Joana Margarida Gaspar

Background/Objectives: Caffeine consumption has been reported to have beneficial effects in metabolic disorders; however, its effects on food intake are not fully elucidated. This study evaluated the impact of chronic caffeine consumption on weight gain, food intake, and metabolic parameters in C57BL/6 male mice. Methods: Eight-week-old male mice (28 animals) were divided into four groups: control (chow diet), caffeine (chow diet + 1 g/L caffeine in drinking water), high-fat diet (HFD), and HFD + caffeine (HFD + 1 g/L caffeine in drinking water). Diets and caffeine were provided ad libitum for 8 weeks. Food and water intake were recorded weekly, and blood glucose was measured every 4 weeks. After 8 weeks of diet and caffeine exposure, metabolic tests were conducted, and tissues were collected for biochemical analysis. Results: HFD consumption for 8 weeks induced an increase in body weight and adiposity compared to the chow diet, without changes in food intake. Caffeine consumption prevented body weight gain and adiposity, although it increased food intake. Caffeine also improved glucose tolerance in the HFD mouse model, without changes in random blood glucose, triglyceride, or cholesterol levels. Analysis of hypothalamic neuropeptide (Agrp, NPY, Pomc, Cart), involved in the control of food intake, showed no differences in expression. There were also no changes observed in locomotion nor in anxiety-like behavior. Conclusions: In conclusion, chronic high-fat diet (HFD) exposure induced obesity characterized by increased body weight and adiposity without altering food intake. Chronic caffeine consumption counteracted HFD-induced weight gain and fat accumulation and improved glucose tolerance, despite increasing food intake. Importantly, caffeine consumption in the HFD group did not affect locomotor activity or anxiety-like behavior, suggesting that its metabolic effects are not driven by changes in general activity or emotional state. Overall, these findings indicate that chronic caffeine consumption improves metabolic homeostasis in HFD-fed mice.

Obesity is a worldwide epidemic disease marked by changes in the function of various tissue and organs, driven by excessive fat accumulation. In recent years obesity was characterized not just by the increase of fat, but also an imbalance of energy homeostasis mechanisms. In parallel with global rise in obesity, the incidence of obesity during pregnancy and lactation had also been steadily increasing. Maternal obesity is a public health issue that affects the child and the mother, in acute and chronic term, being a risk factor for the development of metabolic, hormonal, neurodevelopmental, and psychiatric disorders in offspring. Obesity during the gestation can reprogram the fetal immune, metabolic, endocrine, and neurological systems, influencing offspring's metabolism and mental health. This is supported by the Developmental Origins of Health and Disease (DOHaD) theory, which proposes that environmental factors during critical periods of early development (as the fetal period) can influence the risk of developing diseases later in life. In this review, we focused on how maternal obesity can affect the brain offspring neurodevelopment, neural circuits, synapses, glial cells, and neuroinflammation, which all can influence offspring behavioral disorders. image

Objective: This study aimed to examine the impact of high-fat-diet(HFD)-induced obesity on pain sensitivity and tetrahydrobiopterin (BH4) levels. The effect of moderate-intensity physical exercise, an anti-inflammatory non-pharmacological intervention, on pain scores was also investigated. Methods: Adult male C57BL/J6 mice were fed standard or an HFD for eight weeks. Their total body weight, food intake, locomotor and motivational behavior, and pain reflexes were measured. A subgroup of animals underwent physical exercise for five days per week over six weeks. Blood was collected for glucose tolerance testing and levels of lactate. Urine samples were collected to measure BH4 levels. Results: We showed that the HFD increased weight gain, epididymal white adipose tissue, and the percentage of body weight as epididymal fat. These anthropometric alterations were characterized by impaired glucose tolerance at four and eight weeks of the dietary intervention. It was also observed that reduced locomotor activity and higher pain scores in the HFD-fed mice were prevented by a physical exercise intervention. The HFD also induced an increase in urinary BH4 levels at four and eight weeks of intervention. Conclusions: The HFD increased scores of chemical and mechanical hyperalgesias, as well as urinary BH4 levels. Urinary BH4 can be proposed as a potential easy-to-access, sensitive, and reliable biomarker of pain development, and a promising target for the control of pain hypersensitivity in obesity.

The global prevalence of obesity and type 2 diabetes has increased considerably in recent decades, primarily due to behavioral changes associated with societal progress, such as increased consumption of high-calorie foods and sedentary lifestyles. Obesity is a disease of the energy homeostasis system, not merely a passive accumulation of fat. The hypothalamus serves as the regulatory center for energy balance, and together with peripheral organs, such as liver, pancreas, muscle and adipose tissue, controls food intake, energy expenditure, and whole-body metabolism. Adenosine, a product of ATP catabolism, exerts its effects through various G-protein-coupled receptors: A1R, A2AR, A2BR, and A3R. It plays a key role in regulating peripheral metabolism, including glucose homeostasis, insulin sensitivity, fat beta-oxidation, and lipolysis in adipose tissue. Beyond its roles in the CNS, adenosine receptors are also crucial in metabolic tissues, where they regulate glucose and lipid homeostasis and contribute to overall metabolic function. Several studies have been analyzing the role of adenosine system, specifically the adenosine receptors in the regulation of whole-body metabolism, and the importance of adenosine receptors in context of metabolic diseases and obesity. In this review, we provide an overview of the adenosine signaling system, highlighting its role in metabolic regulation as well as the pathophysiological mechanisms underlying obesity and type 2 diabetes.

