Relationship between concentration of prostaglandin F (PGF) in the oviduct and egg transport in rabbits.

Abstract

Prostaglandin F (PGF) levels were measured by radioimmunoassay in the ampullar, and distal and proximal portions of the oviducts of rabbits killed at various times after an ovulating injection and insemination. The transport of eggs in these animals was studied and it was found that eggs only moved into a particular section of the oviduct when PGF levels declined sharply after reaching a peak value. Maximal levels of PGF were observed in the distal isthmus at 10 h after HCG injection and most eggs were still in the ampulla, while at 30 h PGF concentration in the distal isthmus was low and eggs were then found in that section. At 50 h PGF levels were low in both distal and proximal portions of the isthmus and eggs were in both sections. Thus, there appeared to be a correlation between elevated PGF levels and absence of eggs in isthmic regions of the oviduct. To test the validity of these observations hormonal treatments with estradiol or progesterone known to disrupt egg transport were given to other groups of rabbits, and changes in PGF concentrations in the same sections of oviducts studied. Estradiol caused significant increases in PGF concentrations in the oviduct, ovary and uterus, while by contrast progesterone depressed them to basal levels. In the oviduct of progesterone-treated rabbits egg transport to the uterus was accelerated and there was no indication of any isthmic impediment to egg transport. By contrast in the oviducts of the estradiol-treated rabbits “tubal-blocking” of eggs occurred; there appeared to be a correlation between elevated levels of PGF in the distal and proximal sections of the isthmus up to 30 h after HCG injection and retention of eggs in the ampulla and distal isthmus. These results do not disagree with the hypothesis that normal function of the oviduct is regulated by a balance between the effects of PGFs and PCEs.