The changes in plasma serotonin levels after hormone therapy and their relationship with estrogen responsiveness on bone in postmenopausal women

Improvement in resilience and stress-related blood markers following ten months yoga practice in Antarctica

BACKGROUND

Wintering is associated with distress to humans who work in the isolated and confined environment of Antarctica and yoga has been proved helpful for coping with stress. Therefore, a study was conducted on 14 winter expedition members of Indian Scientific Antarctic Expedition (2016) to find out the effects of yoga on stress-related markers.

METHODS

Participants were divided into yoga, and control (non-yoga) groups. The yoga group practiced yoga for 10 months (from January to October 2016) daily in the morning for an hour. The Resilience test questionnaire was administrated at baseline and endpoint of the study. Blood samples were collected during the study at different intervals for the estimation of 8-hydroxydeoxyguanosine (8-OHdG), brain-derived neurotrophic factor (BDNF), serotonin and cortisol using ELISA.

RESULTS

A trend of improvement was observed in the resilience test score in the yoga group. From January to October, 8-OHdG serum values in the yoga group declined by 55.9% from 1010.0 ± 67.8 pg/mL to 445.6 ± 60.5 pg/mL (Mean ± SD); in the control group, the decline was 49.9% from 1060.4 ± 54.6 pg/mL to 531.1 ± 81.8 pg/mL. In serotonin serum levels in the yoga group, there was a 3.1% increase from 6.4 ± 1.6 ng/mL to 6.6 ± 0.4 ng/mL while no increase was noticed in the control group. Cortisol values in the yoga group decreased by 19.9% from 321.0 ± 189.6 ng/mL to 257.1 ± 133.8 ng/mL; in the control group it increased by 2.8% from 241.2 ± 51.8 ng/mL to 247.8 ± 90.9 ng/mL.

CONCLUSIONS

It could be concluded from the present study that following 10 months yoga practice may be useful for better resilience and management of stress-related blood markers for the polar sojourners.

High Serum Serotonin Predicts Increased Risk for Hip Fracture and Nonvertebral Osteoporotic Fractures: The MrOS Sweden Study

Because several studies have implicated serotonin as a regulator of bone mass, we here explore its potential association on fracture risk and falls, as on bone mineral density (BMD) and muscle strength, in humans. Serum levels of serotonin were analyzed in 950 men (aged 69 to 81 years), participating in the Gothenburg part of the population-based study MrOS Sweden. Men taking selective serotonin reuptake inhibitors (SSRIs) had a mean value of 31.2 μg/L compared with 159.4 μg/L in those not taking SSRIs. SSRI users were excluded from further analysis. During 10-year follow-up, 224 men exhibited fractures, including 97 nonvertebral osteoporotic fractures (57 hip fractures), and 86 vertebral fractures. Serotonin was associated with hip fracture in linear analysis (hazard ratio [HR] = 1.27, 95% confidence interval [CI] 1.03-1.58) and to all fractures in a nonlinear manner, when quintiles of serotonin was included in quadratic terms (HR = 1.12, 95% CI 1.04-1.21). Men in serotonin quintile 5 had, in multivariable analysis, a HR of 2.30 (95% CI 1.31-4.02) for hip fracture and 1.82 (95% CI 1.17-2.85) for nonvertebral fractures compared with men in quintiles 1 to 4. Men in quintile 1 had, in multivariable analysis, a HR of 1.76 (95% CI 1.03-2.99) for nonvertebral fractures compared with men in quintiles 2 to 4. No association was found with vertebral fractures. Individuals in serotonin quintile 1 had higher prevalence of falls compared with quintiles 2 to 5 (odds ratio = 1.90, 95% CI 1.26-2.87). Serotonin was positively associated with hand-grip strength (r = 0.08, p = 0.02) and inversely with hip BMD (r = -0.10, p = 0.003). To assess the association between SSRIs and falls and fractures, the total MrOS Sweden cohort was examined (n = 3014). SSRI users (n = 90) had increased prevalence of falls (16% versus 33%, p = 0.0001) and increased rate of incident fractures (28.0 versus 44.7 per 1000 person-years, p = 0.018). We present novel data showing that high levels of serotonin predict an increased risk for hip fracture and nonvertebral osteoporotic fractures. © 2018 American Society for Bone and Mineral Research.

The Relationship of Serum Serotonin Levels to the Rate of Bone Loss and Fractures in Men

Recent genetic studies in rodents have revealed that circulating serotonin plays a key role in regulating bone formation and skeletal mass. However, the reported effects of circulating serotonin on bone mass in humans have been conflicting. We determined whether circulating serotonin levels influenced the rate of bone loss and fractures in men. We assessed the effect of serum serotonin on bone loss rate in a population-based cohort of 202 ambulatory men aged 56-70 years who were followed up for a median duration of 3.7 years. Serum serotonin levels were assayed, and the Timed Up and Go Test (TUGT) was performed, at baseline. Dual-energy X-ray absorptiometry was performed both at baseline and during follow-up. Fracture prevalence was assessed using questionnaires. The serotonin levels were inversely associated with the lumbar spine bone mineral density (r = -0.174, p = 0.028) at baseline. No association was evident between the bone mineral densities of the femoral neck or total hip and serotonin level. The annual rates of bone loss from the lumbar spine, the femoral neck, and the total hip were 0.01%, 0.46%, and 0.46%, respectively. The baseline serum serotonin level did not predict the bone loss rate in any skeletal site. Lower limb disability evident upon TUGT at baseline predicted bone loss from the total hip. No significant difference of serotonin level was observed between subjects with and without fractures. The serum serotonin level was not associated with the rate of bone loss in elderly men. Thus, the circulating serotonin level does not reliably predict bone loss.

Serum serotonin levels and bone in rheumatoid arthritis patients

In rheumatoid arthritis (RA), a disease characterized by bone loss, increased levels of serotonin have been reported. Recent studies have demonstrated a role for circulating serotonin as a regulator of osteoblastogenesis, inhibiting bone formation. Thus, we measured serum serotonin levels (SSL) in a Portuguese sample of 205 RA patients and related these to anthropometric variables, disease parameters, serum bone biomarkers, and bone mineral density (BMD) assessed by dual-energy X-ray absorptiometry at several sites (total proximal femur, lumbar spine, left hand, and left second proximal phalange). SSL were inversely associated with body mass index (BMI) in RA women (r = - 0.218; p = 0.005), independent of exposure to biologics and/or bisphosphonates. Among biologic naïves, there was an inverse association between SSL and osteoprotegerin in RA women (r = - 0.260; p = 0.022). Serum β-CTX and dickkopf-1 were strongly associated with SSL in RA men not treated with bisphosphonates (r = 0.590; p < 0.001/r = 0.387; p = 0.031, respectively). There was also an inverse association between SSL and sclerostin in RA men (r = - 0.374; p < 0.05), stronger among biologic naïve or bisphosphonates-unexposed RA men. In crude models, SSL presented as a significant negative predictor of total proximal femur BMD in RA women as well as in postmenopausal RA women. After adjustment for BMI, disease duration, and years of menopause, SSL remained a significant negative predictor of total proximal femur BMD only in postmenopausal RA women. Our data reinforce a role, despite weak, for circulating serotonin in regulating bone mass in RA patients, with some differences in terms of gender and anatomical sites.