Altered behaviour of hamsters by prolonged hypergravity: adaptation to 2.5 G and re-adaptation to 1 G.

Abstract

We studied the functional adaptation process in 40 hamsters subjected to either prolonged hypergravity to normal gravity. Subadult golden hamsters (n = 20) exposed to a hypergravity condition of 2.5 G for 6 months were tested to investigate the effect of hyper gravity on the perceptive motor skills and compared with control hamsters (n = 20). The motor coordination of the hypergravity hamsters hardly changed; locomotion was normal and swimming was possible. Equilibrium maintenance was disturbed during the first 3 months as was shown by the higher crossing time (p < 0.001) and higher fall frequency (p < 0.001) for the hypergravity group. Significant differences were also found in orientation during swimming (p = 0.007) and turning behaviour in the rotation task (p < 0.001) and in the no-rotation task (p = 0.029). After 6 months, 10 hamsters of both groups were tested for another 4 months, also the hypergravity hamsters were living at 1 G. Differences in orientation in the two groups did not change during swimming and turning behaviour during the rotation task (p = 0.026). Based on our findings, we conclude that the hamsters functionally adapted to hypergravity, which led to an altered performance of several tasks. The condition continued after 4 months of normal gravity.