BioMetals 1996, 9. 371-375 Endogenous zinc concentrations in cysteamine-induced duodenal ulcers in the rat Branko Troskot*, Velimir N. Simicevic +, Milan Dodig*, Ivo Rotkvic*, Davor Ivankovic * & Marko Duvnjak* * Department of Gastroenterology, University Hospital 'Sestre Milosrdnice', Medical School, University of Zagreb, Zagreb, ~PLIVA Pharmaceutical Co., Research Institute, Biomedical Department, Zagreb and i: Department o.[" Statistics, Epidemiology and lnformatics, School of Public Health Andrija Stampar, Medical School, University of Zagreb, Zagreb, Croatia Rccci\ed 24 February 1996: accepted for publication 19 April 1996 Exogenously administered zinc compounds have been shown to possess anti-ulcer activity against a wide variety of ulcerogenic agents, both in laboratory animal models and in human peptic ulcer disease. However, a strong possibility exists that endogenous zinc may also play an important role during noxious events by various mechanisms. Therefore, the aim of this study was to focus on the changes of endogenous zinc serum and tissue concentrations in cysteamine-induced duodenal lesions. We used atomic absorption spectropho- tometry to determine the tissue and serum concentrations of zinc in normal (control) rats and those with cysteamine-induced duodenal ulcers. The results obtained in this study indicated that the onset, develop- ment and spontaneous healing of ulcer lesions were associated with certain shifts in zinc serum and tissue concentrations. Prior to ulcer formation, a significant increase was noted in serum zinc values. With the onset of duodenal lesions, zinc serum concentrations significantly decreased, while there was a significant increase in duodenal tissue concentrations when compared to healthy control animals. Zinc tissue concen- trations decreased and returned to starting values by the end of the first week of spontaneous healing. This decrease in zinc tissue concentration corresponded to the healing rate of the duodenal ulcers. Serum zinc concentrations also returned to starting values within the first week period. These observations indicate and confirm that zinc could play an important role in duodenal ulcer disease and represent a natural defense system in the body. Keywords: cysteamine, duodenal ulcer, rat, zinc concentrations Introduction Zinc is an essential element for most organisms (Elinder 1986). Compared with most other trace ele- ments, it is relatively non-toxic in viw) (Borovansky & Riley 1989), and has been shown to be a func- tionally essential component of more than 300 enzymes including oxydoreductases, transferases, Addrcss for correspondence: B. Troskot, Department of Gastroenterology. University Hospital "Sestre Milosrdnice', Vinogradska cesta 29. HR 10000 Zagreb. Croatia. Tel: (+385 1) 174 666: Fax: (+385 I) 172 453. hydrolases, lyases, isomerases and lygases (Vallee & Falchuk 1993). Zinc ions are also important for the biosynthesis and catabolism of proteins. The synthesis of DNA and RNA is controlled by this element (Cho 1989). The protective effect of zinc on the organism led to investigations of its influence on experimental stress lesions of the gastric mucosa. Oral adminis- tration of zinc salts has been shown to enhance the rate of healing in human gastric ulcers and to protect against experimental ulcers in different animal models including gastric ulceration induced by ethanol, cold-restraint stress, electric vagal 9 19~)0 Rapid Science P.blishers Ltd London BioMetals Vol 9 1996 371