Small intestinal transections decrease the occurrence of tapeworm-induced myoelectric patterns in the rat.

Abstract Luminal infection by the noninvasive tapeworm, H. diminuta, alters rat small intestinal myoelectric activity. The significance of continuity between small intestinal enteric nervous system (ENS) and that of both the stomach/pylorus and colon/caecum regarding the induction of tapeworm-altered myoelectric patterns was evaluated. A total of 32 rats were implanted with four serosal electrodes placed at sites in the duodenum through the mid-jejunum. Sixteen of the 32 rats underwent intestinal transections and anastomoses at both the duodenum and ileum. After recording myoelectrical activity of both normal and transected intestines, eight rats from each group (normal and transected) were infected with H.diminuta. Phase III frequency, duration of the migrating myoelectric complex (MMC), slow wave frequency, percentage of slow waves associated with spike potentials and the occurrence of the the two tapeworm-initiated myoelectric patterns, repetitive bursts of action potentials (RBAP) and sustained spike potentials (SSP), were measured. In infected rats, the frequency of the RBAP and SSP electric patterns were significantly reduced by the double transection. Intestinal transection did not affect the other changes caused by infection, such as decreased MMC phase III frequency and percentage of slow waves associated with spike potentials. In conclusion, a small intestinal ENS in continuity with other segments of the GI tract is required to generate maximal numbers of tapeworm-induced SSP and RBAP myoelectric activity in the small intestine of the rat.

Intestinal regrowth is amplified after jejunal but not ileal resection during tapeworm infection in the rat.

The ileum possesses functions required by a healthy individual that are not fully supplanted by the duodenum or jejunum. Evidence suggests that the ileum may also be necessary to maintain an enteric parasite-host interaction. We hypothesized that the ileum is essential to the survival of the lumen-dwelling, rat tapeworm, H. diminuta. Male rats were divided into three groups: those with ileal or jejunal resections and nonresected controls. Half of each rat group was infected with the tapeworm. After jejunal resection, the weight but not length of intestinal remnant (duodenum + ileum) in infected rats returned to that of control, nonresected intestine 29 days after surgery and tapeworm numbers were fully maintained. In contrast, after ileal removal intestinal length and weight of the remaining duodenum and jejunum in infected rats were significantly decreased and tapeworm survival diminished. Data indicates that intestinal growth following resection is amplified by tapeworm infection when the ileum remains but diminished when the ileum is removed. Furthermore, loss of the ileum results in decreased infection intensity and dry weight of the tapeworm.

Effect of surgical alteration of the rat gastrointestinal tract on the growth and development of Hymenolepis diminuta.

Eight groups of rats were used to study the involvement of the enteric (ENS) and central (CNS) nervous systems in the development of Hymenolepis diminuta using surgical intestinal transection, or CNS denervation, or both procedures. The transection procedure was used to isolate the ENS of the small intestine from either orad and/or caudal portions of the alimentary system, while the CNS denervation was used to eliminate direct visceral efferent inputs from the CNS. Nine days after the surgical procedures, all rats were infected with 35 cysticercoids of H. diminuta. On 20 days postinfection, the infection intensity, tapeworm dry weight, tapeworm morphology, intestine length, and intestinal wet weight were recorded. Only the combination of the duodenal and ileal transections with a CNS denervation reduced infection intensity and prevented the increased intestinal length normally observed in infected rats. In contrast, none of the various intestinal transection procedures alone or CNS denervation alone had any effect on the survival, ability to produce oncospheres or morphology of the tapeworms. In conclusion, tapeworm survival is decreased when both CNS and ENS inputs into the small intestine are altered or absent.