Intramuscular sex steroid hormones are associated with skeletal muscle strength and power in women with different hormonal status

Abstract

Estrogen (E2)-responsive peripheral tissues, such as skeletal muscle, may suffer from hormone deficiency after menopause potentially contributing to the aging of muscle. However, recently E2 was shown to be synthesized by muscle and its systemic and intramuscular hormone levels are unequal. The objective of the study was to examine the association between intramuscular steroid hormones and muscle characteristics in premenopausal women (n = 8) and in postmenopausal monozygotic twin sister pairs (n = 16 co-twins from eight pairs) discordant for the use of E2-based hormone replacement. Isometric skeletal muscle strength was assessed by measuring knee extension strength. Explosive lower body muscle power was assessed as vertical jump height. Due to sequential nature of enzymatic conversion of biologically inactive dehydroepiandrosterone (DHEA) to testosterone (T) and subsequently to E2 or dihydrotestosterone (DHT), separate linear regression models were used to estimate the association of each hormone with muscle characteristics. Intramuscular E2, T, DHT, and DHEA proved to be significant, independent predictors of strength and power explaining 59–64% of the variation in knee extension strength and 80–83% of the variation of vertical jumping height in women (P < 0.005 for all models). The models were adjusted for age, systemic E2, and total body fat mass. The statistics used took into account the lack of statistical independence of twin sisters. Furthermore, muscle cells were shown to take up and actively synthesize hormones. Present study suggests intramuscular sex steroids to associate with strength and power regulation in female muscle providing novel insight to the field of muscle aging.

Frailty and sarcopenia as the basis for the phenotypic manifestation of chronic diseases in older adults

“…In fact, it has been reported that the positive effects of testosterone levels on muscle strength and physical performance are independent on its influence on muscle mass (Auyeung et al, 2011). In this sense, intramuscular androgens and estradiol levels have been proved to be significant, independent predictors of muscle strength and power in women with differential hormonal status (Pöllanen et al, 2015). Testosterone replacement therapy in men aged 61-71 years resulted in increased muscle fiber diameter and peak power, affecting mainly type I fiber peak force (Fitts et al, 2015) supporting the influence of testosterone on muscle function.…”

Growth Hormone(s), Testosterone, Insulin-Like Growth Factors, and Cortisol: Roles and Integration for Cellular Development and Growth With Exercise

“…Testosterone (T) is an anabolic-androgenic steroid hormone that primarily interacts with androgen receptors (AR) in skeletal muscle whereas the more-potent dihydrotestosterone (DHT) primarily acts within sex-linked tissues with a possible secondary role in skeletal muscle (2) Although skeletal muscle content of DHT has been correlated to muscle strength and power (3), T replacement with and without dutasteride or finasteride (5α-reductase inhibitors) produces similar increases in lean tissue mass and muscle strength (4,5). Thus, it is currently unclear if DHT is more anabolic in skeletal muscle than T alone.…”

“…Cell separation studies indicate that two populations of GH cells (somatotrophs) are present, in roughly equal numbers (∼40%), in the rat pituitary gland. One population (light somatotrophs, also designated the type I cell) has densities <1.071 g/cm 3 , while the other (heavy somatotrophs, also designated the type II cell) has densities in ranges >1.071-1.085 g/cm 3 . The higher density of the type II cell is attributable to large numbers of 300 nm diameter, GH containing, cytoplasmic secretory granules.…”

Profiles Associated with Sarcopenia in Hepatoma Patients Underwent Transcatheter Arterial Chemoembolization: A Data‐Mining Analysis

“…In addition, a major cause of decreased muscle mass is an alteration in the hormonal networks involved in the inflammatory processes, muscle regeneration, and protein synthesis [32]. Estrogens help to maintain muscle mass [33], and in female patients, menopause leads to changes in the systemic steroid hormone profile from a regularly fluctuating estrogen cycle to very low estrogen levels [34]. The decreased estrogen concentrations are associated with an increase in pro‐inflammatory cytokines, such as tumor necrosis factor alpha or interleukine‐6, which might be implicated in the development of sarcopenia [34].…”

“…Estrogens help to maintain muscle mass [33], and in female patients, menopause leads to changes in the systemic steroid hormone profile from a regularly fluctuating estrogen cycle to very low estrogen levels [34]. The decreased estrogen concentrations are associated with an increase in pro‐inflammatory cytokines, such as tumor necrosis factor alpha or interleukine‐6, which might be implicated in the development of sarcopenia [34]. Furthermore, estrogen could have a direct effect on muscle mass, since skeletal muscle fibers have estrogen beta‐receptors on the cell membranes, in the cytoplasm, and on the nuclear membrane [35].…”