AGE-RELATED CHANGE IN THE VASOACTIVE INTESTINAL POLYPEPTIDE-IMMUNOREACTIVE NEURONS IN THE CEREBRAL-CORTEX OF AGED RATS

Recent studies have explored certain changes in neurons containing neu ropeptide with aging. However, until now, the degree of vasoactive int estinal polypeptide (VIP)-containing neuronal cell loss in the aged CN S has not yet been established with certainty, and available data are often contradictory. Changes in the VIP-containing neurons with aging were demonstrated by immunocytochemistry. Major loss of VIP-immunoreac tive neurons in the aged rat brain were observed in frontal cortex are a 3, parietal cortex area 1, hindlimb area, temporal cortex area 1 and 2, monocular part of occipital cortex area, 1, occipital cortex area 2, and retrosplenial cortex. Frontal cortex area 1 and 2, parietal cor tex area 2, forelimb area, binocular part of the occipital cortex area 1, and the dentate gyrus were moderately decreased. The axis of the V IP neurons in the aged group showed an irregular orientation tendency, especially in layers II and III. These results indicate the involveme nt of a neuronal system containing VIP in the aging brain, and provide the first morphological evidence for the loss of VIP neurons in the c erebral cortex of the aged rat.