Dual behavior of N-acetylcysteine during ethanol-induced oxidative stress in embryonic chick brains

Abstract

Objectives: Ethanol (EtOH) causes oxidative stress in embryos. Because N-acetylcysteine (NAC) failures and successes in ameliorating EtOH-induced oxidative stress have been reported, the objective was to determine if exogenous NAC ameliorated EtOH-induced oxidative stress within embryonic chick brains.

Methods: Control eggs were injected with approximately 25 µl of water on day 0, 1, and 2 of development (E_0–2). Experimental eggs were injected with dosages of either 3.0 mmol EtOH/kg egg; 747 µmol NAC/kg egg; 3.0 mmol EtOH and 747 µmol NAC/kg egg; 1000 µmol NAC/kg egg; or 3.0 mmol EtOH and 1000 µmol NAC/kg during the first 3 days of development (E_0–2). At 11 days of development (E₁₁; late embryogenesis), brains were harvested and subsequently assayed for oxidative stress markers including the loss of long-chain membrane polyunsaturated fatty acids (PUFAs); the accumulation of lipid hydroperoxides (LPO); decreased glutathione (GSH) and glutathione/glutathione disulfide (GSSG) levels; and decreased glutathione peroxidase (GPx) activities.

Results: EtOH (3 mmol/kg egg), medium NAC (747 µmol/kg egg), and EtOH and medium NAC promoted oxidative stress. These treatments caused decreased brain membrane long-chain PUFAs; increased LPO levels; decreased GSH levels and GSH/GSSG levels; and decreased Se-dependent GPx activities. High NAC dosages (1000 µmol/kg egg) attenuated EtOH-induced oxidative stress within EtOH and high NAC-treated chick brains.

Discussion: Exogenous EtOH and/or medium NAC propagated oxidative stress. Meanwhile, high NAC ameliorated EtOH-induced oxidative stress.

Keywords:

• Ethanol
• N-acetylcysteine
• Fatty acids
• Lipid hydroperoxides
• Glutathione peroxidase

Disclaimer statements

Contributors All authors contributed equally.

Funding This work was entirely funded by Hillsdale College.

Conflict of interest The authors declare that they have no conflicts of interest.

Ethics approval At the moment, the use of chick embryos falls outside IACUC committees. However animal care (fertile chick eggs) were purchased from Charles Rivers Avian Services (North Franklin, CT) and animal care was in compliance with the Guide for the Care and Use of Laboratory Animals, 8th Edition (National Academies Press, Washington DC, USA, 2011). Because embryonic chicks cannot self-regulate body temperatures and are not self-reliant, chick embryo usage is not currently under the scrutiny of US Institutional Animal Care and Use Committees.

ORCID

Alison K. Bauer http://orcid.org/0000-0003-4477-9899

Mary Fitzgerald http://orcid.org/0000-0003-1393-6484

Sydney Lenhart Sherman http://orcid.org/0000-0001-5648-3783

Benjamin H. Maddock http://orcid.org/0000-0002-4038-6011

Robert R. Miller http://orcid.org/0000-0001-9890-0231