The Actions of Porcine Follicular Fluid and Estradiol on Periovulatory Secretion of Gonadotropic Hormones in Rats*

Rush, Michael E.; Ashiru, Oladapo A.; Lipner, Harry; Williams, Ashley; McRae, C. U.; Blake, Charles A.

doi:10.1210/endo-108-6-2316

Cited by 39 publications

(25 citation statements)

References 26 publications

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“…At the same time, the long-lasting effect on basal FSH and its time course being maximal at several hours after PFF administration indicated that PFF suppressed not only FSH release but also its Huang and Miller (1984) reported that PFF rather intensified an LH-RH mediated LH release. Rush et al (1981) reported that PFF suppressed basal LH secretion during proestrous in female rats. These inconsistent results may be partly due to differences in a potency or a purity of inhibin activity in the preparations used for the experiments.…”

Section: Discussionmentioning

confidence: 97%

Effect of porcine follicular fluid on LH and FSH secretion in rats.

Demura

Suzuki

Nakamura

et al. 1988

Tohoku J. Exp. Med.

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Effect of Porcine Follicular Fluid on LH and FSH Secretion in Rats . Tohoku J. exp. Med., 1988, 156 (2), 157-163 -To investigate a mode and a site of action of inhibin on FSH and LH secretion , in vivo and in vitro effects of porcine follicular fluid (PFF) on FSH and LH secretion were studied in male rats . PFF administerd i.v. suppressed basal FSH levels for 1-8 hr , but did not alter LH levels. O n the contrary, PFF given either 1 or 6 hr in advance , suppressed LH-RH stimulated LH responses as well as LH-RH induced FSH responses . In cultured pituitary cells PFF exerted a partial suppressive effect on LH release. PFF suppressed LH release only under the maximal stimulation with 10-70 M LH-RH and 0.1 mM 3-isobutyl-1-metylxanthine (IBMX) to a lesser degree compared with uniform and greater suppression on FSH release regardless of the experimental conditions. Above results showed a selective suppressive effect of PFF on FSH release and synthesis with a less inhibitory effect on LH release mainly at the pituitary level.inhibin ; porcine follicular fluid ; FSH ; LH ; LH-RH It has been widely demonstrated that follicular or testicular preparations with definite inhibin activities suppressed FSH secretion in rats (Marder et al . 1977;Schwartz and Charming 1977) as well as in other species (Channing et al. 1981 ;Rettori et al. 1982). However, effects of inhibin on LH release are still controversial.To investigate the effect of inhibin on LH and FSH secretion, in vivo and in vitro effects of porcine follicular fluid (PFF) on LH and FSH secretion were studied in male rats under various conditions.

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Section: Discussionmentioning

confidence: 97%

Effect of porcine follicular fluid on LH and FSH secretion in rats.

Demura

Suzuki

Nakamura

et al. 1988

Tohoku J. Exp. Med.

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“…The oestrous component of the FSH hypersecretion in RU486-treated rats was inhibited by bFF, but not affected by ADX, as occurs in the preovulatory surge of FSH on pro-oestrus afternoon (33)(34)(35). The metoestrous component showed a similar endocrine dependency to that of the secondary surge of FSH during early oestrus (25,27,34,36). Therefore, FSH secretion during oestrus and metoestrus in rats injected with RU486 in pro-oestrus cannot be considered a delayed periovulatory secretion.…”

Section: Fsh (Mg/l)mentioning

confidence: 87%

“…Serum FSH levels remain increased until FSH-stimulated follicles secrete enough inhibin and oestradiol which, in turn, suppress FSH secretion (10,31,32). The oestrous component of the FSH hypersecretion in RU486-treated rats was inhibited by bFF, but not affected by ADX, as occurs in the preovulatory surge of FSH on pro-oestrus afternoon (33)(34)(35). The metoestrous component showed a similar endocrine dependency to that of the secondary surge of FSH during early oestrus (25,27,34,36).…”

Section: Fsh (Mg/l)mentioning

confidence: 95%

The steroid antagonist RU486 given at pro-oestrus induces hypersecretion of follicle-stimulating hormone from oestrus afternoon to early metoestrus in the rat

