[Phenylephrine potentiates antidepressive and eliminates sedative action of amitriptyline in rats]

Single i. m. injection of amitriptyline in rats in high doses of 10-30 mg/kg causes a weak an- tidepressive effect because only in 1.3-1.7 times decrease immobilization in Porsolt test. In the specified doses amitriptyline exhibits appreciable sedative effect because in 3-6 times decrease horizontal activity, and also in 2-2.5 times decrease vertical activity of rats in the open field test. Combined single i.m. injection of amitriptyline in a small dose of 3 mg/kg and high dose of 30 mg/kg with phenylephine in threshold, noneffective alone dose of 0.02 mg/kg, causes the ma- ximal antidepressive effect because decreases immobilization in Porsolt test, accordingly, in 3 and 4.6 times, but does not produce side sedative effect in the open field test. The basis of the mec- hanism of potentiation of antidepressive action and elimination of sedative action of amitriptyline is the stimulation of gastric mucosa afferents by phenylephine.