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Hirschsprung's disease (HSCR) is a severe congenital anomaly of the enteric nervous system (ENS) characterized by functional intestinal obstruction due to a lack of intrinsic innervation in the distal bowel. Distal innervation deficiency results from incomplete colonization of the bowel by enteric neural crest cells (eNCCs), the ENS precursors. Here, we report the generation of a mouse model for HSCR--named Holstein--that contains an untargeted transgenic insertion upstream of the collagen-6α4 (Col6a4) gene. This insertion induces eNCC-specific upregulation of Col6a4 expression that increases total collagen VI protein levels in the extracellular matrix (ECM) surrounding both the developing and the postnatal ENS. Increased collagen VI levels during development mainly result in slower migration of eNCCs. This appears to be due to the fact that collagen VI is a poor substratum for supporting eNCC migration and can even interfere with the migration-promoting effects of fibronectin. Importantly, for a majority of patients in a HSCR cohort, the myenteric ganglia from the ganglionated region are also specifically surrounded by abundant collagen VI microfibrils, an outcome accentuated by Down syndrome. Collectively, our data thus unveil a clinically relevant pathogenic mechanism for HSCR that involves cell-autonomous changes in ECM composition surrounding eNCCs. Moreover, as COL6A1 and COL6A2 are on human Chr.21q, this mechanism is highly relevant to the predisposition of patients with Down syndrome to HSCR.

Muscle explants myenteric neural ganglion WT-like neural ganglia, colon function and microbiota inflammed submucosa disrupted epithelial barrier thicker muscles dysbiosis Untreated Hirschsprung mouse GDNF-treated Hirschsprung mouse Wild type mouse P20 distal colon no enteric nervous system, megacolon, premature death Mouse models of Hirschsprung disease exogenous GDNF P20/P56 enema P4 P8 P0 e n d o g e n o u s G D N F hypertrophic extrinsic nerve with Schwann cells submucosal neural ganglion People with Hirschsprung disease resected aganglionic colon enteric neuron +GDNF ctl extrinsic nerve and Schwann cells +GDNF ctl nervous system regeneration, WT-like colon function, survival

de Vries P, Soret R, Suply E, Heloury Y, Neunlist M. Postnatal development of myenteric neurochemical phenotype and impact on neuromuscular transmission in the rat colon. Am J Physiol Gastrointest Liver Physiol 299: G539 -G547, 2010. First published June 3, 2010 doi:10.1152/ajpgi.00092.2010.-Profound changes in intestinal motility occur during the postnatal period, but the involvement of the enteric nervous system (ENS), a key regulator of gastrointestinal (GI) motility, in these modifications remains largely unknown. We therefore investigated the postnatal development of the ENS phenotype and determined its functional repercussion on the neuromuscular transmission in the rat colon. Sprague-Dawley rats were euthanized at postnatal day (P) 1, P3, P5, P7, P14, P21, and P36. Whole mounts of colonic myenteric plexus were stained with antibodies against choline acetyltransferase (ChAT), neuronal nitric oxide synthase (nNOS), and HuC/D. Colonic contractile response induced by electrical field stimulation (EFS) was investigated in organ chambers in absence or presence of N-nitro-L-arginine methyl ester (L-NAME) and/or atropine. In vivo motility was assessed by measurement of the colonic bead latency time. Randomly occurring ex vivo contractions appeared starting at P5. Starting at P14, rhythmic phasic contractions occurred whose frequency and amplitude increased over time. In vivo, bead latency was significantly reduced between P14 and P21. Ex vivo, EFS-induced contractile responses increased significantly over time and were significantly reduced by atropine starting at P14 but were sensitive to L-NAME only after P21. The proportion of ChATimmunoreactive (IR) neurons increased time dependently starting at P14. The proportion of nNOS-IR neurons increased as early as P5 compared with P1 but did not change afterward. Our data support a key role for cholinergic myenteric pathways in the development of postnatal motility and further identify them as putative therapeutic target for the treatment of GI motility disorders in the newborn. postnatal development; enteric nervous system; myenteric plexus; rat; motility; neonates THE POSTNATAL PERIOD is a key period of life and is particularly sensitive to the influence of various environmental factors. This period is characterized by the maturation of various organs and in particular of the gut. Indeed, various gastrointestinal (GI) functions such as intestinal barrier function or motility continue their maturation and development after birth. This is particularly true in rodents such as rats or mice, making them good models for studying GI dysfunctions observed in preterm infants, such as constipation (2).Among the key regulators of GI functions is the enteric nervous system (ENS). The ENS has been shown to control GI motility and intestinal barrier functions (22). Cholinergic excitatory motor neurons [identified as choline acetyltransferase (ChAT)-immunoreactive (IR)] and often colocalized with substance P and nitrergic inhibitory motor neurons [identified as neuronal nitric ox...

