Altered synaptic activities in cultures of neocortical neurons from prenatally X-irradiated rats.
Prenatal X-irradiation can induce severe microcephaly in the brains of offspring. The possible alteration of neuronal synapse formation was examined in such X-irradiated rats with microcephaly using the whole-cell current clamp technique. The total number of neocortical cells from prenatally (E16) X-irradiated rats decreased to 16% of the control value, while the ratio of GABA-positive/MAP2-positive neurons increased 2.2-fold. Neocortical neurons from E17 normal rat fetuses cultured on monolayers of astrocytes for 7-10 days exhibited synchronized synaptically-driven rhythmic depolarizing potentials (RDPs). Neocortical neurons from prenatally (E15 or E16) X-irradiated rats also exhibited synchronized RDPs, however, their amplitude and the number of spikes decreased. These results suggest that, although neurons which survive in X-irradiated rats can form synapses, inhibitory inputs are predominant over excitatory inputs. It is possible that not only acute neuronal loss induced by X-irradiation but also increased inhibitory inputs in neocortex give rise to subsequent neurological disorders in X-irradiated rats.
Nakanishi
Keiko
K
Department of Perinatology, Institute for Developmental Research, Aichi Human Service Center, 713-8 Kamiya-cho, Kasugai, Aichi 480-0392, Japan. nakanishi@inst-hsc.pref.aichi.jp
Watanabe
Kimi
K
Kawabata
Masao
M
Fukuda
Atsuo
A
Oohira
Atsuhiko
A
D000200:Action Potentials / Q000502:physiology / Q000528:radiation effects; D000818:Animals; D015415:Biomarkers; D016923:Cell Death / Q000528:radiation effects; D002478:Cells, Cultured; D018920:Coculture Techniques; D005260:Female; D005333:Fetus; D007395:Interneurons / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects; D008831:Microcephaly / Q000209:etiology / Q000473:pathology / Q000503:physiopathology*; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D019579:Neocortex / Q000473:pathology / Q000503:physiopathology* / Q000528:radiation effects*; D009433:Neural Inhibition / Q000502:physiology / Q000528:radiation effects*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D051381:Rats; D017208:Rats, Wistar; D013569:Synapses / Q000473:pathology / Q000528:radiation effects*; D009435:Synaptic Transmission / Q000502:physiology / Q000528:radiation effects*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D015415:Biomarkers; D008869:Microtubule-Associated Proteins; D005680:gamma-Aminobutyric Acid