In vivo, ex vivo, and in vitro studies on apelin's effect on myocardial glucose uptake

Participation of the nitric oxide pathway in lordosis induced by apelin-13 in female rats

The present study investigated the participation of the nitric oxide pathway in facilitating lordosis behavior induced by intrahypothalamic administration of apelin-13 in ovariectomized rats primed with estradiol benzoate (EB). The experiments involved the administration of a nitric oxide synthase inhibitor (L-NAME) or a nitric oxide-dependent, soluble guanylyl cyclase inhibitor (ODQ), and an inhibitor of protein kinase G (KT5823) to the ventromedial hypothalamus (VMH) of EB-primed rats 30 min before infusion of apelin-13 (0.75 μg/μl). This dose of apelin-13 consistently induces lordosis behavior at 30 min, 120 min, and 240 min following infusion. Results showed that injections of either L-NAME or KT5823 significantly reduced the lordosis induced by apelin at 120 and 240 min. However, VMH infusion of ODQ 30 min before apelin-13 infusion reduced but did not significantly inhibit, the lordosis elicited by this peptide at the same time points. We conclude that the nitric oxide pathway in the VMH plays an important role in lordosis induced by apelin-13 in EB-primed rats.

The role of apelinergic system in metabolism and reproductive system in normal and pathological conditions: an overview

Lifestyle changes have made metabolic disorders as one of the major threats to life. Growing evidence demonstrates that obesity and diabetes disrupt the reproductive system by affecting the gonads and the hypothalamus-pituitary-gonadal (HPG) axis. Apelin, an adipocytokine, and its receptor (APJ) are broadly expressed in the hypothalamus nuclei, such as paraventricular and supraoptic, where gonadotropin-releasing hormone (GnRH) is released, and all three lobes of the pituitary, indicating that apelin is involved in the control of reproductive function. Moreover, apelin affects food intake, insulin sensitivity, fluid homeostasis, and glucose and lipid metabolisms. This review outlined the physiological effects of the apelinergic system, the relationship between apelin and metabolic disorders such as diabetes and obesity, as well as the effect of apelin on the reproductive system in both gender. The apelin-APJ system can be considered a potential therapeutic target in the management of obesity-associated metabolic dysfunction and reproductive disorders.

Structure-function relationship and physiological role of apelin and its G protein coupled receptor

Apelin receptor (APJR) is a class A peptide (apelin) binding G protein-coupled receptor (GPCR) that plays a significant role in regulating blood pressure, cardiac output, and maintenance of fluid homeostasis. It is activated by a wide range of endogenous peptide isoforms of apelin and elabela. The apelin peptide isoforms contain distinct structural features that aid in ligand recognition and activation of the receptor. Site-directed mutagenesis and structure-based studies have revealed the involvement of extracellular and transmembrane regions of the receptor in binding to the peptide isoforms. The structural features of APJR activation of the receptor as well as mediating G-protein and β-arrestin-mediated signaling are delineated by multiple mutagenesis studies. There is increasing evidence that the structural requirements of APJR to activate G-proteins and β-arrestins are different, leading to biased signaling. APJR also responds to mechanical stimuli in a ligand-independent manner. A multitude of studies has focused on developing both peptide and non-peptide agonists and antagonists specific to APJR. Apelin/elabela-activated APJR orchestrates major signaling pathways such as extracellular signal-regulated kinase (ERKs), protein kinase B (PKB/Akt), and p70S. This review focuses on the structural and functional characteristics of apelin, elabela, APJR, and their interactions involved in the binding and activation of the downstream signaling cascade. We also focus on the diverse signaling profile of APJR and its ligands and their involvement in various physiological systems.

Apelin-13 Reverses Bupivacaine-Induced Cardiotoxicity via the Adenosine Monophosphate-Activated Protein Kinase Pathway

BACKGROUND

Cardiotoxicity can be induced by the commonly used amide local anesthetic, bupivacaine. Bupivacaine can inhibit protein kinase B (AKT) phosphorylation and activated adenosine monophosphate-activated protein kinase alpha (AMPKα). It can decouple mitochondrial oxidative phosphorylation and enhance reactive oxygen species (ROS) production. Apelin enhances the phosphatidylinositol 3-kinase (PI3K)/AKT and AMPK/acetyl-CoA carboxylase (ACC) pathways, promotes the complete fatty acid oxidation in the heart, and reduces the release of ROS. In this study, we examined whether exogenous (Pyr1) apelin-13 could reverse bupivacaine-induced cardiotoxicity.