Autism Spectrum Disorder (ASD) is a neurodevelopmental condition characterized by persistent deficits in social communication and interaction, along with restricted and repetitive patterns of behavior, interests, or activities. ASD encompasses a wide spectrum of clinical presentations and functional impairments, ranging from mild to severe. Despite its prevalence, the underlying physiopathological mechanisms of ASD remain largely unknown, resulting in a lack of effective targeted therapeutic interventions, contributing to significant financial and emotional burdens on affected families and the healthcare system. Emerging evidence suggests that dysfunction in the tetrahydrobiopterin (BH4) pathway may impair the activity of monoaminergic and nitric oxide (NO)-dependent neurons in individuals with ASD. To explore this potential mechanism, we conducted a systematic review to analyze such impairments to gather information on whether the off-label use of BH4 could represent a novel pharmacological approach for managing ASD. Following the PRISMA 2020 guidelines, we systematically reviewed the literature from four databases: PubMed, Virtual Health Library, Cochrane Library, and SciELO, from January 1967 to December 2021. The quality of the included studies was assessed using the Newcastle–Ottawa scale. The inclusion criteria for this systematic review focused on identifying articles published in English that contained the following keywords, used in various combinations: autism, ASD, autism spectrum disorder, BH4, tetrahydrobiopterin, neopterin, NO, nitric oxide. The analysis was performed between December 2020 and December 2021. The collected data demonstrated that BH4 metabolism was altered in individuals with ASD. Lower levels of BH4 were reported in biological samples from ASD-affected individuals compared to age- and sex-matched controls. Additionally, neopterin levels were elevated in plasma and urine, but decreased in cerebrospinal fluid, while nitric oxide levels were consistently reported to be higher across studies. Treatment with BH4 has shown potential in improving ASD-related symptoms. The reported increase in neopterin in biological fluids indicates inflammation, while the reduction in BH4 levels suggests a potential shift in its metabolic role. Specifically, BH4 may be diverted from its primary role in neurotransmitter synthesis to function as an antioxidant or to perpetuate inflammation through NO production. Given that BH4 is a critical cofactor in monoaminergic neurotransmission, its dysfunction highlights the molecule's therapeutic potential. BH4, already FDA-approved for other conditions, emerges as a promising off-label candidate to alleviate ASD symptomatology.

Background/Objectives: Autism spectrum disorder (ASD) is associated with several coexisting diseases or comorbidities, including inflammatory and metabolic disorders. In fact, ASD symptoms may be associated with immune system dysfunction. However, studies investigating the peripheral blood levels of immune cells are lacking and have provided mixed findings. In this study, we evaluated the relationship between the intensity level of ASD symptoms and the inflammatory and metabolic profiles in 154 children and adolescents (2–17 years). Methods: Bayesian multilevel models were used to examine the relationship between their symptom intensities and inflammatory/metabolic profiles. Results: Heavier children had higher values for triglyceride and insulin levels. Children with a level 3 of ASD intensity had higher free fatty acids levels. However, when adjusting for ASD intensity, gender, medication use, or weight status, older children appeared to have higher values of triglycerides, insulin levels, and free fatty acids. Conclusions: We concluded that as Brazilian children with ASD became older, they had a higher risk for insulin resistance.

Consumption of high-fat diets (HFD) is associated with brain alterations, including changes in feeding behavior, cognitive decline, and dementia. Astrocytes play a role in HFD-induced neuroinflammation and brain dysfunction; however, this process is not entirely understood. We hypothesized that exposure to saturated fatty acids can compromise astrocyte viability and mitochondrial function. The C6 (astrocytes) cell line was treated with palmitate or stearate (200 µM and 400 µM) for 6 h. Cell viability, morphology, inflammatory markers, and oxidative stress were evaluated. To assess mitochondrial function, various parameters were measured (membrane potential, mass, respiration, and complex activities). We observed that 6 h of treatment with 400 µM palmitate decreased cell viability, and treatment with 200 µM palmitate changed the astrocyte morphology. Palmitate increased inflammatory markers (TNF-α and IL6) but did not induce oxidative stress. Palmitate significantly decreased the mitochondrial membrane potential and mitochondrial mass. Complex I activity also decreased in palmitate-treated cells; however, no changes were observed in mitochondrial respiration. In conclusion, palmitate, a saturated fatty acid, induces inflammation and impairs mitochondrial function, leading to reduced astrocytic cell viability and changes in cellular morphology. Our study provides valuable insights into the potential mechanisms underlying the relationship between saturated fatty acids, astrocytes, and mitochondrial function in obesity-related brain dysfunction.

Editorial: Obesity and diabetes: implications for brain-immunometabolism, volume II

This pre-clinical study investigated the transient receptor potential ankyrin-1 (TRPA1) channels on modulating targets for glucose homeostasis using agonists: the electrophilic agonists, cinnamaldehyde (CIN) and allyl isothiocyanate (AITC), and the non-electrophilic agonist, carvacrol (CRV). A glucose tolerance test was performed on rats. CIN and AITC (5, 10 and 20 mg/kg) or CRV (25, 100, 300, and 600 mg/kg) were administered intraperitoneally (i.p.), and glycemia was measured. In the intestine, Glucagon-like peptide-1 (GLP-1) and disaccharidase activity were evaluated (in vivo and in vitro, respectively). Furthermore, in vivo and in vitro insulin secretion was determined. Islets were used to measure insulin secretion and calcium influx. CIN and AITC improved glucose tolerance and increased insulin secretion in vivo and in vitro. CRV was unable to reduce glycemia. Electrophilic agonists, CIN and AITC, inhibited disaccharidases and acted as secretagogues in the intestine by inducing GLP-1 release in vivo and in vitro and contributed to insulin secretion and glycemia. The effect of CIN on calcium influx in pancreatic islets (insulin secretion) involves voltage-dependent calcium channels and calcium from stores. TRPA1 triggers calcium influx and potentiates intracellular calcium release to induce insulin secretion, suggesting that electrophilic agonists mediate this signaling transduction for the control of glycemia.