GPER1 and Alzheimer disease: Moreover, GPER1 has been observed to stimulate extracellular signal-regulated kinase (ERK) signaling in rat hippocampal neurons, leading to activation of synaptic NMDA receptors and trafficking of AMPA receptors into hippocampal synapses, which in turn causes a persistent increase in synaptic efficacy, suggesting a role for GPER1 in modulating neuronal plasticity in neurodegenerative diseases, including AD (105).