THE OPPOSITE EFFECTS OF LIVER AND PANCREAS UPON THE GROWTH OF PLANARIAN WORMS

Transcription

1 THE OPPOSITE EFFECTS OF LIVER AND PANCREAS UPON THE GROWTH OF PLANARIAN WORMS ROSALIND WULZEN AND ALICE M. BAHRS (From the Rudolph Spreckles Physiological Laboratory of the University of California) During our investigations on the growth promoting power of various substances for planarian worms, the fact emerged that pancreas, although it attracted the worms and was well taken by them, ranked very low in its nutritional value. Table I, a, gives such an experiment. After four weeks of feeding, the liver-fed worms had almost doubled their size with an increase of 211 mm. in total length while the pancreas-fed worms had grown only 65 mm., although they had eaten the pancreas at each feeding until they were distended. We have endeavored to determine whether this large difference between the growth promoting power of liver and pancreas was owing to a lack in the pancreas of some substance essential for the growth of planarian worms or to the presence of some active inhibitor for such growth. The methods previously used in our planarian work (1) have been followed in these investigations. For each experiment worms 6, 7, 8, or rarely 9 mm. in length were chosen from newly regenerated tails which had been cut from our stock worms. There were thirty worms in each set, the total length of which was ascertained at the beginning and at the end of the feeding interval. Food was given twice a week, and between the feedings the worms were kept at a constant temperature of 23" C. In order that the liver and pancreas used in the experiments might be blended into a sufficiently intimate mixture, it was necessary to reduce both to the condition of a fine mush by pressing the finely ground tissues through heavy, close-meshed linen cloth. The various food mixtures were thoroughly blended with a spatula upon a glass plate. 53

2 54 ROSALIND WULZEN AND ALICE M. BAHRS -~ - Food Total length Total length Peedings twice a week in all experiments. of 30 worms of 30 worms Liver of freshly lcillcd guinea pig used at heginning at end. throughout. Pancreas of freshly killed beef used throughout, except in a. Cortex of sliwp's brain nseti throughout. Cortex kept at, 100" for 30 niin. is cdled heat-treated cortex. Inrrease in total length. li! zyi: 1 65 Liver of guinea pig mm. 211 Inm. Pancreas if,i I guinea pig fm. mm. b. Three Week Experirncnt Liver mush.... I'anc~eas mush.... Pancreas mush + liver tnwh (cqnal purt,s of each)... liver rriush + lo():, starch paste (equal parts of each), mm. 204 rnm. 205mm. 201 nirn nm. 252 nim mm. 237 mm. 48 mm. 97 mm. 251 mm. liver mush.... Liver mush + pancreas mush (heated at 80" for 30 mill.) (equal parts of each).,, 270 mru. 143 rnm. d. Five Weck Experiment I3rain cortex, raw.... EIeat-treat,etl cortex..... Heat-treat,etl oories.5 gin. + ether rxtract of liver.05 gin.... Heat-treat,ed,cortex.5 gm. + ether estract 232 mm. 232 mrn. 231 inrn. of pancreas.05 gin.....,231 Inm. Ifeat-treat,etl cortex.ii girl. + Muffo.05 gni. 232 rnm. 573 trim. 355 mm. 386 mm. 316 mm. 354 mm. 342 nim. 123 rnm. 155 m~n mm. Brain cort,ex, raw.... Brain corks, raw.5 gm. + ether cxt,ract of pancreas.05 gin.... Brain cortex, raw.5 gin. + et,her extract of pancreas.i gin.... Heat-treat,ctl cortex mm. 211 irini. 201 mm. 202 mm mm nim. 264 mm. 157 mm mm.

