1 Department of Human Physiology, Medical Academy, Lublin, Poland
2 Institute of Pharmacology, Russian Academy of Medical Sciences, Moscow, Russia
Ocinum sanctum L. (OsL) commonly known as Tulsi, has from ancient times been used in extract form in south-east Asia (India inclusive) as a protector against unfavorable conditions. In our experiments the effects of water extract of Ocinum sanctum (injected intraperitoneally at doses of 200 mg/kg and 1000 mg/kg, 15 minutes before experiment) on the behaviour of white male rats (Wistar strain) in extreme stress situations were examined.
Male rats were placed into a cylindric tube (without base) of 10 cm in diameter, hanging in a water pool ("water chamber" test). They avoided this stress situation only by swimming into the cylinder along the walls and coming out from the other open end. According to this ability the animals were divided into two groups: with high and low emotionality. Using this model we could estimate not only emotional stress response, but also the "intelligence" of animals, because in this case they should resolve the "extrapolation" task. Three parameters of behaviour were measured: (1) number of attempts for avoidance, (2) level of affective reactions (jump from cylinder, vocalizations, generalized locomotive activity), and (3) latency time of avoidance.
Further (after 24 hours) we repeated injection and stress situation on the previously selected high reactivity rats. We observed a clean and direct dose-dependent antistress effect of OsL. We found a decrease of latency time of escape, which was stronger at higher dose, but significant only after second injection: (1) at a dose of 200 mg/kg OsL: 8.1 ± 2.7 s (control group with physiological solution 19.1 ± 3.7 s), p<0.05; (2) at a the dose of 1000 mg/kg OsL: 5.0 ± 1.0 s and 20.13 ± 3.90 s, p<0.05 respectively. Unlike to majority of tranquilizers the stress-protective action of OsL did not induce the disturbances of aimed behaviour realization, orient-searching activity and myorelaxation. Extract of OsL showed a high level of stress-protective activity in relation to emotional behavior in "unescapable" (open-field test) and "escapable" (water chamber test, elevated plus maze test, light-dark test) stress situation.