Francavilla, A

Starzl, TE

English

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I>llrgh .'{' ~S1 )enterologia, ,J/y \fedica Generale raly [tie Apparato illico, '! . Hepatotrophic Effect of Insulin T.E. Starzl and A. Francavilla* Dept. of Surgery, University of Pittsburgh. Pittsburgh. P A USA, * Dept. of Gastroenterology, University of Bari. Bari. Italy A completely diverting portocaval shunt (Eck's fistula) pro-foundly alters the structure and function of the liver in several species. Until recently, these changes were thought in what has been termed the "flow hypothesis"(l) to be caused by and to be proportionate to the reduction in total hepatic blood-flow which the procedure causes. We have suggested instead, that disruption of normal endogenous insulin delivery to the liver for determin-ing this lesions was mainly responsible. We showed that infusion of commercial insulin into the tied-off central portal vein of dogs prevented most of the acute atrophic changes that are ordi-narily very advanced by light microscopy within four days after portocaval shunt. Much of the evidence supporting the importance of insulin as an hepatotrophic factor has to do with what happens when the liver is deprived of portal venous blood or that portion of por-tal blood that emanates from the pancreas. The light microscopic changes in the liver caused by portal blood deprivation include atrophy, fatty infiltration, and degly-cogenation (10) Ultrastructurally, the most striking and specific changes are depletion and disruption of the rough endoplasmic re-ticulum, and reduction in the membrane-bound ribosomes. All these events occur with surprising speed, being about 90% complete within four days. We also know from other work recently summa-rized by Putnam el al. (7) that the same general light and elec-tron microscopic changes have been seen after portal d.iversion in the livers of rats, dogs, swine, baboons, and humans with some variations in degree. Thus, the hepatic injury of Eck fistula is common to all species so far studied. The metabolic consequences have been the mildest in rats and man. 2 HEPATOTROPHIC EFFECT OF INSULIN Body wall L. ·-=:jl Fig.1. Experiments in which Eck fistula is performed and post-operative infusions are made into the left portal vein. (From Starzl et ale (1976) by permission of The Lancet.) Fig. 1 represents the direct test to demonstrate that the li-ver alteration of Eck fistula is caused by deprivation of liver of direct access to endogenous insulin. Seventy dogs were infused with a fine infusion catheter placed into the tied-off left portal branch and led trough the body wall and trough along sub-cutaneous tunnel corporated into animals and the The size of were determined at the time of the right lobes 13) • The results greatly reduced to a small calibrated finger pump that was in-a light body cast. Table 1 reports the group of kind of hormonal infusion. hepatocytes and the . percent of labelled nuclei by biopsy specimens obtained from the left lobe the portocaval shunt (LO). and from the left and (L4 and R4) at the time of killing (5. II, 12, reported in table 2 demonstrate that insulin the acute atrophy that otherwise halved the size of the cells and preserved hepatocyte ultrastructure. In small doses, glucagon did not potentiate the action of insulin, and, in large doses, it may have reduced the insulin benefit. Glucagon alone in either small or large doses had no effect under the con-ditions of this experimental model. TABLE 1. Group N° N° of exp 11 6 13 4 8 8 6 7 7 *All insulin wa, Table 2. Group N° C~ LO 1 0.197 ± 2 0.200 ± 3 0.189 ± 4 0.194 ± 5 0.196 ± 6 0.189 ± 7 0.165 ± 8 0.211 ± 9 0.215 ± * Comparisons we The effect l' striking, as rt' rate was incre;: per 1000 cells. no spill-over effect, nor did uid ormed and post-al vein. (From .te that the li-tion of liver gs were infused tied-off left ough along sub-mp that was in-·ts the group of labelled nuclei Jm the left lobe com the left and Ling (5, 11, 12, that insulin halved the size ucture. In small insulin, and, in enefit. Glucagon .t under the con-, HEPATOTROPHIC EFFECT OF INSULIN .J TABLE 1 • Group N° of Type of Insulin* Glucagon N° exp infusion (units/Kg/day (mg/Kg/day mean ± SD) mean ± SD) 1 11 No treatment 0 0 2 6 Hepar. saline 0 0 3 13 Large dose ins. 