Our previous work have demonstrated that the stimulation of somatosensory area Ⅱ(Sm Ⅱ)of cerebral cortex or N.accumbens(NAc)could activate nucleus raphe magnus(NRM)

produc-ing analgesia.The aim of this work is to study whether the effect of activation of Sm Ⅱ on neu-rons in NRM is related to NAc.The spontaneous discharges of NRM neurons and their nociceptive responses induced bystimulation of tail tip were recorded extracellularly with glass microelectrode.The effects ofstimulation of Sm Ⅱ on the NRM neurons were observed before and after lesion of NAc.Before lesion of NAc

the stimulation of Sm Ⅱ could activate NRM neurons

obviously in-creasing the firing rates in 0～10 minutes after stimulation(P<0.05～0.01)

and their nocicep-tive responses were decreased in 0-10 and 20 minutes(P<0.01～0.001).After lesion of NAc

the firing rates having no clear change

and their nociceptive responses were even slightly en-hanced.It is suggested that the effect of activation of Sm Ⅱ on NRM neurons may need the relayvia the NAc.