Abstract
The prepositus hypoglossi nucleus (PHN) is an important center of the brainstem circuitry involved in controlling horizontal eye movements. Previously, we classified PHN neurons on the basis of three membrane properties: afterhyperpolarization (AHP), firing patterns, and responses to hyperpolarizing current pulses. To further clarify functional significances of the classified PHN neurons, information about neurotransmitters contained in each neuron is needed. In the present study, we investigated the relationship between membrane properties and expression patterns of cellular markers for excitatory and inhibitory neurons using the whole-cell patch clamp technique combined with reverse transcription-polymerase chain reaction (RT-PCR) analysis in rat brainstem slices. From the single-cell RT-PCR analysis, we identified PHN neurons as either glutamatergic (n = 19) or GABAergic neurons (n = 43), although a small number of cholinergic (n = 2) and glycinergic neurons (n = 1) were identified. Both glutamatergic and GABAergic neurons showed a wide variety of membrane properties; however, we found that several membrane properties such as 1) single-component AHP, 2) firing pattern of a delay in the generation of the 1st spike, and 3) firing pattern of the 1st interspike interval (ISI) longer than the 2nd ISI were preferential properties of GABAergic neurons. These preferential membrane properties are useful for identifying GABAergic PHN neurons. [J Physiol Sci. 2007;57 Suppl:S158]
