Detection of acyl-CoA synthetase, acyl-CoA:lysophospholipid acyltransferase and phospholipase A2 activities in non-pregnant and pregnant guinea-pig uterine tissues

Acyl-CoA synthetase (ACS), acyl-CoA:lysophospholipid acyltransferase (ACLAT) and phospholipase (PL) A2 activities were detected in guinea-pig endometrium on days 7 and 15 of the cycle, and on days 15, 29 and 36 of pregnancy. Ovariectomy of non-pregnant animals resulted in an increase in the apparent activities of these three enzymes which was reversed by treatment with oestradiol and/or progesterone. ACS, ACLAT and PLA2 activities were detected in day 15 conceptuses, and in the placenta, sub-placenta, chorion and amnion on days 29 and 36 of pregnancy. Apparent activities of the enzymes were generally higher in the fetal membranes than in the placental tissue. This study has established that the enzymes involved in turnover of arachidonic acid in phospholipids are present in tissues in the non-pregnant and pregnant guinea-pig uterus. The higher apparent activities of enzymes (ACS and ACLAT) involved in arachidonic acid uptake compared to the enzyme (PLA2) involved in arachidonic acid release is in agreement with there being very low concentrations of free arachidonic acid in tissues.