Journal of Neuroscience, Vol 13, 3368-3374, Copyright © 1993 by Society for Neuroscience
Modulation of hippocampal acetylcholine release: a potent central action of interleukin-2
UK Hanisch, D Seto and R Quirion
Douglas Hospital Research Centre, Department of Psychiatry, Montreal, Quebec, Canada.
The potential of the T-cell growth factor interleukin-2 (IL-2) to modulate
the release of ACh from rat hippocampus was studied in vitro, as a means to
investigate the possible functional significance of this cytokine in the
CNS. Hippocampal slices were superfused with Krebs' buffer medium, and
endogenous ACh released into the superfusate was measured using a
radioenzymatic assay. Recombinant human IL-2 present during a stimulation
with 25 mM KCl altered, in a concentration- dependent manner, the evoked
transmitter release. At a concentration of 15 U/ml (< or = 1 nM), IL-2
inhibited ACh release by more than 50% of the control level (evoked ACh
release from the untreated contralateral hemispheres). Inhibition was
observed within 20 min of tissue exposure to IL-2 and lasted for up to 1
hr. The inhibitory effect of IL-2 was reversible since transient tissue
exposure to IL-2 did not affect subsequent evoked ACh release. IL-2 at this
concentration also significantly decreased evoked ACh in frontal cortical
slices, but was ineffective in the parietal cortex and striatum, revealing
that IL-2 selectively modulates the release of ACh from certain, but not
all, cholinergic nerve terminals in the CNS. At very low concentrations
(1.5 mU/ml, < or = 0.1 pM), IL-2 transiently increased hippocampal
evoked ACh release, resulting in a biphasic dose-response profile with no
significant effect observed at 0.015 mU/ml (< or = 1 fM). Other
cytokines (IL-1 alpha, IL-3, IL-5, IL-6, interferon alpha), tested in
hippocampal slice incubations, failed to modulate ACh release.(ABSTRACT
TRUNCATED AT 250 WORDS)