CRUDE AQUEOUS LEAVE EXTRACT OF CARICA PAPAYA LINN (PAWPAW) REDUCED ANXIETY AND FEAR RELATED BEHAVIOUR IN CD1 MICE

*S. A. Bisong, C. O. Nku K. U. Nwoke and E. E. Osim

ABSTRACT

Among many other medicinal uses of the leaves of Carica papya, they are dried and smoked either to relieve asthma or as tobacco substitute. The effect of aqueous leave extract of Carica papya on anxiety and fear was therefore studied in 20 male CD1 mice (20-30g body wt). Mice were either treated with 0mg/kg (Control, n=10) or 10mg/kg body weight of aqueous leaf-extract of C. papaya (p.o.; n=10) for 14 days before testing in the elevated plus maze (EPM), light/dark transition (LD) box and open field (OF). The results in the elevated plus maze showed higher risk taking behaviour such as frequency of entries and percentage time in the open arm for the C. papaya-treated group of mice compared to control (p< 0.01), whereas the risk assessment behaviour such as frequency of stretch attend postures (SAP), and the displacement reactions such as frequency and duration of grooming were lower in the test groups (p<0.05) compared to control. In the light/dark box test, the results followed a similar trend; with decreased SAPs in both light and dark chambers for mice treated with the aqueous leaf-extract of C. papaya, but increase time spent in the light chamber (p< 0.01) for the mice treated with C. papaya extract. The test group of mice also spent more time in the light region of the box when compared to their control (p< 0.01). The open field test showed increased centre square activity (p< 0.01) but decreased SAP (p<0.001) and grooming (p< 0.05). These behaviour in both the EPM, LD box and OF tests indicate that the mice treated with aqueous leaf-extract of C. papaya were less anxious and more willing to take risks. Therefore, the aqueous leaf-extract of Carica papaya reduced anxiety and fear in the mice.

Keywords: Carica papaya, anxiety, mice.