Strain-dependent effects of diazepam and the 5-HT2B/2C receptor antagonist SB 206553 in spontaneously hypertensive and Lewis rats tested in the elevated plus-maze
Braz J Med Biol Res. 2001-05-01; 34(5): 675-682
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1. Braz J Med Biol Res. 2001 May;34(5):675-82.
Strain-dependent effects of diazepam and the 5-HT2B/2C receptor antagonist SB
206553 in spontaneously hypertensive and Lewis rats tested in the elevated
Takahashi RN(1), Berton O, Mormède P, Chaouloff F.
(1)Departamento de Farmacologia, Universidade Federal de Santa Catarina,
Florianópolis, SC, Brasil.
The 5-HT2B/2C receptor antagonist SB 206553 exerts anxiolytic effects in rat
models of anxiety. However, these effects have been reported for standard rat
strains, thus raising the issue of SB 206553 effects in rat strains displaying
different levels of anxiety. Herein, the effects of SB 206553 in a 5-min elevated
plus-maze test of anxiety were compared to those of the reference anxiolytic,
diazepam, in two rat strains respectively displaying high (Lewis rats) and low
(spontaneously hypertensive rats, SHR) anxiety. Diazepam (0.37, 0.75, or 1.5
mg/kg; 30 min before testing) increased in a dose-dependent manner the behavioral
measures in SHR, but not in Lewis rats. On the other hand, SB 206553 (1.25, 2.5,
or 5 mg/kg; 30 min before testing) failed to alter the anxiety parameters in both
strains, whereas it increased closed arm entries in Lewis rats, suggesting that
it elicited hyperactivity in the latter strain. Accordingly, the hypolocomotor
effect of the nonselective 5-HT2B/2C receptor agonist m-chlorophenylpiperazine
(1.5 mg/kg ip 20 min before a 15-min exposure to an activity cage) was prevented
by the 1.25 and 2.5 mg/kg doses of SB 206553 in Lewis rats and SHR, respectively.
Compared with SHR, Lewis rats may display a lower response to
benzodiazepine-mediated effects and a more efficient control of locomotor
activity by 5-HT2B/2C receptors.
PMID: 11323756 [Indexed for MEDLINE]