Renaming NAFLD to MAFLD: Could the LDE System Assist in This Transition?

Gut microbes, diet, and genetics as drivers of metabolic liver disease: a narrative review outlining implications for precision medicine

Metabolic dysfunction-associated steatotic liver disease (MASLD) is rapidly increasing in prevalence, impacting over a third of the global population. The advanced form of MASLD, Metabolic dysfunction-associated steatohepatitis (MASH), is on track to become the number one indication for liver transplant. FDA-approved pharmacological agents are limited for MASH, despite over 400 ongoing clinical trials, with only a single drug (resmetirom) currently on the market. This is likely due to the heterogeneous nature of disease pathophysiology, which involves interactions between highly individualized genetic and environmental factors. To apply precision medicine approaches that overcome interpersonal variability, in-depth insights into interactions between genetics, nutrition, and the gut microbiome are needed, given that each have emerged as dynamic contributors to MASLD and MASH pathogenesis. Here, we discuss the associations and molecular underpinnings of several of these factors individually and outline their interactions in the context of both patient-based studies and preclinical animal model systems. Finally, we highlight gaps in knowledge that will require further investigation to aid in successfully implementing precision medicine to prevent and alleviate MASLD and MASH.

Childhood maltreatment and risk of metabolic dysfunction-associated steatotic liver disease - Evidence of sex-specific associations in the general population

BACKGROUND AND AIMS

Childhood maltreatment (CM) is linked to self-reported liver disease in adulthood. However, specific diagnostic entities, e.g., metabolic dysfunction-associated steatotic liver disease (MASLD) as the most frequent chronic liver disease, and sex-differences have previously not been considered.

METHODS

Cross-sectional analyses were conducted in 4188 adults from a population-based cohort in Northeastern Germany after excluding individuals with excessive alcohol consumption, cirrhosis, or chronic viral hepatitis. CM-exposure was assessed using the Childhood Trauma Questionnaire (CTQ). Liver-related outcomes included serologic liver enzymes, fibrosis-4 score (FIB-4) and, in 1863 subjects who underwent magnetic resonance imaging examination, liver fat content. Sex-stratified linear regression and logistic regression models predicting liver-related outcomes and risk for MASLD, respectively, from overall CTQ scores were adjusted for age, school education, alcohol consumption, and waist circumference. Exploratory analyses investigated effects of CTQ-subscales on liver-related outcomes and risk for MASLD.

RESULTS

In both sexes, overall CM-exposure was associated with higher levels of serum aspartate aminotransferase and FIB-4 score. In men, effects were mainly driven by physical abuse, and in women by emotional neglect. Only in men, overall CM-exposure (β = 0.70, 95%-CI 0.26-1.13, p = 0.002) and four CTQ-subscales were associated with greater liver fat content, and physical abuse (aOR = 1.22, 95%-CI 1.02-1.46, p = 0.034) and physical neglect (aOR = 1.25, 95%-CI 1.04-1.49, p = 0.015) were associated with higher risk for MASLD.

CONCLUSIONS

These results suggest sex differences in the association between CM and objective serum and imaging markers of MASLD in adulthood. For men especially, a history of CM-exposure may increase risk of developing MASLD in adulthood.

Age at menopause and risk of metabolic dysfunction-associated fatty liver disease: A 14-year cohort study

BACKGROUNDS & AIMS

Menopause, characterized by a sudden decline in estrogen levels, has significant effects on women's health, especially when it occurs early. This study aimed to investigate the associations between menopausal age and incidence of metabolic dysfunction-associated fatty liver disease (MAFLD) using a large cohort and a long-term follow-up.

METHODS

Menopausal age was categorized into four groups (G1-4 [<40, 40-44, 45-49, and ≥50 years, respectively]). Cox proportional hazards regression analysis was used to assess the risk of developing MAFLD during the follow-up period according to the menopausal age categories.

RESULTS

A total of 1,888 participants were included in the final analysis and followed for a median period of 12.3 years. The unadjusted hazard ratios (95 % CIs) for the incidence of new-onset MAFLD were 1.11 (0.93-1.32), 1.15 (0.90-1.47), and 1.52 (1.12-2.07) in G3, G2, and G1, respectively, compared with that in G4. After adjusting for confounders, the hazard ratio (95 % CIs) for the incidence of new-onset MAFLD was 1.40 (1.00-1.95) in G1 compared with that in G4.

