Age-related changes of neurons from the large intestine containing neuronal nitric oxide synthase

Abstract

The aim of the study was to identify the localization, percentage and morphometric characteristics of neuronal NO synthase (nNOS)-immunoreactive (IR) neurons in the intramural ganglia of the myenteric (MP) and submucous plexus (SP) of the large intestine of rats of different age groups.
 Material and methods. The work was performed on Wistar rats aged 1, 10, 20, 30, 60 days and 2 years using immunohistochemical methods.
 Results. nNOS-IR neurons were found in the large intestine from the moment of birth and during the remaining age periods. In the intramural ganglia of the MP, the largest percentage of nNOS-IR neurons was detected in the newborn rat and decreased in ontogenesis up to 60 days of life, then did not change until senescence. In the SP, nNOS-IR neurons were also detected in the greatest number in newborns, in the next 20 days the percentage decreased significantly, nNOS-IR neurons were not detected in 30-day and two-month-old animals, but again appeared in large numbers in aged rats. The average cross-sectional area of nNOS-IR neurons increased in the MP from birth during the first two months of life. In the SP, the average size of nNOS-IR cells increased in the first 30 days of life and was significantly larger in aged rats compared with other ages.
 Conclusions. In early postnatal ontogenesis, there is a decrease in the expression of nNOS in neurons of the large intestine and a subsequent increase in aged rats.