抄録
Utilizing slice preparations of GFP-GAD67 knock-in mice, in which GABAergic neurons are specifically labeled with GFP fluorescence, we studied physiological and morphological characteristics of GABAergic neurons of IC by whole-cell patch clamp-recording and biocytin-intracellular-staining techniques.
GABAergic neurons of IC majorly fell into two distinct firing types;1) sustained type neurons and 2)transient type neurons. Sustained type neurons showed regularly repetitive discharge pattern in response to a long depolarization current pulse (200ms) and transient type neurons showed spike discharges just at the onset of current pulse. Most of neurons of both types showed depolarizing sag in response to hyperpolarization current pulse, which were blocked by 0.1mM ZD7288,Ih blocker. Some of sustained type neurons changed its discharge pattern when they were hyperpolarized before injecting current pulse . Most of sustained type neurons showed large AHP ,which were blocked by 0.1mM Cd2+.Morphologically, sustained type neurons are a heterogeneous group, distributed in all regions of IC and including neurons of various cell soma sizes, dendritic field sizes and orientations ,and some of them innervated broadly in IC with many axon collaterals. Some of transient type neurons showed hump after single spike, which were blocked by 0.1mM Ni+. They were found only in the dorsolateral region of IC ,having highly oriented dendritic fields and regionally innervating within the cortices of IC. The functional significance of these neurons will be discussed. [Jpn J Physiol 54 Suppl:S166 (2004)]
