Ileoanal pouch function and release of peptide YY

Evolution of the restorative proctocolectomy and its effects on gastrointestinal hormones

Gastrointestinal (GI) peptide hormones are chemical messengers that regulate secretory, mechanical, metabolic, and trophic functions of the gut. Restorative proctocolectomy (RPC) or resection of the colon and rectum with maintenance of intestinal continuity through the construction of an ileal pouch reservoir and preservation of the anal sphincters has become the standard of care for the surgical treatment of ulcerative colitis and familial adenomatous polyposis. The manipulation of the digestive system to create the ileal pouch involves altering gut-associated lymphoid tissue among other anatomic changes that lead to changes in GI peptides. In addition, the ileal pouch epithelium responds to a wide variety of stimuli by adjusting its cellularity and function. These adaptive mechanisms involve systemic factors, such as humoral and neural stimuli, as well as local factors, such as changes in intestinal peristalsis and intraluminal nutrients. There have been conflicting reports as to whether the alterations in GI hormones after RPC have actual clinical implications. What the studies on alterations of GI peptides' response and behavior after RPC have contributed, however, is a window into the possible etiology of complications after pouch surgery, such as pouchitis and malabsorption. Given the possibility of pharmacologically modifying GI peptides or select components of adaptation as a therapeutic strategy for patients with ileal pouch dysfunction or pouchitis, a clear understanding of human pouch mucosal adaptation is of paramount importance. In this review, we summarize the evolution of the RPC and its effects on the GI hormones as well as their possible clinical implications.

Serum biochemical evaluation of patients with functional pouches ten to 20 years after restorative proctocolectomy

BACKGROUND

Restorative proctocolectomy with an ileal pouch-anal anastomosis is a surgical treatment of choice for ulcerative colitis and familial adenomatous polyposis (FAP). Pouchitis is a significant enigmatic morbidity. In the long-term, these patients, we anticipated, would experience biochemical profiling alterations after years of retaining functionally acceptable pouches. This pilot study was aimed at assessing results of essential biochemical variables more than 10 years after surgery.

METHODS

The investigation was carried out in 91 patients; 39 were women. Eight-eight had ulcerative colitis, while three had FAPs. The hand-sewn ileal reservoirs after mucoso-proctocolectomy were 66 S and 25 J. The analyses were compared short-term vs long-term. Patients were investigated and were their own control.

RESULTS

Long-term, incidence of acute and chronic pouchitis was 2 and 13%. Eleven and 4% of patients had hypomagnesaemia and hypocalcaemia. Mean levels were significantly enhanced (p<0.01 and p<0.0002). Hypomagnesaemia corresponded to episodes of pouchitis and was corrected with oral magnesium and antibiotics. Hypoferric anaemia was diagnosed in 7% and treated with oral iron tablets. Chronic pouchitis and recurrent pouch mucosa bleeding were the cause. Hypohemoglobinemia and hypocyanocobalaminemia were noted in 5% and 5%, respectively. Erythrocyte sedimentation rate and white blood cells were supra-normal in 13 and 10%, which corresponded with pouchitis. A significant (p<0.03) steady rise of mean serum immunoglobulin G without correlation to pouchitis was noted.

CONCLUSION

Long-term functional results did not deteriorate. Pouchitis was a significant enigmatic morbidity. Severe or chronic pouchitis complicated hypoferric and vitamin B(12) anemia and hypomagnesaemia.

Effect of total colectomy and PYY infusion on food intake and body weight in rats

PYY (3-36) is postulated to act as a satiety factor in the gut-hypothalamic pathway to inhibit food intake and body weight gain in humans and rodent models. We determined the effect of 14-day continuous intravenous infusion of PYY (3-36) (175 microg/kg/day) on food intake and body weight gain in colectomized male Wistar rats. Colectomy caused an increase in plasma PYY levels at 7 days which was reduced at 14 days but still significantly elevated compared to basal preoperative values. Animals treated with continuous PYY (3-36) infusion had significantly elevated PYY levels compared to the control group throughout the whole experiment, but showed a similar pattern of food intake and body weight gain. In conclusion, although continuous intravenous infusion is the most physiologically relevant method to mimic high postprandial PYY levels, we did not observe any significant effect on food intake and body weight gain in non-food deprived colectomized animals. This suggests that PYY has, if at all, only a minor role in food intake in rats.