CONCLUSION

The risk of developing MAFLD was higher in women with premature menopause (<40 years) than in those with menopause aged ≥50 years.

Endpoints in NASH Clinical Trials: Are We Blind in One Eye?

This narrative review aims to illustrate the notion that nonalcoholic steatohepatitis (NASH), recently renamed metabolic dysfunction-associated steatohepatitis (MASH), is a systemic metabolic disorder featuring both adverse hepatic and extrahepatic outcomes. In recent years, several NASH trials have failed to identify effective pharmacological treatments and, therefore, lifestyle changes are the cornerstone of therapy for NASH. with this context, we analyze the epidemiological burden of NASH and the possible pathogenetic factors involved. These include genetic factors, insulin resistance, lipotoxicity, immuno-thrombosis, oxidative stress, reprogramming of hepatic metabolism, and hypoxia, all of which eventually culminate in low-grade chronic inflammation and increased risk of fibrosis progression. The possible explanations underlying the failure of NASH trials are also accurately examined. We conclude that the high heterogeneity of NASH, resulting from variable genetic backgrounds, exposure, and responses to different metabolic stresses, susceptibility to hepatocyte lipotoxicity, and differences in repair-response, calls for personalized medicine approaches involving research on noninvasive biomarkers. Future NASH trials should aim at achieving a complete assessment of systemic determinants, modifiers, and correlates of NASH, thus adopting a more holistic and unbiased approach, notably including cardiovascular-kidney-metabolic outcomes, without restricting therapeutic perspectives to histological surrogates of liver-related outcomes alone.

The bidirectional association of nonalcoholic fatty liver disease with depression, bipolar disorder, and schizophrenia

Nonalcoholic fatty liver disease (NAFLD) is a complex metabolic-inflammatory disease associated with poor outcomes and decreased quality of life. NAFLD is overrepresented in patients with psychiatric disorders like depression, bipolar disorder, and schizophrenia; however, a comprehensive review on NAFLD and psychiatric disorders remains to be delineated. This review endeavors to investigate the association of NAFLD with psychiatric disorders, including shared pathogenesis and future clinical derivatives. Extant literature suggests that patients with psychiatric disorders (in particular, mood disorders) are more susceptible to the development of NAFLD due to multiple reasons, including but not limited to hypothalamic-pituitary-adrenal axis dysregulation, metabolic syndrome, and chronic perceived stress. Moreover, the clinical manifestations of mood disorders (e.g., anhedonia, psychomotor retardation, lifestyle modification, etc.), and potentially long-term treatment with weight-gaining agents, differentially affect these patients, making them more prone to NAFLD. Considering the increased morbidity associated with both mood disorders and NAFLD, our review recommends regular screenings for NAFLD in select patients with mood disorders exhibiting signs of increased risk (i.e., obesity, metabolic syndrome, diabetes, or family history of NAFLD) for better diagnosis and holistic care of both potentially interrelated conditions.

Risk of Recurrence of Hepatocarcinoma after Liver Transplantation: Performance of Recurrence Predictive Models in a Cohort of Transplant Patients

Liver transplantation (LT) is a curative treatment for early-stage hepatocellular carcinoma (HCC) unsuitable for surgical resection. However, tumor recurrence (TR) rates range from 8% to 20% despite strict selection criteria. The validation of new prognostic tools, such as pre-MORAL or RETREAT risks, is necessary to improve recurrence prediction. A retrospective study was conducted at Marqués de Valdecilla University Hospital in Cantabria, Spain, between 2010 and 2019 to determine the rate of TR in LT patients and identify associated factors. Patients with liver-kidney transplantation, re-transplantation, HIV infection, survival less than 90 days, or incidental HCC were excluded. Data on demographic, liver disease-related, LT, and tumor-related variables, as well as follow-up records, including TR and death, were collected. TR was analyzed using the Log-Rank test, and a multivariate Cox regression analysis was performed. The study was approved by the IRB of Cantabria. TR occurred in 13.6% of LT patients (95% CI = 7.3-23.9), primarily as extrahepatic recurrence (67%) within the first 5 years (75%). Increased TR was significantly associated with higher Body Mass Index (BMI) (HR = 1.3 [95% CI = 1.1-1.5]), vascular micro-invasion (HR = 8.8 [1.6-48.0]), and medium (HR = 20.4 [3.0-140.4]) and high pre-MORAL risk (HR = 30.2 [1.6-568.6]). TR also showed a significant correlation with increased mortality. Conclusions: LT for HCC results in a 13.6% rate of tumor recurrence. Factors such as BMI, vascular micro-invasion, and medium/high pre-MORAL risk are strongly associated with TR following LT.

