Aberrations of the intrinsic innervation of the anorectum in fetal rats with anorectal malformations

Effect of megarectum on postoperative defecation of female patients with congenital rectovestibular fistula or rectoperineal fistula

Background

To assess the effect of megarectum on postoperative defecation of female patients with congenital rectovestibular fistula or rectoperineal fistula.

Methods

From March 2013 to February 2021, 74 female patients with congenital rectovestibular fistula or rectoperineal fistula were treated. The age of patients ranged from 3 months to 1 year. Barium enema and spinal cord MRI were performed in all children. 4 patients were removed from the study because of spinal cord and sacral agenesis. Finally, 70 patients underwent one-stage anterior sagittal anorectoplasty (ASARP). Anal endoscopy and anorectal pressure measurement were performed 1 year after surgery. All patients were divided into two groups depending on the presence of megarectum (+) and (-) and observed for constipation and anal sphincter function.

Results

16 patients (4 months to 1 year) were complicated with megarectum, and 5 patients (3 months to 9 months) were without megarectum. The incision infection was seen in 3 patients. All patients were followed up for 1 year to 5 years. Fecal soiling was seen in 2 patients and constipation in 14 patients. Among 16 patients with megarectum, soiling was seen in 1 patient and the constipation in 12 patients. Among 54 patients without megarectum, soiling was seen in 1 patient and constipation in 2 patients. There was a significant difference in the incidence of postoperative constipation between the two groups (megarectum (+) 75% vs. megarectum (-) 3.7% (P < 0.05)). However, there was no significant difference in the score of anal sphincters between the two groups (P < 0.05). And there was no significant difference in anal resting pressure (P = 0.49) and length of anal high pressure area (P = 0.76). 7 patients with constipation and megarectum acquired normal anal function after the dilated rectum was resected.

Conclusion

Megarectum increases the possibility of difficult postoperative defecation in the patients with congenital rectovestibular fistula or rectoperineal fistula. However, constipation was not associated with ASARP postoperative effects on sphincter function. Resection of megarectum is helpful to the improvement of constipation.

Abnormal development of intrinsic innervation in murine embryos with anorectal malformations

INTRODUCTION

Constipation, soiling, and incontinence are common problems after definitive repair of anorectal malformations (ARMs) in children. We studied the expression of substance P (SP), vasoactive intestinal peptide (VIP), and c-kit in the rectum of murine embryos with or without ARMs at later developmental stages.

METHODS

On the 9th embryonic day (E9), pregnant Institute of Cancer Research mice were fed etretinate, a synthetic vitamin A analogue (60 mg/kg), whereas controls were fed only with sesame oil. Embryos were excised between E14 and E18, and prepared for histological examination. The SP, VIP, and c-kit expressions were examined by immunohistochemical staining for the SP, VIP, and c-kit antigens, respectively.

RESULTS

On E14 and E15, the expression levels of the anti-SP and anti-VIP antibodies in the rectum did not differ between the control and etretinate-treated group. However, as compared to the controls, a decreased SP and VIP immunoreactivity was observed in the circular muscle layer of the rectum between E16 and E18. On the other hand, on E14 and E15, the expression of anti-c-kit antibody in the rectum did not differ between the etretinate-treated and control group. However, c-kit immunoreactivity was slightly higher in the circular muscle layer of the rectum in the controls on E16 and E17, and considerably higher on E18 than that of the muscle layer in the etretinate-treated group.

CONCLUSION

At later developmental stages, the expression levels of SP, VIP, and c-kit reduced in the circular muscle layer of the rectum in mice with etretinate-induced ARMs. This result indicates that reduced SP, VIP, and c-kit expression levels in the circular muscle layer may cause severe constipation in children who develop severe ARMs after definitive surgery.

Genetics of Hirschsprung disease and anorectal malformations

Hirschsprung disease (HD) and anorectal malformations (ARMs) result from alterations in hindgut development. It has long been recognized that both recur in families and thus result, at least in part, from genetic factors. Progress in the understanding of the genetic basis of HD has been made by the application of findings from genetic animal models of altered enteric nervous system development to human beings. Several genes have been shown to be important for human enteric nervous system development, and current work is progressing to identify genetic interactions that may explain the variable phenotype of HD. By contrast, understanding of the genetic factors underlying ARMs is much less developed. We and others have shown that genetic factors play an important role in the pathogenesis of ARMs, and many mouse genetic models suggest molecular pathways that may be altered in ARMs.

