Rodrigo Antonio Peliciari Garcia

Variações rítmicas são fundamentais para a adaptação dos seres vivos frente às diversas condições ambientais as quais os organismos são constantemente submetidos ao longo da vida. Tais oscilações são observadas na maioria das funções biológicas e nos padrões comportamentais, como ciclo sonovigília, alimentação e jejum, regulação metabólica, secreção hormonal, comportamento reprodutivo, temperatura corpórea, entre outros (1)

Alamandine, a member of the renin-angiotensin system, serves critical roles in cardioprotection, including the modulation of cardiomyocyte contractility. Whether this effect varies along the day is unknown. Our results provide evidence that alamandine via receptor MrgD exerts opposing actions on cardiomyocyte shortening, enhancing, or reducing contraction depending on the time of day. These findings may have significant implications for the development and effectiveness of future cardiac therapies.

In mammals, the central circadian oscillator is located in the suprachiasmatic nucleus (SCN). Hypothalamus–pituitary–thyroid axis components exhibit circadian oscillation, regulated by both central clock innervation and intrinsic circadian clocks in the anterior pituitary and thyroid glands. Thyroid disorders alter the rhythmicity of peripheral clocks in a tissue‐dependent response; however, whether these effects are influenced by alterations in the master clock remains unknown. This study aimed to characterize the effects of hypothyroidism on the rhythmicity of SCN, body temperature (BT) and metabolism, and the possible mechanisms involved in this signalling. C57BL/6J adult male mice were divided into Control and Hypothyroid groups. Profiles of spontaneous locomotor activity (SLA), BT, oxygen consumption () and respiratory quotient (RQ) were determined under free‐running conditions. Clock gene expression, and neuronal activity of the SCN and medial preoptic nucleus (MPOM) area were investigated in light–dark (LD) conditions. Triiodothyronine (T3) transcriptional regulation of Bmal1 promoter activity was evaluated in GH3‐transfected cells. Hypothyroidism delayed the rhythmicity of SLA and BT, and altered the expression of core clock components in the SCN. The activity of SCN neurons and their outputs were also affected, as evidenced by the loss of circadian rhythmicity in and RQ and alterations in the neuronal activity pattern of MPOM. In GH3 cells, T3 increased Bmal1 promoter activity in a time‐dependent manner. Thyroid hormone may act as a temporal cue for the central circadian clock, and the uncoupling of central and peripheral clocks might contribute to a wide range of metabolic and thermoregulatory impairments observed in hypothyroidism. image Key points: Hypothyroidism alters clock gene expression in the suprachiasmatic nucleus (SCN). Thyroid hypofunction alters the phase of spontaneous locomotor activity and body temperature rhythms. Thyroid hormone deficiency alters the daily pattern of SCN and medial preoptic nucleus neuronal activities. Hypothyroidism alterations are extended to daily oscillations of oxygen consumption and metabolism, which might contribute to the development of metabolic syndrome. Triiodothyronine increases Bmal1 promoter activity acting as temporal cue for the central circadian clock.

Innovative techniques such as the “omics” can be a powerful tool for the understanding of intracellular pathways involved in homeostasis maintenance and identification of new potential therapeutic targets against endocrine-metabolic disorders. Over the last decades, proteomics has been extensively applied in the study of a wide variety of human diseases, including those involving the endocrine system. Among the most endocrine-related disorders investigated by proteomics in humans are diabetes mellitus and thyroid, pituitary, and reproductive system disorders. In diabetes, proteins implicated in insulin signaling, glucose metabolism, and β-cell activity have been investigated. In thyroid diseases, protein expression alterations were described in thyroid malignancies and autoimmune thyroid illnesses. Additionally, proteomics has been used to investigate the variations in protein expression in adrenal cancers and conditions, including Cushing’s syndrome and Addison’s disease. Pituitary tumors and disorders including acromegaly and hypopituitarism have been studied using proteomics to examine changes in protein expression. Reproductive problems such as polycystic ovarian syndrome and endometriosis are two examples of conditions where alterations in protein expression have been studied using proteomics. Proteomics has, in general, shed light on the molecular underpinnings of many endocrine-related illnesses and revealed promising biomarkers for both their detection and treatment. The capacity of proteomics to thoroughly and objectively examine complex protein mixtures is one of its main benefits. Mass spectrometry (MS) is a widely used method that identifies and measures proteins based on their mass-to-charge ratio and their fragmentation pattern. MS can perform the separation of proteins according to their physicochemical characteristics, such as hydrophobicity, charge, and size, in combination with liquid chromatography. Other proteomics techniques include protein arrays, which enable the simultaneous identification of several proteins in a single assay, and two-dimensional gel electrophoresis (2D-DIGE), which divides proteins depending on their isoelectric point and molecular weight. This chapter aims to summarize the most relevant proteomics data from targeted tissues, as well as the daily rhythmic variation of relevant biomarkers in both physiological and pathophysiological conditions within the involved endocrine system, especially because the actual modern lifestyle constantly imposes a chronic unentrained condition, which virtually affects all the circadian clock systems within human’s body, being also correlated with innumerous endocrine-metabolic diseases. Keywords Thyroid Diabetes mellitus Reproductive system Endocrine disorders Omics

