Last month I reported on a finding that estrogen acts through calpain, a protein crucial to learning and memory, that acts as a neurotransmitter in the brain. Now a new study has found that BDNF activates calpain, and when it does, the spine structure changes in ways similar to those that occur during learning. When activation was blocked with calpain inhibitors, the addition of BDNF had no effect. All this implies that all the great benefits of BDNF for learning and memory are in fact due to calpain.
(2010). Brain-Derived Neurotrophic Factor and Epidermal Growth Factor Activate Neuronal m-Calpain via Mitogen-Activated Protein Kinase-Dependent Phosphorylation.
J. Neurosci.. 30(3), 1086 - 1095.