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.
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.
The aim of the study was to identify the localization, percentage and morphometric characteristics of neuronal NO synthase (nNOS)-immunoreactive (IR) neurons in the intramural ganglia of the myenteric (MP) and submucous plexus (SP) of the large intestine of rats of different age groups. Material and methods. The work was performed on Wistar rats aged 1, 10, 20, 30, 60 days and 2 years using immunohistochemical methods. Results. nNOS-IR neurons were found in the large intestine from the moment of birth and during the remaining age periods. In the intramural ganglia of the MP, the largest percentage of nNOS-IR neurons was detected in the newborn rat and decreased in ontogenesis up to 60 days of life, then did not change until senescence. In the SP, nNOS-IR neurons were also detected in the greatest number in newborns, in the next 20 days the percentage decreased significantly, nNOS-IR neurons were not detected in 30-day and two-month-old animals, but again appeared in large numbers in aged rats. The average cross-sectional area of nNOS-IR neurons increased in the MP from birth during the first two months of life. In the SP, the average size of nNOS-IR cells increased in the first 30 days of life and was significantly larger in aged rats compared with other ages. Conclusions. In early postnatal ontogenesis, there is a decrease in the expression of nNOS in neurons of the large intestine and a subsequent increase in aged rats.
Investigation of the distribution of guanidine polymethacrylate - as the basis for a future nanocontainer for targeted transport of drugs in living organs and tissues and assessment of its effect on the body as a whole. To assess the effect on the body and the distribution of PMAG in tissues and organs, we used 24 experimental healthy laboratory rats: identical in series, sex, weight and age. A solution of PMAG in 0.9% sodium chloride in three concentrations: 2.5 mg / ml, 5 mg / ml, 10 mg / ml was administered to rats intravenously. Pieces of organs and tissues were fixed in 10% neutral formalin and embedded in paraffin according to the generally accepted technique. Histological sections, 5-7 μm thick, were stained with hematoxylin and eosin. The preparations were examined under an OLYMPUS BX 43 microscope with a digital video camera. Intramuscular injection of nanomaterial causes structural changes in the intestinal wall of rats, which are manifested after the introduction of 1 ml of solution at a dosage of 2.5 mg / ml after two hours. Changes are manifested in circulatory disorders, leukocyte infiltration, degenerative changes and epithelial necrosis. Alterative changes increase as the concentration of the injected solution and the exposure time increase. The results obtained indicate that at this stage it is not yet possible to immediately use this material for targeted drug delivery, but further developments in this direction seem quite promising for the development of new therapeutic anticancer drugs, an innovative strategy for personalized molecular therapy for intestinal cancer.
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