Olanzapine-induced nonalcoholic fatty liver disease: The effects of differential food pattern and the involvement of PGRMC1 signaling

B-GOS alleviates olanzapine-induced lipid disturbances in mice by enriching Akkermansia and upregulation of PGRMC1-Wnt signaling

Although olanzapine (OLZ) remains one of the most efficacious antipsychotic medications for the treatment of schizophrenia, there are significant tolerability issues related to its metabolic profile such as weight gain and dyslipidemia. Our previous studies have demonstrated that progesterone receptor membrane component 1 (PGRMC1) plays a key role in antipsychotic-induced metabolic side effects. Prebiotics showed positive effects on lipid metabolism, however, limited studies focused on their therapeutic potential and mechanisms in treating antipsychotic-induced lipid metabolic disorders. Herein, our study aims to explore the effects of the prebiotic B-GOS on lipid disturbances induced by OLZ and elucidate its underlying mechanisms via PGRMC1 pathway. In an 8-week study, long-term intraperitoneal administration of OLZ at a dosage of 8 mg/kg/day in mice induced lipid disturbances as manifested by significantly increased lipid indexes in plasma and liver. B-GOS effectively alleviated the OLZ-induced abnormal lipid metabolism by enhancing the diversity of the gut microbiota, with a 100-fold increase in Akkermansia abundance and a 10-fold decrease in Faecalibaculum abundance. Followed by the B-GOS related changes of gut microbiota, OLZ-induced substantial hepatic inhibition of PGRMC1, and associated protein factors of Wnt signaling pathway (Wnt3a, β-catenin, and PPAR-γ) were reversed without affecting plasma levels of short-chain fatty acids. Taken together, prebiotics like B-GOS enriching Akkermansia offer a promising novel approach to alleviate antipsychotic-induced lipid disturbances by modulating the PGRMC1-Wnt signaling pathway.

PCSK9 dysregulates cholesterol homeostasis and triglyceride metabolism in olanzapine-induced hepatic steatosis via both receptor-dependent and receptor-independent pathways

Schizophrenia, affecting approximately 1% of the global population, is often treated with olanzapine. Despite its efficacy, olanzapine's prolonged use has been associated with an increased risk of cardiovascular diseases and nonalcoholic fatty liver disease (NAFLD); however, the underlying mechanism remains unclear. Proprotein convertase subtilisin kexin type 9 (PCSK9) plays a crucial role in lipid metabolism and is involved in NAFLD pathogenesis via an unknown mechanism. This study aims to investigate the role of PCSK9 in olanzapine-induced NAFLD. C57BL/6J mice and HepG2 and AML12 cell lines were treated with varying concentrations of olanzapine to examine the effects of olanzapine on PCSK9 and lipid metabolism. PCSK9 levels were manipulated using recombinant proteins, plasmids, and small interfering RNAs in vitro, and the effects on hepatic lipid accumulation and gene expression related to lipid metabolism were assessed. Olanzapine treatment significantly increased PCSK9 levels in both animal and cell line models, correlating with elevated lipid accumulation. PCSK9 manipulation demonstrated its central role in mediating hepatic steatosis through both receptor-dependent pathways (impacting NPC1L1) and receptor-independent pathways (affecting lipid synthesis, uptake, and cholesterol biosynthesis). Interestingly, upregulation of SREBP-1c, rather than SREBP-2, was identified as a key driver of PCSK9 increase in olanzapine-induced NAFLD. Our findings establish PCSK9 as a pivotal factor in olanzapine-induced NAFLD, influencing both receptor-related and metabolic pathways. This highlights PCSK9 inhibitors as potential therapeutic agents for managing NAFLD in schizophrenia patients treated with olanzapine.

The Involvement of PGRMC1 Signaling in Cognitive Impairment Induced by Long-Term Clozapine Treatment in Rats

INTRODUCTION

Progesterone receptor component 1 (PGRMC1) has been identified as a potential target in atypical antipsychotic drug-induced metabolic disturbances as well as neuroprotection in the central nervous system. In our study, we aimed to figure out the essential role of PGRMC1 signaling pathway underlying clozapine-induced cognitive impairment.

METHODS

In male SD rats, we utilized recombinant adeno-associated viruses (BBB 2.0) and the specific inhibitor of PGRMC1 (AG205) to regulate the expression of PGRMC1 in the brain, with a special focus on the hippocampus. Treatments of clozapine and AG205 were conducted for 28 days, and subsequent behavioral tests including modified elevated plus maze and Morris water maze were conducted to evaluate the cognitive performance. Hippocampal protein expressions were measured by Western blotting.

RESULTS

Our study showed that long-term clozapine administration led to cognitive impairment as confirmed by behavioral tests as well as histopathological examination in the hippocampus. Clozapine inhibited neural survival through the PGRMC1/EGFR/GLP1R-PI3K-Akt signaling pathway, leading to a decrease in the downstream survival factor, brain-derived neurotrophic factor (BDNF), and simultaneously promoted neural apoptosis in the rat hippocampus. Intriguingly, by targeting at the hippocampal PGRMC1, we found that inhibiting PGRMC1 mimics, while its upregulation notably mitigates clozapine-induced cognitive impairment through PGRMC1 and its downstream signaling pathways.

CONCLUSION

PGRMC1-overexpression could protect hippocampus-dependent cognitive impairment induced by clozapine. This effect appears to arise, in part, from the upregulated expression of PGRMC1/EGFR/GLP1R and the activation of downstream PI3K-Akt-BDNF and caspase-3 signaling pathways.

Hypothalamic JNK1-hepatic fatty acid synthase axis mediates a metabolic rewiring that prevents hepatic steatosis in male mice treated with olanzapine via intraperitoneal: Additional effects of PTP1B inhibition

Olanzapine (OLA), a widely used second-generation antipsychotic (SGA), causes weight gain and metabolic alterations when administered orally to patients. Recently, we demonstrated that, contrarily to the oral treatment which induces weight gain, OLA administered via intraperitoneal (i.p.) in male mice resulted in body weight loss. This protection was due to an increase in energy expenditure (EE) through a mechanism involving the modulation of hypothalamic AMPK activation by higher OLA levels reaching this brain region compared to those of the oral treatment. Since clinical studies have shown hepatic steatosis upon chronic treatment with OLA, herein we further investigated the role of the hypothalamus-liver interactome upon OLA administration in wild-type (WT) and protein tyrosine phosphatase 1B knockout (PTP1B-KO) mice, a preclinical model protected against metabolic syndrome. WT and PTP1B-KO male mice were fed an OLA-supplemented diet or treated via i.p. Mechanistically, we found that OLA i.p. treatment induces mild oxidative stress and inflammation in the hypothalamus in a JNK1-independent and dependent manner, respectively, without features of cell dead. Hypothalamic JNK activation up-regulated lipogenic gene expression in the liver though the vagus nerve. This effect concurred with an unexpected metabolic rewiring in the liver in which ATP depletion resulted in increased AMPK/ACC phosphorylation. This starvation-like signature prevented steatosis. By contrast, intrahepatic lipid accumulation was observed in WT mice treated orally with OLA; this effect being absent in PTP1B-KO mice. We also demonstrated an additional benefit of PTP1B inhibition against hypothalamic JNK activation, oxidative stress and inflammation induced by chronic OLA i.p. treatment, thereby preventing hepatic lipogenesis. The protection conferred by PTP1B deficiency against hepatic steatosis in the oral OLA treatment or against oxidative stress and neuroinflammation in the i.p. treatment strongly suggests that targeting PTP1B might be also a therapeutic strategy to prevent metabolic comorbidities in patients under OLA treatment in a personalized manner.