Nocturnal oxytocin secretion is lower in amenorrheic athletes than nonathletes and associated with bone microarchitecture and finite element analysis parameters

Abstract

Objective Preclinical data indicate that oxytocin, a hormone produced in the hypothalamus and secreted into the peripheral circulation, is anabolic to bone. Oxytocin knockout mice have severe osteoporosis, and administration of oxytocin improves bone microarchitecture in these mice. Data suggest that exercise may modify oxytocin secretion, but this has not been studied in athletes in relation to bone. We therefore investigated oxytocin secretion and its association with bone microarchitecture and strength in young female athletes. Design Cross-sectional study of 45 females, 14–21 years (15 amenorrheic athletes (AA), 15 eumenorrheic athletes (EA), and 15 nonathletes (NA)), of comparable bone age and BMI. Methods We used high-resolution peripheral quantitative CT to assess bone microarchitecture and finite element analysis to estimate bone strength at the weight-bearing distal tibia and non-weight-bearing ultradistal radius. Serum samples were obtained every 60 min, 2300–0700 h, and pooled for an integrated measure of nocturnal oxytocin secretion. Midnight and 0700 h samples were used to assess diurnal variation of oxytocin. Results Nocturnal oxytocin levels were lower in AA and EA than in NA. After controlling for estradiol, the difference in nocturnal oxytocin between AA and NA remained significant. Midnight and 0700 h oxytocin levels did not differ between groups. At the tibia and radius, AA had impaired microarchitecture compared with NA. In AA, nocturnal oxytocin correlated strongly with trabecular and cortical microarchitecture, particularly at the non-weight-bearing radius. In regression models that include known predictors of microarchitecture in AA, oxytocin accounted for a substantial portion of the variability in microarchitectural and strength parameters. Conclusions Nocturnal oxytocin secretion is low in AA compared with NA and associated with site-dependent microarchitectural parameters. Oxytocin maycontribute to hypoestrogenemic bone loss inAA.

Translational and therapeutic potential of oxytocin as an anti-obesity strategy: Insights from rodents, nonhuman primates and humans

“…In some cases, OT levels are increased in certain obese rat models [95][96][97][98] as well as in obese humans [99] but are reduced following chronic pairfeeding in rats [97] or gastric banding-associated weight loss in humans [99]. In addition, other apparent inconsistencies arise in certain pathological states of energy deficit in humans where it has been shown that nocturnal levels of OT are reduced in both anorexia nervosa [100] and amenorrhea [101]. Whether these are considered adaptive or contributing factors in the development of anorexia nervosa remains to be determined [100].…”

Predicting mouse vertebra strength with micro-computed tomography-derived finite element analysis

“…The popularity of QCT-FEA (a.k.a. homogenized FEA) is evident in the growing number of clinical studies reporting strength predictions with FEAs derived from QCT scans of the hip, 1,2 spine, 3,4 distal tibia 5,6 and distal radius. 7,8 Moreover, as evidence of their ability to make such predictions, QCT-FEAs can differentiate fracture patients from non-fracture patients, although some overlap in predicted strength exists across the cohorts.…”

Oxytocin and bone

“…Indeed, lower OT levels have been found in postmenopausal women with osteoporosis compared with nonosteoporotic women (9). Low OT levels have also been observed in athletes (43) and in girls with anorexia nervosa (44). In these studies, Lawson et al (43,44) analyzed OT in two types of women characterized by their hypoestrogenic status: In amenorrheic athletes, a decrease in nocturnal OT secretion is strongly associated with alteration of bone architecture, assessed by high-resolution peripheral quantitative computed tomography; in women with anorexia nervosa, a decrease in nocturnal OT levels is associated with low bone mineral density.…”