Evidence that tolerance to the anxiogenic-like effects of mCPP does not involve alteration in the function of 5-HT(2C) receptors in the rat choroid plexus.
The mechanisms by which 1-(3-chlorophenyl) piperazine (mCPP) causes anxiety are unclear, but it has been suggested that the serotonin 5-HT(2C) receptor subtype may be involved in this effect. We have therefore studied the effect of chronic treatment (3 weeks) with mCPP in two animal models of anxiety (light/dark choice task in mice and elevated plus-maze test in rats) and subsequently assessed the function of 5-HT(2C) receptors (measured by maximal stimulation of 5-HT(2C) receptor-mediated phosphoinositide hydrolysis) in rat choroid plexus, where the receptor is present at very high levels. mCPP treatment regimens led to a tolerance to the anxiogenic-like action of the drug, but failed to alter the second messenger coupling of the 5-HT(2C) receptors in the choroid plexus, thereby suggesting the involvement of different mechanisms in this behavioral effect.
Békésy Laboratory of Neurobiology, University of Hawaii, 1993 East-West Road, Honolulu, HI 96822, USA.
G.
G
Griebel
J.-L.
JL
Moreau
F.
F
Jenck
V.
V
Mutel
J.R.
JR
Martin
R.
R
Misslin