@article{mbs:/content/journal/micro/10.1099/00221287-135-3-565, author = "Leaver, H. A. and Howie, A. and Aitken, I. D. and Appleyard, B. W. and Anderson, I. E. and Jones, G. and Hay, L. A. and Williams, G. E. and Buxton, D.", title = "Changes in Progesterone, Oestradiol 17β, and Intrauterine Prostaglandin E2 during Late Gestation in Sheep Experimentally Infected with an Ovine Abortion Strain of Chlamydia psittaci", journal= "Microbiology", year = "1989", volume = "135", number = "3", pages = "565-573", doi = "https://doi.org/10.1099/00221287-135-3-565", url = "https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-135-3-565", publisher = "Microbiology Society", issn = "1465-2080", type = "Journal Article", abstract = "The placenta is the primary site of infection of Chlamydia psittaci and is also intimately involved in the control of parturition. Changes in the pattern of placental hormone secretion were investigated in ewes infected with C. psittaci and in saline-injected controls. The concentration of progesterone in peripheral plasma of infected sheep was significantly lower than in control sheep (P < 0·01). A gradual decline in plasma progesterone occurred in Chlamydia-infected sheep, beginning on day 125 of gestation, in comparison with the sharper decline commencing on day 139 of gestation in the control population. The release of oestradiol 17β, which was greatest on the day of parturition in control sheep, was significantly (P < 0·02) increased on the day before parturition in Chlamydia-infected sheep. The concentrations of prostaglandin E2 in amniotic and allantoic fluids were low during late pregnancy in 12 control sheep, but were significantly raised (P < 0·05) in four out of 12 samples obtained from Chlamydia-infected sheep over the same period. The changes in progesterone and prostaglandin E2 were temporally related to the morphological and histochemical changes characteristic of trophoblast infection. These findings suggest that C. psittaci infection may precipitate premature labour by altering placental steroid and prostaglandin release.", }