Background: Increased interleukin-1β (IL-1) in the brain and periphery has been associated with
neurodegenerative and psychiatric disorders. However, results from different IL-1
sources, administrating routes, doses and treatment duration were inconsistent and
confused. The neuroendocrine-immune mechanism by which IL-1-induced behavioral changes
occur is still unclear. Methods : In the present study, the acute and sub-chronic effects of rat recombinant IL-1,
following either intraperitoneal (ip) or intracerebroventricular (icv) injection,
were studied on the behavior, corticosterone secretion, peripheral inflammatory responses
and brain monoamines. Results : In the open field apparatus, IL-1 (ip) increased locomotor activity but decreased
the activity following icv administration. IL-1 had a greater anxiogenic effect in
the elevated plus maze after icv than after ip administration. In the Morris water
maze spatial memory was only impaired following sub-chronic and icv administration.
Both acute and sub-chronic IL-1 increased the serum corticosterone concentration and
decreased the release of the anti-inflammatory cytokine IL-10 from whole blood cultures.
However, centrally administered IL-1 increased, while peripherally administered decreased,
the release of PGE2 from blood cultures. After sub-chronic administration, the noradrenaline
concentration was decreased in several limbic regions, while the turnovers of serotonin
and dopamine were increased. Discussion : These results suggest that 1) IL-1 effects depended on the dose, route and duration
of administration, and 2) IL-1 enhances the responsiveness of rats to stressful environmental
stimuli. In addition, the sub-chronic administration of IL-1 induces behavioral, neurotransmitter,
hormonal and immune changes that may be causally implicated in the mechanism of some
of psychiatric disorders such as depression.
References
Cytokines and the nervous system . London; Landes 1996: 117-144
cai.song@nrc.gc.ca
