A new nootropic preparation nooglutil (N-(5-oxynicotinoyl)-L-glutamic acid), a positive modulator of AMPA receptors for glutamate, administered intraperitoneally in a dose of 70 mg/kg reduced anxiety of rats in the Vogel conflict test after 24-h withdrawal from chronic diazepam treatment (4 mg/kg intraperitoneally for 45 days). Nooglutil (5 nM-750 microM) had no effect on in vitro binding of (3)H-spiperone in intact rats. Systemic administration of 50 mg/kg nooglutil in vivo increased the dissociation constant and density of D(2)receptors. Increasing the dose to 100 mg/kg abolished this effect. Our findings suggest that nooglutil produces an indirect effect on the brain dopaminergic system under normal and pathological conditions and this effect is probably mediated via the glutamatergic system.