NADPH-diaphorase activity in motoneurons in different segments of the spinal cord in white rats in normal conditions and after deafferentation.

Age-related changes in NADPH-diaphorase activity were studied using a histochemical method in spinal cord ventral horn motoneurons at different segmental levels in rats aged 3-90 days from birth in normal conditions and after modeling of chemical deafferentation by i.p. administration of capsaicin. Wave-like age-related changes in enzyme activity were seen in motoneurons at the T(II), L(IV), and S(II) segments of the spinal cord, with an increase by age 60 days followed by a significant decrease by 90 days. Age-related changes in NADPH-diaphorase activity in spinal cord motoneurons in intact rats characterize constructive processes in neurons, while changes seen after deafferentation provide evidence of motoneuron damage resulting in sharp increases in enzyme activity by age 90 days.