Brain estrogen production and the encoding of recent experience

Abstract

The vertebrate central nervous system integrates cognition and behavior, and it also acts as both a source and target for steroid hormones like estrogens. Recent exploration of brain estrogen production in the context of learning and memory has revealed several common themes. First, across vertebrates, the enzyme that synthesizes estrogens is expressed in brain regions that are characterized by elevated neural plasticity and is also integral to the acquisition, consolidation, and retrieval of recent experiences. Second, measurement and manipulation of estrogens reveal that the period following recent sensory experience is linked to estrogenic signaling in brain circuits underlying both spatial and vocal learning. Local brain estrogen production within cognitive circuits may therefore be important for the acquisition and/or consolidation of memories, and new directions testing these ideas will be discussed.

Adverse Effects of Aromatase Inhibition on the Brain and Behavior in a Nonhuman Primate

“…Because AI use should further deplete any E2 synthesis in OVX females and GDX males, peripheral E2 levels were analyzed at the end of the treatment phase. Some studies have also reported increased T following AI use (Taylor et al, 2017), and so T levels were also assessed. Cortisol was also measured as a negative control, as there is little evidence that AIs should influence cortisol synthesis (Bajetta et al, 1999;Rossi et al, 2009).…”

“…Some studies have also reported increased T following AI use (Taylor et al, 2017), and so T levels were also assessed. Cortisol was also measured as a negative control, as there is little evidence that AIs should influence cortisol synthesis (Bajetta et al, 1999;Rossi et al, 2009). A few minutes before lights on (i.e., 8:30 A.M.), marmosets entered a stainless-steel transport box (34.1 ϫ 20.65 ϫ 30.8 cm) attached to their home cage.…”

“…The structural and functional organization of the marmoset brain is comparable with the rhesus or human brain (Chaplin et al, 2013). Marmosets also share many similarities with humans in sleep and thermoregulation patterns (Hoffmann et al, 2012;Gervais et al, 2016), cognitive ability (Spinelli et al, 2004;Yamazaki et al, 2016), and anxiety profiles (Barros et al, 2008;Galvão-Coelho et al, 2008), implicating this species as a strong translational model for studying AI effects on the CNS. Aromatase is expressed in the HPC of marmosets ), suggesting that local estrogen synthesis occurs in this primate, as in humans (for review, see Azcoitia et al, 2011).…”

Sex steroid hormones and brain function:PETimaging as a tool for research

“…Oestrogens were found to play a role in neuronal plasticity and spine synapse formation . Furthermore, many studies have shown positive effects of oestrogens on cognition . In Alzheimer's disease, oestrogens have been shown to protect neurones against the toxicity of amyloid plaques .…”

“…25,26 Furthermore, many studies have shown positive effects of oestrogens on cognition. [27][28][29] In Alzheimer's disease, oestrogens have been shown to protect neurones against the toxicity of amyloid plaques. 30 Nevertheless, more studies are necessary 31 because investigators from the Women's Health Initiative Memory Study found that therapy with a combination of oestrogen and progestin increased the risk for dementia in postmenopausal women and did not improve their performance in mild cognitive tasks.…”