Effects of acute gamma-irradiation on extracellular adenine nucleotide hydrolysis in developing rat brain |
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Authors: | I Stanojevi? D Drakuli? N Veli?kovi? M Milo?evi? S Petrovi? and A Horvat |
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Institution: | (1) Laboratory for Molecular Biology and Endocrinology, “Vinca” Institute of Nuclear Sciences, P.O. Box 522, 11001 Belgrade, Serbia |
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Abstract: | Cell membrane is highly sensitive to irradiation which, acting directly or indirectly, may disturb functions of constitutive
proteins including membrane enzymes. Plasma membrane surface-located enzyme chain of ecto-nucleotide triphospho diphosphohydrolases
(NTPDases) and 5′-nucleotidase are involved in termination of cell purinergic signalization by hydrolyzing extracellular,
excitatory adenosine triphosphate (ATP), as well as nucleotide di-, and mono-phosphate (ADP and AMP) to neuroprotective adenosine.
Extracellular ATP, ADP, and AMP hydrolyzes were examined in purified synaptic plasma membranes after whole-body acute irradiation.
All measurements were done 24 h after irradiation of developing (15-, 30-day-old) and adult (90-day-old) rats with low (50
cGy) and high (2 Gy) dose of gamma-rays. Both, high and low doses inhibited nucleotide hydrolyses in 15-day-old rats; in 30-day-old
rats low dose of radiation inhibited ADP and AMP hydrolyses while high dose inhibited only ATP hydrolyse. In adult rats high
dose induced no effects, while low dose stimulated nucleotides hydrolyses. According to obtained results it was concluded
that ecto-nucleotidases of young rats are more sensitive to irradiation, since even low dose induces inhibition of ecto-nucleotidases
activities. Ionizing radiation, by decreasing brain nucleotide hydrolyses in developing rats, induces accumulation of ATP
and decreases production of adenosine in synaptic cleft which could be neurocytotoxic. On the contrary, in adult rats low
dose of radiation stimulates NTPDase and 5′-nucleotidase activity and protective adenosine production which indicates protective
and adaptive mechanisms developed in adult brain neuronal cells.
The article is published in the original. |
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