Association between serum estradiol concentrations and carotid atherosclerosis in men with type 2 diabetes mellitus

Apolipoprotein C3 is negatively associated with estrogen and mediates the protective effect of estrogen on hypertriglyceridemia in obese adults

BACKGROUND

Both estrogen and apolipoprotein C3 (ApoC3) play crucial roles in lipid metabolism. But the link between them remains unclear, and it is unknown whether estrogen regulates triglyceride (TG) levels via ApoC3. Researchers hypothesized that estrogen exerts a regulatory effect on ApoC3 metabolism, and that this regulation could play a significant role in lipid metabolism. To explore this potential link, the present investigation aimed to examine the associations between estradiol (E2), ApoC3, and TG levels in both males and females.

METHODS

A total of 519 obese people (133 males and 386 premenopausal females) were recruited. Based on their TG levels, the participants were split into two groups [hypertriglyceridemia (HTG) group: TG ≥ 1.7 mmol/L; control group: TG < 1.7 mmol/L]. Serum ApoC3, E2, and TG levels were measured and compared in those two groups for both sexes separately. To ascertain the connection among E2, ApoC3, and TG, linear regression and mediation analysis were used.

RESULTS

Participants in the HTG group presented higher levels of ApoC3 (P < 0.001). In contrast, they tend to have lower E2 levels than the control. Linear regression analysis proposed that in both sexes, E2 was negatively associated with ApoC3 levels. The relationship remained significant after adjustment for confounding factors (male: standardized β = -0.144, t = -2.392, P < 0.05; female: standardized β = -0.077, t = -2.360, P < 0.001). Furthermore, mediation analysis revealed the relationship between reduced E2 levels and elevated TG levels is directly mediated by ApoC3.

CONCLUSIONS

In obese men and premenopausal women, ApoC3 was negatively and linearly correlated with serum E2 levels. The findings showed that estrogen may suppress ApoC3 expression and thus lower TG levels.

Male subclinical hypogonadism and late-onset hypergonadotrophic hypogonadism: mechanisms, endothelial function, and interplay between reproductive hormones, undercarboxylated osteocalcin, and endothelial dysfunction

BACKGROUND

Pathogenesis and endothelial function in subclinical hypogonadism (SCH) remain unclear. Undercarboxylated osteocalcin (ucOC) participates in atherosclerosis and reproduction. We explored the underlying mechanisms and interplay of endothelial dysfunction, unOC and reproductive hormones in SCH and primary late-onset hypogonadism (LOH).

METHODS

In the SCH, LOH, and healthy eugonadal male groups, we measured serum unOC, calculated luteinizing hormone/testosterone (LH/T), LH.T product, and estradiol/T (E/T) as indicators of impaired Leydig cells, androgen sensitivity index (ASI), and aromatase activity, respectively (LH set-point regulators), and assessed flow-mediated dilation of the brachial artery (FMD%), carotid-intima media thickness (CIMT), and aortic stiffness (AS).

RESULTS

↑LH/T, ↑ASI, ↓aromatase activity, normal T, follicle-stimulating hormone (FSH) and sex hormone-binding globulin (SHBG) levels, ↑unOC, and enhanced atherosclerotic markers (↓FMD%, ↑CIMT, ↑AS) are characteristics of SCH. Testosterone was positively correlated with FMD% in SCH. The independent predictors were: SHBG and LH for FMD% and CIMT, respectively, and LH/T, ucOC, FSH, estradiol, and E/T ratio for AS in the LOH group; and LH for FMD% & AS and LH and LH/T for CIMT in all study subjects.

CONCLUSIONS

SCH is a distinct clinical entity characterized by impaired androgen sensitivity and aromatase activity, compensatory elevated unOC, endothelial dysfunction, and anti-atherogenic role of testosterone.

Profiles of Two Glycaemia Modifying Drugs on the Expression of Rat and Human Sulfotransferases

AIMS

To study the effects of blood glucose regulating compounds on human and rat sulfotransferases (SULTs) expressions.

BACKGROUND

Phase-II enzymes, sulfotransferases catalyze the sulfuryl-group-transfer to endogenous/exogenous compounds. The alteration of expressions of SULTs may have influence on the sulfation of its substrate and other biomolecules.

OBJECTIVES

The influence of the altered biotransformation might alter different biochemical events, drug-drug interactions and bioaccumulation or excretion pattern of certain drug.

METHODS

In this brief study, diabetes-inducing drug streptozotocin (STZ; 10 or 50 mg/kg to male Sprague Dawley rat for 2 weeks) or hyperglycemia controlling drug tolbutamide (TLB 0.1 or 10μM to human hepato-carcinoma cells, HepG2 for 10 days) was applied and the SULTs expressions were verified. Extensive protein-protein (STa, SULT2A1/DHEAST) interactions were studied by the STRING (Search-Tool-for-the-Retrieval-of-Interacting Genes/Proteins) Bioinformatics-software.

