Antinociceptive mechanisms of Dipsacus saponin C administered intrathecally in mice

Abstract

Dipsacus saponin C (DSC) administered intrathecally (i.t.) showed antinociceptive effect in a dose-dependent (from 3.75 to 30 μg) manner as measured by the tail-flick assay. The antinociception induced by DSC at the dose of 30 μg reached at peak 7.5 min and almost returned to the control level after 60 min. 5-Amino-valeric acid (5-AVA, a GABA A receptor antagonist, from 1 to 20 μg) and SR 95531 (a GABA B receptor antagonist, from 0.1 to 2 ng) dose-dependently attenuated i.t. administered DSC-induced increase of the inhibition of the tail-flick response. The i.t. injection of yohimbine (an α 2-adrenergic receptor antagonist, from 1 to 20 μg) and methysergide (a serotonin receptor antagonist, from 1 to 20 μg), but not naloxone (from 2 to 8 μg), significantly attenuated inhibition of the tail-flick response induced by DSC (30 μg) administered i.t. Sulfated cholecystokinin (CCK, from 0.05 to 0.5 ng) injected i.t. significantly reduced the inhibition of the tail-flick response induced by DSC (30 μg) administered i.t. Our results suggest that DSC shows an antinociceptive effect when it is administered spinally and GABA A, GABA B, α 2-adrenergic and serotonin receptors located at the spinal cord level, but not opioid receptors, may be involved in DSC-induced antinociception. Furthermore, CCK may play an important role for the modulation of i.t. injected DSC-induced antinociception.