METHODS

We used the bupivacaine-induced inhibition model in adult male Sprague Dawley (SD) rats (n = 48) and H9c2 cardiomyocyte cell cultures to explore the role of apelin-13 in the reversal of bupivacaine cardiotoxicity, and its possible mechanism of action. AMPKα, ACC, carnitine palmitoyl transferase (CPT), PI3K, AKT, superoxide dismutase 1 (SOD1), and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (p47-phox) were quantified. Changes in mitochondrial ultrastructure were examined, and mitochondrial DNA, cell viability, ROS release, oxygen consumption rate (OCR) were determined.

RESULTS

Apelin-13 reduced bupivacaine-induced mitochondrial DNA lesions in SD rats (P < .001), while increasing the expression of AMPKα (P = .007) and PI3K (P = .002). Furthermore, apelin-13 blocked bupivacaine-induced depolarization of the mitochondrial membrane potential (P = .019) and the bupivacaine-induced increases in ROS (P = .001). Also, the AMPK pathway was activated by bupivacaine as well as apelin-13 (P = .002) in H9c2 cardiomyocytes. Additionally, the reduction in the PI3K expression by bupivacaine was mitigated by apelin-13 in H9c2 cardiomyocytes (P = .001). While the aforementioned changes induced by bupivacaine were not abated by apelin-13 after pretreatment with AMPK inhibitor compound C; the bupivacaine-induced changes were still mitigated by apelin-13, even when pretreated with PI3K inhibitor-LY294002.

CONCLUSIONS

Apelin-13 treatment reduced bupivacaine-induced oxidative stress, attenuated mitochondrial morphological changes and mitochondrial DNA damage, enhanced mitochondrial energy metabolism, and ultimately reversed bupivacaine-induced cardiotoxicity. Our results suggest a role for the AMPK in apelin-13 reversal of bupivacaine-induced cardiotoxicity.

Vascular normalisation as the stepping stone into tumour microenvironment transformation

A functional vascular system is indispensable for drug delivery and fundamental for responsiveness of the tumour microenvironment to such medication. At the same time, the progression of a tumour is defined by the interactions of the cancer cells with their surrounding environment, including neovessels, and the vascular network continues to be the major route for the dissemination of tumour cells in cancer, facilitating metastasis. So how can this apparent conflict be reconciled? Vessel normalisation-in which redundant structures are pruned and the abnormal vasculature is stabilised and remodelled-is generally considered to be beneficial in the course of anti-cancer treatments. A causality between normalised vasculature and improved response to medication and treatment is observed. For this reason, it is important to discern the consequence of vessel normalisation on the tumour microenvironment and to modulate the vasculature advantageously. This article will highlight the challenges of controlled neovascular remodelling and outline how vascular normalisation can shape disease management.

Apelin-13 Protects Corpus Cavernosum Against Fibrosis Induced by High-Fat Diet in an MMP-Dependent Mechanism

BACKGROUND

An increased fibrosis of the corpora cavernosa is a prevalent process that underlies most cases of erectile dysfunction. Apelin, an endogenous circulating peptide, has been documented as an important effector on cardiovascular homeostasis, controlling vascular function and reducing fibrosis in multiple pathological conditions. Recently, initial studies have shown that Apelin, acting through the APJ receptor, also modulates penile erection, however, the role of this system on penile structure and intracorporal collagen remodeling has not been investigated yet.

AIMS

Here we sought to investigate the effect of chronic Apelin treatment on the corpus cavernosum structure of hyperchOlesterolemic mice.

METHODS

Apolipoprotein gene-deleted (ApoE^-/-) mice were fed with a Western diet for 11 weeks and received Apelin-13 (2 mg/kg/day) or vehicle during the last 3 weeks. Penile samples were obtained for histological and biochemical analyses to assess the intracorporal collagen content and key proteins expression. Furthermore, the effect of Apelin-13 was evaluated in cultured NIH3T3 mouse fibroblasts stimulated with TGF-β.

OUTCOME

Local expression of Apelin-13 in mouse corpus cavernosum and its protective effect against fibrosis.

