Serotonin and Noradrenaline Metabolism in the Brain of Rats under the Combined Action of Radiation and Hypogravity in a Ground-based Experiment

Operative dysfunction of cosmonauts under the effects of space flight factors is the main limiting factor of interplanetary flights. Travel beyond the Earth’s geomagnetic field is associated with a significant increase in radiation hazard. Hypogravity is another space flight factor that influences CNS functions. It has previously been found that the impact of radiation and hypogravity may cause oppositely directed effects on CNS functions; their combined application may neutralize each other. Here, we have investigated the effects of hypogravity in an experiment with an antiorthostatic suspension and radiation with γ-rays and 12C+6 on the metabolism of serotonin and noradrenaline in morphological structures of the brain that are crucial for realization of stress-induced response in Long Evans outbred rats. The combined actions of the factors resulted in the dominant effect of radiation, which included enhancement of noradrenergic neurotransmission in the prefrontal cortex and attenuation of serotonergic neurotransmission within the prefrontal cortex and amygdala. No changes were found in the hypothalamus. Therefore, we did not find any changes in serotoninergic and noradrenergic neurotransmission that are typical of the stress-induced response.