The heterogeneity of metabolic syndrome presentation and challenges this causes in its pharmacological management: a narrative review focusing on principal risk modifiers

INTRODUCTION

Metabolic syndrome (MetS), i.e. the cluster of cardiometabolic risk factors comprising visceral obesity, impaired glucose metabolism, arterial hypertension and atherogenic dyslipidemia, is prevalent globally and exacts a heavy toll on health care expenditures.

AREAS COVERED

The pathophenotypes of individual traits of the MetS in adults are discussed first, with strong emphasis on nonalcoholic fatty liver disease (NAFLD) and sex differences. Next, I discuss recent studies on phenotypic and outcome heterogeneity of the MetS, highlighting the role of NAFLD, sex, reproductive status, and depressive disorders. In the second half of the article, the therapeutic implications of the variable MetS types and features are analyzed, focusing on the most recent developments, and guidelines.

EXPERT OPINION

I have identified physiological, pathological, social and medical sources of phenotypical heterogeneity in the MetS and its constitutive traits. Improved understanding of these variables may be utilized in the setting of future precision medicine approaches in the field of metabolic disorders and target organ damage.

Metabolic Associated Fatty Liver Disease as a Risk Factor for the Development of Central Nervous System Disorders

MAFLD/NAFLD is the most ordinary liver disease categorized by hepatic steatosis with the increase of surplus fat in the liver and metabolic liver dysfunction, which is associated with bigger mortality and a high medical burden. An association between MAFLD/NAFLD and central nervous system disorders including psychological disorders has been demonstrated. Additionally, MAFLD/NAFLD has been correlated with various types of neurodegenerative disorders such as amyotrophic lateral sclerosis or Parkinson’s disease. Contrasted to healthy controls, patients with MAFLD/NAFLD have a greater prevalence risk of extrahepatic complications within multiple organs. Dietary interventions have emerged as effective strategies for MAFLD/NAFLD. The PI3K/AKT/mTOR signaling pathway involved in the regulation of Th17/Treg balance might promote the pathogenesis of several diseases including MAFLD/NAFLD. As extrahepatic complications may happen across various organs including CNS, cooperative care with individual experts is also necessary for managing patients with MAFLD/NAFLD.

The interplay of post-acute COVID-19 syndrome and aging: a biological, clinical and public health approach

The post-acute COVID-19 syndrome (PACS) is characterized by the persistence of fluctuating symptoms over three months from the onset of the possible or confirmed COVID-19 acute phase. Current data suggests that at least 10% of people with previously documented infection may develop PACS, and up to 50-80% of prevalence is reported among survivors after hospital discharge. This viewpoint will discuss various aspects of PACS, particularly in older adults, with a specific hypothesis to describe PACS as the expression of a modified aging trajectory induced by SARS CoV-2. This hypothesis will be argued from biological, clinical and public health view, addressing three main questions: (i) does SARS-CoV-2-induced alterations in aging trajectories play a role in PACS?; (ii) do people with PACS face immuno-metabolic derangements that lead to increased susceptibility to age-related diseases?; (iii) is it possible to restore the healthy aging trajectory followed by the individual before pre-COVID?. A particular focus will be given to the well-being of people with PACS that could be assessed by the intrinsic capacity model and support the definition of the healthy aging trajectory.

Metabolic Dysfunction-associated Fatty Liver Disease is Associated with Greater Impairment of Lung Function than Nonalcoholic Fatty Liver Disease

BACKGROUND AND AIMS

We compared lung function parameters in nonalcoholic fatty liver disease (NAFLD) and metabolic dysfunction-associated fatty liver disease (MAFLD), and examined the association between lung function parameters and fibrosis severity in MAFLD.

METHODS

In this cross-sectional study, we randomly recruited 2,543 middle-aged individuals from 25 communities across four cities in China during 2016 and 2020. All participants received a health check-up including measurement of anthropometric parameters, biochemical variables, liver ultrasonography, and spirometry. The severity of liver disease was assessed by the fibrosis (FIB)-4 score.

