Effects of ginsenosides injected intrathecally or intracerebroventricularly on antinociception induced by beta -endorphin administered intracerebroventricularly in the mouse

The effect of total saponin fraction of ginseng injected intrathecally (i.t.) or intracerebroventricularly (i.c.v.) on the antinociception induced by beta-endorphin administered i.c.v. was studied in ICR mice in the present study. The antinociception was assessed by the tail-flick test. Total saponin fraction at doses 0.1 to 1.0 microgram, which administered i.t. alone did not affect the latencies of tail-flick threshold, attenuated dose-dependently the inhibition of the tail-flick response induced by i.c.v. administered beta-endorphin (1 microgram). However, total saponin fraction at doses 1 to 20 microgram, which administered i.c.v. alone did not affect the latencies of the tail-flick response, did not affect i.c.v. administered beta-endorphiun (1 microgram)-induced antinociception. The duration of antagonistic action of total saponin fraction against beta-endorphin-induced antinociception lasted at least for 6 h. Various doses (from 0.1 to 1 microgram) of ginsenoside R(c), but not R(b2), R(d), Rg(1), R(b1)and R(e)injected i.t. dose-dependently attenuated antinociception induced by beta-endorphin administered i.c.v. Our results indicate that total saponin fraction injected spinally appears to have antagonistic action against the antinociception induced by supraspinally applied beta-endorphin. Ginsenoside R(c)appears to be responsible for blocking i.c.v. administered beta-endorphin-induced antinociception. On the other hand, total ginseng fraction, at supraspinal sites, may not exert an antagonistic action against the antinociception induced by supraspinally administered beta-endorphin.