Neuroprotective mechanisms of non-classical estrogen-like signaling activators in basal forebrain cholinergic neurons: testing of novel compounds

In the brain, cholinergic neurons play role in learning and attention and these cells are particularly vulnerable in Alzheimer’s disease. Estrogen alters the function of cholinergic neurons and is thought to exert ameliorative effects on these cells. Typically, estrogen alters gene transcription via estrogen-receptor mediated “classical” genomic mechanisms. However, estrogen also exerts faster, non-classical (or non-genomic) effects via a signal transduction system. Estrogen-induced ameliorative effect depends on the activation of non-classical intracellular signaling pathways. The synthetic newly discovered estrogenic compounds so called “Activator of Non-Genomic Estrogen Like Signaling” (ANGELS) such as estren reproduce ameliorative estrogen actions through the non-classical pathway without affecting the reproductive organs. In these experiments we identify new ANGELS compounds using in silico computer modelling and we will test the effect of new ANGELS on beta-amyloid-induced toxicity on basal forebrain cholinergic neurons. Furthermore we characterize the effect of ANGLES on signaling pathway activation in these neurons in vivo using immunohistochemistry, behavioural tests, MALDI-TOF imaging, blood flow measurmetns and transgenic technology. These experiments provide an interdisciplinary platform for endocrine and Alzheimer research.  Most importantly, the results have the potential to contribute significantly to advancing the case for ANGELS four years as a potential therapy that may slow the progression in Alzheimer’s disease.


Single molecule detection of estrogen action on live human neurons 

Whereas the mechanisms underlying classical actions are well established, non-classical estrogen actions are much less well understood. Using novel time-lapse super-resolution imaging and a range of in vivo and in vitro techniques in conjunction with transgenic technology we examine the mechanisms of non-classical estrogen actions on live neurons at single molecule level. The proposed work will define a new estrogen signaling pathway in the cholinergic neurons and provide fundamental information for understanding cognition and Alzheimer’s disease.


Defining a new estrogen pathway to GnRH neurons

Estrogen exerts a critical modulatory action upon the brain to control fertility. The gonadotrophin-releasing hormone (GnRH) neurons in the hypothalamus of the brain represent the key neural cell population regulating fertility. Estrogen exerts a profound regulatory influence upon the activity of GnRH neurons and this is known to be critical for normal reproductive function. Non-classical pathway that has recently come to light in the brain, and elsewhere, is that involving the rapid phosphorylation of cAMP responsive element binding protein (CREB) by estrogen.

CREB is an important transcriptional regulator expressed by many cell types. Our recent studies have shown that estrogen is able to enhance CREB phosphorylation (pCREB) in GnRH neurons in vivo and in vitro within minutes. This represents a new mechanism of estrogen action on GnRH neurons and that will result in the rapid regulation of transcriptional activity in these cells. In this project we determine the signaling cascade resulting in the phosphorylation of CREB and the physiological significance of estrogen-evoked CREB phosphorylation in GnRH neurons using immunohistochenical approach and inducible transgenic mice. These studies hold the prospect of defining a novel estrogen pathway to GnRH neurons that would have a major impact upon our understanding and treatment of fertility.