RESULTS

The prevalence of MAFLD was 20.4% (n=519) and that of NAFLD was 18.4% (n=469). After adjusting for age, sex, adiposity measures, smoking status, and significant alcohol intake, subjects with MAFLD had a significantly lower predicted forced vital capacity (FVC, 88.27±17.60% vs. 90.82±16.85%, p<0.05) and lower 1 s forced expiratory volume (FEV₁, 79.89±17.34 vs. 83.02±16.66%, p<0.05) than those with NAFLD. MAFLD with an increased FIB-4 score was significantly associated with decreased lung function. For each 1-point increase in FIB-4, FVC was diminished by 0.507 (95% CI: -0.840, -0.173, p=0.003), and FEV₁ was diminished by 0.439 (95% CI: -0.739, -0.140, p=0.004). The results remained unchanged when the statistical analyses was performed separately for men and women.

CONCLUSIONS

MAFLD was significantly associated with a greater impairment of lung function parameters than NAFLD.

The advantages of physical exercise as a preventive strategy against NAFLD in postmenopausal women

BACKGROUND

The prevalence and severity of nonalcoholic fatty liver disease (NAFLD) increase in women after menopause. This narrative review discusses the causes and consequences of NAFLD in postmenopausal women and describes how physical activity can contribute to its prevention.

METHODS

The authors followed the narrative review method to perform a critical and objective analysis of the current knowledge on the topic. The Medical Subject Heading keywords 'physical exercise', 'menopause', 'hormone replacement therapy', 'estradiol' and 'NAFLD' were used to establish a conceptual framework. The databases used to collect relevant references included Medline and specialized high-impact journals.

RESULTS

Higher visceral adiposity, higher rate of lipolysis in adipose tissue after oestrogen drop and changes in the expression of housekeeping proteins involved in hepatic lipid management are observed in women after menopause, contributing to NAFLD. Excessive liver steatosis leads to hepatic insulin resistance, oxidative stress and inflammation, accelerating NAFLD progression. Physical activity brings beneficial effects against several postmenopausal-associated complications, including NAFLD progression. Aerobic and resistance exercises partially counteract alterations induced by metabolic syndrome in sedentary postmenopausal women, impacting NAFLD progression and severity.

CONCLUSIONS

With the increased global obesity epidemic in developing countries, NAFLD is becoming a severe problem with increased prevalence in women after menopause. Evidence shows that physical activity may delay NAFLD development and severity in postmenopausal women, although the prescription of age-appropriate physical activity programmes is advisable to assure the health benefits.

Metabolic-Associated Fatty Liver Disease Is Highly Prevalent in the Postacute COVID Syndrome

Background

A proposal has recently been advanced to change the traditional definition of nonalcoholic fatty liver disease to metabolic-associated fatty liver disease (MAFLD), to reflect the cluster of metabolic abnormalities that may be more closely associated with cardiovascular risk. Long coronavirus disease 2019 (COVID-19) is a smoldering inflammatory condition, characterized by several symptom clusters. This study aims to determine the prevalence of MAFLD in patients with postacute COVID syndrome (PACS) and its association with other PACS-cluster phenotypes.

Methods

We included 235 patients observed at a single university outpatient clinic. The diagnosis of PACS was based on ≥1 cluster of symptoms: respiratory, neurocognitive, musculoskeletal, psychological, sensory, and dermatological. The outcome was prevalence of MAFLD detected by transient elastography during the first postdischarge follow-up outpatient visit. The prevalence of MAFLD at the time of hospital admission was calculated retrospectively using the hepatic steatosis index.

Results

Of 235 patients, 162 (69%) were men (median age 61). The prevalence of MAFLD was 55.3% at follow-up and 37.3% on admission (P < .001). Insulin resistance (odds ratio [OR] = 1.5; 95% confidence interval [CI], 1.14–1.96), body mass index (OR = 1.14; 95% CI, 1.04–1.24), and the metabolic syndrome (OR = 2.54; 95% CI, 1.13–5.68) were independent predictors of MAFLD. The number of PACS clusters was inversely associated with MAFLD (OR = 0.86; 95% CI, .76–0.97). Thirty-one patients (13.2%) had MAFLD with no other associated PACS clusters. All correlations between MAFLD and other PACS clusters were weak.

