Autonomous Secretion of Follicle-Stimulating Hormone by Long Term Organ Cultures of Rat Pituitaries

Sheridan, R.; Loras, B; Surardt, Léon; Ectors, Fabien; Pasteels, Jean Lambert

doi:10.1210/endo-104-1-198

Cited by 16 publications

(9 citation statements)

References 13 publications

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“…They demonstrated that whereas FSH secretion was primarily constitutive, LH was secreted mainly through a regulated pathway. This conclusion resembles those reached on the basis of studies with isolated pituitary cells or fragments in vitro (Fallest and Schwartz 19W;Sheridan et al 1979), and also fits with sther studies on relative regulation of synthesis and secretion of the two hormones. We do not h o w at present how involved the paracrine action of activin is in the '6consti-tutive" secretion.…”

Section: Mechanisms Of Differential Regulationsupporting

confidence: 88%

“…When pituitary cells or fragments from rat donors are cultured without GnRH, LH secretion diminishes, while FSH secretion increases with time (Sheridan et al 1979). Estradiol may either increase or decrease secretion (Fdlest and Schwartz 199 1) ; testosterone tends to increase FSH secretion (Bhasin et d. 1987).…”

Section: Role Of Gnwh In Regulating Serum Lh and Fshmentioning

confidence: 99%

“…Stimulation of specific areas of the hypothalamus can lead to differential FSHiLH ratios (Chappel 1987), but we do not h o w whether this is due to a specific FSH-RF or to a change in GnRH pulse frequency. Secretion of FSH from isolated pituitaries in the absence of GnRH persists longer than secretion of LH (Sheridan et al 1979;Fallest and Schwartz 1990), probably as a result of local production of activin (Corrigan et al 1991 ;Bilezikjian et al 1993aBilezikjian et al , 1993bDePaolo et d. 1992). Other peptides such as gdanin, substance P, and NPY (Crowley et al 1987) enhance pituitary secretion of LH in response to GnRH in vitro, but FSH secretion also rises (Bauer-Dmtoin et al 1992).…”

Section: Role Of Hypothalamic Factors Other Than G N Mmentioning

confidence: 99%

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The 1994 Stevenson Award Lecture. Follicle-stimulating hormone and luteinizing hormone: a tale of two gonadotropins

Schwartz¹

1995

Can. J. Physiol. Pharmacol.

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Although most gonadotropes synthesize both luteinizing hormone and follicle-stimulating hormone, the transcription, content, and secretion rates of the two gonadotropins can be separated. The signals external to the gonadotropic cells that appear to be important in the differential regulation are gonadotropin-releasing hormone pulse frequency (high pulse frequency favors luteinizing hormone), steroid feedback (works on both but induces a more powerful negative feedback on luteinizing hormone), and gonadal peptide feedback (activin increases follicle-stimulating hormone; inhibin and follistatin decrease it). We know very little about the pathways within the gonadotropes that favor one gonadotropin rather than another. It is expected that the cloning of the genes for both gonadotropins and the use of specific cell lines and transfections will lead to elucidation of these pathways.

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Section: Mechanisms Of Differential Regulationsupporting

confidence: 88%

Section: Role Of Gnwh In Regulating Serum Lh and Fshmentioning

confidence: 99%

Section: Role Of Hypothalamic Factors Other Than G N Mmentioning

confidence: 99%

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The 1994 Stevenson Award Lecture. Follicle-stimulating hormone and luteinizing hormone: a tale of two gonadotropins

Schwartz¹

1995

Can. J. Physiol. Pharmacol.

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“…FSH secretion from the pituitary may also be more autonomous than LH, as suggested by the in vivo Antag experiments described above as well as observations that FSH secretion persists much longer than LH secretion in vitro in the absence of GnRH [28], Even in the presence of antagonist to GnRH, LH secre tion is higher in proestrous pituitaries than in metestrous pituitaries, suggesting that there may be a higher constitutive release of LH at proestrus. This may not be surprising, since it has been shown that LH content is higher and mRNA for the LH [5-subunit is higher at that time [29,30] and more gonadotropes are secretory for LH at proestrus, than at met estrus [31].…”

Section: Discussionmentioning

confidence: 88%

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

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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.

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“…Separation of the pituitary from GnRH stimulation in male rats abolishes LH synthesis and secretion but allows for continued production of FSH (Sheridan et al 1979, Culler & Negro-Vilar 1986, DePaolo et al 1991 as well as uncombined a-subunit (Grotjan et al 1984). While these experiments revealed that a-subunit and FSH-b are not entirely GnRH dependent, the initial hypothesis for a system controlling the differential regulation of the gonadotropins was derived from studies of the testis (McCullagh 1932) in which a water-soluble testicular extract prevented the formation of 'castration cells' within the anterior pituitary of orchidectomized rats.…”

Section: Activin Follistatin and Inhibinmentioning

confidence: 99%

Intra-pituitary regulation of gonadotrophs in male rodents and primates

Winters¹,

Moore²

2004

Reproduction

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Paracrine and autocrine regulation is well established in many organs including the gonads, but the notion of communication among pituitary cells is a relatively new concept. The FSH-b and GnRH-receptor genes are up-regulated by pituitary activin and down-regulated by pituitary follistatin, and circulating inhibin disrupts this local regulation by functioning as an endogenous competitor of the activin receptor. Activin and follistatin production by folliculostellate cells may play a central role in these responses. a-Subunit expression is maintained at high levels in the absence of GnRH through unknown mechanisms. There is evidence that the intra-pituitary regulation of FSH-b and GnRH-receptor gene expression may activate pubertal maturation in male rats. Finally, there are marked differences in follistatin expression and its regulation by GnRH and androgens in male primates and rats that appear to explain species differences in the differential secretion of FSH and LH, although the physiological significance of these differences is not yet known.

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Autonomous Secretion of Follicle-Stimulating Hormone by Long Term Organ Cultures of Rat Pituitaries

Cited by 16 publications

References 13 publications

The 1994 Stevenson Award Lecture. Follicle-stimulating hormone and luteinizing hormone: a tale of two gonadotropins

The 1994 Stevenson Award Lecture. Follicle-stimulating hormone and luteinizing hormone: a tale of two gonadotropins

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

Intra-pituitary regulation of gonadotrophs in male rodents and primates

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