Hypergravity exposure leads to persistent effects on geotaxis and activity in Drosophila melanogaster

Gravity, a constant force throughout evolution, has fundamentally shaped biology, playing a critical role in locomotion, balance and orientation across species - from unicellular organisms to complex multicellular life. Despite its pivotal role in biomechanics and physiology, how gravity affects different aspects of locomotion remains less understood. Hypergravity induces changes in activity rhythms across taxa. However, comprehensive analyses testing varied gravity intensities and examining how acute or chronic developmental exposure affects locomotion after returning to Earth's gravity remain limited. Using a hypergravity simulator, we found that acute 4 g exposure impairs spontaneous climbing behavior in Drosophila melanogaster, while startle-induced climbing remains unaffected when tested at 1 g. After exposure to higher gravity levels (7 g, 10 g and 13 g), spontaneous climbing deficits become more pronounced, yet startle responses remain largely intact. When examining individual daily activity over 1 week post-exposure, we observed increased activity following 4 g exposure but reduced activity after exposure to higher gravity levels. Notably, these locomotor impairments persisted beyond the exposure period, with recovery occurring later in life, indicating long-lasting effects of hypergravity. In parallel, whole-body triacylglyceride measurements revealed gravity- and time-dependent modulation of energy storage following hypergravity exposure. To explore the effects of developmental and multigenerational exposure, we subjected flies to hypergravity for one or ten generations. Chronic treatment in both cases further reduced activity relative to acute exposure, even at 4 g, with more pronounced reductions at 7 g. Together, our findings demonstrate that altered gravity exposure modulates locomotion, with lasting consequences for activity and energy homeostasis after return to 1 g.