Mayer, M.

Ritter, S.

Thielemann, C.

GSI Repository

Electrophysiological Effects of Ionising Radiation on Cortical Rat Neurons invitro∗M. Mayer1, S. Ritter2, and C. Thielemann11University of Applied Sciences, BioMEMS lab, Aschaffenburg, Germany; 2GSI, Biophysics division, Darmstadt,GermanyMotivationPrevious studies in mice and rats have shown that the de-veloping central nervous system (CNS) is particularly sen-sitive against ionising radiation [3], yet there exists hardlyany information if ionising radiation affects cellular com-munication of neuronal cells. Therefore we for the firsttime investigated the effects of X-ray on neuronal em-bryonic network using the method of microelectrode ar-rays (MEA). The cells, in this case primary cortex neu-rons from 18 to 19 days old rat embryos, were platedonto microelectrode arrays and reaggregated into an spon-taneously, electrically active network. This network typi-cally develops in three phases. First, electrical activity canbe detected as random single spikes. Second, it starts toexpress a train-like spiking activity that further developsinto burst-like activity. These bursts represent the maturesignalling activity of the network [1]. With this methodpossible radiation induced effects can be extracellularlyrecorded.Material and MethodsThe experiments were performed with commerciallyavailable cortical rat neurons, isolated from 18 to 19 daysold rat embryos. The cells were seeded onto the centreof the MEA chips and cultivated over a period of 4 weeks(Fig.1). This method can be used to assess the electricalactivity of neuronal tissue and allows non-invasive, sim-ultaneous recordings from 60 electrodes. In order to ex-amine the effects of ionizing radiation on the neuronal net-work formation, the cells were irradiated after 16 days ofcultivation with X-ray doses of 1 Gy and 2 Gy (90 kV, 33,7mA) at the Technische Universita¨t Darmstadt. Electricalsignals could be recorded for about two weeks after irradia-tion and were analysed with regard to the number of spikesand bursts, the number of spikes per burst, the height of theamplitude, the duration of the bursts and other parameters.Figure 1: Cortical neurons from rat embryos on a MEAchip, cultured for 20 days in vitro.∗Funding for this project was provided by the Federal Ministry of Ed-ucation and Research (02NUK025C).ResultsThe first experiments showed that the neuronal networkfunctionality is very robust and not affected significantly bythe applied doses. None of the examined parameters pro-vided clear evidence of radiation-induced changes in theelectrophysiological response of the networks. As an ex-ample the number of network spikes per minute is shownin figure 2 as a function of dose. This parameter is veryimportant since preceding studies have shown that the ap-plication of several drugs, such as carbamazepine (data notshown) and neurotoxins, such as methyl mercury chloride[2], leads to a reduction of the number of spikes within adefined period of time.Figure 2: Number of spikes per minute of the neuronal net-work after X-ray exposure. The values are normalized tothe measurement before irradiation (Pre Irrad.). Each barrepresents at least three samples.ConclusionOur preliminary results suggest that the irradiation doesaffect neither the neuronal network nor the cell communi-cation. It is planned to repeat this experiment apply-ing higher doses. In addition, immunohistochemical tech-niques will be used to study radiation induced cell death.References[1] Heikkila¨, T.J. et al. (2009) Human embryonic stem cell-derived neuronal cells form spontaneously active neuronalnetworks in vitro. Exp Neurol 218.1, 109-16[2] Outinen, L.Y. et al. (2010) Human cell-based micro electrodearray platform for studying neurotoxicity. Frontiers in Neuro-engineering 3[3] Schull, W.J. et al. (1990) Ionizing Radiation and the Devel-oping Brain. Neurotoxicol Teratol 12, 249-260BIOPHYSICS-16 GSI SCIENTIFIC REPORT 2013218 doi:10.15120/GR-2014-1-BIOPHYSICS-16

Electrophysiological Effects of Ionising Radiation on Cortical Rat Neurons in vitro

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Electrophysiological Effects of Ionising Radiation on Cortical Rat Neurons in vitro

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