3 OPPOSITE EFFECTS OF LIVER AND PANCREAS 55.f. Four Week Expeyiment Heat treated cortex..... Pancreas mush.... Pancreas mush.5 gm. + ether extract, of pancreas.05 gm mm. 211 mm. 209 mm. 297 mm. 2x9 mm. 249 mm. 87 mm. 78 mm. 40 mm. y. Five Week Experiment Heat-treated cortex.5 gm. + ether extract of liver.i gm..... Heat-treated cortex.5 gm. + ether ext,ract of pancreas.i gm..... Heat-treated cortex.5 gm. + ether ext,ract of pancreas.05 gm. + ether extaract of liver.05 gm mm. 200 mm. 198 mm. 315 mm. 174 mm. 229 mm. 120 mm. -26 mm. 31 mm. In experiment b, Table I, mush of liver or pancreas, and a blend of the two in equal parts were fed. Liver mush showed its ordinary strong growth promoting power and produced an increase in length of 237 mm., while pancreas mush manifested its lack of growth promoting power, with a growth increase of only 48 mm. In a combination of the two in equal parts the effect of the pancreas almost completely dominated the mixture with the result that the ensuing growth increase, 97 mm., lay between the two extremes but much nearer the pancreas than the liver. To ascertain whether the worms were obtaining enough liver to produce the maximum growth when the liver was diluted with pancreas, liver mush was blended with an equal weight of 10% starch paste and the result of feeding this mixture was an increase in length of 251 mm., a growth of the same order of magnitude as that due to liver alone. Starch paste had previously been found not to support growth even when it was mixed with liver juice so as to be well taken by the worms. All the mixtures used attracted the worms and were well taken by them. The abundance of enzymes in the pancreas presents itself as a possible explanation of the apparently harmful effect of pancreas upon the growth of the worms, but experiment does not uphold this as a satisfactory answer. In experiment c, Table I, pancreas pulp was heated in a water bath at 80" for

4 56 ROSALIND WULZEN AND ALICE M. BAHRS Fig. 4 Fig.5 Fro. 1. TABLE I-c. BRAIN CORTEX, HAW. FIQ. 2. TABLE I-c. BRAIN CORTEX, RAW. 5 gm. plus ether extract of pancreas.i gm. FIQ. 3. TABLE I-b. LIVER MUBH PLUS 10% STARCH PASTE (EQUAL PARTS OF EACH). FIG. 4. T-4BLB I-b. PANCREAS MUSH. FIG. 5. TABLE I-b. PANCREAS PLUS IiIVER MUSH (EQUAL PARTS OF EACH).

5 OPPOSITE EFFECTS OF LIVER AND PANCREAS min. in order to destroy the enzymes, and was mixed with liver pulp in equal parts. Although the power of pancreas pulp to inhibit the growth due to liver alone was considerably diminished by this heating, the resulting growth increase, 143 mm., was nevertheless far from equal to that due to liver alone, 270 mm. It had been demonstrated previously (2) that tissues which produce good growth when fed to planarian worms lost their growth-promoting power to a greater or less extent when heated, and that this diminished power was partially restored by adding to the heated food an ether extract of liver. We therefore prepared both ether extract of pancreas and ether extract of liver as in our earlier work (1) and compared their ability to restore the growth-promoting power to a tissue which had partially lost it through the application of heat. The extracts were prepared at least once a week. Brain cortex was again used as the basic food. A paste was made of thin slices of the cortex of sheep s brain, the white matter being excluded as much as possible, and the paste was used either raw or after heating in a vial immersed in boiling water for 30 min. If the ether extracts were to be added they were intimately blended with the cortex by means of a spatula. In experiment d, Table I, groups of worms were fed upon (1) raw cortex, (2) heat-treated cortex, (3) heat-treated cortex + liver extract, (4) heat-treated cortex + pancreas extract, and (5) heat-treated cortex + Fluffo, a commercial vegetable fat. The proportions were in each case.5 gm. of cortex to.05 gm. of extract or fat. That all these mixtures were well taken by the worms was easily seen by the gorged appearance of the worms after their feedings throughout the experiment. The experiment was continued five weeks. The heat-treated cortex was found to have diminished in growth-promoting power as had previously been demonstrated (2). The diet of heat-treated cortex resulted in an increase in the length of the worms of 123 mm. compared to 342 mm. increase in those fed on raw cortex. When liver extract was added to the heat-treated cortex the worms increased 155 mm. in length, but when pancreas extract

