[Inhibition of 8-OH-DPAT on spontaneous unit discharges of 5-hydroxytryptamine inhibitory unit in rat primary somatosensory cortex].

AIM:To investigate the effect of 5-hydroxytryptamine (5-HT) on spontaneous unit discharges of primary somatosensory cortex (SI-SUD) and the role of 5-HT1A receptor in 5-HT inhibitory effect on SI-SUD in rat. METHODS:The SI-SUD was recorded before and during microiontophoresis of 5-HT and 8-OH-DPAT (the selective agonist for 5-HT1A receptor. The changes of mean of interspike interval (MISI) of SI-SUD were analysed and handled with the statistics. RESULTS:(1) Effects of 5-HT on SI-SUD may be inhibitory (48/96), excitatory (26/96) or non-responsive (22/96), and the major effect is inhibitory. (2) In 20 of 5-HT inhibited units, 17 are also inhibited with microiontophoresis of 8-OH-DPAT, but 3 have no obvious response to 8-OH-DPAT. CONCLUSION:The major effect of 5-HT on SI-SUD is inhibitory. In majority of 5-HT inhibited units, 5-HT1A receptor may be existence, which may involve in the inhibition of 5-HT on SI-SUD.