Triiodothyronine and brain excitability.
We investigated mechanisms involved in thyroid hormone action on brain excitability. The effect of acute exposure of triiodothyronine (T3) to rat hippocampal slices in vitro was studied. No significant changes could be detected in prevolley, field excitatory postsynaptic potentials (fEPSP) and population spike amplitude, while there was a minor, nonsignificant trend toward shortening of the population spike latency time. T3 had no effect on penicillin-induced epileptiform activity. There was, however, an active accumulation of radioactively labeled T3 in the slices. A rat cervaux-isolé preparation was used to determine focal seizure thresholds in the visual cortex, and no acute (2-4 h) effects were demonstrated. No significant acute effects of T3 on brain excitability in the hippocampus and visual cortex was observed, despite an active accumulation of T3. Thus, the effect of T3 on brain excitability most likely is due to delayed effects.
Taubøll
E
E
Department of Neurology, National Hospital, University of Oslo, Norway.
Lindström
S
S
Stokke
K T
KT
Gjerstad
L
L
D000818:Animals; D003655:Decerebrate State / Q000378:metabolism; D005071:Evoked Potentials / Q000187:drug effects; D006624:Hippocampus / Q000187:drug effects* / Q000502:physiology; D007457:Iodine Radioisotopes / Q000378:metabolism; D008297:Male; D010406:Penicillins / Q000008:administration & dosage; D051381:Rats; D011919:Rats, Inbred Strains; D012640:Seizures / Q000139:chemically induced / Q000378:metabolism; D014284:Triiodothyronine / Q000008:administration & dosage / Q000494:pharmacology*; D014793:Visual Cortex / Q000187:drug effects* / Q000378:metabolism
D007457:Iodine Radioisotopes; D010406:Penicillins; D014284:Triiodothyronine