Upsala J Med Sci 82: 55-59, 1977 Corticosteroid Therapy in Regional Small Bowel lschaemia An Experimental Study in Rats L. RENTZHOG and S. WIKSTROM From the Department of Surgery, University Hospital, Uppsala Sweden ABSTRACT Corticosteroid therapy in pharmacological doses has a well documented positive effect in shock caused by severe in- testinal ischaemia. I n this study the effect of high doses of corticosteroids on the exchange circulation of the mucosa was analysed in varied, regional small howel ischaemia. Thirty minutes after establishment of moderate ischaemia the exchange circulation in the mucosa of the ischaemic intestinal segment in animals treated with 100 mg/kg hydrocortisone showed no improvement compared with un- treated animals. Higher corticosteroid doses impaired the exchange circulation. On analysis 7 days after establishment of the ischaemia, treatment with 100 mg/kg hydrocortisone during the first 3 days was found to have impaired the exchange circulation. The same treatment in rats with more severe intestinal ischaemia gave a greatly increased mortali- ty. Possible reasons for the impaired mucosal circulation following corticosteroid therapy in pharmaeo-logical doses in regional small bowel ischaemia are discussed. One possi- bility is that corticosteroids induce a “steal syndrome” due to the better vasodilative effect on healthy than on ischae- mic intestinal tissue. INTRODUCTION In most experimental studies concerning ischaemia of the small intestine the ischaemia has been pro- duced by central, intermittent interruptions of the blood flow. The significance of bacterial endotoxin in this connection has been pointed out by several authors (13, 19). Selkurt et al. (16) discussed the importance of vasoactive substances in intestinal ischaemia. Kobold & Thal (8) identified a vasoac- tive peptide which was liberated in different types of experimental and clinical ischaemia of the small intestine. Other authors (2, 6, 7) have shown that lysosomal enzymes are released in association with ischaemia in the splanchnic region, and this may well lead to a serious impairment of myocardial function (10, 18). It seems likely that abnormal bacteria-dependent endotoxin production, ischaemic destruction of lysosomes, release of vascoactive substances and activation of vasoconstrictive reflexes can also be induced in connection with regional small bowel ischaemia. These local factors can affect the collat- eral circulation and can also probably cause a re- lease of a myocardial depressant factor (10). Lil- lehei et al. (1 1 ) pointed out that the ability of the intestine to survive a regional ischaemia is highly dependent upon the collateral flow from adjacent intestinal segments. NorlCn, Rentzhog & Wikstrom (14) have demon- strated that antibacterial and antithrombotic therapy improve t h e exchange circulation and chances of survival of the mucosa in regional small bowel ischaemia. Corticosteroids in gram doses increase the survi- val in intestinal ischaemic shock (1, 10). The effect of cortisone in pharmacological doses in severe in- testinal ischaemia has been discussed. Altura & Altura ( 1 ) claim that in these doses corticosteroids unspecifically inhibit the effect of vasoconstriction that may be released in intestinal ischaemia. Lil- lehei et al. (12) assumed that corticosteroids act as alpha receptor blocking agents but provided no de- finite evidence for this assumption. Bruns & Con- nolly (3), on the other hand, considered that the effect was a potentiation of the vasoconstrictive action of the catecholamines. Weissman & Thomas (17) and Glenn & Lefer (6) were of the opinion that the main effect of corticosteroids was t o prevent lysosomal destruction and thereby the release of de- leterious lysosomal enzymes. The effect of corticosteroids in gram doses in re- gional small bowel ischaemia does not appear to have been studied previously. We therefore consid- Upsaln J M e d Sci 82 56 L . Rentzhog and S. Wikstrom ered it of great interest t o examine t h e influence of nal ischaemia-two comprising 1 1 mes end arc and two I5 pharmacological doses of corticosteroids o n the ex- change circulation of the mucosa in standardized, regional small bowel ischaemia both immediately