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1.
Izv Akad Nauk Ser Biol ; (5): 517-21, 2004.
Article in Russian | MEDLINE | ID: mdl-15559127

ABSTRACT

We studied the effect of gamma-radiation on 15-lipoxygenase activity in rat thymocytes. The enzyme activity was determined as the rate of linoleic acid oxidation by the protein fraction isolated from the control and irradiated thymocytes under standard conditions. We demonstrate lipoxygenase activation immediately after irradiation of thymocytes. High lipoxygenase activity is observed in the cells for no more than an hour after irradiation. No high lipoxygenase activity later indicates that its synthesis is not directly induced by irradiation. Irradiation-induced generation of lipid peroxides can be the factor of lipoxygenase activation.


Subject(s)
Arachidonate 15-Lipoxygenase/metabolism , Gamma Rays , Thymus Gland/metabolism , Animals , Enzyme Activation/radiation effects , Linoleic Acid/metabolism , Lipid Peroxidation/radiation effects , Male , Rats , Rats, Wistar , Thymus Gland/cytology
2.
Izv Akad Nauk Ser Biol ; (3): 274-9, 2004.
Article in Russian | MEDLINE | ID: mdl-15354952

ABSTRACT

We studied the effect of specific inhibitors of 5- and 12-lipoxygenases as well as the product of cyclooxygenase activity, prostaglandin E2, on proliferation and death of P388 leukemia cells. Inhibition of 5- and 12-lipoxygenases in the cells inhibits proliferation and induces apoptosis. The concentrations of baicalein, an inhibitor of 12-lipoxygenase, and AA861, an inhibitor of 5-lipoxygenase, causing a 50% death rate (LC50) proved to be the same, 50 microM. Excessive prostaglandin also inhibited proliferation of the cells and induced apoptosis. The LC50 for prostaglandin E2 was 4 microM. The obtained data suggest that apoptosis in P388 cells after lipoxygenase inhibition can be induced by both deficiency of lipoxygenase products and excess of prostaglandins in the cell.


Subject(s)
Apoptosis , Dinoprostone/antagonists & inhibitors , Lipoxygenase Inhibitors , Prostaglandin-Endoperoxide Synthases/metabolism , Animals , Benzoquinones/pharmacology , Cell Proliferation/drug effects , Dinoprostone/biosynthesis , Flavanones/pharmacology , Humans , Leukemia P388 , Lipoxygenase Inhibitors/pharmacology , Mice , Prostaglandin Antagonists/pharmacology , Tumor Cells, Cultured
3.
Radiats Biol Radioecol ; 44(1): 27-31, 2004.
Article in Russian | MEDLINE | ID: mdl-15060936

ABSTRACT

The radiation-induced apoptosis of thymocytes is suppressed by the common inhibitor of lipoxygenases nordihydroguaiaretic acid but not the inhibitors of cyclooxygenases or cytochrome P-450, which indicates the key role of lipoxygenases in apoptosis. However, the specific inhibitors of 5-lipoxygenase (AA861) and of 12-lipoxygenase (baicalein) do not suppress apoptosis and even enhance it. This effect can be explained by an increase in the yield of the 15-lipoxygenase product upon inhibition of 5- and 12-lipoxygenases. Indeed, the addition of 15-hydroxyecosotetraenic acid, a product of 15-lipoxygenase, into the incubation medium induces apoptosis in thymocytes. The results obtained suggest that 15-lipoxygenase is one of the enzymes involved in radiation-induced apoptosis of thymocytes.


Subject(s)
Apoptosis , Flavanones , Lipoxygenase Inhibitors/pharmacology , Lipoxygenase/physiology , Thymus Gland/radiation effects , Animals , Benzoquinones/pharmacology , Cells, Cultured , Cobalt Radioisotopes , DNA/analysis , Electrophoresis , Flavonoids/pharmacology , Male , Radiation Dosage , Rats , Rats, Wistar , T-Lymphocytes , Thymus Gland/cytology
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