RESULTS

Apelin and APJ receptor were expressed (gene and protein) within the corpus cavernosum of ApoE^-/- mice, indicating a local modulation of the Apelin system. Interestingly, 3 weeks of Apelin-13 treatment strongly reduced intracavernosal collagen content. In addition, Apelin-13 enhanced total matrix metalloproteinase (MMP) activity in the mice penis, which was associated with an increased protein expression of MMP-1, MMP-3, MMP-8, and MMP-9, while tissue inhibitor of metalloproteinase were unaltered. These beneficial actions were not associated with changes in nNOS or eNOS protein expression, intracavernosal reactive oxygen species content, or atherosclerotic plaque deposition. Additionally, in cultured fibroblast, Apelin-13 inhibited TGF-β-induced fibroblast to myofibroblast differentiation and collagen production, possibly through the activation of ERK1/2 kinase.

CLINICAL TRANSLATION

These results point out Apelin/APJ system as a potential target to treat intracavernosal fibrosis-related disorders.

STRENGTH & LIMITATIONS

These results provide the first evidence of the Apelin system's positive role on erectile tissue structure/remodeling. Nevertheless, additional functional study addressing erectile response would bring extended validation regarding the relevance of such effect.

CONCLUSION

These results suggest a local modulation of the Apelin system within the corpus cavernosum. Remarkably, Apelin-13 reduced intracavernosal fibrosis in hypercholesterolemic mice by: (i) enhancing MMPs expression and activity; and (ii) inhibiting fibroblast differentiation into myofibroblast. Altogether, these results suggest an essential protective role of Apelin, indicating Apelin/APJ system as a promising candidate for the development of fibrosis-associated erectile dysfunction treatments. Sturny M, Anguenot L Costa-Fraga FP, et al. Apelin-13 Protects Corpus Cavernosum Against Fibrosis Induced by High-Fat Diet in an MMP-Dependent Mechanism. J Sex Med 2021;18:875-888.

The Role of Apelin/Apelin Receptor in Energy Metabolism and Water Homeostasis: A Comprehensive Narrative Review

The apelin receptor (APJ) is a member of the family A of G-protein-coupled receptors (GPCRs) and is involved in range of physiological and pathological functions, including fluid homeostasis, anxiety, and depression, as well as cardiovascular and metabolic disorders. APJ was classically described as a monomeric transmembrane receptor that forms a ternary complex together with its ligand and associated G proteins. More recently, increasing evidence indicates that APJ may interact with other GPCRs to form heterodimers, which may selectively modulate distinct intracellular signal transduction pathways. Besides, the apelin/APJ system plays important roles in the physiology and pathophysiology of several organs, including regulation of blood pressure, cardiac contractility, angiogenesis, metabolic balance, and cell proliferation, apoptosis, or inflammation. Additionally, the apelin/APJ system is widely expressed in the central nervous system, especially in neurons and oligodendrocytes. This article reviews the role of apelin/APJ in energy metabolism and water homeostasis. Compared with the traditional diuretics, apelin exerts a positive inotropic effect on the heart, while increases water excretion. Therefore, drugs targeting apelin/APJ system undoubtedly provide more therapeutic options for patients with congestive heart failure accompanied with hyponatremia. To provide more precise guidance for the development of clinical drugs, further in-depth studies are warranted on the metabolism and signaling pathways associated with apelin/APJ system.

The effect of apelin-13 on pancreatic islet beta cell mass and myocardial fatty acid and glucose metabolism of experimental type 2 diabetic rats

Apelin, a new identified adipokine, and its G protein-coupled receptor named APJ are widely expressed in various tissues. Apelin has been found to play important roles in the physiopathology of multiple diseases. Our aim is to assess the effect of long-term apelin treatment on serum insulin level and pancreatic islet beta-cell mass in the late stage of type 2 diabetes without hyperinsulinemia and to investigate the role of apelin in myocardial fatty acid and glucose metabolism. In the present study, the high-fat diet fed-streptozotocin-induced experimental type 2 diabetic rats were given once daily intraperitoneal injection of apelin-13 (0.1 μmol/kg) for 10 weeks. We observed that apelin significantly improved serum insulin reduction and reduced hyperglycemia. Histologic analysis showed that long-term apelin treatment significantly increased pancreatic islet beta cell mass. Exogenous apelin failed to change dyslipidaemia of type 2 diabetic rats. Apelin treatment markedly decreased elevated myocardial FFA and glycogen content. Treatment of type 2 diabetic rats with apelin markedly reduced increased gene expressions of the cardiac fatty acid transporter CD36, CPT-1, and Peroxisome proliferator-activated receptor (PPAR)-α. Whereas the gene levels of citrate synthase and peroxisome proliferator-activated receptor γ coactivator 1-α (PGC1-α), a transcriptional coactivator, mediating mitochondrial biogenesis in heart were unaltered in response to exogenous apelin. Taken together, longer-term apelin treatment prevented pancreatic beta-cell loss or failure in experimental type 2 diabetic rats. Apelin can regulate myocardial metabolism. Apelin reduced myocadial fatty acid uptake and oxidation through inhibiting PPAR-α but did not affect myocardial mitochondrial biogenesis in type 2 diabetic rats.