Study of the density of ganglion cells in the terminal bowel of rats with anorectal malformations

PURPOSE: To study the ganglion cells (GC) in the terminal bowel of rats with ethylenethiourea (ETU) induced anorectal malformations (ARM). METHODS: The animals were divided into three groups: Group A - normal fetuses from pregnant rats that were not administered ETU; Group B - fetuses without ARM born from pregnant rats that were administered ETU and Group C - fetuses with ARM born from pregnant rats that received ETU. ETU was administered on the 11th day of pregnancy at the dose of 125 mg/kg body weight by gastric gavage. The rats had cesarean section on the 21st day of gestation. The fetuses’ terminal bowel tissue was analyzed by immunohistochemistry to demonstrate ganglion cells. RESULTS: Statistically significant differences were found between groups A, B and C regarding ganglion cell densities. Group A had the highest cell density, followed by Group B and the lowest density was found in Group C. CONCLUSION: Ganglion cell densities are decreased in the terminal bowel of rats with ARM.

The contribution of the sonic hedgehog cascade in the development of the enteric nervous system in fetal rats with anorectal malformations

OBJECTIVE

This study was designed to determine the expression of Sonic hedgehog (Shh) and its downstream genes during development of the enteric nervous system (ENS) in ethylenethiourea (ETU)-exposed fetal rats with anorectal malformations (ARMs).

MATERIAL AND METHODS

Anorectal malformations were induced by 1% ETU (125 mg/kg) given on gestational day 10, and the litter was harvested at term. The fetal anorectum and rectosigmoid region, including any communication with the urinary tract, were collected for gene expression studies and immunofluorescence study of the ENS. Gene expression of Shh cascade was performed using reverse transcription and real-time polymerase chain reaction (PCR). The myenteric plexuses of the ENS in normal and ARM rats were visualized with fluorescent antibodies.

RESULTS

Reverse transcription-PCR confirmed expression of Shh and its target genes in all parts of the ARMs. Quantitative PCR demonstrated that levels of expression of the genes of the Shh cascade were low in the ARMs. The immunoreactivity of neuromarkers was markedly reduced in high ARMs and slightly reduced in low ARMs.

CONCLUSION

This study demonstrates reduced expression of Shh and its target genes in ARMs in ETU-exposed fetal rats. Neurons in the myenteric plexus were decreased in high and low types of ARMs. Our results support a role for the Shh cascade during development of the ENS during hindgut development.

Scintigraphic evaluation of colonic motility in patients with anorectal malformations and constipation

BACKGROUND AND PURPOSE

Constipation is one of the major sequelae in patients after correction of anorectal anomalies (ARAs). The aim of the present work has been to assess the colonic transit time, using radioisotope scintigraphy, in patients operated for ARA and experiencing constipation in the follow-up. The results were compared with transit time from children with true functional constipation.

METHODS

Twelve or 32 patients operated for ARA during the period 1994-2003 experienced mild or severe constipation (6 with high or intermediate form of ARA and 6 with low type) at follow-up. The mean age of this group was 5.8 years. Eighteen patients, mean age 6.7 years, with true functional constipation were studied as well. Colonic transit times were investigated using radioisotope scintigraphy. Normal values for colonic transit time were derived from historical controls. Radioisotope diethylenetriamine pentaacetic acid labelled with indium 111 was administered orally to determine a segmental colonic transit. Images of the abdomen have been taken at 6, 24, 48, and again at 72 hours, if radioactivity was not cleared from the colon. To quantify colonic transit, we calculated the geometric centre (GC) dividing the colon into anatomic regions.

RESULTS

According to normal controls, 2 different type of delayed transit can be observed: (a) slow-transit constipation if GC at 48 hours is less than 4.1; (b) functional rectosigmoid obstruction (FRSO) if GC at 48 hours is 4.1 or more but less than 6.1 at 72 hours. Patients with functional constipation were divided into 2 groups: (a) slow-transit constipation in 12 patients with a GC at 48 hours of 3.7 +/- 0.5; (b) FRSO in 6 patients with a GC of 4.7 +/- 0.04 and 5.02 at 48 and 72 hours, respectively. Patients operated for high ARA had values characteristic of FRSO with GC at 48 hours of 5.1 +/- 0.8 and 4.75 +/- 0.5 at 72 hours. In low ARA, the transit times were similar to the ones observed in patients with high ARA at 48 hours with a GC of 4.9 +/- 0.5.

CONCLUSIONS

Patients with ARA frequently have functional sequelae in the postoperative period such as constipation. According to our results, constipation seems to be secondary to segmental motility disorders limited to the rectosigmoid area, similar to constipated children with FRSO. No evidence of more generalised motility disturbance, as previously postulated, could be recorded.