Abstract
<jats:p>Background. Four decades after the Chernobyl accident, the biological consequences of chronic low-dose radiation exposure remain a subject of scientific interest, particularly in relation to long-lived radionuclides such as cesium-137 (¹³⁷Cs). While hematologic and oncologic outcomes have been extensively investigated, responses of the central nervous system (CNS) under conditions of prolonged internal irradiation remain insufficiently characterized. Objective. To analyze early experimental and clinical data on neurochemical alterations in the CNS associated with chronic internal ¹³⁷Cs intake and to summarize these findings within contemporary redox-oriented concepts of low-dose radiation biology. Methods. Data derived from a three-month experimental model of continuous oral ¹³⁷Cs intake (600 Bq/day) in rats, complementary in vitro brain explant studies, and clinical plasma catecholamine measurements in individuals affected by the Chernobyl accident were reviewed. The findings were analyzed in the context of current approaches emphasizing redox modulation and functional remodeling of neurotransmitter systems. Results. Experimental exposure was associated with region-specific alterations in catecholaminergic and GABAergic systems in the hypothalamus, hippocampus, and striatum, indicating activation of neuroregulatory mechanisms under prolonged internal irradiation. Clinical observations obtained at later time points demonstrated decreased plasma noradrenaline and increased dopamine levels, suggesting altered sympathoadrenal regulation. Conclusions. Chronic internal low-dose exposure to ¹³⁷Cs is accompanied by phased neurochemical changes in the CNS, which may reflect adaptive activation followed by regulatory dysregulation. These findings are consistent with contemporary views on redox-dependent mechanisms underlying long-term functional alterations induced by low-dose radiation.</jats:p>