Chemical characteristics of callosal neurons in the frontal and occipital cortex of Wistar rat were studied by means of combined method of HRP retrograde tracing andimmunocytochemistry of glutamate (Glu) and ?-aminobutyric acid (GABA). Glutamate containing callosal neurons were large or medium sized pyramidal cells and mainly localized in layers Ⅱ/Ⅲ, Ⅴ and Ⅵ. They tended to appear in clusters. GABA containing callosal neurons were also found. They were medium sized nonpyramidal cells with round, elliptic, or fusiform soma and were mostly localized in layers Ⅴ and Ⅵ. They also tended to appear in clusters. The percentage of GABA containing callosal neurons (about 8% and 10% in frontal and occipital cortex respectively)was much less than that of glutamate containing callosal neurons (about 17% and 29% in frontal and occipital cortex respectively). These results further confirmed that part of callosal cells used glutamate as an excitatory transmitter and firstly confirmed that some callosal neurons contained an inhibitory transmitter GABA morphologically. In view of the existence of GABA containing callosal neurons, it also suggested that at least in rat cerebral cortex,some GABA containing neurons had longer projections than local circuit neurons. According to the results of ours and other authors, we suggested that callosal system was the one that contained different kinds of neurotransmitters, and that diversification of the transmitters and their interaction in the callosal system was one of the neuroanatomical bases of the complicated and advanced functions of the callosal neurons.

Objective To observe the protective effects of salidroside on glutamate-induced injury in cultured hippocampal neurons.Methods Primarily cultured hippocampal neurons from fetal Wistar rat were incubated with salidroside(10,20 and 40mg/L) for 24 hours,then glutamate(125?mol/L) was added for 15 minutes to induce injury.Cell viability was detected by MTT assay,the vigor of LDH was determined by biochemistry method,the apoptosis rates were anallyzed using Annexin V-FITC and PI labelling and Hoechst 33342 staining and flow cylometric assay.Fluorescent intensity of intracellular free calcium was observed with laser scanning confocal microscopy(LSCM).Results After the pretreatment with salidroside for 24 hours,the increases of LDH vigor and apoptosis rates and the decrease of cell viability caused by glutamate were resisted obviously.Salidroside inhibited the increase of Ca~2+ in cytoplasm significantly.Conclusion Salidroside can significantly resist the injury induced by glutamate.The neuroprotective activities of salidroside can be related to its ability to reduce Ca~2+ overload in cytoplasm.