STUDY OF LYSOSOMAL CHANGES IN RAT PANCREAS AFTER INGESTING MONOSODIUML-GLUTAMATE

An experiment was conducted on 54 male Wistar rats (36 experimental, 1 8 controls) to study adverse effects of monosodiUM L-glutamate (MSG) o n pancreatic acinar cells by measuring the qualitative and quantitativ e changes in acid phosphatase (ACPase) in these cells. Various concent rations of aqueous MSG were given to rats for various durations (Group I, 1% MSG for 1 month; Group 11, 1% MSG for 1 week; Group III, 0.5% M SG for 1 week; Group IV, 0.2% MSG for 1 week; Group V, 0.1 % MSG for 1 week; Group VI, 0.05% MSG for 1 week). The pancreas was then removed from each specimen for electron microscopic examination, cytochemical localization of ACPase, and cell fractionation for quantitative measur ement of ACPase. Serum level of ACPase was determined in these animals before removal of the pancreas. The ultrastructural changes in pancre atic acinar cells revealed an increase in the number and size of autop hagic vacuoles and various sizes of myelin figures in the cytoplasm an d interstitial space. Dilatation of rough endoplasmic reticulum, swoll en mitochondria, and altered zymogen granules were occasionally found. These changes occurred most often in Group I rats, which ingested 1% MSG for 1 month. The changes became less prominent as the dose of MSG administered was lessened. A reaction product of ACPase could also be seen in autophagic vacuoles in Group I rats. Regarding quantitative me asurement, the serum level of ACPase for Group I rats was markedly hig her than that of the controls and was statistically significant (20.52 +/- 4.92 vs. 12.62 +/- 4.13 U/L; p < 0.05). Although it was not remar kable in other experimental rats, the activity of ACPase in pancreas h omogenate, supernatant, and pellets of experimental Groups I and II ra ts was higher, although not statistically significant, than that of th e controls. The altered ultrastructure of pancreatic acinar cells and increased activities of acid phosphatase found led to the conclusion t hat long-term ingestion of large doses of MSG will induce damage to pa ncreatic acinar cells.