Chronic pentylenetetrazole but not donepezil treatment rescues spatial cognition in Ts65Dn mice, a model for Down syndrome

The most commonly used model of Down syndrome, the Ts65Dn (TS) mouse, is trisomic for most of the region of MMU16 that is homologous to HSA21. This mouse shares many phenotypic characteristics with people with Down syndrome including behavioral and cognitive alterations. The objective of this study was to analyze the ability of two drugs that improve cognition in different experimental models, the acetylcholinesterase inhibitor donepezil and the non-competitive GABA(A) antagonist pentylenetetrazole (PTZ), to improve the cognitive deficits found in TS mice. The drugs were administered p.o. to TS and CO mice for 8 weeks and a behavioral characterization was performed. Sensorimotor abilities, including vision, hearing, strength and motor coordination, as well as locomotor activity in the home cage, were not modified by any chronic treatment in TS and CO mice. TS mice showed altered equilibrium in the aluminium rod, and this effect was larger under PTZ treatment. This result may indicate a potential adverse effect of PTZ in Ts65Dn mice. Learning and memory were evaluated in TS and CO mice after both treatments in the Morris water maze. Donepezil administration did not modify learning and memory in animals of any genotype. On the other hand, PTZ administration rescued TS performance in the Morris water maze.