Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.24.3 (collagenase)
 18,340 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Activin is a protein originally isolated from follicular fluid as a factor stimulating FSH release from the pituitary. The present experiments support the hypothesis that activins may also regulate follicle development by autocrine/paracrine mechanisms. Granulosa-oocyte complexes were isolated by collagenase/dispase dispersion of ovaries from 14- or 21-day-old rats and cultured in serum-free medium. Within 24 h, the cells had spread to form a monolayer. Hormones and growth factors were added at this time. Cell number and thymidine incorporation were measured after an additional 72 h. In the presence of insulin and transferrin, activin-A increased both granulosa cell number and thymidine incorporation more than 2-fold. This effect could be inhibited by follistatin, an activin-binding protein. In addition, activin-A, in the presence of FSH, induced reorganization of follicular structures from monolayer culture of cells from 14-day-old rats and caused cells from primary follicles to develop into large follicle-like structures. These structures contained oocytes, a cumulus layer, an antrum, and a multilayered follicular wall with a diameter of more than 1 mm. Electron microscopy revealed that the cells in the follicle-like structure were connected by gap junctions. Oocytes showed a mature morphology and had closely associated cumulus layers. Dissociation of the follicular wall in these follicle-like structures was induced by the addition of LH, resembling the induction of ovulation in vivo. The findings are important for understanding follicular development and atresia.
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PMID:Activin promotes ovarian follicle development in vitro. 786 93

Activin has been previously demonstrated to directly stimulate the synthesis of GnRH receptors and to increase FSH secretion in non-human pituitary cell cultures (PCC). Several results in Macaque monkeys failed to support an unequivocal role for Inhibin in FSH suppression. Whereas the bioactivity of Inhibin and Activin has been demonstrated in rat PCC, no data exist on human pituitary response to these peptides. We studied, therefore, the secretion of FSH and LH by dispersed human fetal PCC from > 140 midtrimester abortions in response to recombinant human (rh-) Activin-A, Inhibin, and other secretagogues. After mechanical and enzymatic dispersion, using collagenase and deoxyribonuclease, the human fetal pituitary cells were cullured on extracellular matrix (ECM) like material coaled 24 well plate (Primaria, Falcon) in fetal calf serum-containing medium. After 3 days incubation in serum-containing medium, the PCC were washed and preincubated for 90 mins in serum-free medium and incubated with rh-ActivinA, Inhibin, TGF-p, Follistatin, sex steroids, and GnRH in quadruplicate wells. The EC50 of rh-Activin-A for FSH secretion was ~ 10 ng/mL. rh- Activin-A was a more potent secretagogue for FSH secretion than GnRH. On the contrary, GnRH (20 ng/mL) was more potent than rh-Activin A for LH secretion. Nevertheless, a significant increase in LH secretion into the medium was brought about by rh-Activin-A. Inhibin decreased FSH secretion but LH response to Inhibin was inconsistent. GnRH opposed the inhibitory effect of Inhibin on both gonadotropins. In dynamic, short term, repetitive exposure of fetal pituitary fragments to rh-Activin-A (superfusionl we could not receive -a similar increase in LH & FSH as in static incubations, as opposed to a short GnRH exposure. Melatonin did not inhibit LH secretion in human PCC as opposed to rodents. In addition to their endocrine, paracrine, and sutocrine effects and to their role as possible markers, the TGF-b superfamily members may atiect embryogenesis and possibly immunomodulation of the fetus. In contrast to others, who could detect Inhibin-B only in male but not in female fetuses sera, we have measured Inhibin-B in both male and female midtrimester fetal sera, challenging the previous assumption that the fetal origin is only Sertoli cells. Human fetal PCC express the previously reported physiologic responses to Activin and Inhibin generated in non-human experiments on gonadotropin secretion in-vitro, and may serve as a physiologic model for studying human gonadotrope responses to the TGF-b family of peptides. Our preliminary data may provide the first unequivocal evidence for the validity of the Activin/Inhibin hypothesis in human.
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PMID:Response of human fetal pituitary cells to activin, inhibin, hypophysiotropic and neuroregulatory factors in vitro. 1175 7