6 58 ROSALIND WULZEN AND ALICE M. BAHRS was added, the worms increased only 85 mm., a growth materially less than that due to heat-treated cortex alone. That the worms were not harmed by the mixture of additional fatty substance with their diet was shown by the use of the commercially prepared vegetable fat, Fluffo. When the Fluffo was blended with the heat-treated cortex in the same proportion as t,he ether ext>ract of pancreas the result was a growth of 122 mm., identical with that due to the heat-treated cortex alone. The inhibitory power of the ether extract of pancrem upon the growth of planarian worms manifests itself also when the basic food is raw brain cortex which in itself ranks with liver in its growth-promoting power. In the five week experiment, e, Table I, the addition of.05 gm. ether extract of pancreas to.5 gm. raw brain cortex diminished the growth produced in the worms from 200 mm. total length to 157 mm. Double the amount of extract,.i gm., reduced the growth-promoting power of raw cortex still further, to 94 mm. Even when added to pancreas itself, the ether extract of pancreas caused a diminution of the already slight growth due to the feeding of pancreas mush. In the four week experiment, f, Table I, the feeding of heat-treated cortex resulted in an increase in length of 87 mm. while pancreas pulp gave a. growth of 78 mm., ttnd.5 gm. pancreas pulp mixed with.05 gm. ether extract of pancreas resulted in a still further diminution of growth to 40 mm. In such a mixture the amount of pancreas inhibitor is greater than in the native pancreas tissue. Since pancreas and liver mush showed opposite effects in reference to the growth of planarian worms and the ether extracts of each retained the distinctive power of the substance to a consider:+ble extent, it seemed probable that a combination of the two extracts would exhibit a balance between the two effects. This proved true. In t,he five week experiment, g, Table I,.5 gm. heat-treated cortex mixed with.1 gm. ether extract of liver resulted in 120 mm. of growth whereas a mixture of heat-treated cortex with ether extract of pancreas in the same proportion produced an actual falling off in growth below the original length of the worms. The worms so fed were 26 mm. shorter at the

7 OPPOSITE EFFECTS OF LlVER AND PANCREAS 59 end of the experiment than at the beginning of the experiment. This did not indicate any decrease in appetite or failure of the worms to engulf the food. They went to the mixture readily and were distended when they left it. When.5 gm. heattreated cortex was mixed with.05 gm. ether extract of liver and.05 gm. ether extract of pancreas the resulting growth was 31 mm. The combination of the ether extracts of liver and pancreas thus resulted in a growth of the worms intermediate between the growth due to either alone. The amount of lipoid substance was the same in each case and the amount of each extract used in the combination experiment had been shown previously to be ample to give its characteristic effect. These experiments point toward the presence in the pancreas of a substance which actively inhibits the growth-promoting power of liver. Not only do planarian worms grow poorly on pancreas tissue but the high growth-promoting power of liver is readily and largely reduced by admixture of the liver tissue with pancreas. The same opposition is manifested in the ether extracts of the two tissues. The growth-promoting power of brain cortex for plsnarian worms is materially reduced by heating, and this reduced power can be partially restored by adding ether extract of liver to the heat-treated cortex. But the growth promoting power of the heated cortex is still further reduced if, instead of ether extract of liver, ether extract of pancreas is added. Moreover, the addition of pancreas extract to raw brain cortex or to pancreas tissue itself reduces both the great growth-promoting power of the one and the slight growthpromoting power of the other. Like the native pancreas tissue, the ether extract of pancreas when mixed with ether extract of liver, has the ability to neutralize in large part the growthpromoting power of liver extract. BEFEBENCES (1) WULZMN, R.: Science, 1027, Ixv, 331. (2) WULZICN, It.: Univ. of Calif. Pub. Fliysiol., 1926, vii, 1.