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 s tudy. The antinociception was assessed by the tail-flick test. Total saponi n fraction at doses 0.1 to 1.0 CLS, which administered i.t. alone did not a ffect the latencies of tail-flick threshold, attenuated dose-dependently th e inhibition of the tail-flick response induced by i.c.v. administered beta -endorphin (1 mu g). However, total saponin fraction at doses 1 to 20 mu g, which administered i.c.v, alone did not affect the latencies of the tail-f lick response, did not affect i.c.v. administered beta-endorphin (1 mu g)-i nduced antinociception. The duration of antagonistic action of total saponi n fraction against beta-endorphin-induced antinociception lasted at least f or 6 h. Various doses (from 0.1 to 1 mu g) of ginsenoside R-c, but not R-b2 , R-d, Rg(1), R-b1 and R-e injected i.t. dose-dependently attenuated antino ciception induced by beta-endorphin administered i.c.v. Our results indicat e that total saponin fraction injected spinally appears to have antagonisti c action against the antinociception induced by supraspinally applied beta- endorphin. Ginsenoside R-c appears to be responsible for blocking i.c.v. ad ministered beta-endorphin-induced antinociception. On the other hand, total ginseng fraction, at supraspinal sites, may not exert an antagonistic acti on against the antinociception induced by supraspinally administered beta-e ndorphin.