A Potential Mechanism Underlying the Therapeutic Effects of Progesterone and Allopregnanolone on Ketamine-Induced Cognitive Deficits

Progesterone induces neuroprotection associated with immune/inflammatory modulation in experimental traumatic brain injury

An imbalance of immune/inflammatory reactions aggravates secondary brain injury after traumatic brain injury (TBI) and can deteriorate clinical prognosis. So far, not enough therapeutic avenues have been found to prevent such an imbalance in the clinical setting. Progesterone has been shown to regulate immune/inflammatory reactions in many diseases and conveys a potential protective role in TBI. This study was designed to investigate the neuroprotective effects of progesterone associated with immune/inflammatory modulation in experimental TBI. A TBI model in adult male C57BL/6J mice was created using a controlled contusion instrument. After injury, the mice received consecutive progesterone therapy (8 mg/kg per day, i.p.) until euthanized. Neurological deficits were assessed via Morris water maze test. Brain edema was measured via the dry-wet weight method. Immunohistochemical staining and flow cytometry were used to examine the numbers of immune/inflammatory cells, including IBA-1 + microglia, myeloperoxidase + neutrophils, and regulatory T cells (Tregs). ELISA was used to detect the concentrations of IL-1β, TNF-α, IL-10, and TGF-β. Our data showed that progesterone therapy significantly improved neurological deficits and brain edema in experimental TBI, remarkably increased regulatory T cell numbers in the spleen, and dramatically reduced the activation and infiltration of inflammatory cells (microglia and neutrophils) in injured brain tissue. In addition, progesterone therapy decreased the expression of the pro-inflammatory cytokines IL-1β and TNF-α but increased the expression of the anti-inflammatory cytokine IL-10 after TBI. These findings suggest that progesterone administration could be used to regulate immune/inflammatory reactions and improve outcomes in TBI.

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.

Neurosteroid enantiomers as potentially novel neurotherapeutics

Endogenous neurosteroids and synthetic neuroactive steroids (NAS) are important targets for therapeutic development in neuropsychiatric disorders. These steroids modulate major signaling systems in the brain and intracellular processes including inflammation, cellular stress and autophagy. In this review, we describe studies performed using unnatural enantiomers of key neurosteroids, which are physiochemically identical to their natural counterparts except for rotation of polarized light. These studies led to insights in how NAS interact with receptors, ion channels and intracellular sites of action. Certain effects of NAS show high enantioselectivity, consistent with actions in chiral environments and likely direct interactions with signaling proteins. Other effects show no enantioselectivity and even reverse enantioselectivity. The spectrum of effects of NAS enantiomers raises the possibility that these agents, once considered only as tools for preclinical studies, have therapeutic potential that complements and in some cases may exceed their natural counterparts. Here we review studies of NAS enantiomers from the perspective of their potential development as novel neurotherapeutics.

Insight into mitochondrial dysfunction mediated by clozapine-induced inhibition of PGRMC1 in PC12 cells

Clozapine is usually considered as the last resort for treatment-resistant schizophrenia (TRS). However, it shows limited efficacy in cognition improvement. Moreover, the metabolic side effects induced by clozapine can aggravate cognitive impairment, which is closely related to its neurotoxicity. Nevertheless, the mechanisms underlying clozapine's neurotoxicity remain largely elusive. In this study, PC12 cells were simultaneously treated with different concentrations (0μM, 10μM, 20μM, 40μM and 80μM) of clozapine and AG205 which functions as a blocking reagent of progesterone receptor membrane component 1 (PGRMC1). In addition, we examined the effect of PGRMC1 in clozapine-induced neurotoxicity through overexpressing or downregulating PGRMC1. Molecular docking and surface plasmon resonance (SPR) analysis indicated that clozapine and AG205 inhibited the binding of endogenous progesterone to PGRMC1. The results showed that high concentration of clozapine and AG205 induced a significant increase in cytotoxicity, reactive oxygen species (ROS) accumulation and mitochondrial membrane potential (MMP) collapse, all of which were worsened as concentration increases, while overexpression of PGRMC1 reverted the above toxic effect of clozapine on PC12 cells. Furthermore, clozapine and AG205 also downregulated the expression of PGRMC1, glucagon-like peptide-1 receptor (GLP-1R) and mitofusin2 (Mfn2). Interestingly, overexpression of PGRMC1 could revert these effects. Our data suggest that overexpression of PGRMC1 in PC12 cells prevents and restores clozapine-induced oxidative and mitochondrial damage. We propose PGRMC1 activation as a promising therapeutic strategy for clozapine-induced neurotoxicity to facilitate the relief of neuronal damage.

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

Detrimental dietary habits with high-fat food are common in the psychiatric population, leading to higher obesity rate. Olanzapine (OLZ), as one of the mainstream antipsychotic drugs, shows superior efficacy in treating schizophrenia but limited by adverse effects such as obesity, dyslipidemia and liver injury, which are risk factors for the development of nonalcoholic fatty liver disease (NAFLD). Progesterone receptor component 1 (PGRMC1) is a key regulator associated with antipsychotic drug-induced metabolic disorders. Our study aims to investigate whether high-fat supplementation worsens OLZ-induced NAFLD and to validate the potential role of PGRMC1 pathway. In vivo, eight-week OLZ treatment successfully induced hepatic steatosis in female C57BL/6 mice fed with either a high-fat or normal diet, which is independent of body weight gain. Likewise, in vitro, OLZ markedly led to hepatocyte steatosis along with enhanced oxidative stress, which was aggravated by free fatty acids. Moreover, in vivo and in vitro, high-fat supplementation aggravated OLZ-induced hepatic lipid accumulation and oxidative stress via inhibition of hepatic PGRMC1-AMPK-mTORC1/Nrf2 pathways. Inspiringly, PGRMC1 overexpression effectively reversed OLZ-induced hepatocyte steatosis in vitro. Hence, hepatic PGRMC1 is attributable to OLZ-induced NAFLD especially with high-fat supplementation and potentially serves as a novel therapeutic target.