and o n e week after establishment of t h e ischaemia. M A T E R I A L A N D M E T H O D S Male Sprague-Dawley rats weighing 200-300 g were used. The animals were strictly standardized as regards iodine metabolism and were given iodine in their drinking water both before and during the experimental period. Standardized small bowel ischaemia was produced by ligation of a defined number of mesenteric end arcades (mes end arc). The ligature material was 5 : O cardiovascu- lar silk (Ethicon). The first ligature was applied on the 6th mes end arc counted from the ileocaecal angle, and a further 1 1 or 15 mes end arc, in the proximal direction, were then ligated. At the same time a central loop in the devascularized intestinal segment was marked with silk threads. These threads were placed around the intestine without affecting the terminal vessels. The length of the loop thus marked always corresponded to the extent of 2 mes end arc. The mucosal circulation was assessed by a technique described by Nylander & Wikstrom (15), based on the fact that the passive absorption, i.e. the diffusion of a given substance from an intestinal loop of defined size, is an expression of the effective exchange circulation in the mucosa of the intestinal segment. A radioactive iodine isotope ( N a P ) was used as the test substances. At the time of analysis the previously marked intestinal loop (2 mes end arc) was ligated and the test dose was deposited into its lumen b y transmural injection. The pylorus was tied off to prevent gastric contents from passing into the small intestine. After 30 min the animal was killed with ether. The abdomen was opened and the stomach was ligated a t the cardia and resected. The isolated intestinal loop into which the test substance had been deposited was also resected. The radioactivity in the stomach, the in- testinal loop and the whole body (thus excluding the stomach and the test loop) was recorded. Two series of experiments were performed. In all ani- mals a catheter was inserted into the vena cava viajugular vein by technique described by Engberg (4), and left in sitii. In series I (Table I) small bowel ischaemia comprising 1 I mes end arc was produced in four groups of animals. In two groups an intravenous injection of hydrocortisone (Soh-CorteP, Upjohn) in a dose of 100 mg and 300 mg, respectively, per kg body weight, dissolved in 0.2 ml physiological saline was given immediately before the ischaemia was established. The third group was simultaneously given methylprednisolone (Medrone@, Up- john), 30 mg per kg dissolved in 0.2 ml physiological saline. The fourth group, as well as a laparotomy control group (no ischemia) was given 0.2 ml physiological saline alone. The exchange circulation in the ischaemic intestinal segment was analysed 30 min after establishment of the ischaemia. Series I1 (Table 11) consisted of four groups with intesti- Upsala J Med Sci 82 mes end arc. In all groups the exchange circulation was analysed 7 days after establishment of the ischaemia. Two of the groups (one 1 1 and one 15 mes end arc) were treated with hydrocortisone. The first dose (100 mg/kg) was given immediately before the ischaemia was produced, and the next dose (100 mg/kg) 2 h later. A further two doses of 50 mg/kg were given during the rest of the first 24 hours. In the following 2 days four doses of 50 mg/kg were given per day. The other two groups-ischaemic controls-were given physiological saline of the same volume as the hydrocortisone doses in the treated groups. In series I1 a morphological evaluation of the ischaemic intestinal segment was made (Table 11). The material was divided into three different types according to the macroscopical appearance of the small intestine, as fol- lows: T y p e 1 . The intestinal wall appeared intact, apart from moderate thickening. T y p e 2 . Varying length of the intestinal wall were con- siderably thickened. The width of the lumen was normal both above and below the thickened area of the intestinal wall. T y p e 3. The intestinal wall was thickened as in type 2, but proximal to the thickened area the lumen was dilated to the extent of an ileus state. The results of the exchange circulation analyses in the ischaemic segment have