Pirjo Nuutila

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Verified

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• MD, PhD., Professor
• Professor (Full) at University of Turku

Eating is inherently social for humans. Yet, most neuroimaging studies of appetite and food-induced reward have focused on studying brain responses to food intake or viewing pictures of food alone. We used functional magnetic resonance imaging (fMRI) to measure haemodynamic responses to “vicarious” feeding. The subjects (n = 97) viewed series of sh...

In this study, we investigated the impact of bariatric surgery on the adipose proteome to better understand the metabolic and cellular mechanisms underlying weight loss following the procedure. A total of 46 patients with severe obesity were included, with samples collected both before and after bariatric surgery. Additionally, 15 healthy, non-obes...

Anorexia nervosa (AN) is a severe psychiatric disorder, characterized by restricted eating, fear to gain weight, and a distorted body image. Mu-opioid receptor (MOR) functions as a part of complex opioid system and supports both homeostatic and hedonic control of eating behavior. Thirteen patients with AN and thirteen healthy controls (HC) were inc...

Introduction: Diagnostics of small bowel Crohn's disease (CD) can be difficult. Combined positron emission tomography-magnetic resonance enterography (PET-MRE) can be used to evaluate intestinal metabolism, but clinical use has been limited due to accessibility, costs, absence of standardized methods, and diagnostic thresholds. Our aim was to show...

Precise anatomic localization of insulinomas is crucial for surgical treatment. Current routine noninvasive imaging techniques, including CT, MRI, and 68Ga-DOTA-somatostatin analog (DOTA-SSA) PET/CT, have limited sensitivity. Endoscopic ultrasound is highly sensitive but invasive. In this prospective multicenter study, we compared the diagnostic ac...

Photoperiodicity in the human brain function, which is a critical factor for social well-being, has been widely debated. In this study, 432 healthy males underwent fasting-state brain [ ¹⁸ F]fluorodeoxyglucose positron emission tomography (PET) scanning twice: first at the baseline and then at the 5-year follow-up. We analyzed the effect of day len...

38 patients with type 2 diabetes & metformin n = 21 dapagliflozin 10 mg n = 17 placebo Whole-body [ 18 F]FTHA-PET Whole-body [ 18 F]FTHA-PET 6 weeks A Randomized Double-Blind Placebo-Controlled Positron Emission Tomography (PET) Study Conclusions Increase in fatty acid uptake in response to sodium-glucose cotransporter 2 inhibitor treatment extends...

Backgrounds Obesity is associated with alterations in bone turnover markers (BTMs). However, the association between regional fat distribution and bone metabolism has received less attention. This study therefore aimed to identify which specific fat compartments (i.e., abdominal and femoral subcutaneous fat, intra- and extraperitoneal fat, and tota...

OBJECTIVE The aim of this study was to investigate the impact of the sodium–glucose cotransporter 2 (SGLT2) inhibitor dapagliflozin on tissue fatty acid (FA) uptake in the skeletal muscle, brain, small intestine, and subcutaneous and visceral adipose tissue of individuals with type 2 diabetes by using positron emission tomography (PET). RESEARCH D...

Eating is inherently social for humans. Yet, most neuroimaging studies of appetite and food-induced reward have focused on studying brain responses to food intake or viewing pictures of food alone. Here we used functional magnetic resonance imaging (fMRI) to measure haemodynamic responses to "vicarious" feeding. The subjects (n=97) viewed a series...

Aims/hypothesis Stem cell-derived islets (SC-islets) are being used as cell replacement therapy for insulin-dependent diabetes. Non-invasive long-term monitoring methods for SC-islet grafts, which are needed to detect misguided differentiation in vivo and to optimise their therapeutic effectiveness, are lacking. Positron emission tomography (PET) h...

Background Fatty acid uptake can be measured using PET and 14-(R,S)‐[¹⁸F]fluoro‐6‐thia‐heptadecanoic acid ([¹⁸F]FTHA). However, the relatively rapid rate of [¹⁸F]FTHA metabolism significantly affects kinetic modeling of tissue uptake. Thus, there is a need for accurate chromatographic methods to analyze the unmetabolized [¹⁸F]FTHA (parent fraction)...

Objective Acromegaly is associated with increased morbidity and mortality if left untreated. The therapeutic options include surgery, medical treatment, and radiotherapy. Several guidelines and recommendations on treatment algorithms and follow‐up exist. However, not all recommendations are strictly evidence‐based. To evaluate consensus on the trea...

