[Preliminary study of analgesic mechanism of Buthus martensii Karsch (BmK) venom on central nervous system].

AIM: To investigate whether or not the lateral septal nucleus (LS) was one of important analgesic areas of BmK venom in the central nervous system (CNS), and, targeting on which receptor, analgesic effect was produced by it.

METHODS

Pain threshold of skin was observed by the latent period of tail flick evoked by radiant heat. Glass micropipette placed in Pf was used to record unit discharges of neurons in it, before and after 0.01% BmK venom were injected into LS. Stainless steel cannula placed in the lateral cerebral ventricle (icy) and LS was used for microinjection.

RESULTS

After injection of 2 microl 0.01% BmK venom into icy of rat, the pain threshold was apparently raised, which was completely returned by injection of 0.5 microl 0.25% naloxone into icy. After 0.5 microl 0.01% BmK venom was injected into LS, 71% (15/21) nociceptive-on neurons and 83.3% (5/6) nociceptive-off neurons decreased the nociceptive response to tail pinch, but no evident effect was observed in the non-nociceptive neurons.

CONCLUSION

The analgesic effect of BmK venom was probably realized mainly by the opiate receptor, and LS was one of important analgesic areas of BmK venom on CNS.