AGE-RELATED CHANGES OF SENSORY NO SYNTHASE-CONTAINING NEURONS AFTER CHEMICAL DEAFFERENTATION BY CAPSAICIN

In male Wistar rats (n=25) aged 3, 10, 20, 30 and 60 days, subjected to chemical deafferentation by a single injection of capsaicin at postnatal Day 2, localization, relative content and morphometric characteristics of neurons expressing NO synthase (NOS) were studied in caudal ganglion of vagus nerve (CGVN) and sensory ganglia of spinal nerves (SGSN) using immunohistochemical and morphometric methods. The control group consisted of rats (n=25) of the appropriate age. The results suggest that in the control group the proportion of NOS-immunopositive neurons in SGSN increased during the first 10 days of life and decreased between Day 30 and Day 60. In CGVN, the proportion of NOS-immunopositive neurons did not change significantly during the ontogenesis. In animals of the experimental group, the proportion of NOS-positive neurons decreased rapidly during the first 20 days of life. More pronounced decrease in the number of NOS-containing neurons was observed in SGSN as compared to that one in CGVN. The data obtained indicate deleterious effects of capsaicin on NOS-positive neurons, which confirms the role of NO in the mechanisms of nociception.

sensory ganglia, nitric oxide, ontogenesis, immunohistochemistry