Long-term treatment with the mPXR agonist PCN promotes hepatomegaly and lipid accumulation without hepatocyte proliferation in mice.

Pregnane X receptor (PXR) is highly expressed in the liver and plays a pivotal role in xenobiotic and endobiotic metabolism. We previously reported that PXR activation by its specific mouse agonist pregnenolone 16α-carbonitrile (PCN) significantly induces liver enlargement and lipid accumulation. However, the effect of long-term PCN treatment on PXR and mouse liver is still unknown. This study aimed to explore the influence of long-term administration of PCN on mouse liver and hepatic lipid homeostasis. Male C57BL/6 mice were injected intraperitoneally with PCN (100 mg/kg once a week) for 42 weeks. Serum and liver samples were collected for biochemical and histological analysis. PXR activation was investigated by Western blot. Ultra-high-performance liquid chromatography coupled with electrospray ionization high-resolution mass spectrometry (UHPLC-ESI-HRMS)-based lipidomics analysis was performed to explore the change in different lipid categories. The results showed that long-term treatment with PCN significantly promoted hepatomegaly without hepatocyte proliferation and enlargement. Long-term treatment with PCN did not upregulate PXR target proteins in mice, and there was no significant upregulation of CYP3A11, CYP2B10, UGT1A1, MRP2, or MRP4. Lipidomics analysis showed obvious hepatic lipid accumulation in the PCN-treated mice, and the most significant change was found in triglycerides (TGs). Additionally, long-term treatment with PCN had no risk for carcinogenesis. These findings demonstrated that long-term PCN treatment induces hepatomegaly and lipid accumulation without hepatocyte proliferation or enlargement.

Peroxisome proliferator-activated receptor α agonist induces mouse hepatomegaly through the spatial hepatocyte enlargement and proliferation.

Peroxisome proliferator-activated receptor alpha (PPARα) activation-induced hepatomegaly is accompanied by hepatocyte hypertrophy around the central vein (CV) area and hepatocyte proliferation around the portal vein (PV) area. However, the molecular mechanisms underlying this spatial change of hepatocytes remains unclear. In this study, we examined the characteristics and possible reasons for the zonation distinction of hypertrophy and proliferation during PPARα activation-induced mouse liver enlargement. Mice were injected with corn oil or a typical mouse PPARα agonist WY-14643 (100 mg·kg-1·d-1, i.p.) for 1, 2, 3, 5 or 10 days. At each time point, the mice were sacrificed after the final dose, and liver tissues and serum were harvested for analysis. We showed that PPARα activation induced zonal changes in hepatocyte hypertrophy and proliferation in the mice. In order to determine the zonal expression of proteins related to hepatocyte hypertrophy and proliferation in PPARα-induced liver enlargement, we performed digitonin liver perfusion to separately destroy the hepatocytes around the CV or PV areas, and found that PPARα activation-induced increase magnitude of its downstream targets such as cytochrome P450 (CYP) 4 A and acyl-coenzyme A oxidase 1 (ACOX1) levels around the CV area were higher compared with those around the PV area. Upregulation of proliferation-related proteins such as cell nuclear antigen (PCNA) and cyclin A1 (CCNA1) after WY-14643-induced PPARα activation mainly occurred around the PV area. This study reveals that the zonal expression of PPARα targets and proliferation-related proteins is responsible for the spatial change of hepatocyte hypertrophy and proliferation after PPARα activation. These findings provide a new insight into the understanding of PPARα activation-induced liver enlargement and regeneration.

PXR mediates mifepristone-induced hepatomegaly in mice.

Mifepristone (Mif), an effective synthetic steroidal antiprogesterone drug, is widely used for medical abortion and pregnancy prevention. Due to its anti-glucocorticoid effect, high-dose Mif is also used to treat Cushing's syndrome. Mif was reported to active pregnane X receptor (PXR) in vitro and PXR can induce hepatomegaly via activation and interaction with yes-associated protein (YAP) pathway. High-dose Mif was reported to induce hepatomegaly in rats and mice, but the underlying mechanism remains unclear. Here, the role of PXR was studied in Mif-induced hepatomegaly in C57BL/6 mice and Pxr-knockout mice. The results demonstrated that high-dose Mif (100 mg · kg-1 · d-1, i.p.) treatment for 5 days significantly induced hepatomegaly with enlarged hepatocytes and promoted proliferation, but low dose of Mif (5 mg · kg-1 · d-1, i.p.) cannot induce hepatomegaly. The dual-luciferase reporter gene assays showed that Mif can activate human PXR in a concentration-dependent manner. In addition, Mif could promote nuclear translocation of PXR and YAP, and significantly induced the expression of PXR, YAP, and their target proteins such as CYP3A11, CYP2B10, UGT1A1, ANKRD, and CTGF. However, Mif (100 mg · kg-1 · d-1, i.p.) failed to induce hepatomegaly in Pxr-knockout mice, as well as hepatocyte enlargement and proliferation, further indicating that Mif-induced hepatomegaly is PXR-dependent. In summary, this study demonstrated that PXR-mediated Mif-induced hepatomegaly in mice probably via activation of YAP pathway. This study provides new insights in Mif-induced hepatomegaly, and provides novel evidence on the crucial function of PXR in liver enlargement and regeneration.