RESULTS

Present result suggests that while STZ increased the STa (in rat) (dehydroepiandrosterone catalyzing SULT; DHEAST in human HepG2), tolbutamide decreased PPST (phenol catalyzing SULT) and DHEAST activity in human HepG2 cells. Moderate decreases of MPST (monoamine catalyzing SULT) and EST (estrogen catalyzing) activities are noticed in this case. STa/DHEAST was found to be highly interactive to SHBG/- sex-hormone-binding-globulin; PPARα/lipid-metabolism-regulator; FABP1/fatty-acid-binding-protein.

CONCLUSION

Streptozotocin and tolbutamide, these two glycaemia-modifying drugs demonstrated regulation of rat and human SULTs activities. The reciprocal nature of these two drugs on SULTs expression may be associated with their contrasting abilities in influencing glucose-homeostasis. Possible association of certain SULT-isoform with hepatic fat-regulations may indicate an unfocused link between calorie-metabolism and the glycemic-state of an individual. Explorations of this work may uncover the role of sulfation metabolism of specific biomolecule on cellular glycemic regulation.

The impact of type 1 diabetes mellitus on male sexual functions and sex hormone levels

Little is known about type 1 diabetes mellitus (T1DM) impact on the male sexual and reproductive functions. We aim to evaluate the influence of T1DM on male sexual function, quality of sexual life, and sex hormone levels. A total of 57 male patients aged 18 to 50 years (mean = 33) with T1DM (duration mean = 15 years) had a medical examination and completed a set of questionnaires - International Index of Erectile Function-5 (IIEF-5), Beck Depression Inventory (BDI) and Sexual quality of life questionnaire male (SQoL-M). The prevalence of erectile dysfunction was 28.1% (IIEF-5 ≤21). Patients without diabetic nephropathy had better erectile function (p = 0.008). Subjects with better glycemic control (HbA_1c <65 mmol/mol) had also better erectile function (p = 0.041). At least 8.8% patients had retrograde ejaculation. Blood serum levels of sex hormones were determined and compared to laboratory reference values of healthy men. Total testosterone level was not significantly changed, sex hormone binding globulin was higher (p < 0.001) and its level correlated with daily insulin dose adjusted to body weight (p = 0.008). Free androgen index and calculated free testosterone were lower (p = 0.013; p < 0.001), estradiol was not significantly changed, LH was higher (p < 0.001), FSH was unchanged, and prolactin was higher (p < 0.001). Prostate-specific antigen (PSA) negatively correlated with HbA_1c (p < 0.001). To conclude, we found significant changes in sexual functions and sex hormone blood concentrations that indicate impairment of sexual and reproductive functions in T1DM males.

Associations of Endogenous Estradiol and Testosterone Levels With Plaque Composition and Risk of Stroke in Subjects With Carotid Atherosclerosis

RATIONALE

Sex steroids may play a role in plaque composition and in stroke incidence.

OBJECTIVES

To study the associations of endogenous estradiol and testosterone with carotid plaque composition in elderly men and postmenopausal women with carotid atherosclerosis, as well as with risk of stroke in this population.

METHODS AND RESULTS

Data of 1023 postmenopausal women and 1124 men (≥45 years) with carotid atherosclerosis, from prospective population-based RS (Rotterdam Study), were available. At baseline, total estradiol (TE) and total testosterone (TT) were measured. Carotid atherosclerosis was assessed by ultrasound, whereas plaque composition (presence of calcification, lipid core, and intraplaque hemorrhage) was assessed by magnetic resonance imaging. TE and TT were not associated with calcified carotid plaques in either sex. TE was associated with presence of lipid core in both sexes (in women odds ratio, 1.48 [95% confidence interval [CI], 1.02-2.15]; in men odds ratio, 1.23 [95% CI, 1.03-1.46]), whereas no association was found between TT and lipid core in either sex. Higher TE (odds ratio, 1.58 [95% CI, 1.03-2.40]) and lower TT (odds ratio, 0.82 [95% CI, 0.68-0.98]) were associated with intraplaque hemorrhage in women but not in men. In women, TE was associated with increased risk of stroke (hazard ratio, 1.98 [95% CI, 1.01-3.88]), whereas no association was found in men. TT was not associated with risk of stroke in either sex.

CONCLUSIONS

TE was associated with presence of vulnerable carotid plaque as well as increased risk of stroke in women, whereas no consistent associations were found for TT in either sex.

