Acute effects of peritoneal dialysis solutions on appetite in non-uremic rats

Background. Standard peritoneal dialysis (PD) solutions may contribute td a norexia in PD patients due td the peritoneal absorption of glucose from the dialysate, abdominal discomfort and other factors. New PD solutions contai ning alternative osmotic agents, neutral pH and bicarbonate as buffer were recently developed. To test the effect of these solutions on appetite, we i nvestigated haw intraoral (IO) intake of sucrose via an IO cannula was infl uenced by intraperitoneal (IP) infusion of different PD solutions in an app etite model in rats. Methods: The IO intake was measured in male Wistar rats after an IP dwell o f 30 and 120 minutes with the following PD solutions: 1.36%, 2.27% and 3.86 % glucose based and lactate buffered solutions (D);1.36%, 2.27% and 3.86% g lucose based and bicarbonate/lactate buffered solutions (P); 7.5% icodextri n based solution (E); 1.1% amino acid-based solution (N); and, 2.5% glucose -based lactate-buffered solution (GB), using sham injection (injection with out infusion) as control. Prior to the tests, rats were provided with an IO cannula, and were trained for two weeks until the rate of IO intake had st abilized. Results. The D and N solutions inhibited IO intake. For the D solutions, th e degree of appetite suppression was higher with the higher concentration o f glucose. P 3.86%, but not P 1.36% and P 2.27% solutions, inhibited the IO intake. However, a comparison of the degree of appetite inhibition between D and P showed less inhibition with P 1.36%, 2.27% and 3.86% solutions tha n with corresponding D solutions. The E solution did not seem to suppress a ppetite. Finally, no significant difference in IO intake was found between rats given GB 2.5% and D 2.27%. Conclusions. In this appetite model in rats, the measurement of IO intake a fter the IP infusion of different dialysis solutions showed that (1) N and D solutions may reduce appetite, and for the D solutions the degree of appe tite inhibition was related to the dialysate concentrations of glucose; (2) the P solutions had less impact on appetite than the D solutions; (3) the E solution had no impact on appetite during the short dwells of 30 and 120 minutes. The demonstrated differences between the different solutions appea r to be due to different concentrations, and type, of nutrients used as osm otic agent (glucose, amino acids, icodextrin) or buffer (lactate), although differences in dialysate pH, tonicity and concentration of glucose degrada tion products also may be important. The present studies suggest a possible positive effect on appetite by using bicarbonate/lactate buffered solution s instead of lactate buffered solutions.