Background and objectives The global prevalence of severe obesity is a major public health concern due to its association with increased risk of cardiometabolic complications and mortality. Abdominal visceral adipose tissue (VAT) exhibits distinct biomolecular characteristics that contribute to these pathological processes. This study aimed to comp...

Context Increased standing time has been associated with improved health, but the underlying mechanism is unclear. Objectives We herein investigate if increased weight loading increases energy demand and thereby glucose uptake (GU) locally in bone and/or muscle in the lower extremities. Methods In this single-center clinical trial with randomized...

Purpose Brain functional and physiological plasticity is essential to combat dynamic environmental challenges. The rhythmic dopamine signaling pathway, which regulates emotion, reward and learning, shows seasonal patterns with higher capacity of dopamine synthesis and lower number of dopamine transporters during dark seasons. However, seasonal vari...

Anorexia nervosa (AN) is a severe psychiatric disorder, characterized by restricted eating, fear to gain weight, and a distorted body image. Mu-opioid receptor (MOR) functions as a part of complex opioid system and supports both homeostatic and hedonic control of eating behavior. Thirteen patients with AN and thirteen healthy controls (HC) were inc...

Context Proneurotensin (pNT) is associated with obesity and type 2 diabetes (T2D), but the effects of Roux-en-Y gastric bypass (RYGB) on postprandial pNT levels are not well studied. Objective This work aimed to assess the effects of RYGB vs a very low-energy diet (VLED) on pNT levels in response to mixed-meal tests (MMTs), and long-term effects o...

Accurate positron emission tomography (PET) data quantification relies on high-quality input plasma curves, but venous blood sampling may yield poor-quality data, jeopardizing modeling outcomes. In this study, we aimed to recover sub-optimal input functions by using information from the tail (5th–100th min) of curves obtained through the frequent s...

Purpose Aberrant dopaminergic function is linked with motor, psychotic, and affective symptoms, but studies have typically compared a single patient group with healthy controls. Methods Here, we investigated the variation in striatal (caudate nucleus, nucleus accumbens, and putamen) and thalamic type 2 dopamine receptor (D2R) availability using [¹...

Background Diagnostics and follow-up of small bowel Crohn’s disease (CD) can be difficult. Combined PET-MRI enterography (MRE) can be used to evaluate intestinal inflammation. Lack of standardized methods and diagnostic thresholds has limited its clinical use in diagnostics and monitoring of small bowel CD. There is no previous data on the use of P...

Brain functional and physiological plasticity is essential to combat dynamic environmental challenges. The rhythmic in vivo dopamine signaling pathway, which regulates emotion, reward and learning, shows seasonal patterns with higher capacity of dopamine synthesis and lower number of dopamine transporters during dark seasons. However, seasonal vari...

Stem cell derived islets (SC-islets) are being developed as a novel source of beta cells that would enable large scale cell replacement therapy for insulin dependent diabetes. Therapeutic use of SC-islets carries an inherent risk of unwanted growth; and multiple strategies are being explored for optimizing long-term SC-islet graft effectiveness. Ho...

Context Studies on human renal metabolism are scanty. Nowadays, functional imaging allows the characterization of renal metabolism in a non-invasive manner. We have recently demonstrated that [18F]FDG-PET can be used to analyze renal glucose uptake rates (GU), and that the renal cortex is an insulin sensitive tissue. Objective To confirm that rena...

Recently, PET systems with a long axial field of view have become the current state of the art. Total-body PET scanners enable unique possibilities for scientific research and clinical diagnostics, but this new technology also raises numerous challenges. A key advantage of total-body imaging is that having all the organs in the field of view allows...

The human brain undergoes metabolic adaptations in obesity, but the underlying mechanisms have remained largely unknown. We compared concentrations of often reported brain metabolites measured with magnetic resonance spectroscopy ( ¹ H-MRS, 3 T MRI) in the occipital lobe in subjects with obesity and lean controls under different metabolic condition...

Objectives Metformin is the first line therapy recommended for type 2 diabetes. However, the precise mechanism of action remains unclear and up to a quarter of patients show some degree of intolerance to the drug, with a similar number showing poor response to treatment, limiting its effectiveness. A better understanding of the mechanism of action...

