Preliminary Evidence of the role of estrogen and tamoxifen-induced regulation of complement proteins in rat hippocampus

Abstract

Effects of Estrogen (E2) is widespread in the human body; still, an unresolved paradox.Neurodegeneration and neuroinflammation are inherently associated with age progression, debilitating by hormone deprivation, especially in female. Senescent cells accumulate with age and promote tissue deterioration in the body system. Neurodegenerative diseases drive a healthy life towards to morbidity and feebleness; despite the different etiology, uncontrolled inflammation is one of the significant causals factors. We here used post-menopausal model (ovariectomized female rat), E2 replenishment therapy reduces the expression of inflammatory mediators, such as complement proteins (C3, C1q, and C3aR) in these animals.E2 therapy could limit the ovariectomy-induced increase of inflammatory events in brain regions such as the hippocampus. Also, the duration of hormone deprivation could be a determinant for the intensity of the anti-inflammatory actions of estrogen. On the whole, considerable evidence, including that from the present study supports the view that complement biosynthesis, which plays a significant role in phagocytosis of cellular debris and synaptic pruning of postnatal neural circuits goes uncontrolled and could be the inducing factor for enhanced neurodegeneration following hormone deprivation.

Acquisition of Immune Privilege in GBM Tumors: Role of Prostaglandins and Bile Salts

“…Estrogen/estrogen receptor-β signaling elevates AKR1C3 expression, and it has been previously shown that estrogenic tumors are heavily infiltrated by M2-polarized microglia and macrophages [ 1 , 31 ]. Estrogen is known to elevate CCL18 secretion in M2 macrophages [ 51 ], but it downregulates the expression of complement components, including C3, in normal brain tissue [ 52 ]. A recent study demonstrated that CCL18 released by GBM-infiltrating microglia/macrophages promotes glioma growth [ 53 ].…”