Abstract
The neurons of the trigeminal subnucleus caudalis (Sp5C) play an important role in the processing pain and sensory information from the cranio-facial area. In the present study, we investigated the characteristics of GABAergic and non-GABAergic neurons in the Sp5C using neonatal transgenic mice (P2-6) in which green fluorescent protein (GFP) is specifically expressed in GABAergic neurons. We recorded activities of GFP-positive (GABAergic, n=20) and GFP-negative (non-GABAergic, n=33) neurons in a perforated whole-cell patch clamp mode in the sagittal slice of brainstem attaching the trigeminal nerve rootlet. Electrical stimulation to the trigeminal nerve evoked excitatory postsynaptic potentials (EPSPs) in all of the recorded GFP-positive neurons and in 31 GFP-negative neurons. Inhibitory postsynaptic potentials (IPSPs) were evoked in 3 GFP-positive and in 13 GFP-negative neurons. In morphological study, most of GFP-positive neurons had multipolar-shaped somata (n=8/10) and GFP-negative neurons had bipolar (n=5/10) or triangular (n=5/10) somata. The difference of somatic size between GFP-negative and GFP-positive neurons was not significant. These results indicate that GABAergic neurons in the Sp5C are characterized by multipolar-shaped somata, and receive exclusively excitatory postsynaptic inputs from the cranio-facial area. [J Physiol Sci. 2008;58 Suppl:S164]
