, 1979) or of bFF on dioestrus-1 (= metoestrus) (Hermans, Debets, van Leeuwen & de Jong, 1981), initial suppression of levels of FSH is followed by a rebound, resulting in increases in plasma concentrations of FSH.…”

Section: Introductionmentioning

confidence: 99%

Effects of Single Injections of Bovine Follicular Fluid on Gonadotrophin Concentrations Throughout the Oestrous Cycle of the Rat

Hermans¹,

Debets²,

Leeuwen³

et al. 1982

Journal of Endocrinology

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A single injection of steroid-free bovine follicular fluid (bFF), which contains inhibin-like activity, was given to adult female rats at 09.00 h on dioestrus-2 (the day after metoestrus), dioestrus-3, pro-oestrus or oestrus. peripheral concentrations of gonadotrophins were measured at 2-h intervals after injection. Compared with values in control animals treated with bovine plasma, injection of bFF did not influence concentrations of LH. In contrast, at all days studied injection of bFF resulted in suppressed concentrations of FSH, during a period which started between 4 and 10 h after injection and lasted 4-12 h, depending on the day of the cycle. With the exception of pro-oestrus, the period of suppression was followed by one in which fluctuating levels of FSH were found; in general, resulting levels were higher though not significantly increased. This latter effect was most pronounced on dioestrus-2 and dioestrus-3, when levels of FSH, which were already low in control animals, were first suppressed during the 6 h after injection of bFF. These data, in conjunction with results from an earlier study in rats at dioestrus-1, showed that administration of bFF induces a fast and selective suppression of FSH secretion on all days of the cycle. This period of suppression was followed by one with fluctuating levels of FSH which showed a tendency to be higher, indicating that disturbances in FSH secretion, such as are caused by bFF, can be compensated for quickly. In this way the process of follicular maturation might be protected.

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Time-Related Secretion of Gonadotrophins After a Single Injection of Steroid-Free Bovine Follicular Fluid in Prepubertal and Adult Female Rats

Cited by 20 publications

References 0 publications

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

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

Non-Steroidal Follicular Factors Attenuate the Self-Priming Action of Gonadotropin-Releasing Hormone on the Pituitary Gonadotroph

Effects of Single Injections of Bovine Follicular Fluid on Gonadotrophin Concentrations Throughout the Oestrous Cycle of the Rat

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