Abstract
We investigated electrophysiological and morphological characteristics of GABAergic neurons in the pre-Boetzinger complex (PBC, the caudal part of the rostral ventrolateral medulla), the putative kernel site for respiratory rhythm generation. We used GAD67-GFP knock-in neonatal mice, which enabled us to identify GABAergic neurons in a living condition. We recorded respiratory activity from the hypoglossal nerve in medullary transverse slices that contained the PBC and whole-cell recorded activities of GFP-positive neurons in the PBC. Six out of 32 GFP-positive neurons were inspiratory. All of the remaining neurons were non-respiratory. In addition, 6 GFP-negative inspiratory neurons were recorded in the PBC. The electrophysiological properties of GFP-positive inspiratory neurons included high membrane resistance and mild adaptation of spike frequency in response to depolarizing current pulses. The somata of GFP-positive inspiratory neurons were smaller than those of GFP-negative inspiratory neurons. These results indicate that GABAergic inhibition by inspiratory neurons with particular properties in the PBC is involved in neural respiratory control. [J Physiol Sci. 2006;56 Suppl:S138]
