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Nitric oxide synthase and arginase in the rat hippocampus and the entorhinal, perirhinal, postrhinal, and temporal cortices: Regional variations and age‐related changes
Author(s) -
Liu Ping,
Smith Paul F.,
Appleton Ian,
Darlington Cynthia L.,
Bilkey David K.
Publication year - 2003
Publication title -
hippocampus
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.767
H-Index - 155
eISSN - 1098-1063
pISSN - 1050-9631
DOI - 10.1002/hipo.10138
Subject(s) - arginase , hippocampus , entorhinal cortex , nitric oxide synthase , nitric oxide , chemistry , endocrinology , perirhinal cortex , medicine , hippocampal formation , cortex (anatomy) , neuroscience , temporal cortex , biology , temporal lobe , arginine , biochemistry , epilepsy , amino acid
Increasing evidence suggests that nitric oxide synthase (NOS)/nitric oxide (NO) contributes to the aging process. By contrast, the role of arginase, which shares a common substrate with NOS, has not been determined. In the present study, regional variations and age‐related changes in NOS and arginase in the hippocampus and its neighboring structures were investigated for the first time. In young adult rats, high levels of NOS activity were found in the entorhinal, perirhinal, and postrhinal cortices, whereas low values were located in the hippocampus and the temporal cortex. Interestingly, arginase activity showed an overall inverse pattern with the lowest levels in the entorhinal and perirhinal cortices. When a comparison was carried out between young (4‐month‐old) and aged (24‐month‐old) rats, significant increases in total NOS activity were found in the aged entorhinal and temporal cortices, and a significant decrease in arginase activity was observed in the aged postrhinal cortex. Western blotting demonstrated significant decreases in both neuronal and endothelial NOS expression in the aged hippocampus and postrhinal cortex, whereas arginase I and II expression did not show age‐related changes in any region examined. Activity and protein expression of inducible NOS were not detected in any tissue from either group. The present findings of region‐specific changes in NOS and arginase appear to support the potential involvement of NOS/NO in the aging process and raise the issue of a possible contribution of arginase to aging. © 2003 Wiley‐Liss, Inc.