Long-Term Effects of Extrinsic Denervation on VIP and Substance P Innervation in Circular Muscle of Rat Jejunum

Abstract

Intestinal denervation contributes to enteric motor dysfunction after small bowel transplantation (SBT). Our aim was to determine long-term effects of extrinsic denervation on function of nonadrenergic, noncholinergic innervation with substance P and vasoactive intestinal polypeptide (VIP). Contractile activity of jejunal circular muscle strips from six age-matched, naive control rats (NC) and eight rats 1 year after syngeneic SBT was studied in tissue chambers. Spontaneous contractile activity did not differ between groups. Exogenous VIP inhibited contractile activity dose-dependently to a comparable degree in both groups. The VIP antagonist ([D-p-Cl-Phe(6),Leu(17)]-VIP) and the nitric oxide synthase inhibitor L-NG-nitro-arginine did not affect VIP-induced inhibition but increased contractile activity during electrical field stimulation (EFS) in both groups. Exogenous substance P increased contractile activity dose-dependently, greater in NC than SBT. The substance P antagonist ([D-Pro(2),D-Trp(7,9)]-substance P) inhibited effects of exogenous substance P and decreased the excitatory EFS response. Immunohistofluorescence showed tyrosine hydroxylase staining after SBT indicating sympathetic reinnervation. In jejunal circular muscle after chronic denervation, response to exogenous substance P, but not VIP, is decreased, whereas endogenous release of both neurotransmitters is preserved. Alterations in balance of excitatory and inhibitory pathways occur despite extrinsic reinnervation and might contribute to enteric motor dysfunction after SBT.

Role of Hydrogen Sulfide as a Gasotransmitter in Modulating Contractile Activity of Circular Muscle of Rat Jejunum

“…After opening the intestinal segment along the mesenteric border, full-thickness muscle strips (1×8 mm; width × length) were cut in the direction of the circular muscle layer. By doing so, we could measure primarily the effect of circular muscle contraction; contraction of the longitudinal muscle in this experimental methodology should be negligible [8, 10]. We specifically did not remove the mucosa and submucosa purposely in order to maintain an intact, transmural anatomy and all enteric neural connections.…”

“…Contractile activity was monitored by an 8-channel recorder (Grass 7D polygraph; Grass Instrument Co, Quincy, MA) in real-time while being displayed in parallel and stored digitally on a personal computer using dedicated software (MP-100A-CE and AcqKnowledge; Biopac Systems, Inc., Goleta, CA); detailed computer analysis followed later. Our system has been well described previously [10-12] . At the conclusion of the experiment, each muscle strips was blotted on filter paper and weighed to standardize contractile data as per mg tissue weight.…”

Increased proportion of nitric oxide synthase immunoreactive neurons in rat ileal myenteric ganglia after severe acute pancreatitis

“…Such situations have been demonstrated in the pathogenesis of the following disorders: Hirschsprung's disease, achalasia, irritable bowel syndrome, hypertrophic pyloric stenosis, reflux oesophagitis, gastroparesis, chronic intestinal pseudo-obstruction [21]. Alterations in the balance of SP and VIP are associated with enteric motor dysfunction after small bowel transplantation [23]. …”

Age-related changes in functional NANC innervation with VIP and substance P in the jejunum of Lewis rats

“…Although the median life span of Lewis rats seems to be comparable to those of other strains (Altun et al, 2007), objective data about age-related changes in the gastrointestinal tract do not exist for Lewis rats. We were interested particularly in studying Lewis rats, because inbred Lewis rats are used frequently for studies of gut function after the extrinsic denervation necessitated by syngeneic small bowel transplantation; indeed, age-related changes in functional neurotransmission might affect these results, especially in the long-term follow-up (Hirose et al, 1995; Kasparek et al, 2007a; Kasparek et al, 2007b; Tomita et al, 2005). …”

“…1C). In addition based on other observations (Kasparek et al, 2007a; Kasparek et al, 2007b; Kasparek et al, 2008), muscle strips were precontracted with a submaximal concentration of Sub P (10 −7 M), and the effect of a single application of VIP (longitudinal muscle: 10 −6 M; circular muscle: 10 −7 M) on stimulated contractile activity was studied to determine if the effect of VIP was altered by precontraction. A submaximal concentration of Sub P, instead of the maximal concentration of Sub P, was administered to stimulate phasic contractile activity instead of causing a nonphysiologic, tonic contraction.…”