Gestational Ethanol Consumption on Tissue Amino Acid Levels: Decreased Free Histidine and Tryptophan in Fetal Tissues with Concomitant Increase in Urinary Histamine Excretion

The effects of ethanol consumption during pregnancy on maternal, placental, and fetal tissue amino acid levels and metabolism were investigated. Pregnant Sprague-Dawley rats were given 35% ethanol-calorie liquid diet, ad libitum, from gestation day 7 to 21. Control rats were pair-fed with isocaloric sucrose substituted for ethanol. Ethanol consumption decreased fetal body weight and increased placental weight. Twenty-four amino acids were determined in six tissues (maternal plasma and liver, placenta, fetal plasma, liver, and brain) by HPLC with orthophthalaldehyde derivatization. The effects of ethanol on free amino acid levels differed from tissue to tissue. In general, ethanol affected more amino acids in maternal plasma, fetal plasma, and liver. Maternal liver, placenta, and fetal brain amino acids were more resistant to ethanol effect. Two essential amino acids, histidine and tryptophan, were consistently decreased in fetal tissues by maternal ethanol consumption. The values (ethanol vs. control, nmole/ml or g, mean +/- SEM, N = 20) of fetal plasma, liver, and brain for histidine were 51.8 +/- 6.0 vs. 85.3 +/- 4.5 (p = 0.001), 269.0 +/- 26.4 vs. 503.7 +/- 47.3 (p = 0.0004), and 117.9 +/- 7.7 vs. 154.6 +/- 8.7 (p = 0.0055), respectively; and for tryptophan were 105.7 +/- 3.1 vs. 132.2 +/- 4.1 (p = 0.0001), 128.8 +/- 3.7 vs. 144.3 +/- 6.0 (p = 0.0407), and 83.4 +/- 7.2 vs. 103.6 +/- 3.2 (p = 0.0198), respectively. Histidine was also decreased in placenta by ethanol (138.1 +/- 6.6 vs. 189.1 +/- 11.8 nmole/g, p = 0.0014).(ABSTRACT TRUNCATED AT 250 WORDS)