been recorded only for type 1 in the respective experimental groups. R E S U L T S I n series I , in which the exchange circulation of the intestinal mucosa was analysed 30 min after laparotomy or establishment of regional small bowel ischaemia ( 1 1 mes end arc), all animals sur- vived. In Table I it is seen that in the laparotomy control group 26% of the radioactive dose remained in the isolated intestinal loop and a t the end of the analytical period. In the untreated ischaemic group the absorption from the isolated loop was consider- ably impaired 45% of the radioactive dose remain- ing in t h e loop. Treatment with 100 mg/kg hydro- cortisone did not improve the exchange circula- tion significantly in comparison with the untreated ischaemic group; in this case 48% of the dose re- mained in the loop. Following treatment with the higher dose of hydrocortisone (300 mg/kg) and with methylprednisolone (30 mg/kg) the absorption of the radioactive iodine was reduced, 67% and 66% of the dose, respectively, remaining in the loop a t the end of the analytical period. Half of the animals treated with the higher dose of hydrocortisone (300 mg/kg) also received 2 ml physiological saline in a continuous intravenous infusion during the experi- mental period, but these animals showed no differ- Corticosteroid therapy in bowel ischaernia 57 Table I. Series Z. Characteristics of the material and percentage distribution of the radioactive dose 30 rnin after its deposition in the isolated loop ( m e a n values with S . E . ) Body Percentage of dose i n weight Exp. group n fg) isol. loop stomach body LC 20 23 1 k 3 . 8 26.1 k 2 . 2 12.0k0.8 61.9k1.9 11 mes end arc, untreated 18 242 2 6.8 45.2k 3.2 6 . 7 k 0 . 8 48.1 k 2 . 7 11 mes end arc, hydrocortisone treated (100 mg/kg) 20 2 5 2 k l . l 49.1 k 4 . 0 10.1f 1.3 40.8k3.1 11 mes end arc, hydrocortisone treated (300 mg/kg) 20 240 2 5.2 66.8 k 3 . 2 2.2k0.3 31.0k3.2 11 mes end arc, methylpredni- solone treated 10 270f 1 .O 65.8 k5.1 1.9k0.4 3 2 . 3 f 4 . 8 ence in absorption of the test dose from the animals given hydrocortisone alone (65% and 68%, respec- tively, of the test dose remaining in the loop). All animals that were given the higher hydrocortisone dose (300 mg/kg) are therefore placed in one group in Table I. In series I1 the exchange circulation of the small bowel mucosa was analysed 7 days after establish- ment of the ischaemia. In Table I1 it is seen that in the untreated ischaemic group comprising 1 1 mes end arc 3 of 21 animals died. Morphologically, one of these 3 animals was assigned t o type 2 . The other 2 animals that died were of type 3 , exhibiting acute perforation and peritonitis. Of the surviving ani- mals in this group 2 were assigned t o type 3 , with severe ileus, and one of them also had perforation. The other 16 animals in this group were assigned to type 1. In the group with ischaemia comprising 11 mes end arc and treated with hydrocortisone, one of 18 animals died. This animal was of type 3. One of the surviving animals of this group was also as- signed to type 3 , with perforation. It is also seen in Table I1 that in the hydrocortisone-treated ischaemic group the exchange circulation in the ischaemic intestinal segment was sinificantly im- paired compared with the untreated group. Thus 50% of the radioactive dose remained in the iso- lated loop in the former group, and 3 5 % in the untreated group. Among the animals with severe bowel ischaemia (15 mes end arc) (Table II), only one could be assigned to type 1 . The others were of type 3, and four of these died. Hydrocortisone treatment com- bined with this severe degree of ischaemia resulted in death in all cases. Morphologically all animals in this group were assigned t o type 3. DISCUSSION Nylander & Wikstrom (15) showed that the ex- change circulation of the mucosa was greatly im- paired immediately following establishment of small Table 11. Series ZZ. Characteristics of the material, morphological types and percentage distribution of the radioactive dose 30 min after its deposition in the isolated loop ( m e a n values with S . E . ) Morphological types Body weight (g) Percentage of dose in Mor- Exp. group n tality I I1 I11 Initial Final isol. loop stomach body 11 mes end arc, untreated 21 3 16 1 4 284k7.6 285k9.3 34.9k4.2 4 . 