title: Leukocyte and Skeletal Muscle Telomere Length and Body Composition in Monozygotic Twin Pairs Discordant for Long-term Hormone Replacement Therapy.
abstract: Estrogen-based hormone replacement therapy (HRT) may be associated with deceleration of cellular aging. We investigated whether long-term HRT has effects on leukocyte (LTL) or mean and minimum skeletal muscle telomere length (SMTL) in a design that controls for genotype and childhood environment. Associations between telomeres, body composition, and physical performance were also examined. Eleven monozygotic twin pairs (age 57.6 ± 1.8 years) discordant for HRT were studied. Mean duration of HRT use was 7.3 ± 3.7 years in the user sister, while their co-twins had never used HRT. LTL was measured by qPCR and SMTLs by southern blot. Body and muscle composition were estimated by bioimpedance and computed tomography, respectively. Physical performance was measured by jumping height and grip strength. HRT users and non-users did not differ in LTL or mean or minimum SMTL. Within-pair correlations were high in LTL (r = 0.69, p = .020) and in mean (r = 0.74, p = .014) and minimum SMTL (r = 0.88, p = .001). Body composition and performance were better in users than non-users. In analyses of individuals, LTL was associated with BMI (r 2 = 0.30, p = .030), percentage total body (r 2 = 0.43, p = .014), and thigh (r 2 = 0.55, p = .004) fat, while minimum SMTL was associated with fat-free mass (r 2 = 0.27, p = .020) and thigh muscle area (r 2 = 0.42, p = .016). We found no associations between HRT use and telomere length. Longer LTLs were associated with lower total and regional fat, while longer minimum SMTLs were associated with higher fat-free mass and greater thigh muscle area. This suggests that telomeres measured from different tissues may have different associations with measures of body composition.
authors.affiliation: Gerontology Research Centre,Faculty of Sport and Health Sciences,University of Jyväskylä,Jyväskylä,Finland.
authors.forename: Elina
authors.initials: E
authors.lastname: Sillanpää
authors.affiliation: Gerontology Research Centre,Faculty of Sport and Health Sciences,University of Jyväskylä,Jyväskylä,Finland.
authors.forename: Paula
authors.initials: P
authors.lastname: Niskala
authors.affiliation: Gerontology Research Centre,Faculty of Sport and Health Sciences,University of Jyväskylä,Jyväskylä,Finland.
authors.forename: Eija K
authors.initials: EK
authors.lastname: Laakkonen
authors.affiliation: School of Health and Medical Sciences,Örebro University,Örebro,Sweden.
authors.forename: Elodie
authors.initials: E
authors.lastname: Ponsot
authors.affiliation: Department of Medical Rehabilitation,Oulu University Hospital,Oulu,Finland.
authors.forename: Markku
authors.initials: M
authors.lastname: Alén
authors.affiliation: Department of Public Health,University of Helsinki,Helsinki,Finland.
authors.forename: Jaakko
authors.initials: J
authors.lastname: Kaprio
authors.affiliation: School of Health and Medical Sciences,Örebro University,Örebro,Sweden.
authors.forename: Fawzi
authors.initials: F
authors.lastname: Kadi
authors.affiliation: Gerontology Research Centre,Faculty of Sport and Health Sciences,University of Jyväskylä,Jyväskylä,Finland.
authors.forename: Vuokko
authors.initials: V
authors.lastname: Kovanen
authors.affiliation: Gerontology Research Centre,Faculty of Sport and Health Sciences,University of Jyväskylä,Jyväskylä,Finland.
authors.forename: Sarianna
authors.initials: S
authors.lastname: Sipilä
mesh_terms: D001823:Body Composition; D017097:Electric Impedance; D015914:Estrogen Replacement Therapy; D015444:Exercise; D005260:Female; D018737:Hand Strength; D006801:Humans; D007962:Leukocytes / Q000187:drug effects*; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000187:drug effects*; D016615:Telomere / Q000187:drug effects* / Q000648:ultrastructure; D014430:Twins, Monozygotic
keywords: bioimpedance; computed tomography; estrogen; fat-free mass; percentage of fat; post-menopausal; telomeres; twin design