We have developed a simple method to isolate and culture human, rat, or mouse EGC. EGC exhibit similar functional properties on the intestinal barrier independently of the species. This study sets the basis for exploring glial biology and functions in human health and diseases.

Postnatal changes in the enteric nervous system (ENS) are involved in the establishment of colonic motility. In adult rats, butyrate induced neuroplastic changes in the ENS, leading to enhanced colonic motility. Whether butyrate can induce similar changes during the postnatal period remains unknown. Enemas (Na-butyrate) were performed daily in rat pups between postnatal day (PND) 7 and PND 17. Effects of butyrate were evaluated on morphological and histological parameters in the distal colon at PND 21. The neurochemical phenotype of colonic submucosal and myenteric neurons was analyzed using antibodies against Hu, choline acetyltransferase (ChAT), and neuronal nitric oxide synthase (nNOS). Colonic motility and neuromuscular transmission was assessed in vivo and ex vivo. Butyrate (2.5 mM) enemas had no impact on pup growth and histological parameters compared with control. Butyrate did not modify the number of Hu-immunoreactive (IR) neurons per ganglia. A significant increase in the proportion (per Hu-IR neurons) of nNOS-IR myenteric and submucosal neurons and ChAT-IR myenteric neurons was observed in the distal colon after butyrate enemas compared with control. In addition, butyrate induced a significant increase in both nitrergic and cholinergic components of the neuromuscular transmission compared with control. Finally, butyrate increased distal colonic transit time compared with control. We concluded that butyrate enemas induced neuroplastic changes in myenteric and submucosal neurons, leading to changes in gastrointestinal functions. Our results support exploration of butyrate as potential therapy for motility disorders in preterm infants with delayed maturation of the ENS.

For a long time, melanocytes were believed to be exclusively derived from neural crest cells migrating from the neural tube toward the developing skin. This notion was then challenged by studies suggesting that melanocytes could also be made from neural crest‐derived Schwann cell precursors (SCPs) on peripheral nerves. A SCP origin was inferred from lineage tracing studies in mice using a Plp1 promoter‐controlled Cre driver transgene (Plp1‐CreERT2) and a fluorescent Rosa26 locus‐controlled Cre reporter allele (Rosa26FloxSTOP‐YFP). However, doubts were raised in part because another SCP‐directed Cre driver controlled by the Dhh promoter (Dhh‐Cre) was apparently unable to label melanocytes when used with a non‐fluorescent Rosa26 locus‐controlled Cre reporter (Rosa26FloxSTOP‐LacZ). Here, we report that the same Dhh‐Cre driver line can efficiently label melanocytes when used in a pure FVB/N background together with the fluorescent instead of the non‐fluorescent Rosa26 locus‐controlled Cre reporter. Our data further suggest that the vast majority of skin melanocytes are SCP‐derived. Interestingly, we also discovered that SCPs contribute inner ear melanocytes in a region‐specific manner, extensively contributing to the cochlea but not to the vestibule.

BackgroundIntestinal atresia is a rare congenital disorder with an incidence of 3/10 000 birth. About one-third of patients have severe intestinal dysfunction after surgical repair. We examined whether prenatal gastrointestinal obstruction might effect on the myenteric plexus and account for subsequent functional disorders.Methodology/Principal FindingsWe studied a rat model of surgically induced antenatal atresia, comparing intestinal samples from both sides of the obstruction and with healthy rat pups controls. Whole-mount preparations of the myenteric plexus were stained for choline acetyltransferase (ChAT) and nitric oxide synthase (nNOS). Quantitative reverse transcription PCR was used to analyze mRNAs for inflammatory markers. Functional motility and permeability analyses were performed in vitro. Phenotypic studies were also performed in 8 newborns with intestinal atresia. In the experimental model, the proportion of nNOS-immunoreactive neurons was similar in proximal and distal segments (6.7±4.6% vs 5.6±4.2%, p = 0.25), but proximal segments contained a higher proportion of ChAT-immunoreactive neurons (13.2±6.2% vs 7.5±4.3%, p = 0.005). Phenotypic changes were associated with a 100-fold lower concentration-dependent contractile response to carbachol and a 1.6-fold higher EFS-induced contractile response in proximal compared to distal segments. Transcellular (p = 0.002) but not paracellular permeability was increased. Comparison with controls showed that modifications involved not only proximal but also distal segments. Phenotypic studies in human atresia confirmed the changes in ChAT expression.ConclusionExperimental atresia in fetal rat induces differential myenteric plexus phenotypical as well as functional changes (motility and permeability) between the two sides of the obstruction. Delineating these changes might help to identify markers predictive of motility dysfunction and to define guidelines for post-surgical care.