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The structural changes of neurons of the rat hypothalamic supraoptic (SON) and of paraventricular (PVN) nucleus after 48 h of bright light exposure, of 5 Gy whole-body X-irradiation and of their combination subjected to the analysis by means of light-optic and of electron microscopy for the estimation of radimodificated effect of light exposure lasted 24 h a day and plasticity of neuroendocrine transducers interacted with the optic sensory system. The structural changes of neurons of the SON after combined action are less considerable and more prolonged in comparison with the PVN that loas defermined by their direct connection with the optic sensory system via the retinohypothalamic tract.

For estimation of light radiomodification and cellular neuroadaptation of the circadian pacemarker, the morphological changes of suprachiasmatic nuclei (SCN) neurons of rat hypothalamus after 48-hours bright light exposure, the single 5 Gy whole-body X-irradiation and their combination were subjected to analysis. The dynamics of reactive and reparative changes has got a phasic character. Temporary desynchronous changes were developed in the course of the early period. Age morphological changes after X-ray and combined irradiation were discovered in the remote period. The plastic diapason of ventrolateral division (SCNv) is more considerable in comparison with dorsomedial division (SCNd). The synergism of X-irradiation and light exposure was discovered in SCNd.

The effect of the ultralow power pulse-modulated electromagnetic radiation (EMR, power density 10 microW/cm2; carrying frequency 915 MHz; modulating pulses with frequency 2, 4, 6, 8, 12, 16 and 20 Hz) on activity of monoamine oxidase (MAO-A), enzyme involved in the oxidative deamination of monoamines, was investigated. It was established that the increase of activity MAO in hypothalamus reached the maximal meaning at modulation frequency of 6 Hz that corresponded 160% (p < 0.01) of the control level; and at modulation frequency of 20 Hz the decrease of enzyme activity up to 74% (p < 0.01) was found. Mainly the action of ultralow power pulse-modulated EMR on activity of MAO in hippocamp was activating; and the maximal increase of enzyme activity up to 174% (p < 0.01) was registered at modulation frequency of 4 Hz.

Drastic changes in the level of catecholamines (dophamine and noradrenaline) in the central regulatory area of the sympathetic-adrenal system-hypothalamus--caused by continuous gamma irradiation of rats were observed. The irradiation was performed with the doses of 9 to 165 cGy at a rate of 1.1 cGy/day and with the doses of 17 to 315 cGy at a rate of 2.1 cGy/day. Dose dependences of the effect were of a non-monotonic nature. Conclusion was made of a high sensitivity of the sympathetic-adrenal system to the action of chronic low-dose gamma irradiation.

In hybrid mice it was shown that the local irradiation of zones of thymus, hypothalamus-hypophysis (0.5, 1 and 10 Gy in both cases) and gonads (10 Gy) resulted in significant increase in weight at long terms after irradiation. In animals with increased weight the amount of lipids raised, balance of hormones and state of thymus-dependent unit of immune system changed, and exterior symptoms of early aging were observed. After irradiation of spleen and thigh muscles (10 Gy in both cases) all indices at the same period corresponded to age control.

Mice were grafted with syngeneic neonatal thymus 1-3 days or 7.5-8 months after local irradiation of thymus, hypothalamus/hypophysis and gonads. Thymus weight and thymocyte number were measured in autologous and grafted thymus 35-40 days after the transplantation. Thymus transplantation induces significant decrease in weight and cellularity of both autologous and grafted thymus. Irradiation of autologous and grafted thymus in doses of 1 and 10 Gy abrogates this effect. Irradiation of hypothalamus/hypophysis and gonads induces decrease of weight and cellularity of autologous and grafted thymus. Irradiation of gonads does not abrogate inhibitory effect of thymus transplantation. Local irradiation of all three regions decreases titre of serum thymic activity and influence concentrations of some hypophysis and adrenal hormones.

In experiments with thirty rabbits the influence of thirty-minute microwave irradiation (1.5 GHz, pulse intensity 0.3 mW/cm2; pulsed modes: 0.12 Hz, 16 ms or 1000 Hz, 0.4 ms; pack-pulsed mode: pulse frequency 1000 Hz, pack frequency 0.12 Hz) on the total bioelectrical activity of brain structures was studied. The reliable effect was detected only in hippocamp. The total bioelectrical activity of cortex, caudate nucleus, hypothalamus, amygdala and septum was not changed reliably in animal group studied. The reaction of hippocamp was displayed as amplification of theta-range in spectrum within of normal functioning.