Rhythmic regulations are virtually described in all physiological processes, including central nervous system development and immunologic responses. Zika virus (ZIKV), a neurotropic arbovirus, has been recently linked to a series of birth defects and neurodevelopmental disorders. Given the well-characterized role of the intrinsic cellular circadian clock within neurogenesis, cellular metabolism, migration, and differentiation among other processes, this study aimed to characterize the influence of ZIKV infection in the circadian clock expression in human neuronal cells. For this, in vitro models of human-induced neuroprogenitor cells (hiNPCs) and neuroblastoma cell line SH-SY5Y, cultured as monolayer and neurospheres, were infected by ZIKV, followed by RNA-Seq and RT-qPCR investigation, respectively. Targeted circadian clock components presented mRNA oscillations only after exogenous synchronizing stimuli (Forskolin) in SH-SY5Y monolayer culture. Interestingly, when these cells were grown as 3D-arranged neurospheres, an intrinsic oscillatory expression pattern was observed for some core clock components without any exogenous stimulation. The ZIKV infection significantly disturbed the mRNA expression pattern of core clock components in both neuroblastoma cell culture models, which was also observed in hiNPCs infected with different strains of ZIKV. The ZIKV-mediated desynchronization of the circadian clock expression in human cells might further contribute to the virus impairment of neuronal metabolism and function observed in adults and ZIKV-induced congenital syndrome. Graphical Abstract In vitro models of Zika virus (ZIKV) neuronal infection. Human neuroprogenitor cells were cultured as monolayer and neurospheres and infected by ZIKV. Monolayer-cultured cells received forskolin (FSK) as a coupling factor for the circadian clock rhythmicity, while 3D-arranged neurospheres showed an intrinsic oscillatory pattern in the circadian clock expression. The ZIKV infection affected the mRNA expression pattern of core clock components in both cell culture models. The ZIKV-mediated desynchronization of the circadian clock machinery might contribute to the impairment of neuronal metabolism and function observed in both adults (e.g., Guillain–Barré syndrome) and ZIKV-induced congenital syndrome (microcephaly). The graphical abstract has been created with Canva at the canva.com website.

Senescence-Accelerated Mouse-Prone 8 (SAMP8) mice exhibit characteristics of premature aging, including hair loss, cognitive dysfunction, reduced physical activity, impaired metabolic homeostasis, cardiac dysfunction and reduced lifespan. Interestingly, circadian disruption can induce or augment many of these same pathologies. Moreover, previous studies have reported that SAMP8 mice exhibit abnormalities in circadian wheel-running behavior, indicating possible alterations in circadian clock function. These observations led to the hypothesis that 24 h rhythms in behavior and/or circadian clock function are altered in SAMP8 mice and that these alterations may contribute to perturbations in whole-body metabolism. Here, we report that 6-month-old SAMP8 mice exhibit a more prominent biphasic pattern in daily behaviors (food intake and physical activity) and whole-body metabolism (energy expenditure, respiratory exchange ratio), relative to SAMR1 control mice. Consistent with a delayed onset of food intake at the end of the light phase, SAMP8 mice exhibit a phase delay (1.3–1.9 h) in 24 h gene expression rhythms of major circadian clock components (bmal1, rev-erbα, per2, dbp) in peripheral tissues (liver, skeletal muscle, white adipose tissue [WAT], brown adipose tissue [BAT]). Forcing mice to consume food only during the dark period improved alignment of both whole-body metabolism and oscillations in expression of clock genes in peripheral tissues between SAMP8 and SAMR1 mice. Next, interrogation of metabolic genes revealed altered expression of thermogenesis mediators (ucp1, pgc1α, dio2) in WAT and/or BAT in SAMP8 mice. Interestingly, SAMP8 mice exhibit a decreased tolerance to an acute (5 h) cold challenge. Moreover, SAMP8 and SAMR1 mice exhibited differential responses to a chronic (1 week) decrease in ambient temperature; the greatest response in whole-body substrate selection was observed in SAMR1 mice. Collectively, these observations reveal differential behaviors (e.g. 24 h food intake patterns) in SAMP8 mice that are associated with perturbations in peripheral circadian clocks, metabolism and thermogenesis.