Peptide YY release after colectomy in slow transit constipation

BACKGROUND

The gut hormone peptide YY is abundant in the colonic mucosa. Circulating PYY inhibits gastrointestinal motility and decreases food intake. The aim was to determine whether colectomy decreases PYY release in patients with slow transit constipation.

METHODS

Plasma PYY concentrations were measured in 10 patients with slow transit constipation before and 3-24 months after total abdominal colectomy with ileorectal anastomosis, and in 8 healthy controls. A liquid meal was infused intraduodenally to stimulate PYY release.

RESULTS

Postprandial PYY significantly (P < 0.05) increased from a basal value of 15.6 +/- 1.8 pM to a peak of 71.2 +/- 11.6 pM after colectomy. Basal and postprandial plasma PYY concentrations were not significantly different from the results before surgery. Fasting, but not postprandial, plasma peptide YY after colectomy was significantly higher than that in healthy volunteers, 10.9 +/- 0.9 pM.

CONCLUSION

Despite removal of a major source of PYY-secreting cells, colectomy with ileorectal anastomosis does not induce major impairment of PYY release in slow transit constipation.

Gastrointestinal hormone secretion after surgery in neonates with congenital intestinal anomalies during starvation and introduction of enteral nutrition

BACKGROUND/PURPOSE

Gastrointestinal hormones modulate gut function in response to enteral nutrition. Infants with a congenital intestinal anomaly with loss of bowel length either pre-or postnatal, who are on total parenteral nutrition for prolonged periods after surgery, are especially prone to a disturbed secretion of gut hormones. The aim of this study was to determine whether circulating gut hormones were altered in these patients and to collect baseline data for future studies in short bowel patients using different enteral substrates.

METHODS

Gastrin, cholecystokinin, and peptide YY were measured in 14 operated neonates who had a congenital intestinal anomaly during starvation and introduction of enteral nutrition. None of the neonates had a short bowel. Fourteen neonates who underwent surgery for other major congenital anomalies served as age-matched controls. Gut hormones were measured with radioimmunoassays.

RESULTS

Postprandial gut hormone values were higher than basal gut hormone values within both groups. Compared with the controls, postprandial gastrin and cholecystokinin were significantly higher in the patients.

CONCLUSIONS

Neonates with a congenital intestinal anomaly in the absence of a short bowel have a similar secretion pattern of gastrointestinal hormones as neonates with a structurally normal intestinal tract, both during starvation and enteral nutrition.

Impaired release of peptide YY in patients with proctocolectomy and ileal pouch-anal anastomosis

BACKGROUND

Peptide YY (PYY) is a gut hormone produced by endocrine cells in the distal small bowel, colon, and rectum. PYY inhibits upper gastrointestinal secretory and motor functions. The aim of this study was to determine whether basal and postprandial plasma PYY levels in patients with proctocolectomy and ileal pouch-anal anastomosis (IPAA) are reduced and to determine the relationship between plasma PYY and plasma cholecystokinin (CCK) levels.

METHODS

Plasma concentrations of PYY and CCK were measured before and after ingestion of a standardized breakfast in 14 IPAA patients and in 12 healthy control subjects.

RESULTS

Basal PYY was slightly lower in the IPAA patients than in the controls (8.3 +/- 0.3 versus 9.3 +/- 1.1 pM; not significant). Ingestion of the meal induced a small but significant increase of PYY to a maximum of 10.9 +/- 0.9 pM in patients. Integrated postprandial PYY was markedly reduced in patients when compared with the controls (1725 +/- 66 pM*180min versus 3194 +/- 480 pM*180 min; P < 0.005). Plasma PYY concentrations were inversely correlated with plasma CCK concentrations in the 2nd and 3rd h after the meal (r = -0.86; P = 0.0001).

CONCLUSION

PYY release in response to meal ingestion is markedly reduced but not completely absent in patients with proctocolectomy and ileal pouch-anal anastomosis. The inverse relationship between circulating PYY and CCK in the late postprandial phase is compatible with a negative feedback regulation of CCK release by endogenous PYY.