Antidepressive-like Effect of Microcystin-fr in Swiss Albino Mice Tested by a Battery of Behavioural Depression Models

Microcystin-FR a cyclic heptapeptide was isolated from Nostoc spongiaeforme and purified by thin layer chromatography, MALDI TOFF Ms and HPLC methods. The Swiss albino mice dosed with the sub lethal concentration of 0.8μg/kg body weight of microcystin-FR were subjected to a battery of behavioural depression models such as tail suspension test (TST), force swim test (FST) and elevated plus maze test (EPM). A 40% decrease in immobility in both TST and FST was seen in mice treated with microcystin-FR as compared to control. The EPM test showed that the mice treated with microcystin-FR spent 89% more time in open arm as compared to untreated control. The microcystin-FR does not seem to interfere with the normal locomotory activity of mice. The histopathology, serum aspartate aminotransferase (AST), and lactate dehydrogenase (LDH) assays confirm the hepatotoxic nature of microcystin-FR. A dose of 8mg/kg body weight of Cyclosporine-A (CsA) was used to suppress the hepatotoxic effect of microcystinFR in all the above experiments as CsA provided 100% protection over the hepatotoxic nature of microcystin-FR. The results are discussed in light of the inhibition of PP2