Cortical [3H]ketanserin binding and 5-HT(2A) receptor-mediated inositol phosphate production in the spontaneously hypertensive rat and Lewis rat strains
Neuroscience Letters. 1997-10-01; 236(2): 112-116
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Gauffre JC(1), Aguerre S, Mormède P, Chaouloff F.
(1)INSERM CJF 94-05, INRA, Institut F. Magendie, Bordeaux, France.
The spontaneously hypertensive rat (SHR) and Lewis rat strains differ in the
elevated plus-maze of anxiety, the former and the latter strain displaying low
and high anxiety, respectively. A recent study has shown that serotonin
(5-hydroxytryptamine, 5-HT)2A receptor-mediated head shakes, but not
[3H]ketanserin binding at these receptors, are less in Lewis rats, compared with
SHRs. Herein, we have analysed the hypothesis of a difference in 5-HT2A
receptor-effector coupling between these two strains. Confirming our previous
results, the Bmax and KD values for the specific [3H]ketanserin binding at
cortical 5-HT2A receptors were respectively identical in both strains. The
accumulation of total inositol phosphates by the 5-HT2A,2B,2C receptor agonist
1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI; 0.01-100 microM) was
concentration- and strain (Lewis > SHR)-dependent. Preincubation with 0.01 and
0.1 microM of the 5-HT2A receptor antagonist SR 46349B, respectively, decreased
and prevented DOI-elicited inositol phosphate production in both strains. The
aforementioned genetic differences in 5-HT2A receptor-mediated head shakes may
thus lie at some point distal from the 5-HT2A receptor.