Citation: Päivärinta, J.; Anastasiou, I.A.; Koivuviita, N.; Sharma, K.; Nuutila, P.; Ferrannini, E.; Solini, A.; Rebelos, E. Renal Perfusion, Oxygenation and Metabolism: The Role of Imaging. Abstract: Thanks to technical advances in the field of medical imaging, it is now possible to study key features of renal anatomy and physiology, but so far po...

Objective: Cannabinoid type 1 receptors (CB1R) modulate feeding behavior and energy homeostasis, and the CB1R tone is dysgulated in obesity. This study aimed to investigate CB1R availability in peripheral tissue and brain in young men with overweight versus lean men. Methods: Healthy males with high (HR, n = 16) or low (LR, n = 20) obesity risk...

Background: Changes in fatty acid metabolism are an important component of the pathogenesis of type 2 diabetes mellitus (T2DM). Fatty acid uptake in tissues can be measured with positron emission tomography (PET) imaging, employing the fatty acid analogue 18F-FTHA radiotracer. We aimed to evaluate the repeatability of assessments of fatty acid upta...

PURPOSE Aberrant dopaminergic function is linked with motor, psychotic, and affective symptoms, but studies have typically compared a single patient group with healthy controls. METHODS: Here, we investigated the variation in striatal (caudate nucleus, nucleus accumbens, and putamen) and thalamic type 2 dopamine receptor (D 2 R) availability using...

We aimed to investigate the effects of maternal obesity on brain structure and metabolism in frail women, and their reversibility in response to exercise. We recruited 37 frail elderly women (20 offspring of lean/normal-weight mothers (OLM) and 17 offspring of obese/overweight mothers (OOM)) and nine non-frail controls to undergo magnetic resonance...

Human brain metabolism is susceptible to temperature changes. It has been suggested that the supraclavicular brown adipose tissue (BAT) protects the brain from these fluctuations by regulating heat production through the presence of uncoupling protein 1 (UCP-1). It remains unsolved whether inter-individual variation in the expression of UCP-1, whic...

Purpose Secretin activates brown adipose tissue (BAT) and induces satiation in both mice and humans. However, the exact brain mechanism of this satiety inducing, secretin-mediated gut-BAT-brain axis is largely unknown. Methods and results In this placebo-controlled, single-blinded neuroimaging study, firstly using [¹⁸F]-fluorodeoxyglucose (FDG) PE...

Background Diagnostics of small bowel Crohn’s disease (CD) may be difficult. Combined PET-MRI has been documented to be a reliable tool for evaluating intestinal metabolism, but clinical use has been limited due to accessibility, costs and lack of standardized methods to quantify inflammation. Our study aims to prove that combined PET-MRI can be us...

We aimed to integrate genomic mapping from brain mRNA atlas with the protein expression from positron emission tomography (PET) scans of type 1 cannabinoid (CB1) receptor and to compare the predictive power of CB1 receptor with those of other neuroreceptor/transporters using a meta‐analysis. Volume of distribution (VT) from F18‐FMPEP‐d2 PET scans,...

Background/purpose Studying renal glucose metabolism non-invasively in humans is an unmet need. Positron emission tomography (PET) is the current gold standard for measuring regional tissue glucose uptake rates, but the most widely used glucose analog ([¹⁸F]FDG) is not a good substrate for sodium-glucose cotransporters (SGLTs). As a consequence, [¹...

Finnish-specific gene variant p.P50T/ AKT2 (MAF=1.1%), is associated with insulin resistance and increased predisposition to type 2 diabetes. Here, we have investigated in vitro the impact of the gene variant on glucose metabolism and intracellular signalling in human primary skeletal muscle cells, that were established from 14 male p.P50T/ AKT2 va...

Background Congenic leptin receptor deficient rat generated by introgression of the Koletsky leptin receptor mutation into BioBreeding Diabetes Resistant rat (BBDR.lepr−/−) is a novel animal model combining obesity, systemic insulin resistance and diabetes. Systemic insulin resistance is associated with reduced myocardial glucose utilization, but i...

Objective: To investigate whether alterations in brain glucose uptake (BGU), insulin action in the brain-liver axis, and whole-body insulin sensitivity occur in young adults in pre-obese state. Methods: Healthy males with either high (HR, n = 19) or low risk (LR, n = 22) for developing obesity were studied with [18F]fluoro-D-glucose ([18F]FDG) - po...

