Rats were submitted daily to a variable stressor for 1 week with or wi
thout concurrent imipramine (IMI) administration. One day after the la
st injection or stressful event, binding of cortical beta-adrenoceptor
s was determined in all experimental groups. Another group of chronica
lly stressed animals with or without concurrent IMI administration wer
e sacrificed 24 h following the last stress or injection treatment, an
d several immunologic parameters were evaluated. Chronically stressed
rats showed an enhanced number of cortical beta-adrenergic sites witho
ut changes in their affinity. This effect was not present following co
ncurrent administration with the antidepressant. In addition, a decrea
sed percentage of T lymphocytes and a reduced delayed-type hypersensit
ivity reaction was also observed in stressed animals. Both responses w
ere no longer evident when stressed rats were previously administered
IMI. A possible link between behavioral, neurochemical, and immunologi
c alterations due to the stress regime is discussed.