Abstract
In mammalian dorsal cochlear nucleus (DCN), principal cells receive synapses not only from auditory nerve fibers but also from parallel fibers, which consist of granule cells' axons and are known to convey non-auditory information. As in the cerebellum, granule cells have mutual synapses between inhibitory interneurons; Golgi cells. Cerebellar Golgi cells play important roles in motor coordination. So, Golgi cells in DCN may similarly play some roles in modulation of parallel fibers' activity. However, little is known about the properties of Golgi cells because of their small population. Since Golgi cells are known to express mGluR2, we used transgenic mice that express GFP under the control of mGluR2 promoter to facilitate identification of the neuron. By immunohistochemical studies against vesicular Ach transporter and GFP, we demonstrated a presence of some cholinergic projections on Golgi cells, therefore Golgi cells may be a target of cholinergic modulation. We further studied electro-physiological properties of the neuons, demonstrating that carbachol induced a hyperpolarization of the membrane, accompanied with a decrease in the input impedance in current-clamp recordings. Muscarine evoked similar responses, indicating an activation of mAchR. Under a voltage-clamp recording, I-V relation of muscarine-induced currents showed an inward rectification and the reversal potential of the muscarine sensitive current was close to EK. These results may indicate that Golgi cells are suppressed through the activation of GIRK activated by mAchR. [Jpn J Physiol 55 Suppl:S144 (2005)]
