The objective of this research was to test whether sodium hydroxybutyrate (GHB-Na) protects rat neonatal brain against hypoxia-ischemia (HI). Specifically, the objective was to determine the effect of GHB-Na administration on the expression of N-methyl-D-aspartate subunit (NR2B) mRNA in the rat hippocampus. Seven-day-old Sprague-Dawley rats were subjected to ligation of the left carotid artery and were randomly assigned to 5 groups: sham operated (S), saline treated (C), and those treated with GHB-Na (G1, G2, G3), at 3 dosages (50, 100, or 200 mg/kg, ip, thrice daily). NR2B mRNA levels in the left hippocampus were assayed at 2, 6, 12, 24, 72, and 168 hr after HI (exposure to 8% O(2)/92% N atmosphere for 2 hr). The results suggest that HI insult increased NR2B mRNA gene expression in the left hippocampus of the neonatal rats and that GHB-Na administration partially suppressed this effect of HI insult.