0.43 ± 0.05 0 4 4 Small dose ins. 0.16:t0.ll 0 5 8 Purified ins. 0.42 ± 9.08 0 6 8 Small dose glue. 0 0.0053 ± 0.0011 7 6 Large dose glue. 0 0.60 ± 0.10 8 7 2/1 ins./gluc. 0.45 ± 0.03 0.0053 ± 0.0005 9 7 2/100 ins. /glue. 0.42 ± 0.01 0.5 ± 0.02 *All insulin was commercial regular insulin, except in Group 5 Table 2. Group Cell size units (mean + SD) P values* N° (L4 vs R4) LO L4 R4 1 0.197 ± 0.04 0.108 ± 0.02 0.108 ± 0.02 N.S. 2 0.200 ± 0.04 0.105 ± 0.02 0.104 ± 0.01 N. S. 3 0.189 ± 0.03 0.160 ± 0.02 0.100 t 0.02 <0.001 4 0.194 + 0.04 0.143 ± 0.02 0.094 ± 0.01 <0.05 5 0.196 ± 0.04 0.158 ± 0.01 0.095 ± 0.02 <0.001 6 0.189 ± 0.01 0.103 ± 0.01 0.103 ± 0.01 N. S. 7 0.165 ± 0.03 0.085 ± 0.01 0.082 i- 0.01 N.S. 8 0.211 ± 0.05 0.156 ± 0.05 0.094 ± 0.02 <0.05 9 0.215 ± 0.04 0.114 t 0.03 0.073 ± 0.02 <0.05 * Comparisons were by Student's t test. The effect of insulin on hepatocyte proliferation was also striking, as reported in table 3. After Eck fistula, the mitotic rate was increased to about three times normal, from 1.5 to 4.5 per 1000 cells. Insulin more than tripled this cell renewal, with no spill-over to the controlateral lobes. Glucagon alone had no effect, nor did it potentiate the action of insulin. 4 HEPATOTROPHIC EFFECT OF INSULIN Table 3. N° of labelled hepatocytes per 1000 epatocytes P values'" Group (mean ± SD) (L4 vs R4) N° L4 R4 4.9 ± 1.0 4.7 ± 0.9 N.S. 2 4.6 ± 0.8 4.7 ± 0.9 N.S. 3 13.0 ± 3.9 4.6 ± 0.9 < 0.001 4 15.6 ± 2.0 5.3 ± 1.0 < 0.001 5 14.4 ± 1.1 4.8 ± 1.0 < 0.001 6 4.9 ± 0.9 4.3 ± 0.6 < 0.05 7 4.2 ± 1.5 4.3 ± 1.1 N.S. 8 1l.8 ± 1.2 4.5 ± 0.8 < 0.001 9 14.8 ± 1.0 4.5 ± 0.9 < 0.001 *Comparisons were by Student's t test. In unaltered or sham-operated dogs the left and values respectively were 1.6 t 0.4 and 1.6:t0.5. caused by Eck fistula is significant'( P < 0.001). CONCLUSIONS right lobar The increase Non-hypoglicaemic insulin infusions for four days into. the tied-off left portal vein after Eck fistula greatly reduced the left lobar hepatocyte atrophy, permitted the ultrastructure of the protected liver cells to remain essentially normal, and cau-sed a threefold increase in the number of left lobar hepatocytes undergoing mitosis. There was no spill-over effect in the right lobes. Glucagon by itself did not cause any of these changes, and it did not potentiate them when added to insulin at a 2/1 molar insulin/glucagon ratio. At a dose 100 times greater, glucagon may actually have reduced the benefit from insulin. Thus, it has been established that "hepatic insulinopenia" is the most important element in the liver injury of Eck fistula. It is ironic that this answer was so close to detection all the time. Hahn et al. (2) definitely emphasized more than 80 years ago that, tal branch unless the portal vein was ligated above the last por-during the performance of Eck fistula, their dogs re-mained quite normal. This highest vessel drains the pancreas, but of course the endocrinological significance of that fact was not then known. Because of that same ignorance of hormones, specula-tion by Rous and Larimore (9) was vague about the possibility, as they saw it in 1920, that portal blood might have special liver-HE supporting constit almost 20 years a that dogs with Ec remained in much alone in that the evidence of encef peripheral insulir are required in di is given systemic tory hepatic arter treated alloxan-di Reaven, Peterson, structural change, those caused by Ec Another aspect of insulin in the The provision of voked a sustainec heightened mitotic These results study by Younger. alloxan-diabetic 1 Although the liver normal number of L lin was spectacul resection. However diabetic rats ret" generate their Ij insulin treatment any single contr, eration. Holley ( substances, hormol initiate and reg: There is no reas cerning the camp] The conclusion 0 sulin is the mos structure and fu tivity in liver r , ) \d right lobar .5. The increase days into the .tiy reduced the trastructure of .ormal, and cau-bar hepatocytes ct in the right ,se changes, and 1 at a 2/1 molar ,r, glucagon may lsulinopenia" is Eck fistula. It :ection all the ~e than 80 years Ie the last por-, their dogs re-rle pancreas, but nat fact was not rmones, specula-, possibility, as ~e special liver-HEPATOTROI'HIC EFFECT OF INSULIN 5 supporting constituents. A perplexing