Effects of ginsenosides injected intrathecally or intracerebroventricularly on antinociception induced by morphine administered intracerebroventricularly in the mouse

Abstract

1. 1. Total saponin fraction at doses of 0.1 to 1.0 μg, which administered IT alone did not affect the latencies of the tail-flick threshold, dose dependently attenuated inhibition of the tail-flick response induced by ICV-administered morphine (2 μg). 2. 2. Total saponin fraction at doses of 1 to 20 μg, which administered ICV alone did not affect the latencies of the tail-flick response, did not affect ICV-administered morphine-induced antinociception. 3. 3. The duration of antagonistic action of the total saponin fraction against morphine-induced antinociception lasted for at least 6 hrs. 4. 4. Various doses of ginsenosides R b2, R c, R d and R g1, but not R b1 and R e, injected IT dose dependently attenuated antinociception induced by morphine administered ICV. 5. 5. In summary, ginsenosides R b2, R c, R d and R g1 injected spinally appear to have antagonistic action against the antinociception induced by supraspinally applied morphine. On the other hand, the total ginseng fraction, at supraspinal sites, may not have an antagonistic action against the antinociception induced by morphine administered supraspinally.