Postnatal development of the enteric neurons expressing neuronal nitric oxide synthase

Area of Science:

• Neuroscience
• Gastroenterology
• Developmental Biology

Background:

• Enteric neurons expressing neuronal nitric oxide synthase (nNOS) play crucial roles in gut motility.
• The developmental trajectory and age-related changes in nNOS-expressing neurons within the myenteric and submucous plexuses are not fully understood.

Purpose of the Study:

• To quantify the percentage and area of nNOS-immunoreactive (IR) neurons in the myenteric plexus (MP) and submucous plexus (SP) of the rat small intestine (SI) and large intestine (LI) across different age groups.
• To investigate the colocalization of nNOS-IR neurons with choline acetyltransferase (ChAT), vasoactive intestinal polypeptide (VIP), and neuropeptide Y (NPY).

Main Methods:

• Immunohistochemical methods were employed to identify and quantify nNOS-IR neurons.
• Colocalization studies were performed for nNOS with ChAT, VIP, and NPY in the MP and SP of rats at various ages (newborn, 10-day, 30-day, 2-month, and aged).

Main Results:

• The percentage of nNOS-IR neurons in the MP was highest in newborns and decreased significantly by 60 days, remaining stable thereafter.
• In the SP, nNOS-IR neuron percentages decreased after birth but increased again in aged rats.
• Colocalization analysis revealed significant age-dependent changes in nNOS+/ChAT+ and nNOS+/VIP+ neurons in the MP, while SP showed consistent nNOS/ChAT colocalization.

Conclusions:

• nNOS expression in enteric neurons undergoes significant changes during postnatal development and aging.
• These findings highlight the dynamic nature of nNOS-expressing neurons in the gut and their potential roles in age-related physiological changes.