Distribution of Neuropeptide Y and Nitric Oxide Synthase Containing Neurons in the Cerebral Cortex of Aged Rats

Lee, Chang Ho; Huh, Young Buhm; Ahn, Hee Kyung

Abstract

Age-related changes of neuropeptide Y (NPY) and nitric oxide synthase (NOS)/nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) were examined in the rat cerebral cortex by immunohistochemical and histoche-mical methods. Double labeling for NOS and NADPH-d revealed that all NOS-stained neurons also stained for NADPH-d. Double labeling for NPY and NADPH-d showed that about 35~65% of NPY-immunoreactive (NPY-IR) neurons in the cerebral cortex of the control (3-month-old) rats contained NADPH-d and that 40~75% in the aged (24-month-old) rats. The aged rats showed a significant increase in percentage of colocalization of NPY and NADPH-d in comparison with the control rats in the perirhinal cortex and auditory cortex. However, colocalization percentage between control and aged rats was not significantly changed in most cortical areas. In the aged group, the number of NPY-IR/NADPH-d-positive neurons was not significantly decreased in the cerebral cortex compared to the control group. However, the number of NPY-IR/NADPH-d-negative neurons was significantly lowered in frontal association cortex, primary motor cortex, insular cortex, ectorhinal cortex, perirhinal cortex and auditory cortex in the aged group. These results demonstrate that the NADPH-d containing NPY-IR neurons are less influenced by aging than the control group in the cerebral cortex of rats.