Effects Of Ginsenoside-Rd On The Allodynia And The Expression Of Substance P And NK-1Receptor In The Solitary Nucleus Of Rats With Spared Nerve Injure

Ginseng (Panax ginseng C.A.Meyer) is a rare Chinese herbal medicine in China,modern pharmacology proved that ginseng can regulate the balance of the central nervoussystem excitement and inhibition, promote learning and memory, fatigue resistance, andalso have apparent effect to the cerebral blood flow and cerebral energy metabolism. As itsbasic physiological active substances, especially secondary alcohol Ginsenoside-Rd (G-Rd)has been confirmed as a new type of neuroprotective drugs by means of a large number ofbasic and clinical studies. It has specificity to block membrane receptor-operated Ca2+channels, inhibition of glutamate expression, inhibition of substance P and NK–1receptor,antioxidant capacity, and protect the mitochondria etc. Research reports reveal thatsubstance P and NK-1receptor has close relationship with neuropathic pain (NPP), whichprompt G-Rd can be as a potential neurological pain analgesic. Our previously (2011)research discovered that one of mechanisms of G-Rd inhibit neuropathic pain may bedecrease in the expression of SP and NK-1receptor in the spinal dorsal horn.. The present research observed the analgesis of G-Rd on neuropathic pain induced byspared nerve injure (SNI) and the change of SP and NK-1receptor expression in thesolitary nucleus（NTS）. Experiments using SD rats with SNI,we measured the change ofpaw withdrawal mechanical thresholds (PWMT) of the operated side hindpaw before andafter G-Rd administration, and observed the effect of G-Rd on allodynia induced by SNI;Immunofluorescent staining was used to measure the mean fluorescent intensity (MFI) ofanti-SP-like and anti-NK-1receptor-like fluorescent immunoreactivities in NTS. Theresults show that, On10d after SNI, the mean PWMT value on SNI side revealed clearlylower than that of blank control and sham operation groups, and dropped to the lowest at20d. The PWMT value of SNI+G-Rd group was significantly higher compared with thatof SNI and SNI+saline groups. The immunofluorescent staining results revealed that theMFI of anti-SP-like and anti-NK-1receptor-like immunoreactivities in NTS of SNI groupshowed significantly higher compared with that of blank control and sham operationgroups (P﹤0.05). But in SNI+G-Rd group, the MFI of anti-SP-like and anti-NK-1receptor-like immunoreactivities revealed clearly lower than that of SNI and SNI+salinegroups (P﹤0.05).In Conclusion,The G-Rd revealed obvious analgesic effect on neuropathic paininduced by SNI. The descent of SP and NK-1receptor in NTS may be a probablemechanism of its analgesic effect.