Although the pathogenesis of acute pancreatitis remains obscure, it is widely held that autodigestion of the pancreas by prematurely activated pancreatic trypsin is an important factor. A number of studies on the treatment of induced pancreatitis using various trypsin inhibitors was attempted (Coffey et al., 1050, Forell et al., 1955). The results were inconsistent (Hoffman et al., 1953, Rush and Cliffton, 1952). A new product, Trasylol (Bayer), has received wide acclaim for it effectiveness in the treatment of acute pancreatitis in human(Frey, 1953, Bernard et al. 1959, Bedacht, 1960, Maurer, 1962).
Propylthiouracil was claimed to decrease enzyme production at the cellular level by reduction in cellular metabolism. Reid et al. (1958) have offered experimental duodenal-closed-loop pancreatitis by Pfeffer, but as yet there has been no conclusive report concerning the efficacy of this drug in either human or
Hexamethonium and atropine or their congeners appear to be drugs of choice in the relief of pain in acute pancreatitis since their additional pharmacologic effects, which include suppressions of gastric acidity (Davies et al., 1953, Annis and
Hallenbeck, 1951), relaxation of the sphincter(Hong et al., 1956), and inhibition of pancreatic secretion by means of preventing release of secretin or pancreozymin from duodenal mucosa(Hong et al., 1961, Hur, 1962, Elmslie et al., 1964).
The present study was undertaken to evaluate the effects of atropine, hexamethonium, propylthiouracil as well as Trasylol in rabbits with bile-induced experimental pancreatitis, obtaining serial measurement of the serum and the tissue pancreatic enzyme levels and histopathologic study of pancreas.
Materials and Methods
A total of 174 rabbits of both sexes that weighed 1.8 to 2.6kg were used. Details of the experimental procedure were similar to that previously described(Chin, 1964). Experimental pancreatitis was induced in all groups by the method utilizing retrograde instillation of the diluted own-bladder bile through a cannula into the main pancreatic duct, by means of an extraduodenal approach.
Group 1. Two ml of bile, diluted 1:5, were instilled in rabbits. In all other groups pancreatitis was induced as same as Group 1 and they were treated with drugs twice daily before and during the course of experimeental pancreatitis as follows:
Group 2. Thirty four rabbits were treated with 0.5mg per kg of atropine sulfate intramuscularly. Group 3. Thirty six rabbits were treated with 1mg per kg of hexamethonium chloride intramuscularly. Group 4. Thirty four rabbits were treated
with 2,000u of Trasylol intramuscularly. Group 5. Twenty eight rabbits were treated with 25mg of propylthiouracil orally. All animals were killed at 3 and 24 hours and at 2,3,4,5,7, and 10 days after the bile instillation. The gland was excised and weighed. A part of the excised tissue was fixed in 10 per cent formalin, and histologic sections were prepared and stained with hematoxylin eosin. The tissue enzyme determinations were carried out by remaining pancreas. As a normal value of pancreatic tissue enzyme seven intact animals were used.
The method of extraction and the procedures for the differential determination of free trypsin and trypsinogen were based upon the work of Kunitz and Northrop(1936). The proteolytic activity was measured by the method discribed by Anson(1938) for trypsin. The lipolytic or amylolytic activity in either serum or tissue extract was dermined by the method of Cherry and Crandall (1932) or Nelson (1944) respectively.
Serum amidase activity was determined by the method of Nardi (1958), which adopted Conway microdiffusion technique with benzoyl arginine a,ode as a sibstrate/
Serum aminoacid content was measured by the method described by Rapp (1963).
Experimental pancreatitis was prodduced by the method described in the previous report, utilizing retrogade instillation of bile into the pancreatic duct in rabbits.
1. Atropine, hexamethonium, propylthiouracil and Trasylol were more or less effective in reducing the mortality of rabbits with experimental necrotizing pancreatitis. Trasylol was the most and atropine was the least effective agent. In the course of experimental bile-induced pancreatities the mortality in Trasylol and hexamethonium treated rabbits showed 17 and 28% respectively and that in the control animals 63%.
2. The elevation of serum amylase was observed in all animals. In the untreated control animals the elevation reached to the maximal value on the first postoperative day, followed by gradual dcrease, returning to the normal value on the fourth postoperative day. In the Trasylol treated group the elevation was less marked and lasted only one day.
3. The serum amidase was slightly elevated and the total amino acid was slightly decreased in the course of pancreatitis in all groups.
4. The tissue enzyme values of pancreas were progressively decreased after operation in all groups and a marked decrease was observed on the 2nd postoperative day and little activities were seen thereafter in both control and treated groups.
However, in the Trasylol group tissue amylase activity was markedly inhibited after operation earlier than the other groups. Nevertheless, the trypsin activities was preserved longer period in the Trasylol treated animals.
5. Histopathologic alterations consisted of acute hemorrhagic and necrotizing pancreatitis characterized by congestion, interstitial edema, thrombosis, necrotizing vasculitis, necrosis of parenchymal cells and fat tissue, and followed by healing with fibrosis, proliferation of ductules ductal transformation of acini.
The imflammatory signs appeared as early as 1 hour after the instillation of bile into the ligated pancreatic duct and reached to its peak at 24hours, which continued until the 3rd day of the experiment. Thereafter, a healing process took place by gradual resorption of necrotic tissue, fibrosis, proliferation of ductules, ductal dilatation of acini and restoration of survived parenchymal cells.
6. The changes in the groups treated with atropine, hexamethonium, propylthiouracil and Trasylol were ore or less simiar to those seen in simple instilled control group except more pronounced degenerative changes proceeding to actual necrosis of parencymal cells, and the delay of parenchymal and fat necrosis.
The ante(eding degenerative changes consisted of loss of cytoplasmic basophilia, nuclear pyknosis and cytoplasmic vacuolization in the groups treated with atropine, hexamethonium and propylthiouracil, but those in the group treated with Trasylol consisted of shrinkage of acinar cells and rather increased basophilia of cytoplasm. There was also lesser degree of hemorrhagic tendency in the Trasylol treated group.