Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Target Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Query: UNIPROT:P01178 (
oxytocin
)
15,767
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
The role of
oxytocin
(
OXT
) and prostaglandin F2 alpha (PGF2 alpha) in the process of luteal regulation, particularly their function in the early luteal phase is poorly understood. Therefore the effects of both compounds on in vitro steroid release of porcine luteal cells harvested from young/middle-aged (day 4-6, day 0 = 1st estrous day) or old (day 12-14) corpora lutea were tested. As corpora lutea (CL) contain at least two different steroidogenic cell populations, fractions of the so called small (
SLC
) and large (LLC) luteal cells were prepared and tested in separate experiments. In
SLC
as well as LLC from young CL
OXT
and PGF2 alpha inhibited progesterone (P) production but induced a strong increase of estradiol (E2) release. In old
SLC
and LLC
OXT
and PGF2 alpha were still inhibitory to P release but
OXT
was ineffective and PGF2 alpha had a moderate stimulatory effect on luteal E2 secretion. In
SLC
cultures from young but not from old CL E2 exerted a powerful stimulatory effect on progesterone (P) secretion, i.e. E2 has strong luteotrophic effects in the early luteal phase. Indeed, the pronounced inhibitory effect of
OXT
and PGF2 alpha on P release from
SLC
could be counteracted by the addition of exogenous E2 to the culture media. Therefore, we suggest that in the early luteal phase
OXT
as well as PGF2 alpha have an indirect, E2-mediated luteotrophic effect on P release which is stronger than the direct inhibitory action on P secretion.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Different steroidogenic response of young and aged porcine small and large luteal cells to prostaglandin F2 alpha, oxytocin and estradiol. 830 15
Recent investigations have demonstrated an inhibitory effect of
oxytocin
(
OXT
) on luteal cell progesterone (P) release under in vitro conditions. This inhibitory effect was counteracted by an
OXT
antagonist, indicating that it was receptor-mediated. In the present investigation, we demonstrated the presence of
OXT
binding sites in porcine luteal tissue using a radioiodinated
OXT
antagonist, [1-(beta mercapto-beta,beta-cyclopentamethylene propionic acid),2-(ortho-methyl)-Tyr2-Thr4-Orn8-Tyr-NH2] vasotocin (OTA), as ligand. For membrane fractions of porcine luteal tissue, Kd values of 0.7-0.8 nM were obtained; these are comparable to those of porcine myometrial fractions, measured under the same experimental conditions. Competition studies with luteal membrane fractions yielded a Ki(
OXT
) of 10(-9) M. This is a dose of
OXT
that exerts inhibitory effects on P release under both in vitro and in vivo conditions. To evaluate putative variations of luteal
OXT
receptor concentrations during the estrous cycle, membrane fractions prepared from corpora lutea (CL) of the early or midluteal (Days 2-6) and late luteal phase (Days 9-11) were used. While no differences in Kd values were observed,
OXT
binding capacities were significantly (p < 0.05) higher in CL from the early/midluteal phase (Bmax(E/M) = 116 +/- 12 fmol/mg protein) compared to CL from the late luteal phase (Bmax(L) = 65 +/- 10 fmol/mg protein).
OXT
binding sites were present in both small (
SLC
) and large luteal cells (LLC).
SLC
but not LLC responded to hCG with a significant increase of
OXT
binding sites, whereas E2 augmented
OXT
receptor binding in
SLC
as well as in LLC.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Demonstration of oxytocin receptors in porcine corpora lutea: effects of the cycle stage and the distribution on small and large luteal cells. 838 7
