Abstract
Rats were subjected to unpredictable chronic
stress (UCS), which was composed of 3 cycles of 7
kinds of stress for 21 days. Rats given UCS exhibited
a depressive state in behavioral tests such as
emergence tests and forced swim tests.
Administration of cyclosporine-A (CsA), an
immunosuppressive drug, gave rise to antidepressant
effect in rats under the UCS, but not in
stress-free rats. In other words, CsA shortened
both the latency time in emergence tests and the
immobility time in forced swim tests in rats given
UCS. Analysis of brain tissue by HPLC revealed
that CsA caused a significant increase in NE, 5-HT
and 5-HIAA levels in the cortex of UCS treated rats,
but treatment with either UCS or CsA alone resulted
in the opposite effect. Comparing the data of
monoamines and their metabolites in the brain,
cascades may be different between CsA and
imipramine, although both of them showed antidepressive
effect in behavioral tests.
