Abstract
Certain types of neurons in the brain are difficult to study because they cannot be easily identified by location or morphological criteria alone. One approach to identify such neurons is to label them with a reporter protein. GABAergic inhibitory neurons play an important role in the regulation and stabilization of network activities, but they are primarily scattered throughout mammalian central nervous systems and thus can be hardly identified in live brain preparations. GABA is synthesized from glutamic acid by glutamate decarboxylase (GAD) and is accumulated into synaptic vesicles by vesicular GABA transporter (VGAT). Two isozymes of GAD, GAD65 and GAD67 and VGAT are primarily expressed in GABAergic neurons. To facilitate the study of GABAergic neurons, we generated the GAD67-GFP mice using a gene targeting method via homologous recombination in ES cells. EGFP fluorescence was specifically observed in the GABAergic neurons in the GAD67-GFP mice. The GAD67-GFP mice have helped to elucidate the anatomical profile of GABA neuronal network and its electrophysiological activity as well as the development of GABAergic neurons. In addition, we generated bacterial artificial chromosome transgenic rats, which specifically express a modified YFP, Venus protein under the control of the VGAT promoter. In VGAT-Venus rats, Venus fluorescence was sufficiently bright to visualize GABAergic neurons and thus allowed whole-cell patch-clamp recordings from visually identified GABAergic neurons. The detailed morphological and functional analyses of GABAergic neurons in brain slices will greatly benefit from these genetically engineered rodents. [J Physiol Sci. 2006;56 Suppl:S3]
