Insulin is implicated in various neurodegenerative diseases including Alzheimer's Disease that primarily result in memory dysfunctions. Hence, it has been a topic of growing interest among scientists across the globe. We used the model organism Caenorhabditis elegans to elucidate the role of insulin pathway in the learning and memory processes. In C. elegans, the insulin pathway is mediated by a number of insulin peptides and a receptor,
daf-2. Our approach included an appetitive memory paradigm associated with an odor to analyse the learning and memory alterations in this model system. Our study involving both short- and long-term trainings showed that insulin affects learning and memory in a differential manner. Post- dauers with a developmental history of downregulated insulin pathway showed a defective memory recall. However, some mutants in the initial pathway of insulin, like the ligand
ins-1 and the receptor
daf-2, show better retention of memory. We were also able to show that this altered memory is not through the known Akt-1 pathway. In our study, we also found that excess insulin antagonises the pathway and shows extended memory. Our studies also point towards the implications of dopamine in the process. The calcium imaging data also correlates with the role of dopamine neurons in this memory. This work establishes the role of the insulin pathway in learning and memory and that insulin pathway modifies the learning and memory of the worms. Key Words: insulin, Learning and memory,
ins-1,
daf-2, dauers