Effect of octanoate injection on rat blood-brain barrier.

Serum concentrations of short and medium chain fatty acids, including octanoate, are elevated in hepatic encephalopathy and Reye syndrome. Injection of octanoate into animals produces features reminiscent of Reye syndrome, but the mechanisms are unknown. To evaluate the effect of octanoate on blood-brain barrier permeability, three techniques were used. Entry of horseradish peroxidase and trypan blue into brain was not observed after octanoate injection. Brain uptake of tryptamine, tyrosine and methionine was increased significantly by octanoate, while uptake of insulin was unchanged. This study suggests that octanoate may produce central nervous system alterations by facilitating entry of certain low molecular weight compounds into brain. This may represent one mechanism for the development of encephalopathy in liver disease and Reye syndrome.