Purpose Photoperiod determines the metabolic activity of brown adipose tissue (BAT) and affects the food intake and body mass of mammals. Sympathetic innervation of the BAT controls thermogenesis and facilitates physiological adaption to seasonal changes, but the exact mechanism remains elusive. Previous studies have shown that central opioid signa...

Aims/hypothesis SGLT2 inhibition is associated with a reduced risk of cardiac disease that is still largely unexplained. According to one hypothesis, improved myocardial energetics may explain the cardioprotective effects of SGLT2i. However, recent mechanistic studies that have addressed this question have lacked the power to detect discrete but st...

N-acetylaspartate (NAA) is the second most abundant metabolite in the human brain; although it is assumed to be a proxy for a neuronal marker, its function is not fully elucidated. NAA is also detectable in plasma, but its relation to cerebral NAA levels, cognitive performance, or features of cerebral disease has not been investigated. To study whe...

(1) Objective: The aim of this study was to clarify the role of adipokines in the regulation of glucose metabolism in middle-aged obese subjects with impaired glucose tolerance in response to a long-term exercise and dietary intervention. (2) Methods: Skeletal muscle, plasma and serum samples were examined in 22 subjects from an exercise–diet inter...

Renal sinus fat is a fat depot at the renal hilum. Because of its location around the renal artery, vein, and lymphatic vessels, an expanded renal sinus fat mass may have hemodynamic and renal implications. We studied whether renal sinus fat area (RSF) associates with hypertension and whether following bariatric surgery a decrease in RSF associates...

Importance: Long-term results from randomized clinical trials comparing laparoscopic sleeve gastrectomy (LSG) with laparoscopic Roux-en-Y-gastric bypass (LRYGB) are limited. Objective: To compare long-term outcomes of weight loss and remission of obesity-related comorbidities and the prevalence of gastroesophageal reflux symptoms (GERD), endosco...

Secretin activates brown adipose tissue (BAT) and induces satiation in both mice and humans. However, the exact brain mechanism of this satiety inducing, secretin-mediated gut-BAT-brain axis is unknown. In this placebo-controlled, single-blinded neuroimaging study, firstly using [ ¹⁸ F]FDG-PET measures (n = 15), we established that secretin modulat...

Neurofilament light chain (NfL) is a novel biomarker reflecting neuroaxonal damage and associates with brain atrophy, and glial fibrillary acidic protein (GFAP) is a marker of astrocytic activation, associated with several neurodegenerative diseases. Since obesity is associated with increased risk for several neurodegenerative disorders, we hypothe...

Photoperiod drives metabolic activity of brown adipose tissue (BAT), and affects food intake and weight gain in mammals. Sympathetic innervation in BAT controls thermogenesis and facilitates physiological adaption to seasons, but the exact mechanism remains elusive. Previous studies show that the central opioid signaling tunes BAT heating and the b...

Evaluating in vivo the metabolic rates of the human liver has been a challenge due to its unique perfusion system. Positron emission tomography (PET) represents the current gold standard for assessing non-invasively tissue metabolic rates in vivo. Here, we review the existing literature on the assessment of hepatic metabolism, haemodynamics and can...

Background and Aims GIP and meal ingestion increase subcutaneous adipose tissue (SAT) perfusion in healthy subjects. Effects of GIP and meal on visceral adipose tissue (VAT) perfusion is unclear. Our aim was to investigate the effects of meal and GIP on VAT and SAT perfusion in obese subjects with type 2 diabetes (T2DM) before and after bariatric s...

Purpose Recent studies have linked activated spinal glia to neuropathic pain. Here, using a positron emission tomography (PET) scanner with high spatial resolution and sensitivity, we evaluated the feasibility and sensitivity of N,N-diethyl-2-(2-(4-([ ¹⁸ F]fluoro)phenyl)-5,7-dimethylpyrazolo[1,5-a] pyrimidin-3-yl)acetamide ([ ¹⁸ F]F-DPA) imaging fo...

Type 1 cannabinoid (CB1) receptor is expressed in cortex, hippocampus, amygdala, basal ganglia, and cerebellum. With the help of the Allen Human Brain Atlas, genomic maps visualize not only the gene expression across whole brain regions, but also the functional profile of brain structures. Therefore, it is more timely than ever to integrate genomic...

BACKGROUND The dopamine system contributes to a multitude of functions ranging from reward and motivation to learning and movement control, making it a key component in goal-directed behavior. Altered dopaminergic function is observed in neurological and psychiatric conditions. Numerous factors have been proposed to influence dopamine function, but...

