[An experimental study of anti-amnestic activity of piracetam in orchidectomized rats]. / Eksperimental'noe izuchenie antiamnesticheskoi aktivnosti piratsetama u orkhidéktomirovannykh krys.

The decrease of learning ability by 50% as assessed by passive avoidance test and the increase 28% of microviscosity of synaptosomal membranes from brain cortex were observed in rats in a month after orchidectomy as compared with that of intact or sham--operated animals. The treatment of orchidectomized rats with piracetam either by single application or in the course of 10 days applications in the daily dose of 250 mg/kg intraperitoneally failed to improve learning ability of animals in passive avoidance test and to produce a normalizing effect on the structure of membrane lipid matrix. The testosterone content in blood of orchidectomized rats was 10 times lower as compared with control and was not affected by treatment with piracetam.

[A comparative study on the effects of amiridin on learning and memory of old rats during passive avoidance test]. / Sravnitel'noe izuchenie vliianiia amiridina na obuchenie i pamiat' starykh krys v teste uslovnoi reaktsii passivnogo izbeganiia.

18-month rats showed much less learning ability in comparison with that of 3-month rats. 20-days treatment of old rats with amiridin, tacrine, and piracetam improved latency in passive avoidance test to the level of 3-month rats. The activity of acetylcholine esterase (AChE) from homogenates of old rat cortex was reduced as compared with that of young rats. After treatment with amiridin the activity of the enzyme remained unchanged, tacrine stimulate the decrease of activity of AChE while piracetam increased activity of AChE to the level of 3-month rats. The aging of rats is followed by the reduction of unsaturated fatty acids, the increase of cholesterol content and the increase of microviscosity of membranes of brain synaptosomes. Multiple treatment with amiridin, piracetam and tacrine normalized these indices.

[Study of anti-amnesic activity of amiridin in a model of amnesic syndrome]. / Izuchenie antiamnesticheskoi aktivnosti amiridina na modeli amnesticheskogo sindroma.

The model of amnestic syndrome obtained by treatment with scopolamine during 20 days in rats was used to study anti-amnesic activity of amiridin in comparison with that of tacrine, physostigmine and piracetam. Multiple injection of Sc resulted in significant deterioration of rats, performance in passive avoidance test. Behavioral disorders were accompanied by such changes in lipid composition of brain synaptosomes which indicated a decreased membrane fluidity. Amiridin and tacrine as well as piracetam showed anti-amnesic action which in the course of treatment correlated with their normalizing effect on lipid content of synaptosomes. The diverse effect of amiridin and tacrine with respect to physostigmine implies that the former drugs can't be attributed to anticholinesterase preparations which are traditionally used in the treatment of Alzheimer disease.