Human CSF GABA concentrations: revised downward for controls, but not decreased in Huntington's chorea

Area of Science:

• Neuroscience
• Biochemistry

Background:

• Gamma-aminobutyric acid (GABA) is a primary inhibitory neurotransmitter.
• Altered GABAergic function is implicated in various neurological disorders.

Purpose of the Study:

• To measure GABA concentrations in cerebrospinal fluid (CSF) from control subjects and patients with neurological disorders, including Huntington's chorea.
• To evaluate the diagnostic utility of CSF GABA levels for Huntington's chorea.

Main Methods:

• CSF specimens were analyzed for GABA using a modified ion exchange-fluorometric method.
• The method involved a large cation exchange column and reduced sulfosalicylic acid for deproteinization.
• Homocarnosine levels were also measured in CSF.

Main Results:

• Mean CSF GABA concentrations were 87 nmol/L (normal controls), 77 nmol/L (abnormal controls), 82 nmol/L (Huntington's chorea), and 105 nmol/L (other chorea).
• Homocarnosine levels were not reduced in Huntington's chorea patients.
• Reported control CSF GABA levels were significantly lower than previously published values, attributed to improved methodology.

Conclusions:

• Analysis of free GABA in CSF is not a useful diagnostic or predictive test for Huntington's chorea.
• Methodological improvements led to more accurate quantification of CSF GABA.