Parathyroid Hormone Senses Extracellular Calcium To Modulate Endocrine Signaling upon Binding to the Family B GPCR Parathyroid Hormone 1 Receptor

Acculturation and biological stress markers: A systematic review

BACKGROUND

The association of acculturation with health among immigrant populations is believed to be mediated, in part, by acculturation-related stress and stress biology.

OBJECTIVES

To review and qualitatively synthesize empirical findings on the relationship of acculturation with stress-related inflammatory and endocrine biomarkers and composite allostatic load (AL) scores.

METHODS

A literature search was performed in the PubMed and PsycInfo databases. Article titles, abstracts or full-texts were screened and checked for match with the search criteria. Studies were eligible if they empirically tested the relationship between acculturation and inflammatory/endocrine stress biomarkers or composite AL scores, and were published in the English language.

RESULTS

Among the 41 articles identified as relevant and included in this review, the majority were published after 2010, included adult Hispanic U.S.-based populations, used cross-sectional study designs, operationalized acculturation as a unidimensional construct, and varied considerably in the selection of covariates in the analyses. Acculturation was significantly associated with stress biomarkers in 29 studies, but the direction of effects varied across studies. Specifically, acculturation, operationalized as a higher orientation towards the host culture, was associated with inflammatory biomarkers in 10 of 14 studies, with endocrine stress biomarkers in 12 of 20 studies, and with composite AL scores in 7 of 8 studies. Overall, language-based proxy measures of acculturation were related to higher levels of stress-related inflammatory and endocrine biomarkers and to lower levels of AL scores, whereas nativity-, generation status- and length of stay-based proxy measures of acculturation were related to higher levels of inflammatory biomarkers and AL score.

DISCUSSION

The majority of studies reported associations between measures of acculturation and stress biomarkers, however the directions of effects varied across studies. We suggest this heterogeneity may, in part, be a function of limitations imposed by cross-sectional research designs and unidimensional measures of acculturation measures, and we highlight the need for longitudinal studies and use of multidimensional measures of acculturation to better uncover the biobehavioral mechanisms and pathways linking acculturation with health outcomes.

The Effects of Sodium Ions on Ligand Binding and Conformational States of G Protein-Coupled Receptors-Insights from Mass Spectrometry

The use of mass spectrometry to investigate proteins is now well established and provides invaluable information for both soluble and membrane protein assemblies. Maintaining transient noncovalent interactions under physiological conditions, however, remains challenging. Here, using nanoscale electrospray ionization emitters, we establish conditions that enable mass spectrometry of two G protein-coupled receptors (GPCR) from buffers containing high concentrations of sodium ions. For the Class A GPCR, the adenosine 2A receptor, we observe ligand-induced changes to sodium binding of the receptor at the level of individual sodium ions. We find that antagonists promote sodium binding while agonists attenuate sodium binding. These findings are in line with high-resolution X-ray crystallography wherein only inactive conformations retain sodium ions in allosteric binding pockets. For the glucagon receptor (a Class B GPCR) we observed enhanced ligand binding in electrospray buffers containing high concentrations of sodium, as opposed to ammonium acetate buffers. A combination of native and -omics mass spectrometry revealed the presence of a lipophilic negative allosteric modulator. These experiments highlight the advantages of implementing native mass spectrometry, from electrospray buffers containing high concentrations of physiologically relevant salts, to inform on allosteric ions or ligands with the potential to define their roles on GPCR function.

Potential mechanisms linking psychological stress to bone health

Chronic psychological stress affects many body systems, including the skeleton, through various mechanisms. This review aims to provide an overview of the factors mediating the relationship between psychological stress and bone health. These factors can be divided into physiological and behavioural changes induced by psychological stress. The physiological factors involve endocrinological changes, such as increased glucocorticoids, prolactin, leptin and parathyroid hormone levels and reduced gonadal hormones. Low-grade inflammation and hyperactivation of the sympathetic nervous system during psychological stress are also physiological changes detrimental to bone health. The behavioural changes during mental stress, such as altered dietary pattern, cigarette smoking, alcoholism and physical inactivity, also threaten the skeletal system. Psychological stress may be partly responsible for epigenetic regulation of skeletal development. It may also mediate the relationship between socioeconomic status and bone health. However, more direct evidence is required to prove these hypotheses. In conclusion, chronic psychological stress should be recognised as a risk factor of osteoporosis and stress-coping methods should be incorporated as part of the comprehensive osteoporosis-preventing strategy.

Effect of Restraint Stress on Plasma PTH Concentration and Its Molecular Targets Expressions in Wistar Rats

BACKGROUND

There are limited numbers of experimental studies related to the potential role of parathormone/parathyroid hormone (PTH) in response to psychological stress. In the current study, we aimed to cross-examine, for the first time, changes in PTH plasma concentration and the expression of its molecular targets mediated by restraint stress in rats.

METHODS

Male Wistar rats (n = 42) were separated into control and stressed groups. They were further divided into two groups that received chronic restraint stress (CRS) for 7 and 28 consecutive days (n = 7 for each group). Elevated plus maze and tail suspension test were used to determine the anxiety- and depressive-like behaviors of a different set of rats including stress and control groups (n = 7 for each group). The plasma levels of adrenocorticotropic hormone (ACTH), corticosterone, and intact parathormone (iPTH) were measured by enzyme-linked immunosorbent assay (ELISA). In addition, alterations in the expressions of glucocorticoid receptor (GR), calcium sensing receptor (CaSR), and parathormone receptor (PTHR1) of kidney and total thyroid gland tissues were estimated by Western Blotting.

RESULTS

There was no significant difference in the plasma level of iPTH while significant increases in the levels of ACTH and corticosterone were noted in the stressed-animals at day 7 and 21 (P = 0.010 and P = 0.016, respectively) of restraint stress. However, we found a negative correlation between iPTH and corticosterone levels in acute restraint stress (r = 0.771, P = 0.002). In addition, the expression of PTHR1 significantly decreased in the kidney at day 7 (P = 0.001) and in the thyroid gland at day 28 (P = 0.05) in response to CRS.

CONCLUSIONS

To sum up, CRS has a significant effect on the expression of parathormone receptor rather than the iPTH concentration. The present results add a new dimension to stress research through the negative effect of chronic stress on the PTH signaling pathway.