Acute and chronic citalopram treatment differently modulates rat exploratory behavior in the exploration box test: No evidence for increased anxiety or changes in the [H-3]raclopride binding

The effect of acute and chronic desipramine (10 mg/kg) and citalopram (10 m g/kg) treatment on rat exploratory behavior in the recently developed explo ration box test was studied on 5 consecutive days. Acute desipramine but no t citalopram treatment decreased the time spent exploring, the number of li ne crossings, rears, investigative approaches, entries into the large arena , and sum of exploratory events. After 3 weeks of pretreatment, both desipr amine and citalopram attenuated rat exploratory behavior, whereas the numbe r of entries into the large arena was unchanged. In the open field test, ac ute desipramine or citalopram treatment (5, 10, 15 mg/kg) attenuated rat ex ploratory behavior in a dose-dependent manner. In the subsequent rota-rod t est, neither desipramine nor citalopram treatment (0-20 mg/kg) impaired mot or performance capacity. In an additional experiment, [H-3]raclopride bindi ng was unchanged after single as well as 3 weeks of desipramine or citalopr am treatment in the rat brain neostriatum. Our experiments demonstrate that acute citalopram treatment in the open field test and chronic citalopram t reatment in the exploration box test attenuate rat exploratory behavior, bu t these effects may not be implicated with enhanced anxiety or changed dopa mine D-2 receptor characteristics.