7 k 0 . 3 60.4f4.1 11 mes end arc, hydrocortisone treated 18 1 16 - 2 268k1.1 2 4 3 f 4 . 5 4 9 . 8 f 4 . 5 4 . 1 k 0 . 6 46.1k5.5 15 mes end arc, untreated 12 4 1 - 11 234k3.4 - - - - 15 mes end arc, hydrocortisone treated 12 12 - - 12 270f2.9 - - - - Upsulu J M r d Sci 82 58 L . Rentzhog and S. Wikstrom bowel ischaemia. This finding was confirmed in t h e present investigation. A release of lysosomal en- zymes and of vasoactive substances, as well as the influence of bacterial endotoxins, may all presuma- bly influence the collateral circulation and thereby the exchange of the mucosa in the ischaemic in- testinal segment. Theoretically it would therefore seem probable that hydrocortisone would improve the exchange circulation, but no effect of this corti- costeroid in a dose of 100 mg/kg was found in the acute experiments. Altura & Altura (1) reported, however, from acute experiments in the rat, that the survival in intestinal ischaemic shock was only im- proved at a dose of 300 mglkg hydrocortisone or 30 mglkg methylprednisolone. In our experiments this high dose of hydrocortisone and of methylpredni- solone impaired the exchange circulation in the ischaemic intestinal segment, indicating that these steroid doses have a negative effect on the collateral circulation. One possible reason for this surprising effect of high glucocorticoid dose may be a negative in- fluence on the central circulation. In a pre-experi- mental study, however, no such influence was ob- served. In rats with catheters inserted into the fe- moral artery for continuous pressure recording, a transient reduction of the systemic blood pressure was noted immediately after administration of the glucocorticoid, followed by normalization or a slight pressure increase. Another possibility is that a strong general vaso- dilative effect of high doses of glucocorticoids might unmask a hypovolaemia caused by loss of fluid through oedema, for instance, in the ischaemic tissue in these animals. Infusion of physiological saline after administration of the corticosteroid, however, did not affect the results. A further conceivable explanation is that corticosteroids impair the exchange circulation of the mucosa by inducing a “steal syndrome” due to more effective vasodilatation in healthy than in ischaemic intestinal tissue. It is possible that metabolic factors in ischaemic tissue and any re- lease of certain vasoactive substances may counteract a favourable effect of the corticosteroids on the circulation in an ischaemic intestinal seg- ment. The net effect may then be an impaired circu- lation in the ischaemic segment. Folkow ( 5 ) has demonstrated that the circulation of the intestinal wall is built up of several parallel vascular systems. Our method measure3 indirectly L / l , c o / ( i J M r d S c i X 2 the circulation in the mucosal vascular system. It is possible that high corticosteroid doses do not im- pair the total circulation of the ischaemic intestine despite a reduction of the exchange circulation of the mucosa. A redistribution of blood to deeper layers of the intestinal wall is conceivable, especial- ly to the vascular system in the muscular layer. The presence of an adequate circulation during the first days after the development of intestinal ischaemia is of decisive importance for survival and restoration of the intestine. During this initial ischaemic period the available intestinal circulation would seem to be most susceptible to a negative influence of a high sympathetic tone and local re- lease of vasoactive substances, endotoxins and lysoenzymes. High corticosteroid doses during the first 2-3 days might have a positive effect on the local damage and improve the chance of survival. In our second series of experiments, however, there was no definite positive effect of intensive cor- ticosteroid therapy during the first three days following establishment of the ischaemia. In rats with severe ischaemia (15 mes end arc) the high dose of corticosteroid had a distinctly negative ef- fect on the survival. In untreated animals with ischaemia comprising 11 mes end arc the exchange circulation was consid- erably better one week after than immediately