The apelin/APJ system as a therapeutic target in metabolic diseases

INTRODUCTION

Apelin, a bioactive peptide, is the endogenous ligand of APJ, a G protein-coupled receptor which is widely expressed in peripheral tissues and in the central nervous system. The apelin/APJ system is involved in the regulation of various physiological functions and is a therapeutic target in different pathologies; the development of APJ agonists and antagonists has thus increased. Area covered: This review focuses on the in vitro and in vivo metabolic effects of apelin in physiological conditions and in the context of metabolic diseases. Expert opinion: In experimental models, novel APJ agonists are efficient in vivo, to treat metabolic diseases and associated complications. However, more clinical trials are necessary to determine whether molecules that target APJ could become an alternative therapeutic strategy in the treatment of metabolic diseases and associated complications.

Elabela, a newly discovered APJ ligand: Similarities and differences with Apelin

The Apelin/APJ system is involved in a wide range of biological functions. For a long time, Apelin was thought to be the only ligand for APJ. Recently, a new peptide that acts via APJ and has similar functions, called Elabela, was identified. Elabela has beneficial effects on body fluid homeostasis, cardiovascular health, and renal insufficiency, as well as potential benefits for metabolism and diabetes. In this review, the properties and biological functions of this new peptide are discussed in comparison with those of Apelin. Important areas for future study are also discussed, with the consideration that research on Apelin could guide future research on Elabela.

Apelinergic System Structure and Function

Apelin and apela (ELABELA/ELA/Toddler) are two peptide ligands for a class A G-protein-coupled receptor named the apelin receptor (AR/APJ/APLNR). Ligand-AR interactions have been implicated in regulation of the adipoinsular axis, cardiovascular system, and central nervous system alongside pathological processes. Each ligand may be processed into a variety of bioactive isoforms endogenously, with apelin ranging from 13 to 55 amino acids and apela from 11 to 32, typically being cleaved C-terminal to dibasic proprotein convertase cleavage sites. The C-terminal region of the respective precursor protein is retained and is responsible for receptor binding and subsequent activation. Interestingly, both apelin and apela exhibit isoform-dependent variability in potency and efficacy under various physiological and pathological conditions, but most studies focus on a single isoform. Biophysical behavior and structural properties of apelin and apela isoforms show strong correlations with functional studies, with key motifs now well determined for apelin. Unlike its ligands, the AR has been relatively difficult to characterize by biophysical techniques, with most characterization to date being focused on effects of mutagenesis. This situation may improve following a recently reported AR crystal structure, but there are still barriers to overcome in terms of comprehensive biophysical study. In this review, we summarize the three components of the apelinergic system in terms of structure-function correlation, with a particular focus on isoform-dependent properties, underlining the potential for regulation of the system through multiple endogenous ligands and isoforms, isoform-dependent pharmacological properties, and biological membrane-mediated receptor interaction. © 2018 American Physiological Society. Compr Physiol 8:407-450, 2018.

Apelin/APJ system as a therapeutic target in diabetes and its complications

The G-protein-coupled receptor APJ and its endogenous ligand apelin are widely expressed in many peripheral tissues and central nervous system, including adipose tissue, skeletal muscles and hypothalamus. Apelin/APJ system, involved in numerous physiological functions like angiogenesis, fluid homeostasis and energy metabolism regulation, is notably implicated in the development of different pathologies such as diabetes and its complications. Increasing evidence suggests that apelin regulates insulin sensitivity, stimulates glucose utilization and enhances brown adipogenesis in different tissues associated with diabetes. Moreover, apelin is also involved in the regulation of diabetic complications via binding to APJ receptor. Apelin improves diabetes-induced kidney hypertrophia, normalizes obesity-associated cardiac hypertrophy and negatively promotes retinal angiogenesis in diabetic retinopathy. In this review, we provide a comprehensive overview about the role of apelin/APJ system in different tissues related with diabetes. Furthermore, we describe the pathogenesis of diabetic complications associated with apelin/APJ system. Finally, agonists and antagonists targeted to APJ receptor are described in the literature. Thus, we highlight apelin/APJ system as a novel therapeutic target for pharmacological intervention in treating diabetes and its complications.

