The purpose of the study was to examine the effect of RG-tannin, a new
substance of plant origin (purified from rhizoma of Rhea raponticum)
with assumed antipsychotic properties in two pharmacodynamic tests: 1/
in yawning behaviour induced with apomorphine or physostigmine in rat
s as an indicator of central antidopaminergic effects (in the case of
apomorphine) and central anticholinergic effects (in the case of physo
stigmine), 2/ in Porsolt forced swimming test in mice (this test is se
nsitive to drugs activating or inhibiting central noradrenergic and do
paminergic mechanisms). RG-tannin in the dose of 50 mg.kg(-1) (but not
25 mg.kg(-1)) inhibited significantly yawning induced with apomorphin
e (0.1 mg.kg), but failed to decrease yawning to a significant extent
in rats treated with physostigmine (0.075 mg.kg(-1)). RG-tannin given
intraperitoneally in mice in the dose of 25 mg.kg and 50 mg.kg(-1) bod
y weight increased statistically significantly the time of immobility
in forced swimming test in comparison with mice treated only with sali
ne. All these findings indicate that RG-tannin has interesting neurole
ptic properties, which could be useful also in veterinary medicine.