Studies On Age-Related Changes In The Structures Of Cerebellar Cortex Of Cat

The cerebellum, a brain region important for coordinating body motor, primarily accepts information concerning motor functions, including soma sensory and partially peripheral sensory. All of those informations will be converged to Purkinje cells (PCs), which ultimately send projections to the spinal cord, brain stem and cerebral cortex via the deep cerebellar nuclei by PC's long axons. Aging greatly affects the cerebellar configurations, cell components and neurotransmitter system, which will in turn, degenerate the cerebellar functions. The cat, as a kind of higher order mammal, is frequently used in various biology studies. Previous researches indicate that the cat's brain does undergo considerably functional and/or morphological changes during aging. However, whether and how cat's cerebellar cortex undergo age-related morphological changes remain unknown. In view of this, we compared the structures of cerebellar cortex in young adult and old cats expecting to accumulate data for exploring the mechanisms for functional retrogression underlying these changes during senescence.1. Cerebellar cortex from 4 young adult (1-3 years old, 2-2.5 Kg) and 4 old cats (12-13 years old, 3-3.5 Kg) were used. Nissl stain was applied to exhibit cortical neurons and the cortical layers. Immunohistochemical method was used to display glial fibrillary acidic protein immunoreactive (GFAP-IR) astrocytes and neurofilament immunoreactive (NF-IR) neurons. Compared with young adult ones, the old cats showed a significantly decreased thickness of the molecular layer and the total cerebellar cortex as well as an increased thickness of the granular layer. The density of neurons in each layer was significantly lower in old cats than in young adults. Astrocytes in old cats were significantly denser than in young adult ones, accompanied with evident hypertrophy of cell body and enhanced immunoreaction of GFAP substance. PC in old cats showed much less NF-IR dendrites and smaller cell body than in young adult cohorts. Those results indicated an evident neuron loss and degenerative structure of PCs in old cerebellar cortex, which might potentially retrogress the afferent efficacy and information integration...