Ionizing Radiation Alters Neuronal Excitability in Hippocampal Slices of the Guinea Pig

• Published in: Radiation research 1987-12, Vol.112 (3), p.555-563
• Main Authors: Tolliver, J. M., Pellmar, T. C.
• Format: Article
• Language: English
• Subjects: Action potentials; Animals; Biological and medical sciences; Biological effects of radiation; Brain; Brain damage; Dose response relationship; Electrophysiology; Fundamental and applied biological sciences. Psychology; Guinea Pigs; Hippocampus; Hippocampus - physiology; Hippocampus - radiation effects; In Vitro Techniques; Ionizing radiation; Ionizing radiations; Male; Neurons; Neurons - physiology; Neurons - radiation effects; Radiation damage; Radiation dosage; Radiation dose response relationship; Space life sciences; Tissues, organs and organisms biophysics
• ISSN: 0033-7587; 1938-5404
• DOI: 10.2307/3577107

To investigate the effects of ionizing radiation on an isolated neuronal network without complicating systemic factors, slices of hippocampus from the guinea pig were isolated and studied in vitro. Slices were irradiated with a 60 Co source and compared to paired, sham-irradiated controls. Electrophysiological activity in the CA1 population of pyramidal cells was evoked by stimulation of the stratum radiatum. Analysis of the somatic and dendritic responses suggested sites of radiation damage. Orthodromically evoked activity was significantly decreased in slices receiving greater than 75 Gy γ radiation. The effects were dose and dose-rate dependent. At 20 Gy/min, doses of 50 Gy and greater produced synaptic impairment while doses of 75 Gy and greater also produced postsynaptic damage (i.e., the ability of the synaptic response to generate an action potential). A lower dose rate, 5 Gy/min, reduced the sensitivity of synaptic damage to radiation exposure; synaptic impairment required a dose of 100 Gy or greater at the lower dose rate. In contrast, postsynaptic damage was not sensitive to dose rate. This study demonstrates that ionizing radiation can directly affect the integrated functional activity of neurons.