Effect of nitric oxide on auditory cortical neurons of aged rats.
Age-related changes in the effects of nitric oxide (NO) on neurons of the auditory cortex have not been determined. We therefore evaluated the anatomical changes and neurophysiological characteristics of these neurons in rats as a function of age. The numbers of cresyl violet stained cells, the numbers and areas of NADPH-d-positive neuronal cell bodies, and their optical density, were measured in Sprague-Dawley rats aged 24 months (aged group) and 4 months (control group). The modulatory effects of NO on K(+) currents of acutely isolated rat auditory cortical neurons were also assessed. There were no between-group differences in the distribution patterns of glial cells and neurons, or in the numbers and areas of NADPH-d-positive neuronal cell bodies. However, the optical density of NADPH-d-positive neuronal cell bodies was significantly greater in the aged group than in the control group. In addition, voltage-gated K(+) currents of rat auditory cortical neurons were activated by increased levels of NO. As activation of the K(+) current likely suppresses neuronal excitability, age-associated increases in NO production can hinder the function of the acoustic center by inhibiting neuron excitability.
Department of Physiology, Biomedical Science Institute, Medical Research Center, Kyung Hee University School of Medicine, Seoul, South Korea.
Jong-Ju
JJ
Lee
Young-Wuk
YW
Cho
Youngbuhm
Y
Huh
Chang Il
CI
Cha
Seung Geun
SG
Yeo
D000367:Age Factors; D000375:Aging / Q000502:physiology*; D000818:Animals; D001303:Auditory Cortex / Q000166:cytology*; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D009249:NADP / Q000378:metabolism; D009474:Neurons / Q000187:drug effects*; D009569:Nitric Oxide / Q000494:pharmacology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D010396:Penicillamine / Q000031:analogs & derivatives / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
D020030:Nitric Oxide Donors; C110881:S-nitro-N-acetylpenicillamine; D009569:Nitric Oxide; C002744:3-nitrotyrosine; D014443:Tyrosine; D009249:NADP; D010396:Penicillamine