[Effect of thermal selection of the male gametes on the resistance to temperature and chlorophos of the body and muscles in tadpoles of the common frog]. / Vliianie teplovogo otbora muzhskikh gamet na ustoichivost' k temperature i khlorofosu organizma i myshts golovastikov travianoi liagushki.

A study was made of the effect of thermal selection of parental spermatozoa on the heat resistance of the whole organism and of muscles in progeny of Rana temporaria, as well as of the organismal resistance to pesticides (0.0025 M chlorophos). The thermal selection of spermatozoa was performed by exposing their suspension to 36 degrees C for 30-40 minutes. With tadpoles, the resistance of muscles to 38 degrees C, was determined, in addition to the resistance of the organism to 34 degrees and to 0.0025 M chlorophos. The results of selection were stage--specific: at stages of growth (stages 39, 42, 50) the heat resistance of the organism was lower and that of muscles was higher than in controls. At the stage of metamorphosis proper (stage 52) the heat resistance of both the organism and muscles increased. The thermal selection of parental spermatozoa exerted no effect on the resistance of the progeny to 0.0025 M chlorophos.

[Mechanisms of the genoprotective action of a phytoecdysteroid drug (BTK-8L) in chromatin damage by chlorofos]. / Mekhanizmy genoprotektornogo deistviia preparata na osnove fitoékdisteroidov (BTK-8L) v usloviiakh povrezhdeniia khromatina khlorofosom.

Genoprotective effect of preparation BTK-8L from plant steroids at prophylactic injection to experimental animals at chromatin damage by chlorofos was revealed. Antioxidant action of the preparation, being most highly expressed in the transcriptionally active chromatin fraction, is, probably, the most likely mechanism of the action. The realization of this action might be carried out as a result of the direct binding of BTK-8L with the chromatin protein-lipid complex, which was revealed during the analysis of the model systems showing binding of the preparation with chromatin fractions in vitro. Correction of structural chromatin organization and its transcriptional activity modified with intoxication of animals by chlorofos may occur as a result of such binding. Genoprotective properties in BTK-8L correlate to some extent with the lowering of the death rate of experimental animals at the early stage of intoxication by chlorofos at the prophylactic injection of the preparation, which, nevertheless, was not so significant, as in the case of intoxication by tetrachloromethane. Such fact allowed suggesting the existence of delayed unfavourable consequences for the organism (mutagenesis, cancerogenesis) as a result of the realization of the genotoxic action of chlorofos.

Metrifonate increases neuronal excitability in CA1 pyramidal neurons from both young and aging rabbit hippocampus.

The effects of metrifonate, a second generation cholinesterase inhibitor, were examined on CA1 pyramidal neurons from hippocampal slices of young and aging rabbits using current-clamp, intracellular recording techniques. Bath perfusion of metrifonate (10-200 microM) dose-dependently decreased both postburst afterhyperpolarization (AHP) and spike frequency adaptation (accommodation) in neurons from young and aging rabbits (AHP: p < 0.002, young; p < 0.050, aging; accommodation: p < 0.024, young; p < 0.001, aging). These reductions were mediated by muscarinic cholinergic transmission, because they were blocked by addition of atropine (1 microM) to the perfusate. The effects of chronic metrifonate treatment (12 mg/kg for 3 weeks) on CA1 neurons of aging rabbits were also examined ex vivo. Neurons from aging rabbits chronically treated with metrifonate had significantly reduced spike frequency accommodation, compared with vehicle-treated rabbits. Chronic metrifonate treatment did not result in a desensitization to metrifonate ex vivo, because bath perfusion of metrifonate (50 microM) significantly decreased the AHP and accommodation in neurons from both chronically metrifonate- and vehicle-treated aging rabbits. We propose that the facilitating effect of chronic metrifonate treatment on acquisition of hippocampus-dependent tasks such as trace eyeblink conditioning by aging subjects may be caused by this increased excitability of CA1 pyramidal neurons.