Exogenous folate ameliorates ethanol-induced brain hyperhomocysteinemia and exogenous ethanol reduces taurine levels in chick embryos

Abstract

The effects of exogenous ethanol and/or folic acid on endogenous homocysteine (HoCys) and SAM (S-adenosylmethionine)/SAH (S-adenosylhomocysteine) levels in chick brains were studied at 11 days of development. Embryonic EtOH (3.0 mmol/kg egg) exposure caused a 1.6-fold increase in brain HoCys levels and a 9-fold decrease in brain SAM/SAH levels as compared to controls ( p ≤ 0.05). Brain HoCys and SAM/SAH levels returned to control values when injected with a mixture of EtOH and folic acid (3.0 mmol EtOH/kg egg and 34 μmol folic acid/kg egg). The effects of exogenous EtOH on the remethylation pathway, as measured by 10-formyltetrahydrofolate dehydrogenase (10-FTHF DH) activities, and the transsulfuration pathway, as measured by taurine levels, were studied at 18 days of development. A single dosage of EtOH (3.0 mmol/kg egg; E 0) and two daily dosages of EtOH ( E 0–1) failed to influence brain and hepatic 10-FTHF DH activities when compared to controls. However, three daily dosages of EtOH ( E 0–2) caused approximately a two-fold increase in brain 10-FTHF DH activities and a three-fold increase in hepatic 10-FTHF DH activities as compared to controls ( p ≤ 0.05). Three daily EtOH dosages ( E 0–2) caused reduced taurine levels in both brain and hepatic tissues ( p ≤ 0.05). Meanwhile, a single EtOH dosage ( E 0), two daily EtOH dosages ( E 0–1), and three daily EtOH dosages ( E 0–2), caused reduced hepatic taurine levels as compared to controls ( p ≤ 0.05).