EVALUATION OF NEURONAL LOSS, ASTROCYTOSIS AND ABNORMALITIES OF CYTOSKELETAL COMPONENTS OF LARGE MOTOR-NEURONS IN THE HUMAN ANTERIOR HORN INAGING

In order to identify possible morphological changes which occur in the anterior horn of normal individuals during aging, 40 controls with no neurological disease were studied. Brain and spinal cord tissue was p rocessed according to a brain banking protocol. Controls were grouped according to age in 10 year intervals. Serial sections (20 mu m) of fo rmalin fixed, paraffin-embedded tissue were obtained, from each cervic al, thoracic and lumbar spinal cord segment. Every 5th section (until 2 mm) was stained with haematoxylin and eosin and the numbers of motor neurons in the anterior horn counted at x 400 magnification. Descript ive statistical analysis was performed using the SPSS program. Paralle l sections (5 mu m) of the same spinal segments were immunostained wit h a panel of antibodies including glial fibrillary acidic protein (GFA P), tau, ubiquitin and two phosphorylated neurofilaments subunits. Sig nificant neuronal loss with aging was found by regression line analysi s where three equations were used to calculate the number of motor neu rons by age in each spinal segment. In 24/40 cases spheroids were obse rved and they were more numerous in the lumbar segment. GFAP staining revealed a distinctive cellular pattern in the anterior horn of oldest cases. Large and intensely stained astrocytes were seen in the anteri or horn of cases aged over 75 years. The number of astrocytes increase d progressively with age up to 70 years. Some of the changes observed in the present study may be the result of a selective vulnerability of large motor neurons to aging which could play an important role in th e progression of MND. Most of these changes may also have similar path ophysiological mechanisms.