Proliferative processes within the equine corpus luteum may depend on paracrine progesterone actions.
Soon after ovulation, the corpus luteum (CL) starts secreting progesterone (P(4)), a hormone necessary for implantation. The aim of the study was to evaluate whether P(4) exerts an autocrine/paracrine action on luteal angiogenic activity and P(4), prostaglandin E(2) (PGE(2)) and NO production in the mare. Corpora hemorrhagica (CH) and mid-luteal phase CL (MCL) were cultured with (i) no hormone (Control); (ii) P(4); (iii) a P(4) precursor - pregnenolone; or (iv) a P(4) antagonist - onapristone [10(-4) M;10(-5) M; all steroids]. NO production decreased in MCL, with respect to CH, when treated with P(4) [10(-4) M] and pregnenolone [10(-5) M]. PGE(2) increased from CH to MCL, and showed a tendency to rise in pregnenolone treated luteal tissues (10(-4) M; p=0.06). In the CH, P(4) decreased with pregnenolone [10(-4) M] compared to control, P(4) [10(-5) M], onapristone [10(-4) M;10(-5) M] and pregnenolone [10(-5) M](p<0.05). In the MCL, pregnenolone [10(-5) M] decreased (p<0.05) and P(4) tended to decrease (p=0.06) bovine aortic endothelial cell (BAEC) mitogenesis. Onapristone [10(-4) M] increased BAEC proliferation with respect to P(4) (p=0.01). Since there was no direct effect of treatments on BAEC, these data suggest that long-lasting effects of P(4) and its precursor may inhibit angiogenic factor(s) production by equine MCL, preparing for CL functional and structural regression.
Ferreira-Dias
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C.I.I.S.A., Faculdade de Medicina Veterinária TU Lisboa, Lisboa, Portugal. gmlfdias@fmv.utl.pt
Costa
A S
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Mateus
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Korzekwa
A
A
Redmer
D A
DA
Skarzynski
D J
DJ
D000818:Animals; D048708:Cell Growth Processes / Q000187:drug effects / Q000502:physiology; D003338:Corpus Luteum / Q000098:blood supply / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology*; D015232:Dinoprostone / Q000096:biosynthesis; D042783:Endothelial Cells / Q000166:cytology* / Q000187:drug effects; D005260:Female; D006067:Gonanes / Q000494:pharmacology; D006736:Horses / Q000097:blood / Q000502:physiology*; D018919:Neovascularization, Physiologic; D009569:Nitric Oxide / Q000096:biosynthesis; D011284:Pregnenolone / Q000494:pharmacology; D011374:Progesterone / Q000096:biosynthesis / Q000097:blood / Q000494:pharmacology*
D006067:Gonanes; D009569:Nitric Oxide; D011374:Progesterone; D011284:Pregnenolone; C053238:onapristone; D015232:Dinoprostone