Figure 1. Estrogen levels rhythmically fluctuate throughout reproductive life. In young healthy females, the robustness of the neuroendocrine-immune network maintains physiological homeostasis by mutual regulation between the neural, endocrine and immune mediators. During reproductive aging however, perimenopausal surge in estrogen followed by its precipitous decline post menopause leads to neuroendocrine-dysfunction, peripheral denervation and immunosenescence compounded by the lack of trophic factors, neurotransmitters, signalling molecules and defunct antioxidant machinery.