Effect of Wrightia tinctoria on the brain monoamines and metabolites in rats

Abstract

The effect of acute administration of Wrightia tinctoria (Wt) (leaves) methanolic extractives, constituting indigotin (HPTLC, relative abundance 21.97%), indirubin (27.13%), tryptanthrin (21%), isatin (2.70%) and rutin (14.24%), was studied on the rat brain concentrations of monoamines and their metabolites in five different brain regions, viz. hypothalamus, hippocampus, striatum, pons medulla and frontal cortex. Wt extract was administered at the doses of 25 and 50 mg/kg, i.p. and the brain monoamines were assayed after 30 minutes of the treatment. Wt treatment significantly and dose dependently decreased the levels of serotonin (5-HT), its metabolite 5-hydroxy indole acetic acid (5-HIAA) and their turnover in all the brain regions assayed. On the other hand, Wt treatment significantly and dose dependently augmented the levels of norepinephrine (NE), its metabolite methyl hydroxy phenyl glycol (MHPG) and also the turnover in all the brain regions studied. Similarly, the levels of dopamine (DA) was also significantly augmented in the hypothalamus, striatum and frontal cortex. Likewise, the levels of dihydroxy phenyl acetic acid (DOPAC), a metabolite of DA, was also increased in hypothalamus and frontal cortex. However, the treatment produced a significant decrease in the DOPAC in striatum. This differential modulation of the neurotransmitters and their metabolites can explain the behavioural effects of Wt, namely anxiolytic and antidepressant effects.