Does long-term physical exercise counteract age-related Purkinje cell loss? A stereological study of rat cerebellum

Abstract

Physical exercise affects properties of the central nervous system that may increase the brain's ability to counteract degenerative changes. We have previously reported that rats trained from 5 to 23 months of age have less age-related decrease in spontaneous motor activity than sham-treated sedentary rats. Each rat ran at a speed of 20 m/min on a horizontal treadmill, for 20 minutes, two times per day, 5 days a week. In the present study we have carried out stereological analyses of the cerebella of the same rats. The total number of Purkinje cells was estimated with the optical fractionator technique, the local volumes of individual Purkinje cells with the planar rotator technique, and the volumes of the cerebellar layers with Cavalierìs principle. We found that sedentary aged rats have 11% fewer Purkinje cells and 9% smaller Purkinje cell soma volumes (both 2P = 0.02) than exercised aged rats, and that exercised aged rats have the same number of Purkinje cells as young rats. These findings indicate that the degree of age-associated degenerative changes in parts of the central nervous system is dependent on earlier life style and health habits and may be prevented or delayed by physical exercise.

Chronic treadmill exercise in rats delicately alters the Purkinje cell structure to improve motor performance and toxin resistance in the cerebellum

“…As aged Purkinje cells show reduced target field for granule cells and spine density (5,12), morphologically abridged cells are likely to be functionally defective. Life-time exercise (from 5 to 23 mo of age) in rats prevents age-induced Purkinje cell number loss (18). The mean volume of Purkinje cell soma in either exercised or sedentary aged rats is much larger than that in young rats, indicating a life-long growth of the soma of these cells.…”

“…Many neurodegenerative conditions in the cerebellum are associated with the degeneration of Purkinje cell structure and function. For example, an early loss of Purkinje neurons in the cerebellum is a common feature in aging and ataxia (18,29). As aged Purkinje cells show reduced target field for granule cells and spine density (5,12), morphologically abridged cells are likely to be functionally defective.…”

“…As physically active older adults require less error monitoring and show improvements in motor performance (26), it is desirable to explore the beneficial effects of exercise on the cerebellum. Purkinje cells in aged rats show pronounced dendrite degeneration and spine reduction (5), while rats subjected to treadmill exercise for 18 mo show more Purkinje cells and larger soma volume than age-matched sedentary rats (18). Animal studies of this kind, together with the human studies, demonstrate that physical activities generally improve motor functions via modulating Purkinje cell structure in older adults.…”

Differential effects and rates of normal aging in cerebellum and hippocampus

“…1 and 2), whereas significant loss of Purkinje neurons occurs in the cerebellum (3,4). Stereological assessments of hippocampal pyramidal and granule neurons and cerebellar granule and Purkinje neurons in the same mice aged 12 or 28 months revealed stability in hippocampal neurons and cerebellar granule neurons and significant loss of Purkinje neurons (5).…”

“…Several forms of synaptic plasticity were assessed at different ages in CBA mice: long-term depression (LTD) in both cerebellum and hippocampus and NMDA-mediated long-term potentiation (LTP) and voltage-dependent calcium channel LTP in hippocampus. Forty-four CBA mice tested at one of five ages (4,8,12,18, or 24 months) demonstrated statistically significant age differences in cerebellum-dependent delay eyeblink conditioning, with 24-month mice showing impairment in comparison with younger mice. These same CBA mice showed no significant differences in contextual or cued fear conditioning.…”