Acute anorectic effect of single and combined drugs in mice using a non-deprivation protocol.

Author(s): Rowland NE, Lo J, Robertson K

Affiliation(s): Department of Psychology, University of Florida, Gainesville 32611-2250, USA. nrowland@ufl.edu

Publication date & source: 2001-09, Psychopharmacology (Berl)., 157(2):193-6.

Publication type:

RATIONALE: Studies of the effect of anorectic drugs such as fenfluramine in mice have indicated the desirability of using experimental protocols that do not involve deprivation. OBJECTIVE: We have developed a non-deprivation or "dessert" protocol for use in mice that are maintained in standard housing conditions, and examine the effects of a serotonergic agent dexfenfluramine (DFEN), a dopaminergic agent phentermine (PHEN), and a selective norepinephrine uptake inhibitor thionisoxetine (TNIX) alone and in combination. METHODS: Female C57BL/6J mice were adapted to 30 min daily presentation of a gelatinized form of sweetened milk using a holder that hooks over the side of the cage during tests; food spillage and contamination are minimal. Dose-inhibition curves were determined for DFEN, PHEN, and TNIX alone and for fixed ratio combinations of DFEN with either PHEN or TNIX. RESULTS: Each drug produced a near linear dose-inhibition curve with the 50% inhibitory doses (DI50) of 5.6, 3.2 and 12.2 mg/kg, respectively. By isobolographic analysis, the effects of the drug combinations were strictly additive. CONCLUSION: The procedure described is highly suitable for testing anorectic drugs in mice and is adaptable to a variety of housing conditions and diets. The DFEN+ PHEN combination was additive, which contrasts with its reported supra-additive effect in rats.