Sympathetic innervation of the development, maturity, and aging of the gastrointestinal tract.

The sympathetic nervous system inhibits gut motility, secretion, and blood flow in the gut microvasculature and can modulate gastrointestinal inflammation. Sympathetic neurons signal via catecholamines, neuropeptides, and gas mediators. In the current review, we summarize the current understanding of the mature sympathetic innervation of the gastrointestinal tract with a focus mainly on the prevertebral sympathetic ganglia as the main output to the gut. We also highlight recent work regarding the developmental processes of sympathetic innervation. The anatomy, neurochemistry, and connections of the sympathetic prevertebral ganglia with different parts of the gut are considered in adult organisms during prenatal and postnatal development and aging. The processes and mechanisms that control the development of sympathetic neurons, including their migratory pathways, neuronal differentiation, and aging, are reviewed.

Postnatal development of the enteric neurons expressing neuronal nitric oxide synthase.

Neurons, expressing neuronal nitric oxide synthase (nNOS) in the enteric ganglia are inhibitory motor neurons or interneurons. The aim of the study was to identify the percentage, cross-sectional area of nNOS-immunoreactive (IR) neurons and their colocalization with choline acetyltransferase (ChAT), vasoactive intestinal polypeptide (VIP), and neuropeptide Y in the intramural ganglia of the myenteric (MP) and submucous plexus (SP) of the small intestine (SI) and large intestine (LI) of rats of different age groups using immunohistochemical methods. In the intramural ganglia of the MP, the largest percentage of nNOS-IR neurons was detected in newborn rats in the LI (81 ± 0.9%) and SI (48 ± 4.1%). Subsequently, it decreased in ontogenesis up to 60 days of life (26 ± 0.9% LI, 29 ± 3.2% SI), and did not change until senescence. In the SP, abundant nNOS-IR neurons were also detected in newborns (82 ± 7.0% SI, 85 ± 3.2% LI), while their percentage decreased significantly in the next 20 days. Furthermore, a very small number of nNOS-IR neurons was detected in 30-day- and 2-month-old animals, but they again appeared in large numbers in aged rats. In the MP, the highest percentage of nNOS+/ChAT+ neurons was in 1-day-old, 10-day-old, and 2-year-old rats. In the SP, the largest number of nNOS-IR neurons colocalized ChAT regardless of age. In the MP of all rats, many nNOS-IR neurons colocalized VIP, and the maximal percentage of nNOS+/VIP+ neurons was found in 2-year-old rats, minimal-in newborns. In conclusion, nNOS expression in neurons of the gut is decreased in early postnatal ontogenesis and subsequently increased in aged rats.

Age related changes of neuropeptide Y-ergic system in the rat duodenum.

Neuropeptide Y (NPY) is widely distributed in the autonomic nervous system and acts as a neurotransmitter and a trophic factor. However, there is no report concerning the expression of NPY and its receptors in the intestine during postnatal ontogenesis. In the current study, immunohistochemistry and western blot analysis was used to label NPY, Y1R, Y2R and Y5R receptors in the duodenum from rats of different ages (1-, 10-, 20-, 30-, 60-day-old and 2-year-old). The obtained data suggest age-dependent changes of NPY-mediated gut innervation. NPY-immunoreactive (IR) neurons were observed in the myenteric (MP) and submucous (SP) plexus from the moment of birth. In the MP, the percentage of NPY-IR neurons was low and varied from 4.1 ±â€¯0.32 in 1-day-old to 2.9 ±â€¯0.62 in 2-year-old rats. The proportion of NPY-IR myenteric neurons did not change significantly through the senescence (p > .05). In the SP, the proportion of NPY-IR neurons significantly increased in the first month of life from 56.3 ±â€¯2.4% in 1-day-old to 78.1 ±â€¯5.18% in 20-day-old and significantly decreased from 75.6 ±â€¯4.62% in 30-day-old rats to 59.8 ±â€¯4.24% in 2-year-old rats. The expression of NPY in the duodenum did not change significantly during the development by western blot analysis. The expression of Y1R and Y2R was low in newborns and upregulated in the first ten days of life. The expression of Y5R was maximal in newborn pups and significantly decreased in in the first 20 days. Thus, there are some fluctuation of the percentage of NPY-IR neurons accompanies changes in relation of different subtypes of NPY receptors in the small intestine during postnatal ontogenesis.

Development of Calbindin- and Calretinin-Immunopositive Neurons in the Enteric Ganglia of Rats.

Calbindin D28 K (CB) and calretinin (CR) are the members of the EF-hand family of calcium-binding proteins that are expressed in neurons and nerve fibers of the enteric nervous system. CB and CR are expressed differentially in neuronal subpopulations throughout the central and peripheral nervous systems and their expression has been used to selectively target specific cell types and isolate neuronal networks. The present study presents an immunohistochemical analysis of CB and CR in the enteric ganglia of small intestine in rats of different ages (newborn, 10-day-old, 20-day-old, 30-day-old, 60-day-old, 1-year-old, and 2-year-old). The data obtained suggest a number of age-dependent changes in CB and CR expression in the myenteric and submucous plexuses. In the myenteric plexus, the lowest percentage of CB-immunoreactive (IR) and CR-IR neurons was observed at birth, after which the number of IR cells increased in the first 10 days of life. In the submucous plexus, CB-IR and CR-IR neurons were observed from 10-day-old onwards. The percentage of CR-IR and CB-IR neurons increased in the first 2 months and in the first 20 days, respectively. In all animals, the majority of the IR neurons colocalized CR and CB. From the moment of birth, the mean of the cross-sectional area of the CB-IR and CR-IR neuronal profiles was larger than that of CB- and CR-negative cells.