Age-Related Changes of Catalase Immunoreactivity in the Main Olfactory Bulbs of Wistar and Spontaneously Hypertensive Rats / 대한해부학회지

ABSTRACT

The reactive oxygen species (ROS) is well-known for the causative factors inducing ischemia, Parkinson's disease, Alzheimer, amylotrophic lateral sclerosis, hypertension and aging. Catalase (CAT) is an important endogenous antioxidant enzyme against ROS because it removes H2O2 during metabolic processes. Hence, we examined the age-related changes of CAT-immunoreactivity in the main olfactory bulbs (MOB) of the Wistar and spontaneous hypertensive rat (SHR) at various aging stages over 2 years periods; postnatal month 6 (PM 6), PM 12, PM 18 and PM 24. CAT immunoreactive (IR) neurons in Wistar rats were located in the glomerular layer (GL), external plexiform layer (EPL), internal plexiform layer (IPL) and granule cell layer (GCL). The number of CAT-IR neurons slightly decreased agedependently and nearly disappeared at PM 24. At PM 6 and PM 12, the CAT-IR neurons located in the EPL were morphologically identified as granule cells. However, at PM 18 and PM 24, CAT-IR neurons located in the EPL and mitral cell layer (MCL) were morphologically identified as tufted and mitral cells, respectively. CAT-IR neurons in the SHR were located in all layers of the MOB. The number of CAT-IR neurons and CAT immunoreactivity decreased agedependently and nearly disappeared especially in the GL and EPL at PM 24. These findings indicate that the decrease of CAT immunoreactivity may be one of the causative factors for increase of oxidative stress, and these damages may underlie age-related changes in the olfactory process. The early decrease of CAT immunoreactivity in the SHR than in the Wistar rat suggests that the early decreae of CAT may be associated with the cause of hypertensive neuronal damage.