Acute low-dose ketamine produces a rapid and robust increase in plasma BDNF without altering brain BDNF concentrations.

Peripheral BDNF changes after ketamine administration have been proposed as a biomarker for brain BDNF changes. However, published data are conflicting and come from studies in paired animal groups. This study determined the time course of plasma BDNF concentrations following the administration of a single 10 mg/kg dose of ketamine by different routes of administration in rats. Brain BDNF concentrations in prefrontal cortex, hippocampus and cortex were measured in the same animals. Ketamine administration resulted in a rapid and robust increase in plasma BDNF concentrations that were sustained for 240 min. In contrast, there were no changes in brain BDNF concentrations in prefrontal cortex, hippocampus or cortex and there were no correlations between peripheral and central BDNF concentrations. These data suggest that peripheral BDNF is unlikely to be a useful biomarker of acute central BDNF changes following ketamine.