Effects of all three trimester moderate binge alcohol exposure on the foetal hippocampal formation and olfactory bulb

Abstract

Objective: Pre-natal alcohol exposure results in injury to the hippocampus and olfactory bulb, but currently there is no consensus on the critical window of vulnerability. This study tested the hypothesis that pre-natal exposure to a moderate dose of alcohol during all three trimester-equivalents alters development of the hippocampal formation and olfactory bulb in an ovine model, where all brain development occurs pre-natally as it does in humans.

Research design and methods: Pregnant sheep were divided into saline control and a binge drinking groups (alcohol dose 1.75 g kg⁻¹; mean peak blood alcohol concentration 189 + 19 mg dl⁻¹).

Outcome and results: The density, volume and total cell number were not different between groups for the dentate gyrus, pyramidal cells in the CA1 and CA2/3 fields and mitral cells in the olfactory bulb.

Conclusions: A moderate dose of alcohol administered in a binge pattern throughout gestation does not alter cell numbers in the hippocampus or olfactory bulb and exposure during the third trimester-equivalent is required for hippocampal injury, unless very high doses of alcohol are administered. This has important implications in establishing the sensitivity of imaging modalities such as MRI in which volumetric measures are being studied as biomarkers for pre-natal alcohol exposure.

• Ethanol
• foetal alcohol syndrome
• hippocampus
• olfactory bulb
• sheep

Declaration of interest

The authors report no conflicts of interest. This work was supported by NIAAA Grant AA10940 and AA018166-01 (SW).