Qualitative enzyme histochemistry and microanalysis reveals changes in ultrastructural distribution of calcium and calcium-activated ATPases after microwave irradiation of the medial habenula.
The localization of calcium and calcium-activated ATPases was investigated electron microscopically in the medial habenula of mice after whole body irradiation with modulated microwaves. In non-irradiated animals calcium-containing precipitates were seen in different subcellular compartments and were often localized on the luminal side of membranes of synaptic vesicles in nerve terminals. At 1 h after 16-Hz modulated microwave irradiation, the number of synaptic vesicles containing calcium precipitates decreased, and reaction products appeared at new locations: in the synaptic clefts and on non-synaptic surfaces of the neuronal plasma membrane. This modified calcium distribution remained unchanged for 24 h following irradiation. Calcium-activated "ecto"-localized ATPase was detected as a punctuated-linear distribution of the reaction product outlining whole areas of glial and neuronal plasma membrane in the habenula of control animals. This pattern did not change on microwave irradiation. However, a quercetin-sensitive "endo"-localized Ca(2+)-ATPase activity appeared in some nerve terminals 24 h after irradiation. Thus, microwave irradiation can influence neuronal calcium homeostasis by inducing Ca2+ redistribution across the plasma membrane and by modifying Ca(2+)-ATPase activity. However, no direct correlation between these effects could be demonstrated by the present study.
Kittel
A
A
Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary.
Siklós
L
L
Thuróczy
G
G
Somosy
Z
Z
D000818:Animals; D002118:Calcium / Q000032:analysis*; D000252:Calcium-Transporting ATPases / Q000032:analysis*; D004798:Enzymes; D019262:Habenula / Q000201:enzymology / Q000528:radiation effects* / Q000648:ultrastructure*; D006651:Histocytochemistry / Q000379:methods; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D008872:Microwaves / Q000009:adverse effects*
D004798:Enzymes; D000252:Calcium-Transporting ATPases; D002118:Calcium