Figure 2.

Time course of BCAA treatment required to restore conditioned fear response. (A) BCAA supplemented water (100 mM, black bars) or plain water (open bars) were offered ad libitum to brain-injured mice for 2, 3, 4, 5, or 10 days. Conditioned fear responses, as measured by the percentage of observations in which the animal demonstrated freezing behavior, were recorded for each animal. All animals in all treatment groups demonstrated at least some freezing, and the average level of freezing was calculated for each group. Freezing was restored to normal levels at the 5- and 10-day time points (*P < 0.05). Conditioned fear responses in naïve animals were not significantly different from conditioned fear responses in either the 5- or 10-day BCAA treated groups. (B) Water containing BCAAs (0.26 g/kg) or untreated water was administered via oral gavage once daily for 3 or 5 days. Significant improvement in freezing behavior was observed following five consecutive days of gavage BCAA treatment (*P < 0.05), but not after 3 days of treatment, and 5-day gavage results were not significantly different from the 5-day supplemented water results. Abbreviations: FPI, fluid percussion injury; BCAAs, branched chain amino acids.