Effect of systemic administration of adenosine on brain adenosine levels in pentylenetetrazol-induced seizure threshold in mice.

Adenosine is one of the inhibitory neuromodulators in the brain. The present study was carried out to elucidate the effect of adenosine on the pentylenetetrazol (PTZ)-induced seizure threshold in mice. Further, the study also correlated the brain adenosine levels in PTZ-induced seizure threshold. PTZ (0.5%, w/v) was infused through lateral tail vein of mouse at a constant rate of 0.3 ml/min until various stages of convulsions were observed. Minimal dose of PTZ (mg/kg) needed to induce different phases (myoclonic jerks, generalized clonus and tonic extensor) of PTZ convulsions were noted as an index of seizure threshold. Intravenous infusion of PTZ resulted in a significant decrease in brain adenosine levels. Systemic administration of adenosine (100 and 200 mg/kg, i.p.), 30 min before PTZ infusion, produced a dose-dependent elevation of PTZ-seizure threshold and also enhanced brain adenosine levels as compared to vehicle treated group. The behavioral and neurochemical observations demonstrated a relationship between adenosine levels in the brain and the PTZ seizure threshold in mice.