Advantages and Limitations of Animal Schizophrenia Models

Mental illness modeling is still a major challenge for scientists. Animal models of schizophrenia are essential to gain a better understanding of the disease etiopathology and mechanism of action of currently used antipsychotic drugs and help in the search for new and more effective therapies. We can distinguish among pharmacological, genetic, and neurodevelopmental models offering various neuroanatomical disorders and a different spectrum of symptoms of schizophrenia. Modeling schizophrenia is based on inducing damage or changes in the activity of relevant regions in the rodent brain (mainly the prefrontal cortex and hippocampus). Such artificially induced dysfunctions approximately correspond to the lesions found in patients with schizophrenia. However, notably, animal models of mental illness have numerous limitations and never fully reflect the disease state observed in humans.

Basic approaches, challenges and opportunities for the discovery of small molecule anti-tumor drugs

Chemotherapy is one of the main treatments for cancer, especially for advanced cancer patients. In the past decade, significant progress has been made with the research into the molecular mechanisms of cancer cells and the precision medicine. The treatment on cancer patients has gradually changed from cytotoxic chemotherapy to precise treatment strategy. Research into anticancer drugs has also changed from killing effects on all cells to targeting drugs for target genes. Besides, researchers have developed the understanding of the abnormal physiological function, related genomics, epigenetics, and proteomics of cancer cells with cancer genome sequencing, epigenetic research, and proteomic research. These technologies and related research have accelerated the development of related cancer drugs. In this review, we summarize the research progress of anticancer drugs, the current challenges, and future opportunities.

Progesterone Suppresses Cholesterol Esterification in APP/PS1 mice and a cell model of Alzheimer's Disease

AIMS

Cholesteryl ester(CE), generated from the mitochondria associated membrane (MAM), is involved in the pathogenesis of Alzheimer's Disease (AD). In theory, the different neuroprotective effects of progesterone in AD are all linked to MAM, yet the effect on cholesterol esterification has not been reported. Therefore, this study was aimed to investigate the regulation of progesterone on intracerebral CE in AD models and the underlying mechanism.

METHODS

APP/PS1 mice and AD cell model induced by Aβ 25-35 were selected as the research objects. APP/PS1 mice were daily administrated intragastrically with progesterone and The Morris Water Maze test was performed to detect the learning and memory abilities. Intracellular cholesterol was measured by Cholesterol/Cholesteryl Ester Quantitation Assay. The structure of MAMs were observed with transmission electron microscopy. The expression of acyl-CoA: cholesterol acyltransferase 1 (ACAT1), ERK1/2 and p-ERK1/2 were detected with western blotting, immunohistochemistry or immunofluorescence.

RESULTS

Progesterone suppressed the accumulation of intracellular CE, shortened the length of abnormally prolonged MAM in cortex of APP/PS1 mice. Progesterone decreased the expression of ACAT1, which could be blocked by progesterone receptor membrane component 1 (PGRMC1) inhibitor AG205. The ERK1/2 pathway maybe involved in the progesterone mediated regulation of ACAT1 in AD models, rather than the PI3K/Akt and the P38 MEPK pathways.

SIGNIFICANCE

The results supported a line of evidence that progesterone regulates CE level and the structure of MAM in neurons of AD models, providing a promising treatment against AD on the dysfunction of cholesterol metabolism.

Clozapine Induced Disturbances in Hepatic Glucose Metabolism: The Potential Role of PGRMC1 Signaling

Newly emerging evidence has implicated that progesterone receptor component 1 (PGRMC1) plays a novel role not only in the lipid disturbance induced by atypical antipsychotic drugs (AAPD) but also in the deterioration of glucose homoeostasis induced by clozapine (CLZ) treatment. The present study aimed to investigate the role of PGRMC1 signaling on hepatic gluconeogenesis and glycogenesis in male rats following CLZ treatment (20 mg/kg daily for 4 weeks). Recombinant adeno-associated viruses (AAV) were constructed for the knockdown or overexpression of hepatic PGRMC1. Meanwhile, AG205, the specific inhibitor of PGRMC1 was also used for functional validation of PGRMC1. Hepatic protein expressions were measured by western blotting. Meanwhile, plasma glucose, insulin and glucagon, HbA1c and hepatic glycogen were also determined by assay kits. Additionally, concentrations of progesterone (PROG) in plasma, liver and adrenal gland were measured by a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. Our study demonstrated that CLZ promoted the process of gluconeogenesis and repressed glycogenesis, respectively mediated by PI3K-Akt-FOXO1 and GSK3β signaling via inhibition of PGRMC1-EGFR/GLP1R in rat liver, along with an increase in fasting blood glucose, HbA1c levels and a decrease in insulin and hepatic glycogen levels. Furthermore, through PGRMC1-EGFR/GLP1R-PI3K-Akt pathway, knockdown or inhibition (by AG205) of PGRMC1 mimics, whereas its overexpression moderately alleviates CLZ-induced glucose disturbances. Potentially, the PGRMC1 target may be regarded as a novel therapeutic strategy for AAPD-induced hepatic glucose metabolism disorder.