Ornithine decarboxylase activity in maternal and fetal tissues during inanition in pigs.

Abstract

The relationships between maternal liver and fetal brain and liver ornithine decarboxylase (ODC) activity and porcine fetal development were investigated. Yorkshire gilts were subjected to prolonged inanition (40 days; 0 kcal/day; water only) from Day 50 to Day 90 of gestation and, on Day 90, either hysterectomized or realimentated to a full diet and allowed to advance to term; controls received a full diet (7,028 kcal/day) until hysterectomy at Day 90 or throughout pregnancy. ODC activity was determined in maternal liver tissue collected from 6 experimental and 6 control gilts on Days 50, 70, 89 and 91. Furthermore, ODC activity of Day 90 fetal brain and liver tissue was determined in 6 fetuses from each of 3 additional experimental and control dams (36 fetuses). Prolonged inanition of gilts during late pregnancy had a marked effect upon maternal liver ODC activity. Liver ODC activity in full-fed guts remained constant across days, with a mean activity of 59 (pmol CO3 released per 60 mm per mg soluble protein). ODC activity before inanition (Day 50) in experimental gilts was similar to that of controls, but by Day 70 and continuing to Day 89 (during inanition), was reduced greater than 7-fold. In contrast, after 1 day realimentation (Day 91), ODC activity had increased by greater than 10-fold to levels similar to controls. Day 90 fetal brain ODC activity in inanition gifts was greater than the activity observed in control gilts, and fetal brain weights were similar in all dams, suggesting that ODC may play a role in maintenance of normal fetal brain development. ODC activity of Day 90 fetal liver tissue was decreased in inanition as compared with control gilts, as were fetal liver weights. Reproductive performance, as determined by fetal survival rates, body weight, litter weight and size, was similar in inanition and control gilts. These data indicate that changes in ODC activity may play a role in compensatory responses of the porcine dam and fetus during periods of severe nutrient deprivation to allow normal fetal survival and dev#{231}lopment.