Interrelation between genotypes of the vitamin D receptor gene and serum sex hormone concentrations in the Polish elderly population: the PolSenior study

Oxytocin Receptor Gene Polymorphism in Lactating Dogs

Simple Summary

Oxytocin is commonly known for its role in mammalian bonding. Several studies have proved that polymorphisms of the oxytocin receptor gene are related to complex social behaviors in humans, but studies on the possible correlation between canine social behavior and oxytocin are mainly focused on the human–dog bond, and there are no data on the possible correlation between oxytocin receptor gene polymorphism and the maternal behavior of this species. Since mother–litter interactions could have a severe impact in determining later behavior in domestic dogs, the aim of this work was to investigate the possible correlation between salivary oxytocin, maternal care and the one known single-nucleotide polymorphism (rs8679684) located in the untranslated regulatory region of the oxytocin receptor gene in 19 lactating Labrador Retriever dogs. A significant correlation between oxytocin receptor gene polymorphism, peripheral oxytocin and maternal behavior in dogs was found. This implies that a more functional oxytocinergic system would lead to better mothering in dogs.

Abstract

Genetic variations in the oxytocinergic system, known to regulate social behavior throughout the evolution of mammals, are believed to account for differences in mammalian social behavior. Particularly, polymorphic variants of the oxytocin receptor (OXTR) gene have been associated with behavioral variations in both humans and dogs. In this study, we offered evidence of the correlation between levels of salivary oxytocin (sOXT), maternal behavior and a single-nucleotide gene variant in OXTR (rs8679684) in nineteen lactating Labrador Retriever dogs. Carriers of at least one copy of the minor A allele showed higher levels of sOXT and maternal care in comparison with the homozygous T allele carriers. Considering the relevance of mother care in newborn development, these findings could help us to better understand the possible impact of variants in the OXTR gene in selecting dams.

Reviewing the Evidence on Vitamin D Supplementation in the Management of Testosterone Status and Its Effects on Male Reproductive System (Testis and Prostate): Mechanistically Dazzling but Clinically Disappointing

PURPOSE

Vitamin D supplementation has been suggested to increase testosterone levels. The primary purpose of this literature review was to critically assess the physiologic effects of vitamin D supplementation on serum testosterone concentrations in men and the secondary purpose was to evaluate the feasibility of vitamin D status toward urologic health (testis and prostate).

METHODS

A structured literature review was performed using the Cochrane, MEDLINE, and Web of Science databases. The literature search encompassed studies published between 2011 and 2019.

FINDINGS

Observational studies suggest an association between higher testosterone and serum vitamin D concentrations. Conversely, most randomized clinical trials that investigated the effect of vitamin D administration on testosterone levels have failed to detect any significant effect. Physiologically, vitamin D is engaging in spermatogenesis, but it remains unclear whether vitamin D is a determinant of fertility. With prostate support, the management of vitamin D status has been associated with a decreased prevalence of benign prostatic hyperplasia and symptoms (ie, lower urinary tract symptoms). However, with prostate cancer, there is a paucity of evidence pertaining to vitamin D supplementation.

IMPLICATIONS

Mechanistically, vitamin D exhibits essential roles in the testis and prostate; otherwise, there is no apparent evidence to support the use of vitamin D supplementation to increase testosterone levels and to improve clinical outcomes related to the male reproductive system.

The Impact of Vitamin D Receptor Gene Polymorphisms on the Susceptibility of Diabetic Vascular Complications: A Meta-Analysis

Background: To determine whether vitamin D receptor (VDR) gene polymorphisms are correlated with susceptibility to diabetic vascular complications. Methods: We included all eligible studies, and used Stata12.0 to calculate the pooled results. Results: Eight thousand eleven diabetic patients and 1635 normal controls from 27 studies were included. Our results showed that there was no correlation between VDR gene TaqI variants and diabetic nephropathy (DN) or diabetic retinopathy (DR) susceptibility. In comparison with diabetic patients without DN, there was a link between the VDR gene ApaI variant and DN susceptibility under allelic model (p = 0.029) in all populations. In addition, the VDR gene BsmI variant correlated with DN under both dominant (p = 0.005) and allelic (p = 0.003) models in Asian populations. The VDR gene FokI variant was also correlated with DN susceptibility under the recessive model (p = 0.027) in the Asian subgroup. In comparison with diabetic patients without DR, we identified a link between the VDR gene ApaI variant and DR susceptibility under the dominant model (p = 0.034) in all populations. Also, the VDR gene FokI variant was correlated with DR under the recessive (p = 0.016), the allelic (p = 0.001), and the dominant (p < 0.001) models in all populations. When compared with healthy controls, the VDR gene BsmI variant was associated with DR under the additive (p = 0.014), the allelic (p = 0.033), and the dominant (p < 0.001) models in Indian populations. Conclusions: The VDR gene BsmI, ApaI, and FokI gene variants are associated with DN and DR susceptibility. No association was found between the VDR gene TaqI gene variants and diabetic vascular complications.

