Gamma-aminobutyric acid (GABA) levels in platelets were measured in 19 patients with migraine (7 males and 12 females, average age: 36.5 years) and 27 patients with chronic tension-type headache (TH; 9 males and 18 females, average age: 48.9 years). Twenty-one normal healthy volunteers composed the control group (11 males and 10 females, average age 34.9 years). The GABA levels in platelets were determined using high performance liquid chromatography with fluorescent detection (HPLC-FC). The GABA levels in platelets were 30.8 $plusmn; 11.7 pmol/109 platelets (mean ± S.D.) in the patients with migraine, 43.1 ± 11.8 pmol/109 platelets in the patients with TH and 34.7 ± 8.1 pmol/109 platelets in the healthy controls. The platelet GABA levels in the patients with TH were significantly higher than in the migraine patients end the healthy controls (p<0.05).
The possible role of GABA in headache is discussed. We consider that TH may be a state of neuronal hyperexcitability similar to migraine and that GABA in the platelets of patients during TH attacks may be elevated to counterbalance it. Alternatively, we suggest that the rise of GABA levels in platelets is related to emotional factors, such as depression, in the TH patients. Further studies must be undertaken concerning the relationship between platelet GABA levels and headache.