Comparative effects of chronic exposure to glucose or sodium butyrate on surfactant development in fetal rabbits.
BACKGROUND
Infants of diabetic mothers (IDM) often have delayed lung development and are thus at an increased risk of Respiratory Distress Syndrome (RDS). Both hyperglycemia and/or hyperinsulinemia have been implicated in this delay but the precise mechanism has not been clarified. Another metabolite, sodium butyrate, which is increased in IDM has been shown to decrease surfactant production in vitro but its effects on the development of the fetal lung surfactant system in vivo have not been studied.


OBJECTIVE
To investigate the in vivo effects of high glucose and sodium butyrate treatment on maternal and fetal glucose and insulin levels and on fetal lung surfactant maturation using timed-pregnant New Zealand White rabbits.


METHODS
On the 24th day of gestation the doe was implanted s.c. with time release pellets containing either glucose (300 mg), sodium butyrate (200 mg) or matching placebo. On the 27th or 30th day maternal (ear vein) and fetal (cardiac puncture) blood samples were drawn for glucose and insulin determinations. Fetal surfactant pools (both intra- and extracellular) were quantitatively harvested using differential and density gradient centrifugation and their phospholipid profiles determined. Data were statistically compared with ANOVA and Duncan's Multiple Range Test.


RESULTS
Neither glucose nor sodium butyrate affected maternal plasma glucose or insulin. Both metabolites significantly increased fetal plasma insulin, decreased fetal plasma glucose but did not delay any of the parameters of surfactant maturation examined.


CONCLUSIONS
Fetal hyperinsulinemia, whether attained by prolonged exposure to elevated glucose or sodium butyrate in vivo does not appear to be the causative agent for delayed lung maturity which frequently occurs in infants of diabetic mothers.
Tshiyombo
T D
TD
Dalhousie University, Department of Obstetrics and Gyneccology, IWK Grace Health Center, Halifax, Nova Scotia, Canada. ttshiyombo@iwkgrace.ns.ca
Oulton
M R
MR
D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D002087:Butyrates / Q000008:administration & dosage*; D005260:Female; D005312:Fetal Blood / Q000737:chemistry; D005325:Fetal Organ Maturity; D020567:Fetal Weight; D005947:Glucose / Q000008:administration & dosage*; D007328:Insulin / Q000097:blood; D008168:Lung / Q000196:embryology; D010713:Phosphatidylcholines / Q000032:analysis; D010716:Phosphatidylinositols / Q000032:analysis; D010743:Phospholipids / Q000032:analysis; D010919:Placebos; D011247:Pregnancy; D011254:Pregnancy in Diabetics / Q000150:complications; D011663:Pulmonary Surfactants / Q000032:analysis / Q000378:metabolism*; D011817:Rabbits
D001786:Blood Glucose; D002087:Butyrates; D007328:Insulin; D010713:Phosphatidylcholines; D010716:Phosphatidylinositols; D010743:Phospholipids; D010919:Placebos; D011663:Pulmonary Surfactants; D005947:Glucose