Biomedical subjects
Publications and source records attributed to K B Ovanesov.
Epiphysisectomy was shown to increase depression in swimming rats, whereas epiphysisectomy combined with blending decreased it. Epiphysisectomy alone affected the minute rhythms of haloperidol catalepsy while the combined action was less obvious.
Removal of the rat pineal gland entailed an attenuation of haloperidol-induced catalepsy and readjustment of its time-course. This may depend on either direct of indirect effects of the pineal factors, mostly in the ventral portion of the striatum whose hyperactivity determines the main parameters of the neuroleptic effect.
After chronic administration of epithalamin (a pineal peptide drug), an increase in the amplitude and shifts in the acrophase of rat's circadian locomotor activity to late hours were observed. These results were obtained only in rats with low initial amplitude of their circadian rhythm. Epithalamin also changed the time-course of forced swimming and decreased the rhythmic index of depression. These observations suggest that the pineal gland of the rat, via its peptides, may prevent the development of depressive-like events.
Chronic administration of pineal peptide drug epitalamin (0.5 mg/kg for 5 to 10 days) modulated the rat circadian locomotor activity: the animals with low circadian rhythm amplitude were activated whereas the rats with an obvious circadian fluctuations were depressed. The epitalamine obviously decreased an apomorphine-induced stereotype at 13.00 hours rather than at 19.00 hours. The rhythmicity of the stereotype changed in different ways depending on the rat individual susceptibility. The drug decreased the number of 1-3-minute waves if it had been high initially, and increased it if slow fluctuations had dominated. Pineal peptides seem to participate in the maintenance of homeostatic equilibrium at the expense of stabilizing different periods of rhythmical processes.
Acute administration of melatonin (10 mg/kg) produced a depressed effect on the mice behavior. But it's injection after chronic imipramine (10 mg/kg/day, 2 weeks) potentiated antidepressant ability and shortened the duration of immobility in the structure of swimming. In rats, which had a high amplitude of circadian rest-activity rhythm, melatonin produced imipramine effect on circadian mobility, but potentiated antidepressant action in animals with low initial level of locomotor activity.
Pinealectomized rats did not differ from pseudooperated animals in the time of onset, degree and duration of apomorphine-induced stereotypy. However, pinealectomy normalized stereotypy during repeated apomorphine injections to young (7-8 weeks), but not old (26-28 weeks) rats, slowing down minute fluctuations of stereotyped motions.
A peptide preparation of the pineal, epithalamin, when administered chronically, exerts a modulating influence on the diurnal fluctuations of the motoric activity of rats. It also decreases the amplitude of apomorphine stereotypy and induces a restructuring of a modulatory character in its rhythmic structure. It is hypothesized that the pineal peptides participate in the maintenance of homeostasis by means of the stabilization of rhythmic processes of various periods.
After chronic use of melatonin (3 mg before night-time for 14 days) campimetry showed a significant decrease of the threshold of brilliance sensitiveness of the retina in the absence of authentic changes of the sensorimotor response latency in individuals of the older age group. A connection between the eye light sensitivity and the direct effect of the hormone on the photoreceptors is suggested.
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The chronic administration of piracetam over a period of four weeks in patients with heavy cerebrocraneal traumas led to a significant decrease in the retina sensitivity threshold and in the sensomotor response delay time. It is suggested that the increase in the sensitivity is related to the nootrope effect upon the GABAergic processes in the retina.
The chronic administration of piracetam over a period of four weeks in patients after heavy craniocerebral traumas significantly improves the color discrimination of retina with respect to all four colors studied. It is suggested that the improved functioning is related to the nootrope effect upon the GABAergic processes both in the retina and in the related cerebral structures.
Enhanced anxiety state is accompanied by limitation of the color-discrimination function of retina in young humans. Chronic administration of tofisopam (grandaxin) or tinctura leonuri decreased anxiety and significantly improved the color discrimination function of retina with respect to all four colors studied. It is suggested that this improvement is related to the drug action upon the GABAergic processes both in the retina and in the related cerebral structures.
On the pinealectomized rats shifts of main parameters of forced swimming and its time course with increase of rhythmical depression index were observed. Pinealectomy also potentiated depressogenic effect of reserpine which was attenuated by melatonin. At the same time on this model pineal compounds (melatonin, peptides) after acute and chronic administration demonstrated their own antidepressant activity.
The chronic administration of melatonin (0.75 mg at night, 10 days) led to a significant decrease in the thresholds of retinal brightness sensitivity and improved the emotional state in anxious young subjects. Analogous changes were less pronounced after the treatment with common motherwort (Leonurus cardiaca) tincture. It is suggested that there is a relation between the limitation of anxiety and the improvement of visual function (sensitivity).
Imizine (10 mg/kg, 14 days) was shown to change the temporal dynamics of forced swimming in rats and to decrease the biorhythmical index of depression. The antidepressant also produced reorganization of the circadian rest-activity rhythm with the acrophase shift for the late night hours. A pineal hormone melatonin (1 and 10 mg/kg, 7 days) administered in combination with imizine attenuated the main rhythmic indices of its action and precipitated the occurrence of tolerance.
After acute (10 mg/kg) and chronic (1 mg/kg, 10 days) administration melatonin facilitated parameters of rats relearning in the Y-maze. A simultaneous shortening of latency avoidance reaction was observed. Haloperidol (0.1 mg/kg) against the background of chronic melatonin administration more strongly optimized the animals' relearning. The hormonal action is supposed to depend on its sedative properties.
Rhythmical structure of forced swimming was studied on rats. Reserpine (1 mg/kg, 24 h before testing), clonidine (150 mkg/kg) and prolonged repeated striatal stimulation induced behavioural depression with reorganization of swimming rhythm and increase of short cycles (less than 6 s) of immobility. After chronic administration of antidepressants (imipramine, amitriptyline, niamid, 10 mg/kg/day, during 14 days), on the contrary, the number of these cycles diminished, while the number of active swimming cycles increased. Chrono-biological "index of depression" is suggested to express more exactly behavioural depression and specific activity of antidepressants than usual registration of immobility time.
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