Fluoxetine-induced hepatic lipid accumulation is linked to elevated serotonin production

The janus face of serotonin: Regenerative promoter and chronic liver disease aggravator

The progression of liver diseases, from viral hepatitis and fatty liver disease to cirrhosis and hepatocellular carcinoma (HCC), is the most representative series of pathological events in liver diseases. While serotonin (5-HT) primarily regulates brain functions such as psychology, mood, and appetite in the central nervous system (CNS), peripheral 5-HT plays a crucial role in regulating tumor development, glucose and lipid metabolism, immune function and inflammatory response related to liver diseases. These peripheral physiological processes involving 5-HT are the key mechanisms driving the development of these liver diseases. This study presents an overview of the existing literature, focusing on the role of 5-HT in HCC, cirrhosis, fatty liver disease, viral hepatitis, and liver injury. In summary, while 5-HT promotes liver regeneration, it can also contribute to the progression of chronic liver disease. These findings indicate the potential for the development and use of 5-HT-related drugs for the treatment of liver diseases, including HCC and cirrhosis.

Intestinal tryptophan metabolism in disease prevention and swine production

Tryptophan (Trp) is an essential amino acid that cannot be synthesized by animals. It has been characterized into two different isomers, levorotation-Trp (L-Trp) and dextrorotation-Trp (D-Trp), based on their distinct molecule orientation. Intestinal epithelial cells and gut microbiota are involved in metabolizing L-Trp in the gut via the activation of the kynurenine, serotonin, and indole pathways. However, knowledge regarding D-Trp metabolism in the gut remains unclear. In this review, we briefly update the current understanding of intestinal L/D-Trp metabolism and the function of their metabolites in modulating the gut physiology and diseases. Finally, we summarize the effects of Trp nutrition on swine production at different stages, including growth performance in weaned piglets and growing pigs, as well as the reproduction performance in sows.

Association between antidepressant use and liver fibrosis in patients with type 2 diabetes: a population based study

BACKGROUND

The prevalence of liver fibrosis among diabetic patients is increasing rapidly. Our study aims at exploring the relationship between antidepressant use and liver fibrosis in diabetic patients.

METHODS

We conducted this cross-sectional study through the cycle of National Health and Nutrition Examination Survey (NHANES) 2017-2018. The study population were consisted of patients with type 2 diabetes and reliable vibration-controlled transient elastography (VCTE) results. The presence of liver fibrosis and steatosis were assessed by the median values of liver stiffness measurement (LSM) and controlled attenuation parameter (CAP), respectively. Antidepressants included selective serotonin reuptake inhibitors (SSRIs), tricyclic antidepressants (TCAs), serotonin and norepinephrine reuptake inhibitors (SNRIs) and serotonin antagonists and reuptake inhibitors (SARIs). Patients with evidence of viral hepatitis and significant alcohol consumption were excluded. Logistic regression analysis was performed to evaluate the association between antidepressant use and both steatosis and significant (≥ F3) liver fibrosis after adjustment for potential confounders.

RESULTS

Our study population consisted of 340 women and 414 men, of whom 87 women(61.3%) and 55(38.7%) men received antidepressants. The most commonly used antidepressants were SSNIs(48.6%), SNRIs(22.5%) and TCAs(12.7%), followed by SARIs(10.6%) and other antidepressants(5.6%). 165 participants had significant liver fibrosis by VCTE, with a weighted overall prevalence of 24%(95% CI 19.2-29.5). In addition, 510 patients had evidence of hepatic steatosis by VCTE with a weighted overall prevalence of 75.4%(95% CI 69.2-80.7). After adjusting confounders, no significant association was observed between antidepressant use and significant liver fibrosis or cirrhosis.

CONCLUSIONS

In conclusion, in this cross-sectional study, we found that antidepressant drugs was not associated with liver fibrosis and cirrhosis in patients with type 2 diabetes in a nationwide population.

Non-alcoholic fatty liver disease (NAFLD) and mental illness: Mechanisms linking mood, metabolism and medicines

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in the world and one of the leading indications for liver transplantation. It is one of the many manifestations of insulin resistance and metabolic syndrome as well as an independent risk factor for cardiovascular disease. There is growing evidence linking the incidence of NAFLD with psychiatric illnesses such as schizophrenia, bipolar disorder and depression mechanistically via genetic, metabolic, inflammatory and environmental factors including smoking and psychiatric medications. Indeed, patients prescribed antipsychotic medications, regardless of diagnosis, have higher incidence of NAFLD than population norms. The mechanistic pharmacology of antipsychotic-associated NAFLD is beginning to emerge. In this review, we aim to discuss the pathophysiology of NAFLD including its risk factors, insulin resistance and systemic inflammation as well as its intersection with psychiatric illnesses.

Increased gut serotonin production in response to bisphenol A structural analogs may contribute to their obesogenic effects

Obesogens are synthetic, environmental chemicals that can disrupt endocrine control of metabolism and contribute to the risk of obesity and metabolic disease. Bisphenol A (BPA) is one of the most studied obesogens. There is considerable evidence that BPA exposure is associated with weight gain, increased adiposity, poor blood glucose control, and nonalcoholic fatty liver disease in animal models and human populations. Increased usage of structural analogs of BPA has occurred in response to legislation banning their use in some commercial products. However, BPA analogs may also cause some of the same metabolic impairments because of common mechanisms of action. One key effector that is altered by BPA and its analogs is serotonin, however, it is unknown if BPA-induced changes in peripheral serotonin pathways underlie metabolic perturbations seen with BPA exposure. Upon ingestion, BPA and its analogs act as endocrine-disrupting chemicals in the gastrointestinal tract to influence serotonin production by the gut, where over 95% of serotonin is produced. The purpose of this review is to evaluate how BPA and its analogs alter gut serotonin regulation and then discuss how disruption of serotonergic networks influences host metabolism. We also provide evidence that BPA and its analogs enhance serotonin production in gut enterochromaffin cells. Taken together, we propose that BPA and many BPA analogs represent endocrine-disrupting chemicals that can influence host metabolism through the endogenous production of gut-derived factors, such as serotonin.

