Immunohistochemical Study on the Distribution of Kv1.2 in Aged Rat Brain

Chung, Yoon Hee; Kim, Sung Su; Kim, Kyung Yong; Lee, Won Bok

Abstract

In the present study, we demonstrated age-related changes in Kv1.2 immunoreactivity in the rat brain for the first time. Twelve adult (4~6 month old) and 15 aged (20~29 month old) Sprague-Dawley rats were examined in this study. Immunohistochemistry was performed in accordance with the free-floating method, and densitometric measurement using a NIH image program (Scion Image) determined the staining density. In the cerebral cortex of aged rats, there was a significant increase in the number of Kv1.2-immunoreactive neurons in the cingulate cortex, infralimbic cortex and piriform cortex, compare to adult rats. In the hippocampal CA1-3 regions, moderate Kv1.2 immunoreactivity was found in the cell bodies and processes of some medium to large-sized neurons in aged rats. The intensity was increased in the cell bodies of Kv1.2-positive neurons in the amygdala of aged rats, whereas the number of immunoreactive neurons was not significantly increased. It was noteworthy that age-related changes in Kv1.2-immunoreactive neurons were prominent in the facial nuclei, raphe magnus nuclei, and pontine and medullary reticular formation. Although the present study has not addressed multiple mechanisms contributing to neuronal degeneration during aging, the first demonstration of age-related changes in Kv1.2 immnuoreactivity may offer a comprehensive understanding of the pathophysiology of aging and age-related neurodegenerative diseases such as Alzheimer's disease.