RESUMO
Ageing is associated in many organisms with a reduction in motor movements. We have previously shown that the rate of feeding movements of the pond snail, Lymnaea, decreased with age but the underlying cause is not fully understood. Here, we show that dopamine in the cerebro-buccal complex is an important signalling molecule regulating feeding frequency in Lymnaea and that ageing is associated with a decrease in CNS dopamine. A proteomic screen of young and old CNSs highlighted a group of proteins that regulate stress responses. One of the proteins identified was 14-3-3, which can enhance the synthesis of dopamine. We show that the Lymnaea 14-3-3 family exists as three distinct isoforms. The expression of the 29 kDa isoform (14-3-3Lym3) in the cerebro-buccal complex decreased with age and correlated with feeding rate. Using a 14-3-3 antagonist (R18) we were able to reduce the synthesis of L-DOPA and dopamine in ex vivo cerebro-buccal complexes. Together these data suggest that an age-related reduction in 14-3-3 can decrease CNS dopamine leading to a consequential reduction in feeding rate.