125I-iomazenil binding shows stress- and/or diazepam-induced reductions in mouse brain: supporting data for 123I-iomazenil SPECT study of anxiety disorders.
Effects of repeated swim stress on the binding of 125I-iomazenil were examined in the brains of diazepam-treated and non-treated mice. The mice were orally administered diazepam or vehicle (0.5% ethylene glycol) and subjected to daily swim stress (at 20 degrees C for 10 min) for seven consecutive days. The distribution and the amount of 125I-iomazenil binding were analyzed autoradiographically after in vivo and in vitro binding experiments. Repeated swim stress decreased the in vivo binding in the hippocampus (p < 0.05) and cerebral cortex (p < 0.05) of vehicle-treated mice but caused no significant changes in diazepam-treated mice. Subchronic treatment with diazepam decreased the in vivo binding approximately 50% in all brain regions examined (p < 0.01). The in vitro experiment, however, revealed no significant changes except in the hippocampus, where a small but significant decrease in the binding was observed after subchronic treatment with diazepam (p < 0.01). The stress- or diazepam-induced reductions seem to represent alterations in the in vivo environment related to 125I-iomazenil binding. These results suggest that we can investigate the pathophysiology of stress and anxiety with 123I-iomazenil SPECT. Care must be taken concerning the effects of benzodiazepines.
Takahashi
M
M
Department of Psychiatry, Niigata University School of Medicine, Japan. makoto@med.niigata-u.ac.jp
Odano
I
I
Fujita
S
S
Ohkubo
M
M
D000818:Animals; D014151:Anti-Anxiety Agents / Q000494:pharmacology*; D001008:Anxiety Disorders / Q000000981:diagnostic imaging / Q000378:metabolism*; D001345:Autoradiography; D001921:Brain / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000378:metabolism*; D003975:Diazepam / Q000494:pharmacology*; D005442:Flumazenil / Q000031:analogs & derivatives* / Q000378:metabolism; D007457:Iodine Radioisotopes / Q000378:metabolism; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D013312:Stress, Physiological / Q000000981:diagnostic imaging / Q000378:metabolism; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*
D014151:Anti-Anxiety Agents; D007457:Iodine Radioisotopes; D005442:Flumazenil; C063038:iomazenil; D003975:Diazepam