Abstract
The neurotransmitter releases from the presynaptic terminals are triggered by the calcium inflow through voltage-dependent calcium channels (VDCCs), which are classified into several subtypes encoded by different genes. In the previous study of mouse hippocampus we have shown physiological evidences that mossy fiber (MF) terminals are not homogenous in the sensitivities to toxins specific to N- and R-type VDCCs. The possibility was investigated that MF terminals are heterogeneous in the expression of VDCC subtype molecules. The MF terminals were labeled by fluorescent dextrans which were injected at the dentate granule cell layer of hippocampal slice. Synaptosomes were obtained from the CA3 region and immunolabeled with antibodies to synaptophysin, N- and R-type VDCC alpha1 subunits. The synaptophysin immunoreactivity was usually co-localized with fluorescent dextrans in the large MF boutons. The N-type and R-type immunoreactivities were observed in cluster with the synaptophysin immunoreactivity in some boutons but was absent in others. Therefore, it is suggests that the MF terminals were not homogeneous in the expression of N- and R-type VDCC at the molecular level. [Jpn J Physiol 54 Suppl:S159 (2004)]
