UNASSIGNED: Ambulatory instability and falls are a major source of morbidity in the elderly. Age-related @entity427 is a major contributing factor to this morbidity, and deterioration of the afferent limb of the stretch reflex is a potential contributing factor to such age-dependent @entity427 . To evaluate this, we assessed the number and distribution of muscle spindle afferent fibers in @entity1 sacral spinal ganglia (S1) and tibial nerve samples obtained at autopsy, using immunohistochemical staining for the a3 isoform of @entity4024 , @entity3529 -ATPase (a3NKA), a marker of muscle spindle afferents. Across all age groups, an average of 26  4% of myelinated fibers of tibial nerve and 17  2% of ganglion neuronal profiles were a3NKA-positive (n=8 per group). Subject age explained 85% of the variability in these counts. The relative frequency of a3NKA-labeled fibers/neurons starts to decline during the 5th decade of life, approaching half that of young adult values in 65-year-old subjects. At all ages, a3NKA-positive neurons were among the largest of @entity528 . However, as compared to younger subjects, the population of a3NKA-positive neurons from advanced-age subjects showed diminished numbers of large (both moderately and strongly labeled), and medium-sized (strongly labeled) profiles. Considering the critical significance of ion transport by @entity4757 for neuronal activity, our data suggest that functional impairment and, also, most likely @entity194 and/or degeneration of muscle spindle afferents, are mechanisms underlying @entity427 with age. The larger and more strongly a3NKA-expressing spindle afferents appear to be proportionally more vulnerable.

Age-dependent decline in density of @entity1 nerve and XXXX expressing the a3 isoform of @entity4024 / @entity3529 -ATPase.

@entity1 :: ('9606', 'Species') :: ['human'] @entity3529 :: ('D011188', 'Chemical') :: ['K(+)'] @entity4024 :: ('D012964', 'Chemical') :: ['Na(+)'] @entity194 :: ('MESH:D001284', 'Disease') :: ['atrophy'] @entity4757 :: ('6863', 'Gene') :: ['NKA'] @entity427 :: ('MESH:D012021', 'Disease') :: ['loss of tendon reflexes'] @entity528 :: ('MESH:D009410', 'Disease') :: ['spinal ganglia neurons']
@entity528 :: (MESH:D009410,Disease) :: ['spinal ganglia neurons']
