α-Guanidinoglutaric acid and other guanidino compounds in a cobalt epileptogenic focus of cat cerebral cortex

An epileptogenic cortical focus was induced by the topical application of cobalt powder to the sensori-motor cortex, then guanidino compounds in the cobalt focus were analysed by HPLC. An extraordinally high peak was observed in the epileptogenic focus 24 hours after the cobalt application. α-Guanidinoglutaric acid (GGA), which is synthesized from glutamic acid and S-methylisothiourea sulfate, was confirmed by GC/MS as a dimethylpyrimidyl derivative of GGA. An unknown substance was isolated from the cobalt focus and identified as GGA by the same GC/MS technique as in the case of an authentic sample. GGA was present in the normal cat cortex in amounts of 1n mol/g. GGA increased after cobalt application, and reached a maximum after 24 hours. The abnormal GGA recovered to the normal level about 40days after the application by which time the cobalt focus had disappeared. Other guanidino compounds, that is taurocyamine, guanidinosuccinic acid, guanidinoacetic acid, β-guanidinopropionic acid, creatinine, γ-guanidinobutyric acid, arginine, and methylguanidine, except for guanidine tended to decrease in the cobalt focus. Taurocyamine and α-guanidinobutyric acid were still decreased 40 days after the cobalt application. Spike and wave complex was induced after topical application of 0.2M GGA to the sensori-motor cortex, and a burst continued for one hour.