Conclusions

Metabolic-associated fatty liver disease was highly prevalent after hospital discharge and may represent a specific PACS-cluster phenotype, with potential long-term metabolic and cardiovascular health implications.

Separating the apples from the oranges: from NAFLD heterogeneity to personalized medicine

Recently, Arrese and Colleagues have published a review article entitled, “Insights into Nonalcoholic Fatty-Liver Disease (NAFLD) Heterogeneity” (Semin Liver Dis. 2021;41:421-34. doi: 10.1055/s-0041-1730927). This milestone publication clearly and exhaustively explains the multitude of pathogenic pathways involved in the development and progression of disease eventually conducive to heterogeneous clinical phenotypes and different disease outcomes. The present commentary first briefly discusses the biological grounds of NAFLD heterogeneity and then illustrates the work by Arrese et al. In conclusion, the presently adopted nomenclatures appear inadequate in rendering the complexity of disease in the individual patient. In order to adopt the principles of personalized care, what remains to be done is to propose and validate a simple and accurate classification system. This should give full consideration to the principal disease modifiers and should shape a scheme to be adopted in both clinical practice and in the research arena. Care should be taken to not neglect the systemic nature of disease.

Separating the apples from the oranges: from NAFLD heterogeneity to personalized medicine

Recently, Arrese and Colleagues have published a review article entitled, “Insights into Nonalcoholic Fatty-Liver Disease (NAFLD) Heterogeneity” (Semin Liver Dis. 2021;41:421-34. doi: 10.1055/s-0041-1730927). This milestone publication clearly and exhaustively explains the multitude of pathogenic pathways involved in the development and progression of disease eventually conducive to heterogeneous clinical phenotypes and different disease outcomes. The present commentary first briefly discusses the biological grounds of NAFLD heterogeneity and then illustrates the work by Arrese et al. In conclusion, the presently adopted nomenclatures appear inadequate in rendering the complexity of disease in the individual patient. In order to adopt the principles of personalized care, what remains to be done is to propose and validate a simple and accurate classification system. This should give full consideration to the principal disease modifiers and should shape a scheme to be adopted in both clinical practice and in the research arena. Care should be taken to not neglect the systemic nature of disease.

Bile Acid Receptors and the Gut-Liver Axis in Nonalcoholic Fatty Liver Disease

The prevalence of nonalcoholic fatty liver disease (NAFLD) has been significantly increased due to the global epidemic of obesity. The disease progression from simple steatosis (NAFL) to nonalcoholic steatohepatitis (NASH) is closely linked to inflammation, insulin resistance, and dysbiosis. Although extensive efforts have been aimed at elucidating the pathological mechanisms of NAFLD disease progression, current understanding remains incomplete, and no effective therapy is available. Bile acids (BAs) are not only important physiological detergents for the absorption of lipid-soluble nutrients in the intestine but also metabolic regulators. During the last two decades, BAs have been identified as important signaling molecules involved in lipid, glucose, and energy metabolism. Dysregulation of BA homeostasis has been associated with NAFLD disease severity. Identification of nuclear receptors and G-protein-coupled receptors activated by different BAs not only significantly expanded the current understanding of NAFLD/NASH disease progression but also provided the opportunity to develop potential therapeutics for NAFLD/NASH. In this review, we will summarize the recent studies with a focus on BA-mediated signaling pathways in NAFLD/NASH. Furthermore, the therapeutic implications of targeting BA-mediated signaling pathways for NAFLD will also be discussed.

The Risk of Colorectal Adenoma in Nonalcoholic or Metabolic-Associated Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of liver disease associated with various metabolic disorders. Metabolic dysfunction-associated fatty liver disease (MAFLD) emphasizes metabolic dysfunction in NAFLD. Although the relationship between NAFLD and colorectal adenomas has been suggested, the effect of MAFLD on colorectal adenoma has yet to be investigated. In this study, we examined the relationship between NAFLD/MAFLD and colorectal adenoma in comparison with other metabolic factors.

METHODS

Examinees who underwent colonoscopy and abdominal ultrasonography on the same day from January 2012 to December 2012 were included. NAFLD was diagnosed according to the findings of ultrasonography. The Fibrosis-4 (FIB-4) index was used as a surrogate marker for advanced hepatic fibrosis. A logistic regression model was used to analyze the risk of NAFLD/MAFLD for colorectal adenoma.