A cross-sectional study on the associations of insulin resistance with sex hormone, abnormal lipid metabolism in T2DM and IGT patients

Type 2 diabetes mellitus (T2DM) is a long-term metabolic disorder. It is characterized by hyperglycemia, insulin resistance (IR), and relative impairment in insulin secretion. IR plays a major role in the pathogenesis of T2DM. Many previous studies have investigated the relationship between estrogen, androgen, and obesity, but few focused on the relationship between sex hormones, abnormal lipid metabolism, and IR. The goal for the present study was to identify the association of IR with sex hormone, abnormal lipid metabolism in type 2 diabetes, and impaired glucose tolerance (IGT) patients.In total 13,400 participants were analyzed based on the results of the glucose tolerance test. Using a cross-sectional study, we showed the relationship between IR and the level of sex hormones among 3 different glucose tolerance states: normal control people, IGT, and T2DM patients. We also analyzed the relationship between IR and abnormal lipid metabolism.Significantly, luteinizing, progesterone, estradiol, prolactin, and follicle-stimulating hormone levels decreased in T2DM and IGT patients compared with those in normal control people. The association between IR and lipid metabolism disorders in T2DM and IGT patients was also observed.Our clinical findings may offer new insights into understanding the mechanism of metabolic disorders and in new therapeutic methods for the treatment of the prevalence of type 2 diabetes.

Testosterone, dihydrotestosterone and estradiol are differentially associated with carotid intima-media thickness and the presence of carotid plaque in men with and without coronary artery disease

Clarifying the relationship of sex hormones to preclinical atherosclerosis could illuminate pathways by which androgens are associated with cardiovascular events and mortality. Our aim was to determine hormone profiles associated with carotid intima-media thickness (CIMT) and carotid atheroma, in men with and without known coronary artery disease (CAD). We included 492 community-based men aged 20-70 years (Group A) and 426 men with angiographically proven CAD aged <60 years (Group B). Fasting early morning sera were assayed for testosterone (T), dihydrotestosterone (DHT) and estradiol (E2) using mass spectrometry. CIMT and carotid plaque were assessed ultrasonographically. Mean (±SD) age was Group A: 53.8±12.6 and Group B: 49.6±5.1 years. Higher T was associated with reduced CIMT (-0.011 mm per 1-SD increase, p=0.042) and lower prevalence of carotid plaque (odds ratio [OR] per 1-SD increase, 0.68, p=0.012) in Group A, but not B. E2 was associated with increased CIMT in Group A (0.013 mm, p=0.011) but not B. Higher DHT and E2 were associated with reduced carotid plaque in Group B (DHT: OR=0.77, p=0.024; E2: OR=0.75, p=0.008), but not A. In community-dwelling men, higher T is associated with favourable CIMT and lower prevalence of carotid plaque, while higher E2 is associated with worse CIMT. In men with CAD, higher DHT or E2 are associated with less carotid plaque. T, DHT and E2 are differentially associated with preclinical carotid atherosclerosis in a cardiovascular phenotype-specific manner. Interventional studies are needed to examine effects of exogenous T and its metabolites DHT and E2, on atherogenesis.

Low plasma testosterone and elevated carotid intima-media thickness: importance of low-grade inflammation in elderly men

CONTEXT AND OBJECTIVE

An inverse correlation between plasma testosterone levels and carotid intima-media thickness (IMT) has been reported in men. We investigated whether this association could be mediated or modified by traditional cardiovascular risk factors as well as inflammatory status.

METHODS

In the Three-City population-based cohort study, 354 men aged 65 and over had available baseline data on hormones levels and carotid ultrasonography. Plasma concentrations of testosterone (total and bioavailable), estradiol and sex hormone-binding globulin (SHBG), together with cardiovascular risk factors were measured. IMT in plaque-free site and atherosclerotic plaques in the extracranial carotid arteries were determined using a standardized protocol. Multiple linear regression models were used to analyze this association and interaction study.

RESULTS

Analyses with and without adjustment for cardiovascular risk factors showed that carotid IMT was inversely and significantly correlated with total and bioavailable testosterone levels but not with SHBG and estradiol levels. This association depended on C-reactive protein (CRP) levels (p for interaction <0.05). Among men with low-grade inflammation (CRP ≥2 mg/L), mean IMT was higher in subjects with bioavailable testosterone ≤ 3.2 ng/mL than in those with bioavailable testosterone > 3.2 ng/mL (0.76 mm and 0.70 mm respectively, p < 0.01). By contrast, among men with CRP ≤ 2 mg/L, mean IMT was similar in both groups (0.72 mm and 0.71 mm respectively, p = 0.77). Similar results were found for total testosterone although not significant. No association was found between plasma hormones levels and atherosclerotic plaques.

CONCLUSION

In elderly men, low plasma testosterone is associated with elevated carotid intima-media thickness only in those with low-grade inflammation. Traditional risk factors have no mediator role.