after establishment of the ischaemia. This is in full agreement with previous results of Nylander & Wikstrom (15). On the other hand, treatment with a corticosteroid in gram doses during the first 3 days after ischaemia had been produced resulted in no improvement of the mucosal circulation 7 days la- ter. A probable explanation, as in the acute experi- ments, is that gram doses of corticosteroids impair the collateral circulation in regional ischaemia due to a “steal syndrome”. Another possibility is that corticosteroid therapy favours bacterial invasion in this ischaemic intestinal wall, with consequent oedema and fibrosis, leading to an impairment of the mucosal circulation. ACKNOWLEDGEMENT This investigation has been supported by grants from the Swcdish Medical Research Council (B76-17X-2809-06). Excellent technical assistance was provided by Mrs Inger Fogelberg. Corticosteroid therapy in bowel ischaemia 59 REFERENCES 1 . Altura, B. M. & Altura, B. T.: Peripheral vascular actions of glucocorticoids and their relationship to protection in circulatory shock. J Pharmacol Exp Ther 190: 300, 1974. 2. Bitensky, L., Chayen, J., Cunningham, J. G . & Fine, J . : Behaviour of lysosomes in hemorrhagic shock. Nature, London, 199: 493, 1963. 3 . Bruns, D . L. & Connolly, J . E.: Comparative study of the effectiveness of adrenal cortical compounds in hemorrhagic shock. Surg Forum 10: 382, 1960. 4. Engberg, A , : A technique for repeated renal clearance measurements in undisturbed rats. Acta Physiol Scand 75: 170, 1969. 5 . Folkow, B.: Role of nervous system in the control of muscular tone. Circulation 21: 760, 1960. 6. Glenn, T . M . & Lefer, A . M.: Protective effect of thoracic lymph diversion in hemorrhagic shock. Amer J Physiol219: 1305, 1970. 7. Janoff, A , , Weissmann, G . , Zweifach, B. & Thomas, L.: Pathogenesis of experimental chock: 1V. Studies on lysosomes in normal and tolerant animals sub- jected to lethal trauma and endotoxemia. J Exp Med 116:451, 1962. 8. Kobold, E . E. & Thal, A. P.: Quantitation and identification of vasoactive substances liberated dur- ing various types of experimental and clinical intesti- nal ischemia. Surg Gyn Obst 117: 315, 1963. 9. Lefer, A . M.: Role of myocardial depressant factor in the pathogenesis of circulatory shock. Fed Proc 29: 1836, 1970. 10. Lefer, A. M. & Vernier, R. L.: Role of corticosteroids in the treatment of circulatory collapse states. Clin Pharm Ther 11:630, 1970. 1 1 . Lillehei, R. C., Goott, B. & Miller, F. A,: The physiological response of the small bowel of the dog to ischemia including prolonged in vitro preservation of the bowel with successful replacement and survi- val. Ann Surg 150: 543, 1959. 12. Lillehei, R. C., Longerbeam, J . K . , Block, J. H. & Manax, W. G . : The modern treatment of shock based on physiological principles. Clin Pharm Ther 5: 63, 1964. 1 3 . Milliken, J . , Nahor, A . & Fine, J.: Study of the factors involved in the development of peripheral vascular collapse following release of the occluded superior mesenteric artery. Brit J Surg52:699, 1965. 14. Norlen, K . , Rentzhog, L. Wikstrom, S . : Experimen- tal ischemia of the small intestine. Effect of antibotic and antithrombotic drugs on the mucosal exchange circulation. Acta Chir Scand 141: 780, 1975. 15. Nylander, G . & Wikstrom, S.: Propulsive gastrointestinal motility in regional and graded ischemia of the small bowel. An experimental study in the rat. I. Immediate results. Acata Chir Scand, Sup- pl. 385, 1968. 16. Selkurt, E. E., Scibetta, M. P. & Cull, T. E.: Hemodynamies of intestinal circulation. Circ Res 6:92, 1958. 17. Weissman, G . & Thomas, L.: Studies on lysosomes: I. Effects of endotoxin tolerance and cortisone on the release of acid hydrolases from a granular fraction of rabbit liver. J Exp Med 116:433, 1962. 18. Williams, L . F., Jr., Goldberg, A. H., Polansky, B. J. & Byrne, J . J . : Myocardial effects of acute intestinal ischemia. Surgery 66: 138, 1969. 19. Witznitzer, T. & Rozin, R.: Bacterial factor in shock following superior mesenteric artery occlusion. Israel Med J 22: 4 , 1963. Received July 20, 1976 Address for reprints: Stig Wikstrom, M.D. Department of Surgery University Hospital S-750 14 Uppsala Sweden Upsulu J Med Sci 82