Production of leukotrienes and prostaglandins in the rat uterus during peri-implantation period.
We have measured by radioimmunoassay the production of leukotrienes (LTC4 and LTB4) and prostaglandins (PGE2 and PGF2 alpha) in the rat uterus on Days 1 through 6 of pregnancy. The production is defined as the synthesis minus the degradation for a defined period. The production of LTC4 or LTB4 remained unaltered on days 1-3, but exhibited a marked increase on Day 4 showing a peak at noon. This was then followed by a sharp decline on Day-5 morning. A small but consistent peak in uterine LT production was also noticed on Day-5 noon prior to implantation and this was followed by a decline on Day-6 morning i.e. after initiation of implantation. The production profile of PGE2 and PGF2 alpha showed a striking resemblance to that of LTs; one exception being that maximal PG production was noticed on Day-4 morning and preceded the peak production of LTs. These vasoactive arachidonate derivatives reached their peak production rates at around the time when a surge in estrogen level is noticed in the uterus on Day 4. Implantation is a local proinflammatory type of reaction that is associated with increased uterine vascular permeability. Vascular changes in inflammatory reactions are provoked by two kinds of chemical mediators: vasodilators and agents that increase vascular permeability. PGs (especially of the E series) are known as vasodilators, while LTs and histamine mediate increases in vascular permeability. Therefore, an interaction between LTs, PGs, and histamine could be important for uterine preparation for implantation and/or implantation per se.
D000818:Animals; D002199:Capillary Permeability; D015237:Dinoprost; D015232:Dinoprostone; D010064:Embryo Implantation; D005260:Female; D007975:Leukotriene B4 / Q000096:biosynthesis*; D011247:Pregnancy; D011453:Prostaglandins / Q000096:biosynthesis*; D011458:Prostaglandins E / Q000096:biosynthesis; D011460:Prostaglandins F / Q000096:biosynthesis; D051381:Rats; D013189:SRS-A / Q000096:biosynthesis*; D014599:Uterus / Q000098:blood supply / Q000378:metabolism*
D011453:Prostaglandins; D011458:Prostaglandins E; D011460:Prostaglandins F; D013189:SRS-A; D007975:Leukotriene B4; D015237:Dinoprost; D015232:Dinoprostone