Changes in neurons of medulla oblongata nuclei under conditions of chronic NO-synthase inhibition.

ABSTRACT

Nucleus tractus solitarius and giant-cell and lateral reticular nuclei were studied using the reaction to NADPH-diaphorase in 7-, 10-, 14-, 30-, 45-, 60-day-and 3- and 6-month-old rats receiving L-NAME (50 µg/kg, 2 times a day) on days 1-6 of life. In 7-14-day-old rats, the compound reduced NO-synthase activity in the majority of NO-neurons and the total number and to a lesser degree the relative number of these neurons, while cell cross-section areas remained practically unchanged. The differences in the corresponding quantitative parameters between the control (D-NAME administration) and experimental groups decreased with time after the last L-NAME injection and became undetectable starting from the age of 30-45 days. In the nucleus tractus solitarius, the changes in metric parameters after exposure to NO-synthase inhibitor were more pronounced than in the reticular formation nuclei.