Introduction: Central μ-opioid receptors (MORs) modulate affective responses to physical exercise. Individuals with higher aerobic fitness report greater exercise-induced mood improvements than those with lower fitness, but the link between cardiorespiratory fitness and the MOR system remains unresolved. Here we tested whether maximal oxygen uptak...

Background Obesity is a pressing public health concern worldwide. Novel pharmacological means are urgently needed to combat the increase of obesity and accompanying type 2 diabetes (T2D). Although fully established obesity is associated with neuromolecular alterations and insulin resistance in the brain, potential obesity-promoting mechanisms in th...

Purpose While brown adipose tissue (BAT) activity is known to be associated with both muscle and adipose tissue volumes, the association between BAT and muscle composition remains unclear, especially in adults. Therefore, the present study aimed to examine the association between BAT parameters (glucose uptake and fat-fraction) and muscle volumes a...

Activation of thermogenic brown and beige adipocytes is considered as a strategy to improve metabolic control. Here, we identify GPR180 as a receptor regulating brown and beige adipocyte function and whole-body glucose homeostasis, whose expression in humans is associated with improved metabolic control. We demonstrate that GPR180 is not a GPCR but...

The cardiac benefits of gastrointestinal hormones have been of interest in recent years. The aim of this study was to explore the myocardial and renal effects of the gastrointestinal hormone secretin in the GUTBAT trial (NCT03290846). A placebo-controlled crossover study was conducted on 15 healthy males in fasting conditions, where subjects were b...

The endogenous mu-opioid receptor (MOR) system modulates a multitude of social and reward-related functions, and exogenous opiates also influence sex drive in humans and animals. Sex drive shows substantial variation across humans, and it is possible that individual differences in MOR availability underlie interindividual of variation in human sex...

The endogenous mu-opioid receptor (MOR) system modulates a multitude of social and reward-related functions, and exogenous opiates also influence sex drive in humans and animals. Sex drive shows substantial variation across humans, and it is possible that individual differences in MOR availability underlie interindividual of variation in human sex...

Secretin is the first hormone that has been discovered, inaugurating the era and the field of endocrinology. Despite the initial focus, the interest in its actions faded away over the decades. However, there is mounting evidence regarding the pleiotropic beneficial effects of secretin on whole-body homeostasis. In this review, we discuss the eviden...

Background Peripheral artery disease (PAD) affects >200 million people worldwide and is associated with high mortality and morbidity. We sought to identify genomic variants associated with PAD overall and in the contexts of diabetes and smoking status. Methods We identified genetic variants associated with PAD and then meta-analyzed with published...

Brown adipose tissue (BAT) expresses uncoupling protein-1 (UCP1), which enables energy to be exerted towards needed thermogenesis. Beige adipocytes are precursor cells interspersed among white adipose tissue (WAT) that possess similar UCP1 activity and capacity for thermogenesis. The raccoon dog (Nyctereutes procyonoides) is a canid species that ut...

Eating behavior varies greatly between individuals, but the neurobiological basis of these trait-like differences in feeding remains poorly understood. Central μ-opioid receptors (MOR) and cannabinoid CB1 receptors (CB1R) regulate energy balance via multiple neural pathways, promoting food intake and reward. Because obesity and eating disorders hav...

BACKGROUND The dopamine system contributes to a multitude of functions ranging from reward and motivation to learning and movement control, making it a key component in goal-directed behavior. Altered dopaminergic function is observed in neurological and psychiatric conditions. Numerous factors have been proposed to influence dopamine function, but...

Objective: Insulinomas are rare functional pancreatic neuroendocrine tumours. As previous data on the long-term prognosis of insulinoma patients are scarce, we studied the morbidity and mortality in the Finnish insulinoma cohort. Design: Retrospective cohort study Methods: Incidence of endocrine, cardiovascular, gastrointestinal and psychiatric dis...

Surgery with curative intent can be offered to Congenital Hyperinsulinism (CHI) patients, provided that the lesion is focal. Radiolabeled Exendin-4 specifically binds the glucagon-like peptide 1 receptor (GLP-1R) on pancreatic beta cells. In this study we compared the performance of [18F]F-DOPA positron emission tomography/computed tomography (DOPA...

