Stability of Neuroactive Amino Acids in Cerebrospinal Fluid under Various Conditions of Processing and Stor-

Free amino acids (AAs) are widely distributed within the central nervous system and play an important role as transmitters of synaptic excitation and/or modulators of synaptic function (1). Because the content of free AAs in cerebrospinal fluid (CSF) has been demonstrated to cor-relate with brain AA content (2), a reliable measurement of CSF AA concentrations is a potentially useful tool for investigating central nervous system function. Changes in concentrations of AAs with known excitatory function, e.g., aspartate (ASP) and glutamate (GLU), or putative inhibitory function, e.g., glycine (GLY) and taurine (TAU), play an important role in the physiopathology of several neuropsychiatric disorders (3). Varying AA concentra-tions have been found in the CSF in controls and in neurological disorders. Increased, decreased, and un