Parathyroid hormone response to different vitamin D levels in population-based old and very-old Polish cohorts

BACKGROUND

Low vitamin D (VD) is not always followed by the development of secondary hyperparathyroidism (SHPT). The study aimed to assess the prevalence of SHPT and functional hypoparathyroidism (FHPT) in relation to VD deficiency/insufficiency and factors predisposing to parathyroid hormone (PTH) response in old and very-old Caucasians.

METHODS

A sub-study of the cross-sectional PolSenior project analyzed serum 25(OH)D, intact PTH (iPTH) and C-terminal fibroblast growth factor 23 (cFGF23) concentrations in 3472 (1658 women) individuals aged ≥65 years. SHPT was defined as iPTH concentration > 65 pg/mL, while FHPT as iPTH within the reference range in the presence of 25(OH)D < 30 ng/mL.

RESULTS

SHPT was diagnosed in 426 participants (14%) and was more frequent in very-old (≥ 80 years) than in the old (65-79 years) subgroup (18.8 vs 9.8%; OR = 2.12; 95% CI: 1.72-2.62). While, FHPT was found in 2269 subjects (85.2%) with 25(OH)D < 30 ng/mL, and was more prevalent in the old than very-old subgroup (89.3 vs 80.1%; OR = 2.03; 95% CI: 1.63-2.52). Multiple regression analysis showed that age ≥ 80 years, use of loop diuretics, decreased glomerular filtration rate, higher cFGF23 level but lower calcium and phosphate concentrations, predispose for the occurrence of SHPT.

CONCLUSIONS

The interrelation between 25(OH)D deficiency and PTH response is complex. In older adults, PTH response is related to VD deficiency, age, impaired kidney function, the use of loop diuretics and the levels of calcium, phosphate, and cFGF23.

Exploratory data analysis of a clinical study group: Development of a procedure for exploring multidimensional data

Thorough knowledge of the structure of analyzed data allows to form detailed scientific hypotheses and research questions. The structure of data can be revealed with methods for exploratory data analysis. Due to multitude of available methods, selecting those which will work together well and facilitate data interpretation is not an easy task. In this work we present a well fitted set of tools for a complete exploratory analysis of a clinical dataset and perform a case study analysis on a set of 515 patients. The proposed procedure comprises several steps: 1) robust data normalization, 2) outlier detection with Mahalanobis (MD) and robust Mahalanobis distances (rMD), 3) hierarchical clustering with Ward's algorithm, 4) Principal Component Analysis with biplot vectors. The analyzed set comprised elderly patients that participated in the PolSenior project. Each patient was characterized by over 40 biochemical and socio-geographical attributes. Introductory analysis showed that the case-study dataset comprises two clusters separated along the axis of sex hormone attributes. Further analysis was carried out separately for male and female patients. The most optimal partitioning in the male set resulted in five subgroups. Two of them were related to diseased patients: 1) diabetes and 2) hypogonadism patients. Analysis of the female set suggested that it was more homogeneous than the male dataset. No evidence of pathological patient subgroups was found. In the study we showed that outlier detection with MD and rMD allows not only to identify outliers, but can also assess the heterogeneity of a dataset. The case study proved that our procedure is well suited for identification and visualization of biologically meaningful patient subgroups.

Association of the vitamin D receptor FokI gene polymorphism with sex- and non-sex-associated cancers: A meta-analysis

Currently higher morbidity and mortality rates are observed in cancer diseases, especially sex-dependent cancers. A positive role of endogenous vitamin D concentration in cancer diseases has been reported in many publications. Furthermore, there has been observed a relationship between serum vitamin D and testosterone concentrations in an elderly Caucasian population carrying the vitamin D receptor FokI gene polymorphism. The aim of this study was to investigate whether the vitamin D receptor FokI polymorphism is associated with cancerogenesis in sex-dependent cancers. The MEDLINE and ResearchGate databases were used to search for articles up to January 2017, and 96 articles concerning the FokI polymorphism were chosen. Odds ratios with 95% confidence intervals were used to assess the strength of associations between polymorphisms of vitamin D receptor and cancer risk in the described populations. The fixed-effects model and the DerSimonian-Laird random-effects model (with weights based on the inverse variance) were used to calculate summary odds ratios, and both within- and between-study variation were considered. Generally, the F variant reduces the risk of cancer by 4% (odds ratio = 0.96, p value = 0.0057). This effect is particularly evident in female sex-associated cancers (odds ratio = 0.96, 95% confidence interval: 0.93-0.99, p value = 0.0259), but it is not observed in non-sex-associated cancers. Polymorphism FokI is associated with breast and ovarian cancers.