Interactions between Tryptophan Metabolism, the Gut Microbiome and the Immune System as Potential Drivers of Non-Alcoholic Fatty Liver Disease (NAFLD) and Metabolic Diseases

The prevalence of non-alcoholic fatty liver disease (NAFLD) is increasing and therefore is its burden of disease as NALFD is a risk factor for cirrhosis and is associated with other metabolic conditions such as type II diabetes, obesity, dyslipidaemia and atherosclerosis. Linking these cardiometabolic diseases is a state of low-grade inflammation, with higher cytokines and c-reactive protein levels found in individuals with NAFLD, obesity and type II diabetes. A possible therapeutic target to decrease this state of low-grade inflammation is the metabolism of the essential amino-acid tryptophan. Its three main metabolic pathways (kynurenine pathway, indole pathway and serotonin/melatonin pathway) result in metabolites such as kynurenic acid, xanturenic acid, indole-3-propionic acid and serotonin/melatonin. The kynurenine pathway is regulated by indoleamine 2,3-dioxygenase (IDO), an enzyme that is upregulated by pro-inflammatory molecules such as INF, IL-6 and LPS. Higher activity of IDO is associated with increased inflammation and fibrosis in NAFLD, as well with increased glucose levels, obesity and atherosclerosis. On the other hand, increased concentrations of the indole pathway metabolites, regulated by the gut microbiome, seem to result in more favorable outcomes. This narrative review summarizes the interactions between tryptophan metabolism, the gut microbiome and the immune system as potential drivers of cardiometabolic diseases in NAFLD.

Intestinal Dysbiosis, the Tryptophan Pathway and Nonalcoholic Steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) progresses from simple steatosis to steatohepatitis (NASH), which may then progress to the development of cirrhosis and hepatocarcinoma. NASH is characterized by both steatosis and inflammation. Control of inflammation in NASH is a key step for the prevention of disease progression to severe sequalae. Intestinal dysbiosis has been recognized to be an important causal factor in the pathogenesis of NASH, involving both the accumulation of lipids and aggravation of inflammation. The effects of gut dysbiosis are mediated by adverse shifts of various intestinal commensal bacterial genera and their associated metabolites such as butyrate, tryptophan, and bile acids. In this review, we focus on the roles of tryptophan and its metabolites in NASH in association with intestinal dysbiosis and discuss possible therapeutic implications.

Fluoxetine-induced hepatic lipid accumulation is mediated by prostaglandin endoperoxide synthase 1 and is linked to elevated 15-deoxy-Δ12,14 PGJ2

Major depressive disorder and other neuropsychiatric disorders are often managed with long-term use of antidepressant medication. Fluoxetine, an SSRI antidepressant, is widely used as a first-line treatment for neuropsychiatric disorders. However, fluoxetine has also been shown to increase the risk of metabolic diseases such as non-alcoholic fatty liver disease. Fluoxetine has been shown to increase hepatic lipid accumulation in vivo and in vitro. In addition, fluoxetine has been shown to alter the production of prostaglandins which have also been implicated in the development of non-alcoholic fatty liver disease. The goal of this study was to assess the effect of fluoxetine exposure on the prostaglandin biosynthetic pathway and lipid accumulation in a hepatic cell line (H4-II-E-C3 cells). Fluoxetine treatment increased mRNA expression of prostaglandin biosynthetic enzymes (Ptgs1, Ptgs2, and Ptgds), PPAR gamma (Pparg), and PPAR gamma downstream targets involved in fatty acid uptake (Cd36, Fatp2, and Fatp5) as well as production of 15-deoxy-Δ^12,14 PGJ₂ a PPAR gamma ligand. The effects of fluoxetine to induce lipid accumulation were attenuated with a PTGS1 specific inhibitor (SC-560), whereas inhibition of PTGS2 had no effect. Moreover, SC-560 attenuated 15-deoxy-Δ^12,14 PGJ₂ production and expression of PPAR gamma downstream target genes. Taken together these results suggest that fluoxetine-induced lipid abnormalities appear to be mediated via PTGS1 and its downstream product 15d-PGJ₂ and suggest a novel therapeutic target to prevent some of the adverse effects of fluoxetine treatment.

Serotonergic Regulation of Hepatic Energy Metabolism

The liver is a vital organ that regulates systemic energy metabolism and many physiological functions. Nonalcoholic fatty liver disease (NAFLD) is the commonest cause of chronic liver disease and end-stage liver failure. NAFLD is primarily caused by metabolic disruption of lipid and glucose homeostasis. Serotonin (5-hydroxytryptamine [5-HT]) is a biogenic amine with several functions in both the central and peripheral systems. 5-HT functions as a neurotransmitter in the brain and a hormone in peripheral tissues to regulate systemic energy homeostasis. Several recent studies have proposed various roles of 5-HT in hepatic metabolism and inflammation using tissue-specific knockout mice and 5-HT-receptor agonists/antagonists. This review compiles the most recent research on the relationship between 5-HT and hepatic metabolism, and the role of 5-HT signaling as a potential therapeutic target in NAFLD.