[Expression of Nerve Growth Factor and Type 3 of Acid Sensitive Ion Channels in Rat Model of Type â ¢ Prostatitis].

OBJECTIVE: To investigate the expressions of nerve growth factor (NGF) and acid-sensing ion channel 3 (ASIC3) in prostatic tissue of experimental rats with type Ⅲ prostatitis. METHODS: Thirty SD rats were randomly allocated into control group and experimental group. The rats in control group were subjected to pelvic and bilateral scapular subcutaneous injections of 0.9% sodium chloride,while the rats in experimental group were given pelvic and bilateral scapular subcutaneous injections of mixed suspension of complete Freund's adjuvant and prostatic tissue to induce autoimmune prostatitis (EAP).Tactile allodynia was quantified using Von-Frey as a measure of pelvic pain behavior. This measurement was performed on 0th,5th,10th,20th,30th and 40th day in the two groups. After that,the prostate samples were collected and processed for HE staining,while the expressions of NGF and ASIC3 were measured by immunohistochemistry and Western blot. RESULTS: Von-Frey filaments measurement showed that pelvis pain in EAP group was significantly more obvious than that in control group. HE staining found lymphocytes and neutrophils infiltrated in the prostate of EAP rats,but no inflammatory cells in the prostate of control group rats. The expressions of NGF and ASIC3 were significantly increased in EAP group when compared with control group ( P<0.01). CONCLUSION: The expressions of NGF and ASIC3 in the prostate with EAP were significantly increased,which may be the important mediators of chronic pelvic pain.

[Role of mast cells in experimental autoimmune prostatitis in rats].

OBJECTIVE: To investigate the role of mast cells in chronic prostatitis / chronic pelvic pain syndrome (CP/CPPS). METHODS: Forty-five male SD rats were equally randomized into a control, an experimental autoimmune prostatitis (EAP) model, and an intervention group. The EAP model was made in the latter two groups by subcutaneous injection of mixed suspension of complete Freund's adjuvant and prostate tissue, while the controls were treated subcutaneously with 0.9% sodium chloride. Tactile allodynia was quantified in the pelvic region of the control and EAP animals using Von-Frey filaments at 5, 10, 20, 30 and 40 days. After successful establishment of the EAP model, the rats of the intervention group were injected intraperitonieally with cromolyn sodium for 10 days, and meanwhile tactile allodynia was detected in the rats of the intervention and EAP model groups every other day. Then the prostates of the rats were harvested for HE and toluidine blue staining and measurement of the expression of mast cell tryptase by immunohistochemistry and Western blot. RESULTS: Von-Frey assessment showed a more severe pelvic pain in the EAP model than in the control rats, but milder in the intervention group than in the EAP models. HE staining revealed infiltration of lymphocytes and neutrophils in the prostate and congestion surrounding the gland in the EAP model rats, but none in the controls. However, both the infiltration and congestion were significantly alleviated in the intervention group. Toluidine blue staining shown that. Compared with the control group, the total count of mast cells and the number degranulated mast cells were markedly increased in the EAP models (P <0.01) but decreased in the intervention group (P <0.05). Both immunohistochemistry and Western blot manifested that the expression of tryptase in the mast cells was remarkably upregulated in the EAP (both P <0.01) but down-regulated in the intervention group (P <0.05 and P <0.01). CONCLUSIONS: Both the total count of mast cells and the number of degranulated mast cells are significantly increased in the prostate of EAP rats. Mast cells are one of the most important mediators of type Ⅲ prostatitis-induced chronic pelvic pain, which can be used as a target for the intervention and treatment of type Ⅲ prostatitis.

Schisandrol B promotes liver enlargement via activation of PXR and YAP pathways in mice.

BACKGROUND: Schisandrol B (SolB) is one of the bioactive components from a traditional Chinese medicine Schisandra chinensis or Schisandra sphenanthera. It has been demonstrated that SolB exerts hepatoprotective effects against drug-induced liver injury and promotes liver regeneration. It was found that SolB can induce hepatomegaly but the involved mechanisms remain unknown. PURPOSE: This study aimed to explore the mechanisms involved in SolB-induced hepatomegaly. METHODS: Male C57BL/6 mice were injected intraperitoneally with SolB (100 mg/kg) for 5 days. Serum and liver samples were collected for biochemical and histological analyses. The mechanisms of SolB were investigated by qRT-PCR and western blot analyses, luciferase reporter gene assays and immunofluorescence. RESULTS: SolB significantly increased hepatocyte size and proliferation, and then promoted liver enlargement without liver injury and inflammation. SolB transactivated human PXR, activated PXR in mice and upregulated hepatic expression of its downstream proteins, such as CYP3A11, CYP2B10 and UGT1A1. SolB also significantly enhanced nuclear translocation of PXR and YAP in human cell lines. YAP signal pathway was activated by SolB in mice. CONCLUSION: These findings demonstrated that SolB can significantly induce liver enlargement, which is associated with the activation of PXR and YAP pathways.