Evidence against a role for blastocyst-secreted oxytocin in early pregnancy maintenance in sheep.
Analysis of ovine conceptus RNA by slot blotting, Northern analysis and nested polymerase chain reaction failed to detect oxytocin-neurophysin prohormone mRNA. Probes used hybridized with both the 3' end of the prohormone mRNA and the oxytocin-coding sequence. Northern analysis of bovine and porcine conceptus RNA was also negative, and polymerase chain reaction demonstrated oxytocin-neurophysin mRNA in ovine corpus luteum, but not in human corpus luteum or decidua, or in ovine endometrium. Infusion of oxytocin into the uterine lumen in cyclic ewes between days 9 and 19 or 20 after oestrus failed to prolong the luteal phase of the cycle and had no effect on endometrial oxytocin receptor concentrations or uterine prostaglandin F secretion. Oxytocin administered systematically prevented luteolysis and reduced uterine prostaglandin F secretion. Taken together, these data suggest that blastocyst-derived oxytocin is unlikely to contribute to corpus luteum maintenance in early pregnancy. They are inconsistent with a previous report that the ovine blastocyst synthesizes and secretes oxytocin.
AFRC Research Group on Hormones and Farm Animal Reproduction, University of Nottingham, Faculty of Agricultural Science, Loughborough, Leics.
T J
TJ
Parkinson
H J
HJ
Stewart
M G
MG
Hunter
D S
DS
Jones
D C
DC
Wathes
A P
AP
Flint
D000818:Animals; D001755:Blastocyst / Q000737:chemistry / Q000502:physiology*; D015152:Blotting, Northern; D005260:Female; D010121:Oxytocin / Q000235:genetics / Q000494:pharmacology / Q000502:physiology*; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D011255:Pregnancy Maintenance / Q000187:drug effects / Q000502:physiology*; D011270:Pregnancy, Animal / Q000502:physiology*; D011460:Prostaglandins F / Q000378:metabolism; D015347:RNA Probes; D012333:RNA, Messenger / Q000032:analysis; D012756:Sheep / Q000502:physiology*; D014599:Uterus / Q000187:drug effects / Q000378:metabolism
D011460:Prostaglandins F; D015347:RNA Probes; D012333:RNA, Messenger; D010121:Oxytocin