Further evidence to support a manganese
accumulation in lysosomes of the pancreas in rodents
Yoshihiro Okamoto, Fumio Nasu, Yumi Kondo, Yasuhiko Sato, Saburo
Aita, Jitsuya Takada, Hiroshi Ishizuka, Kazuyoshi Nishikawa,
Yoshiharu Kobayashi, Mikio Nishida
Biomed. Res., 11(3), 225-229, 2000.
It was already reported (Okamoto et al., Biomed. Res. 9, 29-33,
1998) that the pancreas accumulated a larger amount of manganese
(Mn) than any other organs when the rats were exposed to excess
amount of Mn, whereas, species difference in toxicity and/or
susceptibility of various chemicals was recognized between mice and
rats. In the present study we analyzed the localization of Mn in
mice by biochemical determination and morphological analysis with
electron microscopy with X ray-micro analysis, and found the
similarity in Mn distribution in the pancreas of mice as in rats.
Thus, Mn accumulation in pancreatic cells is not specific in rats.
Furthermore the study showed that in the pancreas, Mn-rich particler
structure in envelop was indeed the lysosomes, confirmed by a
histochemical staining of a lysosomal marker enzyme. In mice and rats
the common mechanism for Mn accumulation must exist in the lysosomes.
These observation will contribute to elucidate the biological
meanings of Mn accumulation in the lysosomes and support a
speculative process of toxic element excretion pathway in rodents.
Key word:
manganese (Mn), mice, pancreas, neutron activation analysis, X-ray
micro-analysis