Heungshik S. Lee

Changes in the expression of calbindin D-28k in the gerbil hippocampus following seizure.

Previous studies have reported that calbindin D-28k (CB), a calcium-binding protein, containing neurons in the hippocampus play an important role in hippocampal excitability in epilepsy, because CB modulates the free calcium ion during seizure. Hence, in the present study, we investigated changes of CB expression in the hippocampus and its association in the Mongolian gerbil to identify roles of CB in epileptogenesis. CB immunoreactivity in the hippocampus was significantly lower in the pre-seizure group of seizure sensitive (SS) gerbils as compared with those seen in the seizure resistant (SR) gerbils. The distribution of CB immunoreactivity in the hippocampus showed significant difference after seizure on-set in SS gerbils. CB immunoreactivity in the hippocampal CA1, CA2 areas, and subiculum was lowest at 3h after seizure on-set; thereafter, the immunoreactivity became to increase to 12h after seizure on-set. Mossy fibers, Schaffer collaterals and dentate granule cells showed the highest CB immunoreactivity at 3h after seizure on-set; thereafter, the immunoreactivity became to decrease. In the case of the intrinsic and output connections of the hippocampus, a rapid decrease of CB serves an inhibitory function, which regulates the seizure activity and output signals from the hippocampus.

The existence of substance P in Purkinje cells in cerebellum of the gerbil.

We performed this study to identify the characteristics of substance P localization in gerbil cerebellum by immunohistochemistry. Substance P immunoreactivity was present in Purkinje cells of cerebellar cortex but not in other structures. It is suggested that the cerebellar mechanism of gerbil may be different from that of other species.

Immunohistochemical localization of calcium binding proteins and some neurotransmitters in myenteric plexus of goat stomach.

To understand the neurochemical properties of the gastric myenteric plexus of ruminants, the expression patterns of calbindin D-28k (CB), calretinin (CR), substance P (SP) and calcitonin gene-related peptide (CGRP) were explored in the Korean native goat. In gastric myenteric plexus, CB and SP immunoreactivity were observed in round- or oval-shaped neurons. CR and CGRP immunoreactivity were detected only in the nerve fibers. This immunohistochemical localization of CB, CR, CGRP and SP in the myenteric plexus of the goat stomach exhibited species-specific patterns. These findings suggest that these substances may be directly or indirectly related to the gastric functions of the goat stomach.

Age-related changes in ionized calcium-binding adapter molecule 1 in the gerbil hippocampal CA1 region

Reciprocal induction between preand postsynaptic cells is believed to be important for the differentiation of the synaptic structures. The induction process likely involves regulation of gene transcription, yet the identity and function of genes that are induced during this process remain largely unknown. Here, we aim to investigate the mechanisms of how innervation-dependent gene expression in the postsynaptic cell supports synaptic differentiation, using the neuromuscular system in Drosophila. We performed microarray analysis of individually isolated muscle cells to detect changes of gene expression in the postsynaptic cells. By comparing expression profiles of muscles before and after innervation and muscles in mutants that lack innervation, we identified 82 candidate genes that are potentially regulated by nerve innervation. These included extracellular matrix components, transcription factors and various enzymes. We are now performing genetic analyses of these genes to elucidate their roles in synaptic differentiation.