New adipokines

Adipose tissue is now widely recognized as "an organ" able to synthesize and secrete hundred factors collectively called adipokines. These secreted molecules exert pleiotropic actions, notably on the regulation of glucose and lipid metabolism, inflammation, reproduction, or angiogenesis. Over the past two decades, a considerable amount of work was performed on the two "star" adipokines, leptin and adiponectin, particularly because of their involvement in energy metabolism. The present review is focused on the three most recently discovered adipokines that are clearly emerging as important actors in metabolism: apelin, fibroblast growth factor-21, and neuroregulin-4. Moreover, given a number of clinical and experimental data, these three adipokines represent promising targets in the context of metabolic disorders associated with obesity.

Treatment with metformin and a dipeptidyl peptidase-4 inhibitor elevates apelin levels in patients with type 2 diabetes mellitus

BACKGROUND

The objective of this study was to assess the effects of metformin monotherapy or combined treatment with a dipeptidyl peptidase-4 inhibitor (vildagliptin) on apelin levels in patients with type 2 diabetes mellitus.

METHODS

Twenty-five patients with poor glycemic control (glycosylated hemoglobin >6.5% [48 mmol/mol]) taking 1,000 mg of metformin daily and 25 healthy controls matched for age and body mass index were enrolled in this study. Anthropometric parameters, glycemic and lipid profile, insulin resistance (homeostasis model assessment of insulin resistance index), and apelin levels were measured at baseline and at 12-week and 24-week visits.

RESULTS

At baseline, apelin levels were higher in the T2DM patients than in the controls (1.93±1.81 ng/mL versus 6.09±4.90 ng/mL; P<0.05). After 12 weeks, when vildagliptin was added, fasting blood glucose and glycosylated hemoglobin decreased, and apelin levels increased further (from 6.09±4.90 ng/mL to 24.23±12.59 ng/mL; P<0.05). Follow-up at 24 weeks showed no further improvement in the glycemic profile and no further increase in apelin levels.

CONCLUSION

Both metformin and vildagliptin favorably changed glycemic indices and apelin levels. For patients inadequately controlled on a low dose of metformin, addition of vildagliptin may be helpful.

Apelin receptors: From signaling to antidiabetic strategy

The G protein-coupled receptor APJ and its cognate ligand, apelin, are widely expressed throughout human body. They are implicated in different key physiological processes such as angiogenesis, cardiovascular functions, fluid homeostasis and energy metabolism regulation. On the other hand, this couple ligand-receptor is also involved in the development and progression of different pathologies including diabetes, obesity, cardiovascular disease and cancer. Recently, a new endogenous peptidic ligand of APJ, named Elabela/Toddler, has been identified and shown to play a crucial role in embryonic development. Whereas nothing is yet known regarding Elabela/Toddler functions in adulthood, apelin has been extensively described as a beneficial adipokine regarding to glucose and lipid metabolism and is endowed with anti-diabetic and anti-obesity properties. Indeed, there is a growing body of evidence supporting apelin signaling as a novel promising therapeutic target for metabolic disorders (obesity, type 2 diabetes). In this review, we provide an overview of the pharmacological properties of APJ and its endogenous ligands. We also report the activity of peptidic and non-peptidic agonists and antagonists targeting APJ described in the literature. Finally, we highlight the important role of this signaling pathway in the control of energy metabolism at the peripheral level and in the central nervous system in both physiological conditions and during obesity or diabetes.

