TY - JOUR
T1 - Steroids as local regulators of ovarian activity in domestic animals
AU - Schams, D.
AU - Berisha, B.
PY - 2002/7
Y1 - 2002/7
N2 - The presented overview gives clear evidence for steroids as local regulators of follicular and luteal activity. In the follicle, estrogen receptor-α (ERα) and ERβ expression are demonstrated in cow, ewe and pig. Besides species specific effects in general, there is evidence that estradiol-17β (E2) exerts a dose-dependent inhibition on the secretion of progesterone (P4) by both theca interna cells (TI) and granulosa cells (GC). GC enhance the ability of the TI to produce androstendione by supplying them with progestin precursor. Androgen produced by TI enhances the ability of the GC to make E2, and high concentrations of E2 in the preovulatory follicle inhibit 3β-HSD in both TI and GC and thus, may promote the use of the pathway Δ5 for TI androgen production. The authors suggest that E2 acts within the follicle to exert positive feedback on androgen and E2 production, and exerts mitotic and anti-atretic or anti-apoptotic effects on follicular cells. Parts of the E2-mediated local action are regulated by stimulating effects on hormone receptors (LH, FSH, oxytocin). Gap junctions permit transfer of nutrients and cytokines to and from the avascular GC and oocyte, and formation is stimulated by estrogens. In bovine corpus luteum (CL) there is evidence that P4 may directly regulate the production of P4, oxytocin and prostaglandins (PGs) in a cycle dependent fashion. In most of domestic animal species, there is clear evidence for CL production of E2 with clear stimulatory and luteotropic effects on P4, and an intraluteal circuit that involves paracrine effects of E2, oxytocin and PGF2α (especially in pigs). In contrast, there are species (ruminants, mares) in which the evidence for important local effects of E2 is less clear, although expression of ERα, ERβ and progesterone receptor (PR) is documented. Progesterone is very important for the regulation of CL lifetime by effects on the endometrium and release of the luteolytic signal PGF2α. In conclusion, steroids as local regulators of ovarian activity are now documented and may stimulate further research in this field.
AB - The presented overview gives clear evidence for steroids as local regulators of follicular and luteal activity. In the follicle, estrogen receptor-α (ERα) and ERβ expression are demonstrated in cow, ewe and pig. Besides species specific effects in general, there is evidence that estradiol-17β (E2) exerts a dose-dependent inhibition on the secretion of progesterone (P4) by both theca interna cells (TI) and granulosa cells (GC). GC enhance the ability of the TI to produce androstendione by supplying them with progestin precursor. Androgen produced by TI enhances the ability of the GC to make E2, and high concentrations of E2 in the preovulatory follicle inhibit 3β-HSD in both TI and GC and thus, may promote the use of the pathway Δ5 for TI androgen production. The authors suggest that E2 acts within the follicle to exert positive feedback on androgen and E2 production, and exerts mitotic and anti-atretic or anti-apoptotic effects on follicular cells. Parts of the E2-mediated local action are regulated by stimulating effects on hormone receptors (LH, FSH, oxytocin). Gap junctions permit transfer of nutrients and cytokines to and from the avascular GC and oocyte, and formation is stimulated by estrogens. In bovine corpus luteum (CL) there is evidence that P4 may directly regulate the production of P4, oxytocin and prostaglandins (PGs) in a cycle dependent fashion. In most of domestic animal species, there is clear evidence for CL production of E2 with clear stimulatory and luteotropic effects on P4, and an intraluteal circuit that involves paracrine effects of E2, oxytocin and PGF2α (especially in pigs). In contrast, there are species (ruminants, mares) in which the evidence for important local effects of E2 is less clear, although expression of ERα, ERβ and progesterone receptor (PR) is documented. Progesterone is very important for the regulation of CL lifetime by effects on the endometrium and release of the luteolytic signal PGF2α. In conclusion, steroids as local regulators of ovarian activity are now documented and may stimulate further research in this field.
UR - http://www.scopus.com/inward/record.url?scp=0036638340&partnerID=8YFLogxK
U2 - 10.1016/S0739-7240(02)00145-5
DO - 10.1016/S0739-7240(02)00145-5
M3 - Article
C2 - 12142226
AN - SCOPUS:0036638340
SN - 0739-7240
VL - 23
SP - 53
EP - 65
JO - Domestic Animal Endocrinology
JF - Domestic Animal Endocrinology
IS - 1-2
ER -