Running fits and .GAMMA.-aminobutyric acid of the superior colliculus of the mouse.

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Abstract
The present experiment was performed to examine the relationship between the content of γ-aminobutyric acid of the superior colliculus and running fits induced by injection of semicarbazide (SC), an antivitamin B6, into the superior colliculus of the mouse. (1) The distribution of 4-aminobutyrate: 2-oxoglutarate aminotransferase [EC 2.6.1.19] of the superior colliculus was studied histochemically. A high activity was observed in the superficial and medial gray layers of the superior colliculus. Pretreatment with aminooxyacetic acid at a dose which inhibits running fits induced by intracollicular injection of SC depressed the activity. (2) The contents of γ-aminobutyric acid in superior colliculi of mice which received an intracollicular injection of SC were 60 per cent of the control, when measured immediately after the first running fit. Administration of pyridoxine together with SC inhibited the fall. (3) Intracollicular injection of thiosemicarbazide and 4-deoxypyridoxine, other antivitamins B6, also induced running fits. These results suggest that the running fits by SC injected intracollicularly are induced by the decrease of γ-aminobutyrate due to insufficient vitamin B6 in the superior colliculus.