Development of nNOS-positive neurons in the rat sensory and sympathetic ganglia.

Neurochemical features in sympathetic and afferent neurons are subject to change during development. Nitric oxide (NO) plays a developmental role in the nervous system. To better understand the neuroplasticity of sympathetic and afferent neurons during postnatal ontogenesis, the distribution of neuronal NO synthase (nNOS) immunoreactivity was studied in the sympathetic para- and prevertebral, nodose ganglion (NG) and Th2 and L4 dorsal root ganglia (DRG) from female Wistar rats of different ages (newborn, 10-day-old, 20-day-old, 30-day-old, 2-month-old, 6-month-old, 1-year-old, and 3-year-old). nNOS-positive neurons were revealed in all sensory ganglia but not in sympathetic ones from birth onward. The percentage of nNOS-immunoreactive (IR) neurons increased during first 10 days of life from 41.3 to 57.6 in Th2 DRG, from 40.9 to 59.1 in L4 DRG and from 31.6 to 38.5 in NG. The percentage of nNOS-IR neurons did not change in the NG later during development and senescence. However, in Th2 and L4 DRG the proportion of nNOS-IR neurons was high in animals between 10 and 30days of life and decreased up to the second month of life. In 2-month-old rats, the percentage of nNOS-IR neurons was 52.9 in Th2 DRG and 51.3 in L4 DRG. We did not find statistically significant differences in the percentage of nNOS-IR neurons between Th2 and L4 DRG and between young and aged rats. In NG and DRG of 10-day-old and older rats, a high proportion of nNOS-IR neurons binds isolectin B4. In newborn animals, only 41.3%, 45.3% and 28.4% of nNOS neuron profiles bind to IB4 in Th2, L4 DRG and NG, respectively. In 10-day-old and older rats, the number of sensory nNOS-IR neurons binding IB4 reached more than 90% in DRG and more than 80% in NG. Only a small number of nNOS-positive cells showed immunoreactivity to calcitonin gene-related peptide, neurofilament 200, calretinin. The information provided here will also serve as a basis for future studies investigating mechanisms of the development of sensory neurons.

Age-associated changes in sympathetic neurons containing neurofilament 200 kDa during chemical deafferentation.

Neurofilament with a molecular weight of 200 kDa is detected in the rat sympathetic ganglia since birth. The percentage of neurons containing this neurofilament decreases during the first 20 days of life. Just solitary neurofilament-positive neurons are detected in rats at the age of 180 and 360 days. Chemical deafferentation by capsaicin, used as a model of age-associated neuron degeneration, leads to a significant reduction of the level of neurofilament-200-imminopositive neurons in comparison with the control starting from day 10 of life. Presumably, part of the sympathetic ganglionic neurons are capsaicin-positive and their function is afferent.

[Peculiarities of age changes of NF200(+)-neurons in the sensory ganglia of different segmental levels after chemical deafferentation].

Morphological features of the neurons containing neurofilaments with molecular mass of 200 kD (NF200+), were studied in the sensory ganglia of thoracic and lumbar spinal nerves in rats (n = 80) during the first year of their life. Capsaicin treatment (150 mg/kg) of the newborn animals resulted in the change of age dynamics of NF200+ neurons. This was reflected by a reduction of NF200+ neuron numbers and their cross-sectional areas in both ganglia. Segmental differences included greater reduction of NF200+ neuron number in the sensory ganglion of lumbar spinal nerve in both early and late developmental periods.