Enzymatic intracrine regulation of white adipose tissue

Dehydroepiandrostenedione sulphate (DHEAS) levels predict high risk of rheumatoid arthritis (RA) in subclinical hypothyroidism

INTRODUCTION

The presence of rheumatism is well recognized in primary hypothyroidism. Dehydroepiandrstenedione sulphate (DHEAS) is associated with rheumatological diseases like rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). This study aims to explore relationship between joint pains and DHEAS levels in primary hypothyroidism.

METHODS

Retrospective study of 78 subjects with subclinical hypothyroidism, with TSH within reference range. The joint pains were evaluated by European Union League against rheumatism (EULAR-CSA) score and compared with serum DHEAS, RA factor, Anti-TPO antibody, highly sensitive C-recative protein (hsCRP), vitamin D levels.

RESULT

DHEAS levels <43.6 mcg/dl significantly predicted clinical features of pre RA as assessed by EULAR CSA criteria with acceptable specificity (82%). EULAR CSA score is fairly valid in assessing imminent RA in primary hypothyroidism.

CONCLUSION

Lower DHEAS predicts clinical features of imminent RA in subjects with primary hypothyroidism. This is akin to low DHEAS seen in many rheumatological disease with possibly similar mechanism. Another possibility is low DHEAS alters hepato-hypothalamo pituitary adrenal axis in presense of cytokines and induces a hitherto unrecognized state of pre rheumatoid arthritis like syndrome. Future studies on primary hypothyroidism should focus on role of lower DHEAS levels in inducing symptoms of fatigue and joint pains.

Paracardial fat remodeling affects systemic metabolism through alcohol dehydrogenase 1

The relationship between adiposity and metabolic health is well established. However, very little is known about the fat depot, known as paracardial fat (pCF), located superior to and surrounding the heart. Here, we show that pCF remodels with aging and a high-fat diet and that the size and function of this depot are controlled by alcohol dehydrogenase 1 (ADH1), an enzyme that oxidizes retinol into retinaldehyde. Elderly individuals and individuals with obesity have low ADH1 expression in pCF, and in mice, genetic ablation of Adh1 is sufficient to drive pCF accumulation, dysfunction, and global impairments in metabolic flexibility. Metabolomics analysis revealed that pCF controlled the levels of circulating metabolites affecting fatty acid biosynthesis. Also, surgical removal of the pCF depot was sufficient to rescue the impairments in cardiometabolic flexibility and fitness observed in Adh1-deficient mice. Furthermore, treatment with retinaldehyde prevented pCF remodeling in these animals. Mechanistically, we found that the ADH1/retinaldehyde pathway works by driving PGC-1α nuclear translocation and promoting mitochondrial fusion and biogenesis in the pCF depot. Together, these data demonstrate that pCF is a critical regulator of cardiometabolic fitness and that retinaldehyde and its generating enzyme ADH1 act as critical regulators of adipocyte remodeling in the pCF depot.

Premature Adrenarche and its Association with Cardiovascular Risk in Females

Early activation of the adrenal zona reticularis, leading to adrenal androgen secretion, mainly dehydroepiandrosterone sulfate (DHEAS), is called premature adrenarche (PA). The fact that adrenal hyperandrogenism in females has been linked to a cluster of cardiovascular (CV) risk factors, even in prepubertal children, warrants investigation. Controversial results have been obtained in this field, probably due to genetic, constitutional, and environmental factors or differences in the characteristics of participants. In an attempt to understand, in depth, the impact of PA as a potential activator of CV risk, we critically present available data stratified according to pubertal status. It seems that prepubertally, CV risk is increased in these girls, but is somewhat attenuated during their second decade of life. Furthermore, different entities associated with PA, such as polycystic ovary syndrome, non-classical congenital adrenal hyperplasia, heterozygosity of CYP21A2 mutations, and the impact of DHEAS on CV risk, are reviewed. At present, firm and definitive conclusions cannot be drawn. However, it may be speculated that girls with a history of PA display a hyperandrogenic hormonal milieu that may lead to increased CV risk. Accordingly, appropriate long-term follow-up and early intervention employing a patient-oriented approach are recommended.