Apelin and energy metabolism

A wide range of adipokines identified over the past years has allowed considering the white adipose tissue as a secretory organ closely integrated into overall physiological and metabolic control. Apelin, a ubiquitously expressed peptide was known to exert different physiological effects mainly on the cardiovascular system and the regulation of fluid homeostasis prior to its characterization as an adipokine. This has broadened its range of action and apelin now appears clearly as a new player in energy metabolism in addition to leptin and adiponectin. Apelin has been shown to act on glucose and lipid metabolism but also to modulate insulin secretion. Moreover, different studies in both animals and humans have shown that plasma apelin concentrations are usually increased during obesity and type 2 diabetes. This mini-review will focus on the various systemic apelin effects on energy metabolism by addressing its mechanisms of action. The advances concerning the role of apelin in metabolic diseases in relation with the recent reports on apelin concentrations in obese and/or diabetic subjects will also be discussed.

[The APJ receptor: a new therapeutic approach in diabetic treatment]

The APJ receptor cloned in 1993 found its ligand in 1998 with the discovery of apelin. The presence of APJ in the central nervous system (more particularly in the hypothalamus) and in various tissues (heart, blood vessels, stomach, etc.) makes it a potential pharmacological target. Interest in APJ has allowed the development of peptidic molecules able to stimulate and/or inhibit the receptor and, more recently, to discover another endogenous ligand: apela. Among the functions regulated by the APJ/apelin system, the control of energy metabolism appears today in the forefront. A better understanding of the pharmacology of APJ receptor should allow innovative therapeutic approaches in the treatment of metabolic diseases.

Plasma apelin: A novel biomarker for predicting diabetes

BACKGROUND

Apelin regulates insulin sensitivity and secretion in animals. However, whether plasma apelin predicts incident diabetes in humans remains unknown.

METHODS

We studied a cohort including 447 subjects (148 men, 299 women) without diabetes and followed for an average of 3y. Diabetes was diagnosed by an oral glucose tolerance test, plasma hemoglobin A1c, and if the subject was taking medications for diabetes. Plasma apelin-12 at baseline was measured with a commercial kit.

RESULTS

Plasma apelin concentrations were higher in women than in men at baseline (p=0.007). During follow-up, 43 subjects developed type 2 diabetes. Higher plasma apelin concentrations were associated with a higher risk of diabetes in men (p=0.049) but not in women. Plasma apelin predicted incident type 2 diabetes in men (hazard ratio, 2.13, 95% CI 1.29-3.51, p<0.05), but not in women, adjusted for age, family history of diabetes, hemoglobin A1c, body mass index, hypertension, and HOMA2-IR. Apelin could improve the prediction ability beyond traditional risk factors in men, and the sensitivity and specificity of plasma apelin at 0.9ng/ml for this prediction were 63.2% and 58.9%, respectively. In men at risk for diabetes (HbA1c 5.7-6.4%, FPG 100-125mg/dl, or OGTT-2h-PG 140-199mg/dl), the risk for developing diabetes was higher in those with higher plasma apelin concentration than in those with lower plasma apelin concentrations (10.6%/year vs. 5.1%/year, p<0.001).

CONCLUSIONS

Plasma apelin is a novel biomarker for predicting type 2 diabetes in men.

The apelinergic system: sexual dimorphism and tissue-specific modulations by obesity and insulin resistance in female mice

It has been proposed that the apelinergic system (apelin and its receptor APJ) may be a promising therapeutic target in obesity-associated insulin resistance syndrome. However, due to the extended tissue-distribution of this system, the therapeutic use of specific ligands for APJ may target numerous tissues resulting putatively to collateral deleterious effects. To unravel specific tissular dysfunctions of this system under obesity and insulin-resistance conditions, we measured the apelinemia and gene-expression level of both apelin (APL) and APJ in 12-selected tissues of insulin-resistant obese female mice fed with a high fat (HF) diet. In a preliminary study, we compared between adult male and female mice, the circadian plasma apelin variation and the effect of fasting on apelinemia. No significant differences were found for these parameters suggesting that the apelinemia is not affected by the sex. Moreover, plasma apelin level was not modulated during the four days of the estrous cycle in females. In obese and insulin-resistant HF female mice, plasma apelin concentration after fasting was not modified but, the gene-expression level of the APL/APJ system was augmented in the white adipose tissue (WAT) and reduced in the brown adipose tissue (BAT), the liver and in kidneys. BAT apelin content was reduced in HF female mice. Our data suggest that the apelinergic system may be implicated into specific dysfunctions of these tissues under obesity and diabetes and that, pharmacologic modulations of this system may be of interest particularly in the treatment of adipose, liver and renal dysfunctions that occur during these pathologies.