Sánchez-Criado

Tébar²,

Ruiz³

et al. 1997

European Journal of Endocrinology

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Administration of the steroid antagonist RU486 to cyclic rats at pro-oestrus blunts the preovulatory surge of LH and suppresses the first and second surges of FSH. In addition, administration of oestradiol to RU486-treated rats reactivates the LH surge the following day. The present study explored the effects of RU486 (4 mg/0·2 ml oil), administered at 0800 h on the day of pro-oestrus, on serum FSH and LH concentrations through oestrus and early metoestrus. RU486 induced a hypersecretion of FSH, which started at 1400 h on the day of oestrus and was maintained until 0800 h on the day of metoestrus. Because the timing and magnitude of this secretion of FSH were similar to those of the periovulatory secretion of FSH during pro-oestrus and early oestrus in intact cyclic rats, we investigated the effects of: 1) LHRH antagonist (LHRHa) injected at either 0900 h or 2000 h on the day of oestrus, 2) oestradiol benzoate injected at 1600 h on the day of pro-oestrus and at 0900 h on the day of oestrus, 3) bovine follicular fluid (bFF) given either at 1100 h or at 2000 h on the day of oestrus, or 4) adrenalectomy (ADX) at 1100 h on the day of oestrus, on serum FSH and LH concentrations at 1800 h on the day of oestrus and at 0200 h on the day of metoestrus in rats injected with RU486 at pro-oestrus. The results showed that 1) both components (late oestrus and early metoestrus) of FSH hypersecretion in RU486-injected rats in pro-oestrus were inhibited by oestradiol benzoate and bFF, 2) the metoestrous component was not affected by LHRHa, whereas the oestrous component was partially reduced, and 3) ADX partially reduced serum FSH concentrations only on the day of metoestrus, possibly because, as the serum concentrations of corticosterone reflected, the antiglucocorticoid activity of 4 mg RU486 lasted only 24 h. The results support the hypothesis that blockade of progesterone actions at pro-oestrus results in the maintenance of the daily neural signal that activates the release of gonadotrophins. Whereas the expression of LH secretion requires high levels of oestradiol, FSH secretion is expressed against a background of low oestradiol levels. The results of this study also indicate that the release of FSH during oestrus and metoestrus in rats injected with RU486 at pro-oestrus is a consequence of the lack of ovarian negative feedback inhibition on the pituitary.

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“…Furthermore, exogenous P administered to ovariectomized estrogen-primed rats extinguishes the ability of the hypothalamus to generate daily LH surges [26, 27]. Little [28]or no attention [16, 24, 25, 29, 30, 31, 32, 33]has been paid to the proestrous afternoon P action on the secretion of FSH on estrous afternoon. To our knowledge the data from the present study are the first to deal with the effects of LH-dependent progesterone secretion on proestrous afternoon on FSH secretion the following day.…”

Section: Discussionmentioning

confidence: 99%

“…In contrast, PB injection blocks the LHRH-dependent LH surge and, consequently, LH-dependent ovarian endocrine events in proestrus [25, 28, 37]. However, both PB and RU prevent proestrous afternoon P inhibition of the neural stimulus controlling LHRH release the following day [16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32]. Thus, differences in LH and FSH secretion on estrous afternoon between RU- and PB-injected rats in proestrus must be attributable to the different ovarian hormone background from proestrus to estrus.…”

Section: Discussionmentioning

confidence: 99%

Mechanism of the Stimulatory Action of Antisteroid RU486 on Follicle-Stimulating Hormone Secretion in the Cyclic Rat

1999

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These experiments explored the mechanism underlying FSH hypersecretion on estrous afternoon in rats injected with RU486 (RU) on proestrus. Four-day cyclic rats were injected with RU at 12:00 h on proestrus (1 or 4 mg/0.2 ml oil; s.c.), and its effects on LH and FSH secretion at 18:30 h on estrus were compared with those of antiprogestagens ZK299 (ZK) (1 or 4 mg/0.2 ml oil; s.c.) and Org31806 (OR) (2 or 8 mg/0.2 ml oil; s.c.). Additionally, rats treated with RU or nembutal (PB) (60 mg/kg; i.p. at 13:00 h on proestrus) were injected with an LHRH antagonist (LHRHa) at 10:00 h on estrus (1 mg/0.2 ml saline; s.c.) or progesterone (P) (7.7, 15.5 or 30.9 mg/0.2 ml oil; s.c.) on proestrus at 10:00 h in RU-injected rats and at 14:00 h in PB-injected rats. Animals were killed by decapitation at 18:30 h on estrus and serum LH and FSH concentrations were determined. Rats trated with 1 or 4 mg of RU or Org or 4 mg of ZK recorded increased serum FSH on estrous afternoon, while 1 mg ZK had no effect. PB increased mainly serum LH levels and, to a lesser extent, FSH levels. P decreased serum FSH concentrations in both RU- and PB-injected rats. LHRHa reversed the effects of PB on FSH secretions, but reduced FSH hypersecretion induced by RU only. These results are interpreted to mean that, in the absence of proestrous afternoon P-inhibitory action of the neural stimulus controlling LHRH release, FSH secretion on estrous afternoon involves two components: one is LHRH dependent while, in contrast to LH secretion, the other is LHRH independent, and only expressed in a low estrogen background.

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The Actions of Porcine Follicular Fluid and Estradiol on Periovulatory Secretion of Gonadotropic Hormones in Rats*

Cited by 39 publications

References 26 publications

Effect of porcine follicular fluid on LH and FSH secretion in rats.

Effect of porcine follicular fluid on LH and FSH secretion in rats.

The steroid antagonist RU486 given at pro-oestrus induces hypersecretion of follicle-stimulating hormone from oestrus afternoon to early metoestrus in the rat

Mechanism of the Stimulatory Action of Antisteroid RU486 on Follicle-Stimulating Hormone Secretion in the Cyclic Rat

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