observation of our own from almost 20 years ago contained a strong clue (6). It was noticed that dogs with Eck fistula plus insulin-treated alloxan diabetes remained in much better health than animals with Eck fistula alone in that the diabetic dogs gained weight and were spared all evidence of encephalopathy. The now-obvious explanation ~~ that peripheral insulin concentrations of two to three times normal are required in diabetics to maintain normoglycaemia when insulin is given systemically, thus inadvertently providing a compensa-tory hepatic arterial increase in the hormone. Conversely, in un-treated alloxan-diabetic rats with unaltered hepatic circulation. Reaven, Peterson, and Reaven (8) have demonstrated acute ultra-structural changes in the liver cells that were remarkably like those caused by Eck fistula. Another aspect which is related with this result is the role of insulin in the area of cell growth control and regeneration. The provision of exogenous insulin in the present studies pro-voked a sustained burst of proliferation beyond the already heightened mitotic background. These results were consistent with those in the important study by Younger, King, and Steiner (15) who allowed rats to be alloxan-diabetic for a month before treating them with insulin. Although the livers were thought to already contain a higher than normal number of hepatocytes, the proliferative response to insu-lin was spectacular, being similar to that after a 68% liver resection. However, Younger and his colleagues also showed that diabetic rats retained a potent although subnormal ability to re-generate their livers after an actual hepatic resection, even if insulin treatment was withheld. Accordingly, it is unlikely that any single control factor will be the sole explanation of regen-eration. Holley (3) and Leffert (4) have summarized the dozens of substances, hormonal (including insulin) and others, that can initiate and regulate cell growth in tissue-culture systems. There is no reason to doubt the relevance of their comments con-cerning the complexities of growth control to in-vivo situations. The conclusion on the basis of this clear experiment is that in-sulin is the most important factor in controlling hepatocyte structure and function, and that, furthermore, it shows some ac-tivity in liver regeneration not yet fully understood (14). 6 HEPATOTROPHIC EFFECT OF INSULIN REFERENCES 1. BoHman, J.L. (1961): Psysiol. Rev., 41:602-621. 2.Hahn, M., Massen, 0., Nencki, M., and Pawlow, J. (1893): Arch. Ep. Pathol. PharmaKol., 32:161-210. 3.Holley, R.W. (1975): Nature, 258:487. 4.Leffert, H.L., Koch, K.S., Moran, T., and Rubalcava, B. (1979): Gastroenterology, 76:1470-1482. 5.Loud, A.V. (1968): J. Cell BioI., 37:27. 6.Meyer, W.H., and Starzl, T.E. (1959): Surgery, 45:760. 7.Putnam, C.W., Porter, K.A., and Starzl, T.E. (1976): Ann. Surg., 184: 155-161. 8.Reaven, E.P., Peterson, D.T., and Reaven, G.M. (1973): J. Clin. Invest., 52:248-262. 9.Rous, P., and Larimore, L.D. (1920): J. Exp. Med., 31:609-632. 10.Starzl, T.E., Porter, K.A., Watanabe, K., and Putnam, C.W. (1976): Lancet, 1:821-825. 11.Starzl, T.E., F.R., Porter, Surg. Gynecol. 12.Starzl, T.E., sell, W.J.I., 140:549-562. Francavilla, A., Halgrimson, C.G., Francavilla, K.A., Brown, T.H., and Putnam, C.W. (1973): Obstet., 137:179-199. Porter, K.A., Kashiwagi, N., Lee, I.Y., Rus-and Putnam, C.W. (1975): Surg. Gynecol. Obstet., 13.Starzl, T.E., Porter, K.A., Kashiwagi, N., and Putnam, C.W. (1975): Surg. Gynecol. Obstet., 141:843-858. 14.Starzl, T.E., Porter, K.A., and Francavilla, A., (1983): Current Problems in Surgery, 20:692-752. IS.Younger, L.R., King, J., and Steiner, D.F. (1966): Cancer Res., 26: 140-148. Prevaler Diabe G. Buzzelli, ( IstitUl. L An impaired long known to their prevalenc· varies from 5% (l , 8 , 15) and fr an impaired gl and 5-55% (2,8,: Various fad such discrepanc groups studied factors not y€ such as a pos: variabili ty of intolerance and The present ~ 1) assessing and diab, by taking history OJ 2) evaluatinl criteria diabetes. One hundred compensated vi: (8 females and wi th chronic Ih 50 males, meaT! 

Hepatotrophic effect of insulin

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Hepatotrophic effect of insulin

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