The low-dose effect (100 mg/kg, intraperitoneally) of the nootropic drug pyracetam on some DA-ergic neurochemical parameters of the rat striatum, as well as on the locomotion activity of rats were studied using the "open-field" test. It was shown that pyracetam (l mM) in vitro increases the K(+)-stimulated (28 mM) DA release from the perfused isolated striatum to 148 +/- 14 pmole/mg tissue compared to the control animals: 101 +/- 10 pmole /mg (p < 0.05, Student's t-test). Pyracetam in a dose of 100 mg/kg increased the DA level and decreased the 5-HT level in the striatum homogenates: DA- to 121% and 5-HT-to 81% (p < 0.05), respectively. The content of DOPAC, HVA and 5-HIAA in the tissue remained the same. In addition to the mentioned effects pyracetam promoted the locomotion activity of rats in the "open field" -putative behavioral marker of the striatum DA-ergic function. Thus pyracetam is capable of modifying the DA-ergic activity of the rat striatum, thus stimulating the neuromediator release.