Maintenance of bone mass despite estrogen depletion in female common marmoset monkeys (Callithrix jacchus)

Estrogen depletion leads to bone loss in almost all mammals with frequent regular ovarian cycles. However, subordinate adult female common marmosets (Callithrix jacchus) undergo socially induced anovulation and hypoestrogenism without clinically apparent adverse skeletal consequences. Thus, we speculated that this non human primate might have evolved a mechanism to avoid estrogen-depletion bone loss. To test this possibility, we performed three experiments in which lumbar-spine (L5-L6) bone mineral content (BMC) and density (BMD) were assessed using dual-energy X-ray absorptiometry: (i) cross-sectionally in 13 long-term ovariectomized animals and 12 age- and weight-matched controls undergoing ovulatory cycles; (ii) longitudinally in 12 animals prior to, 3-4 and 6-7 months following ovariectomy (ovx), and six controls; and (iii) cross-sectionally in nine anovulatory subordinate and nine dominant females. In Experiments 1 and 3, plasma estradiol and estrone concentrations were measured and uterine dimensions were obtained by ultrasound in a subset of animals as a marker of functional estrogen depletion. Estrogen levels, uterine trans-fundus width, and uterine dorso-ventral diameter were lower in ovariectomized and subordinate females than in those undergoing ovulatory cycles. However, no differences were found in L5-L6 BMC or BMD. These results indicate that estrogen depletion, whether surgically or socially induced, is not associated with lower bone mass in female common marmosets. Thus, this species may possess unique adaptations to avoid bone loss associated with estrogen depletion.

Ovarian estradiol supports sexual behavior but not energy homeostasis in female marmoset monkeys

OBJECTIVE

In adult female rodents, ovarian estradiol (E₂) regulates body weight, adiposity, energy balance, physical activity, glucose-insulin homeodynamics, and lipid metabolism, while protecting against diet-induced obesity. The same E₂ actions are presumed to occur in primates, but confirmatory studies have been lacking.

METHODS

We investigated the consequences of ovariectomy (OVX) and E₂ replacement in female marmoset monkeys on major metabolic and morphometric endpoints. Sexual behavior and uterine diameters were assessed as positive controls for E₂ treatment efficacy. Metabolic parameters were measured 1 mo prior to OVX, and 3 and 6 mo thereafter. During OVX, animals received empty or E₂-containing silastic s.c. implants. To test the interaction between E₂ and diet, both treatment groups were assigned to either a higher fat diet (HFD) or a low-fat diet (LFD).

RESULTS

As anticipated, OVX animals exhibited diminished frequency (p = 0.04) of sexually receptive behavior and increased rejection behavior (p = 0.04) toward their male partners compared with E₂-treated OVX females. OVX also decreased (p = 0.01) uterine diameter. There were no treatment effects on total caloric intake. There were no significant effects of OVX, E₂ treatment, or diet on body weight, body composition, energy expenditure, physical activity, fasting glucose, or glucose tolerance. Regardless of E₂ treatment, serum triglycerides were higher (p = 0.05) in HFD than LFD females. Postmortem qPCR analysis of hypothalamic tissues revealed higher mRNA expression (p < 0.001) for PGR in E₂-treated monkeys versus OVX controls regardless of diet, but no differences between groups in other selected metabolic genes. In contrast, regardless of E₂ treatment, there was a decreased mRNA expression of PGC1α (PPARGC1A), HTR1A, and HTR5A in HFD compared with LFD females.

CONCLUSIONS

Our findings, overall, document a greatly diminished role for ovarian E₂ in the metabolic physiology of a female primate, and encourage consideration that primates, including humans, evolved metabolic control systems regulated by extra-ovarian E₂ or are generally less subject to E₂ regulation.