In recent years we are witnessing active search for antidepressants with minimal side effects. A group of drugs influencing simultaneously the nervous and the immune system is of relative interest, in particular native peptide thymus drug — tactivine. Previously we have studied its mnemotropic and anxiolytic effect. The study was carried out on 30 breedless white male rats weighing 200—250 g each. Animals were divided in 3 groups. The first group (n = 10) was intra-abdominally injected with 0,5 ml of physiological solution — control group. The second group (n = 10) was intra-abdominally injected with 0,5 mg/kg of tactivine (experimental group). The third group consisted of intact animals. The study used method of forced swimming by S. Nomura (1982) modified by G.M. Molodavkin (1994). This method makes it possible to quantify antidepressant effect objectively registered by the number of rotations of the “salvation wheel” by the rats (the more rotations there are the more antidepressant effect shows itself). Statistical processing of the data was carried out with the help of nonparametric criteria of Wilcoxson using Statistica 6.0 software. No statistically significant difference was revealed in the behavior of control and intact groups. Summary duration of motional activity in this test for tactivine-injected group surpasses the level of the control group (p > 0,05) by 1,19 times, which is in line with the results received earlier as a result of the test on forced swimming by R. Porsolt. Meanwhile, tactivine acted similarly to specimen antidepressant amitriptyline, i. e. prolonged the duration of motional activity of the animal. However, tactivine did not increase the number of rotations of the wheel which in our opinion may be explained by the alteration of activity of the serotonergic system. According to М.Е. Page with co-authors (1998) increase of the duration of active swimming without rotation of the wheel is deemed to be connected with serotonergic system. According to the data received by us previously tactivine increases the level of serotonin in the ratio of serotonin/noradrenaline in different brain structures during animal stressing. Thus, obtained data indicates antidepressant activity of tactivine, thymus compound, in conditions of modified methodic of forced swimming.
The influence of highintensity (110 dB) sound vibrations on experimental rats was studied on the behavior level. Classical behavioral tests (open field, holeboard, light/dark box) were used to examine behavioral changes during 5 min acoustic impact of either audible or infrasound spectrum. Statisticallysignificant changes in locomotor activity and grooming reactions were observed, following either aural or infrasound impact. The set of observed effects could be classified as active avoidance reaction.
Effect of histidinecontaining dipeptide carnosine on passive avoidance response in normal conditions and under the influence of acute hypobaric hypoxia was analyzed using a threecompartment apparatus that consisted of a light compartment, a dark dangerous compartment in which foot shock was delivered, and a dark safe compartment where the rats were never shocked. The experiment revealed, that carnosine normalized physiological parameters, disrupted by acute hypobaric hypoxia, and increased preference of the safe compartment in both intact rats and hypoxiatreated animals.
Introduction taktivina and thymulin after thymectomy accelerates the formation of a conditioned reflex of active avoidance. Thymic preparations prevent a weakening of the immune system, as well as a reduced ability to learn and remember.
We studied analgesia, induced by immobilization stress. It was found that the contribution of the opioid system in the analgesic effects of control rats was more expressed than in tactivin treated animals. In case of blocking opioid receptors by naloxone, analgesia induced by immobilization stress was the same both in the saline and tactivin treated animals. On the basis of these results, we assumed that the thymus peptides prevent the depletion of the opioid system
Influence of T-activin on anxiety level in rats in the Porsolt test and the tail suspension test has been studied. Positive effect of thymic polypeptides resulted in the reduction of immobility and in the increase of escape-related activity.
The effects of T-activin, the thymus-derived polypeptide, on the content level of monoamines and their metabolites in frontal cerebral cortex, striatum, hypothalamus, nucleus accumbens and hippocampus of rats under emotional stress conditions using HPLC technique have been studied. The substance was shown to reduce the indices of emotional tension and to improve adaptation in stressful conditions at rats that may be the evidence of the anxiolytic action of T-activin. It may be suggested that the positive influence of the thymus polypeptide manifested on the serotonin/norepinehrine balance in favor of the first in hypothalamus and frontal cerebral cortex.
