Interactions of angiotensin II with piracetam in exploratory behavior and convulsive-seizure threshold

The interactions between angiotensin II (AT II) and piracetam in exploratory behavior of rats in open field and in pentylenetetrazol (PTZ) convulsive-seizure threshold in mice were studied. AT II at a dose of 0.5 microgram injected intracerebroventricularly (i.c.v.) increased exploratory behavior. Piracetam at a dose of 600 mg.kg-1 administered orally twice daily for 7 days increased the frequency of the exploratory behavior components. AT II decreased this effect of piracetam. AT II (0.5 microgram i.c.v.) tended to increase the PTZ convulsive-seizure threshold. On single administration piracetam had no effect on the convulsive-seizure threshold but on multiple administration it increased the threshold. The two drugs applied together increased the PTZ convulsive-seizure threshold to a larger extent as compared to the effect they exerted when administered alone. The changes in exploratory behavior and in convulsive-seizure threshold, increased by the combination of AT II and piracetam, are explained by the interactions between the two drugs at the level of AT II and GABA binding sites in brain.