Counteraction of perforated cecum lesions in rats: Effects of pentadecapeptide BPC 157, L-NAME and L-arginine

ARTICLE HIGHLIGHTS

Research background

To illustrate the background, present status, and significance of the study we should emphasize that in cecum perforation studies the immediate post-perforation threat is rarely studied. On the other hand, we recently claimed that treatment with the prototype cytoprotective agent, stable gastric pentadecapeptide BPC 157, induces bypassing of occlusions in rats that underwent vessel occlusions through the rapid presentation of collaterals, and exert its free radical scavenger effect in both ischemia and reperfusion. As a consequence, in this study, we focused on the resolving of the cecum perforation lesion, particularly the rapid disappearance of blood vessels in the cecum serosa that are instantly emptied and thereby “disappear”, perforation defect enlargement, bleeding and fluid leakage, increased oxidative stress and disturbed NO levels in cecum tissue.

Research motivation

The main topics, the key problems to be solved, and the significance of solving these problems for further research are related to reverse the immediate post-perforation threat in the cecum (and, therefore, the complete downhill course). We focused on perforated cecum, the stable gastric pentadecapeptide BPC 157, the NOS-blocker L-NAME, and the NOS-substrate L-arginine, as well as on the initial post-perforation period, rapid disappearance of blood vessels at the cecum serosa (emptied/disappeared), a large immediate defect, bleeding, leakage of fluid, increased oxidative stress and disturbed NO levels in cecum tissue. The rationale was that BPC 157 rapidly activated the collateral circulation from the existing vessels in rats with ischemic colitis or inferior caval vein occlusion. This was further perceived as an extended cytoprotection background (endothelium maintenance → epithelium maintenance = blood vessel recruitment and activation toward injury), also described as “bypassing” occlusion via alternative ways, as demonstrated with BPC 157, which, in principle, can likely cure rats with perforated cecum and thereafter.

Research objectives

The main objectives, the objectives that were realized, and the significance of these objectives for future research could be summarized as follows. In practice, as described previously, our approach to cure perforated cecum begins with the original understanding of stomach cytoprotection (a very rapid protection of the stomach endothelium and epithelium against diverse direct injuries; endothelium maintenance → epithelium maintenance), as “bypassing” occlusion via alternative ways, as demonstrated with BPC 157. Furthermore, we used these findings as the general argument that under analogous or even worse conditions (i.e., perforated cecum) a similar positive outcome can appear. Consequently, BPC 157 can attenuate cecum perforation syndrome; in BPC 157-treated rats, therapy may lead to attenuation and reversal of the consequent tissue damage. Especially, reversal of vessel disappearance to vessel “running” toward the defect (vessel filled/reappeared), reversal of defect enlargement to defect narrowing, reversal of prolonged bleeding to bleeding attenuation can induce reduction in the increased MDA values and normalization of NO values in cecum tissue. In subsequent days and weeks, this may lead to a closed cecum defect and attenuation of adhesion formation.

Research methods

As an advantageous principle, methodology includes direct monitoring of the events occurring in rats during perforation of the cecum and immediately thereafter with the application of the stable gastric pentadecapeptide BPC 157, as a cytoprotective agent, and NO-agents, L-NAME and L-arginine. In deeply anaesthetized rats the cecum was exposed, and a perforation (5-mm diameter) was made at the ventral face of the basal region of the cecum close to the largest curvature; the rats were monitored for the next 15 min. The agents’ application (after 1 minute, medication (/kg, 10 mL/2min bath/rat) includes: BPC 157 (10 μg), L-NAME (5 mg), L-arginine (100 mg) alone or combined, and saline baths (controls)) on the rat perforate caecum injury. Alongside with the agents’ application, we continuously assessed the gross reappearance of the vessels (USB microcamera) quickly propagating toward the defect at the caecum surface, defect contraction, bleeding attenuation, MDA- and NO-levels in colon tissue at 15 min, and, in repalaratomized rats severity of colon lesions and adhesions at 1 and 7 days.

Research results

The study of the counteraction of perforated cecum lesions in rats and the effects of pentadecapeptide BPC 157, L-NAME and L-arginine merits several emphasizes to summarize the research findings, their contribution to the research in the field, and the problems that remain to be solved. First, as an issue so far not fully addressed, to reverse the immediate post-perforation threat in the cecum (and, therefore, the complete downhill course) we focused on this immediate post-perforation period. We also addressed the novel aspect of vascular rescue through the application of cytoprotective agents, known, as a class, to function in endothelium maintenance in the gastrointestinal tract (and, thus, mucosal maintenance). Of note, with applied BPC 157 therapy, the whole initial syndrome (in particular, instantly emptied blood vessels at the cecum serosa (thus rapid “disappearance” of the existing vessels and vessel function failure upon injury)) and, consequently, perforation defect enlargement and fluid leakage, profuse bleeding, increased oxidative stress and disturbed NO levels in cecum tissue were accordingly affected. This specific level of healing (initial and final) can be not obtained from the effect of NOS-blockade (L-NAME) or NOS-substrate (L-arginine).

Research conclusions

As the new findings, we suggest that this recovering of the perforated cecum should be an activity much like an activity seen when BPC 157 rapidly activated the collateral circulation from existing vessels in rats with ischemic colitis or inferior caval vein occlusion. Thus, the essential findings (i.e., cecum perforation syndrome occurs in BPC 157-treated rats with attenuation and reversal of the consequent tissue damages) indicate the rapidly activated bypassing loops (i.e., through arcade vessels or the left ovarian vein and other veins, corresponding to the prompt particular vascular rescue seen after perforation). Vascular rescue may be vessels “running” toward the defect (vessel filled/reappeared), and a small-vessel network appears around the perforated defect with BPC 157 bath administration. Each considered a break of blood flow, suggests that the therapy resolving the defect (i.e., cecum defect enlargement reversed to defect contraction in BPC 157-treated rats) may be reestablishing blood flow. That explanation represents the newest theoretical extension of cytoprotection theory background (endothelium maintenance → epithelium maintenance = blood vessel recruitment and activation toward injury, providing also described “bypassing” of occlusion through alternative ways). Since all chains of events could be accordingly and promptly involved to rapidly initiate and achieve a full healing effect. The bleeding time from the perforated cecum is thereby shortened, as previously demonstrated in rats with amputation, anticoagulant application, or vein obstruction. Furthermore, defect closing corresponds to the previously demonstrated closing of various fistula defects, which were surgically made by particular defect creations in corresponding organs. The implications of this study for clinical practice in the future can be that BPC 157, with certain vascular effects and NO-effect, can be used in the perforated cecum and bleeding therapy.

Research perspectives

The main experiences and lessons that can be learnt from this study may be the evidence that BPC 157 promptly facilitates and extends the cytoprotection background (endothelium maintenance → epithelium maintenance = blood vessel recruitment and activation toward injury, providing also described “bypassing” of occlusion through alternative ways). Thus, the evidence was obtained that all chains of events were accordingly and promptly involved to rapidly initiate and achieve a full healing effect, and with the respect to the corresponding positive effects in two other studies (ischemic/reperfusion colitis; inferior caval vein occlusion), the beneficial effect in rats with perforated cecum may be generally observed. Thereby, the future research should be related to the similar and/or even worse condition, to verify full significance of the presented beneficial findings seen in rats after cecum perforation and BPC 157 therapy application.