@article {1807, title = {Impairments in remote memory caused by the lack of Type 2 IP3 receptors}, journal = {Glia}, volume = {67}, year = {2019}, pages = {1976-1989}, abstract = {

Abstract The second messenger inositol 1,4,5-trisphosphate (IP3) is paramount for signal transduction in biological cells, mediating Ca2+ release from the endoplasmic reticulum. Of the three isoforms of IP3 receptors identified in the nervous system, Type 2 (IP3R2) is the main isoform expressed by astrocytes. The complete lack of IP3R2 in transgenic mice was shown to significantly disrupt Ca2+ signaling in astrocytes, while leaving neuronal intracellular pathways virtually unperturbed. Whether and how this predominantly nonneuronal receptor might affect long-term memory function has been a matter of intense debate. In this work, we found that the absence of IP3R2-mediated signaling did not disrupt normal learning or recent (24{\textendash}48 h) memory. Contrary to expectations, however, mice lacking IP3R2 exhibited remote (2{\textendash}4 weeks) memory deficits. Not only did the lack of IP3R2 impair remote recognition, fear, and spatial memories, but it also prevented naturally occurring post-encoding memory enhancements consequent to memory consolidation. Consistent with the key role played by the downscaling of synaptic transmission in memory consolidation, we found that NMDAR-dependent long-term depression was abnormal in ex vivo hippocampal slices acutely prepared from IP3R2-deficient mice, a deficit that could be prevented upon supplementation with D-serine - an NMDA-receptor co-agonist whose synthesis depends upon astrocytes{\textquoteright} activity. Our results reveal that IP3R2 activation, which in the brain is paramount for Ca2+ signaling in astrocytes, but not in neurons, can help shape brain plasticity by enhancing the consolidation of newly acquired information into long-term memories that can guide remote cognitive behaviors.

}, keywords = {astrocyte, Behavior, Ca2+ signaling, long-term memory, synaptic plasticity}, doi = {https://doi.org/10.1002/glia.23679}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/glia.23679}, author = {Pinto-Duarte, Ant{\'o}nio and Roberts, Amanda J. and Ouyang, Kunfu and Sejnowski, Terrence J.} }