RESULTS

The prevalence of NAFLD and MAFLD was 37.5% and 32.8%, respectively. In the multivariate analysis, male sex, older age, diabetes, and smoking increased the risk of colorectal adenoma. NAFLD and MAFLD were the most important risk factors for colorectal adenoma only in females [adjusted odds ratio (OR) 1.43 and 95% confidence interval (CI) 1.01-2.03, and OR 1.55, 95% CI 1.09-2.20, respectively]. NAFLD and MAFLD with an advanced fibrosis index were significantly associated with an increased risk of colorectal adenoma. (NAFLD: OR 1.38, 95% CI, 1.04-1.83, p = 0.027; MAFLD: OR 1.45, 95% CI, 1.13-1.96, p = 0.004, respectively).

CONCLUSION

NAFLD and MAFLD were significantly associated with a higher risk of colorectal adenomas, especially in females. NAFLD and MAFLD with advanced fibrosis were associated with an increased risk of colorectal adenoma. Colonoscopic examinations may be emphasized for patients with NAFLD/MAFLD, for women, or patients with the presence of hepatic fibrosis.

Links between metabolic syndrome and metabolic dysfunction-associated fatty liver disease

Metabolic dysfunction-associated fatty liver disease (MAFLD) is a chronic condition characterized by hepatic fat accumulation combined with underlying metabolic dysregulation. Having evolved from the previous term of nonalcoholic fatty liver disease (NAFLD), the term MAFLD more closely implicates the presence of overweight/obesity, type 2 diabetes, or metabolic dysregulation as essential pathogenic factors, leading to better identification of individuals with this metabolic liver disease. Low-grade inflammation, increased oxidative stress, mitochondrial dysfunction, and intestinal dysbiosis are also involved in its pathogenesis. MAFLD is not only associated with liver-related complications, but also with adverse cardiometabolic outcomes. Further studies are needed to assess whether the newly proposed definition of MAFLD is more accurate than the NAFLD in predicting the adverse liver-related and extrahepatic outcomes.

Perspectives on Precision Medicine Approaches to NAFLD Diagnosis and Management

Precision medicine defines the attempt to identify the most effective approaches for specific subsets of patients based on their genetic background, clinical features, and environmental factors. Nonalcoholic fatty liver disease (NAFLD) encompasses the alcohol-like spectrum of liver disorders (steatosis, steatohepatitis with/without fibrosis, and cirrhosis and hepatocellular carcinoma) in the nonalcoholic patient. Recently, disease renaming to MAFLD [metabolic (dysfunction)-associated fatty liver disease] and positive criteria for diagnosis have been proposed. This review article is specifically devoted to envisaging some clues that may be useful to implementing a precision medicine-oriented approach in research and clinical practice. To this end, we focus on how sex and reproductive status, genetics, intestinal microbiota diversity, endocrine and metabolic status, as well as physical activity may interact in determining NAFLD/MAFLD heterogeneity. All these factors should be considered in the individual patient with the aim of implementing an individualized therapeutic plan. The impact of considering NAFLD heterogeneity on the development of targeted therapies for NAFLD subgroups is also extensively discussed.

Cerebral Insulin Bolus Revokes the Changes in Hepatic Lipid Metabolism Induced by Chronic Central Leptin Infusion

Central actions of leptin and insulin on hepatic lipid metabolism can be opposing and the mechanism underlying this phenomenon remains unclear. Both hormones can modulate the central somatostatinergic system that has an inhibitory effect on growth hormone (GH) expression, which plays an important role in hepatic metabolism. Using a model of chronic central leptin infusion, we evaluated whether an increase in central leptin bioavailability modifies the serum lipid pattern through changes in hepatic lipid metabolism in male rats in response to an increase in central insulin and the possible involvement of the GH axis in these effects. We found a rise in serum GH in leptin plus insulin-treated rats, due to an increase in pituitary GH mRNA levels associated with lower hypothalamic somatostatin and pituitary somatostatin receptor-2 mRNA levels. An augment in hepatic lipolysis and a reduction in serum levels of non-esterified fatty acids (NEFA) and triglycerides were found in leptin-treated rats. These rats experienced a rise in lipogenic-related factors and normalization of serum levels of NEFA and triglycerides after insulin treatment. These results suggest that an increase in insulin in leptin-treated rats can act on the hepatic lipid metabolism through activation of the GH axis.