A new study investigates brown adipose tissue (BAT) volume in young, metabolically healthy adults. The focus is on the associations between BAT volume and BMI, waist circumference, whole-body adipose tissue mass, visceral adipose tissue mass and cold-induced BAT activity. Of note, the reported associations differed in men and women.

Brown adipose tissue (BAT) thermogenesis is activated by feeding. Recently, we revealed a secretin-mediated gut–BAT–brain axis, which stimulates satiation in mice, but the purpose of meal-induced BAT activation in humans has been unclear. In this placebo-controlled, randomized crossover study, we investigated the effects of intravenous secretin on...

Obesity is a growing burden to health and the economy worldwide. Obesity is associated with central µ-opioid receptor (MOR) downregulation and disruption of the interaction between MOR and dopamine D2 receptor (D2R) system in the ventral striatum. Weight loss recovers MOR function, but it remains unknown whether it also recovers aberrant opioid-dop...

Bariatric surgery is the most effective method for weight loss in morbid obesity. There is significant individual variability in the weight loss outcomes, yet factors leading to postoperative weight loss or weight regain remain elusive. Alterations in the µ-opioid receptor (MOR) and dopamine D2 receptor (D2R) systems are associated with obesity and...

Cardiovascular effects of glucagon-like peptide-1 receptor (GLP-1R) agonist therapies are potentially mediated by anti-inflammatory effects on atherosclerosis. Our study demonstrates that ⁶⁸ Ga-NODAGA-exendin-4, a radioligand specifically targeting GLP-1R, detects GLP-1R expression in inflamed atherosclerotic lesions in nondiabetic and diabetic hyp...

Imaging brain glucose metabolism with fluorine-labelled fluorodeoxyglucose ([18F]-FDG) positron emission tomography (PET) has long been utilized to aid the diagnosis of memory disorders, in particular in differentiating Alzheimer’s disease (AD) from other neurological conditions causing cognitive decline. The interest for studying brain glucose met...

The melanocortin system is involved in the control of adiposity through modulation of food intake and energy expenditure. The single nucleotide polymorphism (SNP) rs17782313 near the MC4R gene has been linked to obesity, and a previous study using magnetoencephalography has shown that carriers of the mutant allele have decreased cerebrocortical res...

Background: Sympathetic activity causes changes in electrocardiogram (ECG) during cold exposure and the changes have been studied mostly during hypothermia and less during mild acute nonshivering cold exposure. Cold-induced sympathetic activity also activates brown adipose tissue (BAT) and increases arterial blood pressure (BP) and plasma catechol...

Objective: Gray matter (GM) volume in different brain loci has been shown to vary in obesity and diabetes, and elevated fasting plasma nonesterified fatty acid (NEFA) levels have been suggested as one potential mechanism. The hypothesis presented in this study is that brown adipose tissue (BAT) activity may correlate with GM volume in areas negati...

Aims: To explore early effects of dapagliflozin on myocardial function and metabolism in patients with type 2 diabetes without heart failure. Materials and methods: Patients with type 2 diabetes on metformin treatment were randomized to double-blind 6-week placebo or dapagliflozin 10 mg daily treatment. Investigations included cardiac function a...

Background: Bariatric surgery is the most effective method for weight loss in morbid obesity. There is significant individual variability in the weight loss outcomes, yet factors leading to postoperative weight loss or weight regain remain elusive. Alterations in the mu-opioid receptor (MOR) and dopamine D2 receptor (D2R) systems are associated wit...

Background Laparoscopic sleeve gastrectomy (LSG) and Roux-en-Y gastric bypass (LRYGB) are both effective surgical procedures to achieve weight reduction in patients with obesity. The trial objective was to merge individual-patient data from two RCTs to compare outcomes after LSG and LRYGB. Methods Five-year outcomes of the Finnish SLEEVEPASS and S...

Objective: Whereas insulin resistance is expressed as reduced glucose uptake in peripheral tissues, the relationship between insulin resistance and brain glucose metabolism remains controversial. Our aim was to examine the association of insulin resistance and brain glucose uptake (BGU) during a euglycemic hyperinsulinemic clamp in a large sample...

Seasonal rhythms influence emotion and sociability. The brain μ-opioid receptor (MOR) system modulates a multitude of seasonally varying socioemotional functions, but its seasonal variation remains elusive with no previously reported in vivo evidence. Here, we first conducted a cross-sectional study with previously acquired human [11C]carfentanil P...