In vitro models have long been used to further our understanding of skeletal muscle metabolism. Using these methods, researchers can study the mechanistic response to various stimuli (e.g., nutrient exposure/withdrawal, electric stimulation etc) that may be difficult to achieve or isolate in large human trials. Supraphysiological treatment conditions are often used on immortalised cells (often not derived from humans) and create an even more artificial milieu – rendering it difficult to translate in vitro findings to humans.

In recent years, there has been an ever-growing focus on the potential presence of sexual dimorphism in various aspects of muscle physiology, however, to date there has been little specific focus on female sex hormones. Female physiology is characterized by fluctuations in hormone levels throughout the menstrual cycle, such that oestrogen levels peak during the late follicular phase while progesterone levels are highest during the mid-luteal phase. Skeletal muscle expresses both oestrogen and progesterone receptors (1), and oestrogen has been purported to ‘protect’ muscle from exercise induced muscle damage via several different mechanisms in animal models (2). Moreover, progesterone treatment impairs insulin stimulated glucose metabolism in rodents implying a direct effect of progesterone on skeletal muscle that warrants further investigation (3).

In this talk, I will describe the findings from recent experiments whereby immortalised human skeletal muscle cells (4) were utilised to understand the effects of female sex hormones on skeletal muscle anabolism. To further enhance the translatability of such findings, serum samples obtained at different phases of the menstrual cycle (early follicular phase – low oestrogen/progesterone, late follicular phase – high oestrogen and mid luteal phase – high oestrogen/progesterone) were applied to cells to allow physiologically relevant concentrations/ratios of these hormones to be studied. Such a model can therefore provide  a greater depth of understanding of the role of female sex hormones on human skeletal muscle anabolism.