Endometrial caspase 1 and interleukin-18 expression during the estrous cycle and peri-implantation period of porcine pregnancy and response to early exogenous estrogen administration

Reprod Biol Endocrinol. 2010 Apr 9;8:33. doi: 10.1186/1477-7827-8-33.


Background: The role for endometrial secretion of cytokines during the establishment of pregnancy in a number of mammals is well established. The current study determined endometrial expression of caspase 1 (CASP1) and interleukin-18 (IL18) during the estrous cycle and early pregnancy, and following early estrogen administration, which induces conceptus loss during early development in pigs.

Methods: Gilts were hysterectomized on either D 0, 5, 10, 12, 15 and 18 of the estrous cycle, or D 10, 12, 15 or 18 of pregnancy. The abundance of endometrial CASP1 mRNA was unaffected by day of the estrous cycle, however there was a 6 and 10-fold increase in expression on D 15 and 18 of pregnancy. Endometrial expression of IL18 mRNA increased 5-fold between D 10 to 18 in cyclic and pregnant gilts. Total recoverable IL18 in uterine flushings was greater in pregnant compared to cyclic gilts on D 15 and 18.In the second experiment, mated gilts were treated with either corn oil (CO) or estrogen (E) on D 9 and 10 and hysterectomized on either D 10, 12, 13, 15 or 17 of pregnancy. The current study localizes the presence of CASP1 to the epithelial layer of the endometrium for the first time. Further, a day x treatment interaction was detected for endometrial CASP1 mRNA and protein abundance as E stimulated an earlier increase on D 13 compared to CO gilts. Although IL18 mRNA expression remained unaltered from the E treatment, protein abundance was significantly attenuated on D 15 and 18 in response to E treatment.

Conclusions: Endometrial expression of CASP1 and IL18 is associated with establishment of pregnancy in pigs. Alteration of CASP1 and IL18 following premature exposure of the uterus to estrogen during early pregnancy may contribute to conceptus loss between Days 15 to 18 of pregnancy.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Caspase 1 / genetics
  • Caspase 1 / metabolism*
  • Embryo Implantation / drug effects
  • Embryo Loss / chemically induced
  • Embryo Loss / pathology
  • Embryo, Mammalian / drug effects
  • Embryo, Mammalian / pathology
  • Embryonic Development* / drug effects
  • Endometrium / drug effects
  • Endometrium / enzymology*
  • Endometrium / pathology
  • Epithelium / enzymology
  • Epithelium / pathology
  • Estradiol / analogs & derivatives
  • Estradiol / toxicity
  • Estrogens / toxicity*
  • Estrous Cycle / metabolism*
  • Female
  • Gene Expression Regulation, Enzymologic / drug effects
  • Interleukin-18 / genetics
  • Interleukin-18 / metabolism*
  • Organ Specificity
  • Pregnancy
  • RNA, Messenger / metabolism
  • Random Allocation
  • Reverse Transcriptase Polymerase Chain Reaction
  • Sus scrofa / physiology*
  • Time Factors


  • Estrogens
  • Interleukin-18
  • RNA, Messenger
  • Estradiol
  • estradiol 17 beta-cypionate
  • Caspase 1