AGE-RELATED CHANGE OF NEUROPEPTIDE Y-IMMUNOREACTIVE NEURONS IN THE CEREBRAL-CORTEX OF AGED RATS

Recent studies have explored certain changes with aging of neurons con taining neuropeptides. The extent of loss in aged central nervous syst em (CNS) of neuronal cells containing neuropeptide Y (NPY) has not yet been established with certainty, and available data is often contradi ctory. Changes of NPY-containing neurons with aging in the cerebral co rtex of aged rat were demonstrated by immunocytochemistry. A major los s of NPY-immunoreactive (ir) neurons in the aged rat brain was observe d in the retrosplenial cortex, frontal cortex area 1 and 2, parietal c ortex area 1 and 2, occipital cortex area 1 and 2, temporal cortex are a 3, cingulate cortex and the hippocampus proper. A loss of NPY-ir neu rons was observed mostly in layers V and VI; in addition, the number a nd length of dendritic branches appeared to be decreased and shortened in the aged group. These results indicate the involvement of NPY-ir n eurons in the aging process of cerebral cortex, and provide the first morphological evidence for the loss of NPY neurons in the cerebral cor tex of aged rats.