Associations of vitamin D status and vitamin D-related polymorphisms with sex hormones in older men

OBJECTIVE

Evidence regarding relationships of serum 25-hydroxyvitamin D (25(OH)D) with sex hormones and gonadotropin concentrations remains inconsistent. Polymorphisms in vitamin D-related genes may underly these relationships. Our aim was to examine the relationship of vitamin D status and polymorphisms in vitamin D-related genes with sex hormone and gonadotropin levels.

DESIGN AND MEASUREMENTS

We analysed data from the Longitudinal Aging Study Amsterdam, an ongoing population-based cohort study of older Dutch individuals (65-89 years). We included data of men with measurements of serum 25-hydroxyvitamin D (25(OH)D) (n=643) and determination of vitamin D-related gene polymorphisms (n=459). 25(OH)D concentrations were classified into four categories: <25, 25-50, 50-75 and >75nmol/L. Outcome measures were total testosterone, calculated bioavailable and free fraction testosterone, SHBG, estradiol, LH and FSH concentrations. Hypogonadism was defined as a total testosterone level <8.0nmol/L.

RESULTS

Serum 25(OH)D was positively associated with total and bioavailable testosterone levels. After adjustments for confounders, men with serum 25(OH)D less than 25 (n=56), 25-50 (n=199) and 50-75nmol/L (n=240) had lower total testosterone levels compared to men with serum 25(OH)D higher than 75nmol/L (n=148) (β (95% confidence interval): -2.1 (-3.7 to -0.4nmol/L), -0.8 (-1.9 to 0.4nmol/L) and -1.4 (-2.4 to -0.3nmol/L), respectively). For bioavailable testosterone the association was significant only for men with serum 25(OH)D less than 25nmol/L (-0.8 (-1.4 to -0.1nmol/L)) compared to men with serum 25(OH)D >75nmol/L. Serum 25(OH)D was not related to SHBG, estradiol or gonadotropin levels. Hypogonadism (n=29) was not associated with lower serum 25(OH)D. No significant differences were found in hormone levels between the different genotypes of the vitamin D-related gene polymorphisms. Also, the polymorphisms did not modify the relationships of serum 25(OH)D with sex hormones or gonadotropins.

CONCLUSION

Vitamin D status is positively associated with testosterone levels. No association was found between vitamin D-related gene polymorphisms and hormone levels.

Vitamin D receptor gene polymorphisms in Alzheimer's disease patients

THE AIM

The aim of this study was to determine whether polymorphisms of the VDR gene may increase the risk of Alzheimer disease (AD) development in Lower Silesian patients in comparison with other populations.

MATERIAL AND METHODS

108 AD patients (aged 73.7±8.6) vs 77 healthy volunteers (aged 64.5±7.8) in the Lower Silesian population were studied. We investigated the frequency of the VDR polymorphisms rs731236 (TaqI), rs7975232 (ApaI), rs10735810 (FokI) and rs1544410 (BsmI) in the AD group vs the healthy group. Afterwards, MEDLINE and ResearchGate were studied to compare our investigation with other populations, due to the relatively small group size in our study.

RESULTS

We did not observe any significant differences in frequency of genotypes of rs731236 (TaqI), rs10735810 (FokI) or rs1544410 (BsmI) VDR polymorphisms between the two Lower Silesian groups. Frequency of allele A of ApaI in the control group was significantly higher vs AD patients (p<0.0177) in the Lower Silesian population. Furthermore the difference in the occurrence of allele t in TaqI and allele A in ApaI between AD patients vs the control group was significant (respectively p<0.0056, p<0.0140) in British Europeans. This observation may suggest that allele "a" of the ApaI polymorphism is a risk allele in AD Lower Silesian patients. We compared our results with those obtained for the population of British Europeans. In multivariate stepwise regression, allele "A" of ApaI was associated with 30% lower risk of AD (OR=0.70, p=0.0009) in total treated Polish and British populations. We did not observe similar results in Turkish and Iranian populations.

CONCLUSION

Our data suggest that the allele "A" VDR genotype of ApaI reduces AD risk, probably depending on ethnic origin and climatic conditions.

