Age-related changes in the distribution of Kv1.1 and Kv3.1 in rat cochlear nuclei

Abstract

Objectives: To identify age-related changes in voltage-gated K+ (Kv) channels that contribute to temporal processing in neurons of the central auditory system, we investigated the distribution of Kv1.1 and Kv3.1 in the auditory brainstem of adult and aged rats. Methods: Immunohistochemistry was performed in accordance with the free-floating method described earlier. Results: Among the auditory nuclei, only the posterior ventral cochlear nucleus (PVCN) showed age-related changes. Kv1.1 immunoreactivity was increased in the octopus cell bodies, while the staining intensity was significantly decreased in the neuropil. Image analysis demonstrated the specific increase in Kv1.1 immunoreactivity in aged cochlear nucleus neurons although the mean density of the entire selection was significantly decreased. In contrast, the number of Kv1.1-immunoreactive neurons was not significant different between control and aged groups. The immunoreactivily for Kv3.1 was decreased in take octopus cells and neuropil of aged PVCN, which was confirmed by image analysis. The number of K3.1-positive cells was also significantly decreased in aged PVCN. Discussion: This study may provide useful data to compare age-related changes in Kv1.1 and Kv3.1 with known physiological properties of auditory neurons.