Extensive loss of subcortical neurons in the aging rat brain

Analysis of subcortical structures of groups of rats revealed significant brain shrinkage as well as neuronal loss in the ventromedial and lateral hypothalamic nuclei, the septum, the corticoamygdaloid nucleus, the substantia nigra, and the reticular formation.

Abstract

We examined the number and size of neurons in subcortical structures of groups of rats that were 90 and 880 days of age. Our analysis revealed significant brain shrinkage as well as neuronal loss in the ventromedial and lateral hypothalamic nuclei (vmh and hl), the septum, the corticoamygdaloid nucleus, the substantia nigra, and the reticular formation. Only the lateral amygdaloid nucleus (alp) failed to show age-related cell loss. Furthermore, neuronal shrinkage could be observed in the vmh, hl, and alp. Although our analysis of subcortical structures was not exhaustive, the data indicate that the subcortical regions involved in the regulation of consummatory and emotional behaviors are as vulnerable to neuronal loss and atrophy as are cortical and cerebellar regions of the central nervous system.