Association between vitamin D concentration and levels of sex hormones in an elderly Polish population with different genotypes of VDR polymorphisms (rs10735810, rs1544410, rs7975232, rs731236)

BACKGROUND

Vitamin D co-regulates the synthesis of sex hormones in part by interaction with its nuclear receptor. The aim of this study was to determine whether there is an association of vitamin D concentration vs the level of sex hormones in elderly Polish individuals with different genotypes of the vitamin D receptor (VDR) gene.

MATERIALS AND METHODS

Rs10735810, rs1544410, rs7975232, and rs731236 polymorphisms of VDR, the serum sex hormone level, free estrogen index (FEI) and free androgen index (FAI) as well as vitamin D, were evaluated in 766 persons (362 women and 404 men) selected from 5695 Polish population, aged 65-90years from the PolSenior survey.

RESULTS

We observed that women with GG (rs731236), TT (rs7975232), BB (rs1544410) and FF (rs10735810) genotypes were characterized by a significant correlation between vitamin D vs testosterone concentration and FAI value. We found a significant correlation between testosterone level and FAI vs vitamin D concentration in men with heterozygote AG in the rs731236 polymorphism and in the GG (rs7975232), the BB (rs1544410), and the Ff (rs10735810) genotypes.

CONCLUSION

In elderly selected Polish population with different genotypes of VDR polymorphisms, a statistically significant relationship between vitamin D concentration vs testosterone level was observed.

Classic PCOS phenotype is not associated with deficiency of endogenous vitamin D and VDR gene polymorphisms rs731236 (TaqI), rs7975232 (ApaI), rs1544410 (BsmI), rs10735810 (FokI): a case-control study of lower Silesian women

CONTEXT

The role of endogenous vitamin D and vitamin D receptor (VDR) gene polymorphism in polycystic ovary syndrome (PCOS) is still controversial.

OBJECTIVE

The objective of this study was to investigate for the first time in women with "classic" PCOS phenotype and healthy controls the role of the serum endogenous vitamin D level and VDR gene polymorphisms in PCOS etiology.

DESIGN

Ninety-two women with "classic" PCOS phenotype and 85 controls from lower Silesia with comparable body mass index (BMI) were studied. In all women the waist circumference, android/gynoid fat deposit, parameters of lipid and glucose metabolism, testosterone, free androgen index, sex hormone binding globulin (SHBG) and vitamin D were evaluated. Also, VDR gene polymorphisms rs731236, rs7975232, rs1544410 and rs10735810 were assessed.

RESULTS

Serum vitamin D levels in both groups were comparable. Also high, comparable frequencies of hypovitaminosis and vitamin D deficiency in both groups were observed. Women with "classic" PCOS phenotype had statistically significantly higher values of all measured parameters, except serum SHBG and high-density lipoprotein (HDL)-cholesterol, which were lower. The frequency of VDR genotype polymorphism was also comparable in both groups.

CONCLUSIONS

For the first time, we show that endogenous vitamin D deficiency and VDR polymorphisms are not associated with homogeneous "classic" PCOS phenotype.

Vitamin D receptor gene polymorphisms in relation to the risk of colorectal cancer in the Polish population

The protective effect of vitamin D against several cancers including colorectal cancer is modulated by the vitamin D receptor (VDR) and its ligand, the active form of vitamin D. VDR response has been found to play a role in various genes encoding proteins involved in crucial cellular pathways. Single nucleotide polymorphisms (SNPs) of the VDR gene that modulate its activity are located in the promoter region, exons 2–9, and their vicinity and also in the 3′UTR region. Some of them have been previously studied in relation to cancer susceptibility and prognosis. The aim of our study was to investigate four polymorphisms, BsmI, ApaI, TaqI, and FokI, of the VDR gene in Polish patients with sporadic colorectal cancer and to evaluate their association with susceptibility to cancer. We found a significant association between the BsmI genotype and cancer (individuals with the bb genotype are more susceptible to cancer compared to those with other genotypes, p = 0.025, Fisher’s exact test for 2 × 2 table). Also, the TT genotype at TaqI and the AA genotype at ApaI are correlated with a higher risk of cancer (p = 0.00071 and p = 1.0 × 10⁻⁵, respectively). We found relatively strong linkage disequilibrium between the TaqI and ApaI loci (T with A and t with a, respectively). Both of these loci are associated with cancer. We do not observe any such association for the FokI polymorphism. In conclusion, a small modification in VDR expression may play a role in such a multipathway process as tumorigenesis.