In addition to being expressed in hippocampal neurons, both ER-_ and ER-_ have also been reported to be expressed in glia in the CA1-CA3 [284,289], which is of interest due to the growing appreciation of astrocytes as a component of the tripartite synapse. In higher primates such as the monkey, ER-_ mRNA has been reported to be dense in the dentate gyrus, CA1-CA4 and the prosubiculum/subiculum areas of the hippocampus [290]. There are only a few studies in the literature on the distribution of ER-_ in the monkey hippocampus. One study reported a failure to detect ER-_ in monkey hippocampus using in situ hybridization or immunohistochemistry [290]. However, another study did detect ER-_ mRNA in the female monkey hippocampus using RT-PCR, but there was much higher ER-_ expression as compared to ER-_ [291]. With respect to the cerebral cortex, Wang et al. [285] found that ER-_ mRNA is widely expressed in neurons in the monkey prefrontal cortex with the largest concentration present in layers IV–VI. Studies in humans have shown that both ER-_ and ER-_ mRNA are expressed in the hippocampus and cortex, with the hippocampus displaying higher expression for ER-_ than ER-_ [286]. Thus, there seems to be good agreement throughout the species of higher ER-_ expression in the hippocampus as compared to ER-_. Finally, as discussed previously, the putative membrane estrogen receptor, GPR30 is also reported to be expressed in both the hippocampus and cortex in rodents, and could have a role in mediating estrogen actions in these regions of the brain [58–60].