Prenatal Intestinal Obstruction Affects the Myenteric Plexus and Causes Functional Bowel Impairment in Fetal Rat Experimental Model of Intestinal Atresia

Abstract

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.

Involvement of the enteroendocrine system in intestinal obstruction

“…Morphologically, our results confirmed the global changes previously described in several animal models [ 9 , 11 , 20 ] with a large distension of the lumen and muscle hypertrophy above the obstruction. However, the debate is still ongoing in the literature between those promoting the impairment of the proximal segment [ 21 – 22 ] and those promoting that of the distal segment [ 6 , 10 ] for explaining the postnatal pathophysiology of this condition.…”

“…Most genes encoding neurotransmitters are not affected by the intestinal ligature with the exception of the acetylcholinesterase gene which is the most expressed gene in the ENS [ 3 ]. This downregulation has previously been described by IHC in the proximal segment [ 29 ] although a higher proportion of ChaT neurons was found based on the mRNA expression [ 11 ]. Our results indicate a downregulation of acetylcholinesterase in both segments.…”

“…A histological study has identified an immature ENS pattern below the obstruction [ 10 ]. Additional investigations have shown very heterogeneous findings or morphological changes in both the proximal and distal segments [ 11 ].…”

Enteric Neuron Imbalance and Proximal Dysmotility in Ganglionated Intestine of the Sox10Dom/+ Hirschsprung Mouse Model

“…The mechanisms driving the altered proportions of NC derivates within HSCR mutants are unclear at this time. Prenatal obstruction (atresia) has been shown to affect NC derivatives in rats, 47 and the extent of aganglionosis in the Sox10 Dom HSCR model may effectively be producing a varying length of obstruction. We realize obstruction cannot be excluded as a factor that impacts NC derivative choice; however, Sox10 Dom /+ mice are born in Mendelian ratios relative to their wild-type littermates, and the majority survive to weaning, which suggests that obstruction does not play a large role prenatally.…”

MicroRNA‐211 causes ganglion cell dysplasia in congenital intestinal atresia via down‐regulation of glial‐derived neurotrophic factor

“…Time‐dated pregnant Wistar rats were purchased from Janvier Laboratories (Le Genest Saint Isle, France). The surgical procedure was performed as previously described . Briefly, general anesthesia was initiated by an intramuscular injection of ketamine (12 mg/100 g bodyweight) and chlorpromazine (0.07 mg/100 g) in pregnant rats.…”