Fetal alcohol exposure and temporal vulnerability: effects of binge-like alcohol exposure on the ventrolateral nucleus of the thalamus

BACKGROUND: Prenatal alcohol exposure disrupts motor performance in affected offspring. The ventrolateral nucleus (VLN) of the thalamus functions to relay information between the cerebellum and motor cortex. Reductions in the size of the thalamus have been found in children with fetal alcohol syndrome, and therefore a rat model system was used to determine whether VLN size and neuronal number were altered by alcohol exposure during development. METHODS: Rat pups were exposed to alcohol in utero during the first 10 days of gestation (first trimester equivalent), the second 10 days of gestation (second trimester equivalent), or the first two trimesters equivalent combined. Some pups were exposed to alcohol in utero during the time of VLN neurogenesis. In addition, offspring from some of the dams treated during the first two trimesters equivalent were reared artificially from postnatal day (P) 4 through P9 (part of the third trimester equivalent) and received binge-like alcohol during this time, resulting in offspring exposed to alcohol during all three trimesters equivalent. Other offspring from untreated dams were reared in the same manner but received alcohol only during the third trimester equivalent. Control animals (nutritional and untreated) were reared for all treatment conditions. All pups were perfused on P10. RESULTS: A unique effect of alcohol treatment was not found for the VLN volume or the number of neural cells within the VLN. However, the period of VLN neurogenesis was found to be sensitive to both alcohol and nutritional control treatments, resulting in significant decreases in the VLN volume and neural cell number. CONCLUSIONS: Motor deficits seen in offspring exposed prenatally to alcohol do not seem to result from direct effects on the structure of the VLN of the thalamus.