AGE-RELATED CHANGES OF NO-CONTAINING SYMPATHETIC NEURONS IN RAT SPINAL CORD

Objective - to determine the localization, percentage and morphometric characteristics of sympathetic preganglionic neurons containing NO synthase (NOS) in rat spinal cord. Material and methods. The study was conducted on 35 female albino Wistar rats aged 3, 10, 20, 30, 60 days, 6 months and 3 years. In spinal cord sections taken at the level of its TII-segment, NOS and enzyme of acetylcholine synthesis cholineacetyltransferase (ChAT) were demonstrated using the immunohistochemical methods. Nerve cell area and the percentage of immunoreactive neurons were evaluated. Results. In the spinal cord of newborn and 10-day-old rats, the majority of sympathetic preganglionic neurons contained NOS and ChAT. However, in these age groups a population of NOS-positive/ChAT-negative neurons was detected, which were not observed in older animals (26% in the newborns and 8% in 10-day-old rats). During the first 20 days, the proportion of NOS-immunopositive neurons decreased significantly, while that of ChAT-positive neurons increased. Conclusions. In the early postnatal ontogenesis, there is an age-related decrease in the number of sympathetic preganglionic NOS-expressing neurons, that, probably, affects the mechanisms of NO-ergic sympathetic transmission

preganglionic sympathetic neurons, spinal cord, NO synthase, immunohistochemistry, rat