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Possible otoprotective properties of cocarboxylase were studied on the model of amikacin-induced ototoxicity in immature rabbits. Auditory function was evaluated by the short-latency auditory brainstem response (ABR) and distortion product otoacoustic emission (DPOAE) tests. Administration of cocarboxylase after modeling of amikacin-induced ototoxicity resulted in a decrease in the ABR peak I threshold and prevented damage to the outer hair cells.

Monoamine oxidase activity was quantitatively assessed by cytochemical method in brain structures (layers III and V of the sensorimotor cortex, caudate nucleus, nucleus accumbens, hippocampal CA3 fi eld) of rats of August line and Wistar population with high and low locomotor activity in the open fi eld test. Monoamine oxidase activity (substrate tryptamine) predominated in the nucleus accumbens of Wistar rats with high motor activity in comparison with rats with low locomotor activity. In August rats, enzyme activity (substrates tryptamine and serotonin) predominated in the hippocampus of animals with high motor activity. Comparison of August rats with low locomotor activity and Wistar rats with high motor activity (i.e. animals demonstrating maximum differences in motor function) revealed signifi cantly higher activity of the enzyme (substrates tryptamine and serotonin) in the hippocampus of Wistar rats. The study demonstrates clear-cut morphochemical specifi city of monoaminergic metabolism based on the differences in the cytochemical parameter “monoamine oxidase activity”, in the studied brain structures, responsible for the formation and realization of goaldirected behavior in Wistar and August rats.

Auditory function of immature rabbits was evaluated using two electrophysiological methods, brainstem auditory evoked response (BAER) and distortion product otoacoustic emission (DPOAE), in chronic experiments following administration of therapeutic doses of gentamicin. Impairment of auditory function manifested in increased thresholds and decreased amplitude of the 1st BAER peak was established. DPOAE parameters were not significantly changed. It was suggested that gentamicin decreased activity of spiral ganglion neurocytes in animals with immature auditory analyzer.

Activity of NADP-dependent isocitrate dehydrogenase (EC 1.1.1.42) increases and the catalytic characteristics of the enzyme isolated from the liver of rats are changed under conditions of apoptosis induction in comparison with these characteristics in health. Injection of melatonin induced a trend to normalization of kinetic parameters of catalytic activity and of some regulatory characteristics of the enzyme.

Quantitative interferometry showed that chronic amphetamine administration to August rats (2.5 mg/kg/day for 3 weeks) increased the area of neuronal cytoplasm and nuclei and content and concentrations of proteins in hippocampal CA3 neurons. These changes persisted after single injection of delta sleep-inducing peptide (60 microg/kg). The reaction of the entire neuronal population of hippocampal CA3 neurons to amphetamine is similar.