Aims/hypothesis: During pregnancy, maternal metabolic disease and hormonal imbalance may alter fetal beta cell development and/or proliferation, thus leading to an increased risk for developing type 2 diabetes in adulthood. Although thyroid hormones play an important role in fetal endocrine pancreas development, the impact of maternal hypothyroidism on glucose homeostasis in adult offspring remains poorly understood. Methods: We investigated this using a mouse model of hypothyroidism, induced by administration of an iodine-deficient diet supplemented with propylthiouracil during gestation. Results: Here, we show that, when fed normal chow, adult mice born to hypothyroid mothers were more glucose-tolerant due to beta cell hyperproliferation (two- to threefold increase in Ki67-positive beta cells) and increased insulin sensitivity. However, following 8 weeks of high-fat feeding, these offspring gained 20% more body weight, became profoundly hyperinsulinaemic (with a 50% increase in fasting insulin concentration), insulin-resistant and glucose-intolerant compared with controls from euthyroid mothers. Furthermore, altered glucose metabolism was maintained in a second generation of animals. Conclusions/interpretation: Therefore, gestational hypothyroidism induces long-term alterations in endocrine pancreas function, which may have implications for type 2 diabetes prevention in affected individuals.

During pregnancy, maternal metabolic diseases and hormonal imbalance may alter fetal beta cell development and/or proliferation, thus leading to an increased risk for developing type 2 diabetes in adulthood. Although thyroid hormones play an important role in fetal endocrine pancreas development, the impact of maternal hypothyroidism on glucose homeostasis in adult offsprings remains poorly understood. Here, we show that when fed normal chow, adult mice born to hypothyroid mothers were more glucose-tolerant due to beta cell hyperproliferation and increased insulin sensitivity. However, following high fat feeding, these offsprings became profoundly hyperinsulinemic, insulin-resistant and glucose-intolerant compared to controls from euthyroid mothers. Suggesting presence of epigenetic changes, altered glucose metabolism was maintained in a second generation of animals. As such, gestational hypothyroidism induces long-term and persistent alterations in endocrine pancreas function, which may have important implications for type 2 diabetes prevention in affected individuals. SIGNIFICANCE: Diabetes and hypothyroidism are two major public health issues, affecting ∼ 9 and 2 % of the population worldwide, respectively. As master metabolic gatekeepers, the thyroid hormones play an essential role in metabolism and fetal development. However, gestation increases demand on the thyroid axis in the mother, leading to hypothyroidism in 0.5 % of pregnancies. Maternal hypothyroidism is associated with deficits in fetal growth that may lead to long-term alterations in metabolism in the offspring. We therefore sought to investigate the effects of gestational hypothyroidism on glucose metabolism in adult offspring and their descendants, and how this may predispose to diabetes development.

Diabetes increases risk of various comorbidities, including retinopathy, neuropathy, and cardiovascular disease, comprising both ischemic and non-ischemic cardiomyopathy. Cardiac dysfunction during diabetes is associated with perturbations at histologic, metabolic, biochemical and molecular levels. The circadian clock is misaligned in multiple organs during diabetes, including the heart. Such alterations in clock function have been postulated to play a causal role in cardiac dysfunction even though the mechanisms leading to circadian misalignment are currently unknown. Melatonin has been reported to alter heart circadian clock components and its circulating levels are decreased during diabetes. These observations led to the hypothesis that decreased melatonin levels during diabetes could be related to mismanagement of the heart clock. To evaluate this hypothesis, in the current study male Wistar and non-obese type 2 diabetic Goto-Kakizaki (GK) rats were given melatonin supplementation in their drinking water during the dark phase (for 12-wks), followed by assessment of clock component and the mRNA expression of the clock-controlled genes in the hearts of these animals. Melatonin supplementation significantly altered mRNA expression of targeted genes in both euglycemic and diabetic rat hearts. Collectively, under the condition of diabetes, the jeopardized pineal melatonin synthesis with misalignment of cardiac circadian clock components may likely mediate heart metabolic dysfunction, and/or even cause cardiovascular diseases.