Carbon tetrachloride induced mitochondrial division, respiratory chain damage, abnormal intracellular [H+] and apoptosis are due to the activation of 5-HT degradation system in hepatocytes.

Previously we found that acute liver injury (ALI) with inflammation caused by carbon tetrachloride (CCl4) was associated with the activation of the 5-HT degradation system (5DS), which includes monoamine oxidase A (MAO-A), the 5-HT2A receptor, and 5-HT synthases in hepatocytes. This study aimed to determine the role of 5DS in mitochondrial damage and apoptosis. In hepatocyte LO2 cells, CCl4 activated 5-HT2A receptor at the gene level, and then 5-HT2A receptor mediated the expression of 5-HT synthase and MAO-A at the gene level. Suppression of 5DS with the 5-HT2A receptor antagonist, MAO-A inhibitor, or gene silencing MAO-A significantly reduced the CCl4-induced production of mitochondrial reactive oxygen species (ROS). The ROS-associated upregulation of mitochondrial division proteins (FIS1 and DRP1); downregulation of mitochondrial fusion-associated protein 1, respiratory chain proteins (ND1 and CYTB), and ATP6; and decrease of ATP levels were reversed. Moreover, ROS-associated abnormal levels of caspase pathway-associated proteins (Bcl-2, Bax, cleaved-caspase3 and cleaved-caspase9) and apoptosis were suppressed. Notably, a combination of 5-HT2A receptor antagonist and MAO-A inhibitor almost abolished CCl4 cytotoxicity; abolished mitochondrial membrane potential (MMP) depolarization, mitochondrial structural abnormality, and high mitochondrial pH, with low pH states of the nucleus and cytoplasm. The effects of both were more significant than either alone. LO2 cells exposed to H2O2 or depleted mitochondrial ROS showed that ROS induced mitochondrial division and apoptosis and inhibited the levels of respiratory chain proteins. CCl4-induced abnormalities of ATP generation and MMP were dependent on both ROS and other 5DS-associated factors, probably NH3. Investigation of CCl4-induced ALI mice showed that hepatic injury and apoptosis occur at the site of 5DS activation and are significantly inhibited by the 5-HT2A receptor antagonist and 5-HT synthetic inhibitor in a synergistic manner, as well as mitochondrial damage. Together, we revealed the close relationship between CCl4-induced activation of 5DS and mitochondrial damage, abnormal intracellular [H+], and apoptosis in hepatocytes.

A Synchronous Magnitude Estimation with P-Wave Phases' Detection Used in Earthquake Early Warning System.

How to estimate an earthquake's magnitude rapidly and accurately is a challenge for any earthquake early warning system. In order to reach a balance between accuracy and timeliness, a synchronous magnitude estimation method with P-wave phases' detection is proposed. In this method, the P-wave phases are detected by the changes of the signal-to-noise ratio (SNR) of the seismic records, where the SNRs are calculated by the short-term power and long-term power ratio (STP/LTP). Meanwhile, the variations of the SNR are applied to estimate the magnitude of the earthquake. By the statistics of some earthquake cases, a synchronous magnitude estimation model of the variation of the P-wave phases' SNR, the earthquake magnitude, and the hypocentral distance was built. Compared with some other magnitude estimation methods, the suggested method inherits the robustness of the STP/LTP method and is more accurate and rapid than the peak displacement (Pd) method.

Use of multiple recreational drugs is associated with new HIV infections among men who have sex with men in China: a multicenter cross-sectional survey.

BACKGROUND: There is limited information about the types of recreational drugs used by men who have sex with men (MSM) in China or the consequent impact on sexual health and human immunodeficiency virus (HIV) acquisition. METHODS: We recruited MSM from seven cities in China between 2012 and 2013 using multiple approaches including advertisements on gay websites, collaborating with local MSM community-based organizations, peer referrals, and venues such as gay bars and bathrooms visited by MSM. We divided participants into four subgroups based on the number of recreational drugs (RDs) used in the previous 6 months. We defined use of multiple RDs as use of ≥2 types of RDs. Demographics and HIV-related high-risk behaviors were collected, and blood samples were tested for recent HIV infection by the HIV-1 subtypes B, E, and D immunoglobulin G capture enzyme immunoassay (BED-CEIA). We used multivariable logistic regression adjusted for sociodemographics to determine the adjusted odds ratios (aORs) and associated 95% confidence intervals (CIs) of the subgroups of RD use for recent or established HIV infection. RESULTS: A total of 4496 Chinese MSM participated; 28.4% used RDs, and 5% used multiple types of RDs. The prevalence of each RD use was as follows: poppers (25.9%), ecstasy (2.4%), ketamine (1.2%), amphetamine (0.6%), tramadol (0.4%), methamphetamine (3.8%), and codeine (1.9%). Users of multiple RDs commonly used poppers combined with one or more other types of RDs. Multiple RD users were likely to be aged 26-30 years (vs. 18-25 and > 30 years), live in non-local cities (vs. local cities), never married (vs. married), have a high monthly income (vs. no income and 1-599 USD), use versatile positions during anal intercourse (vs. top or bottom), and have inadequate HIV-related prevention knowledge (vs. adequate). As the number of RDs used in the previous 6 months increased, the prevalence of HIV-related high-risk behaviors increased (P < 0.05 for all). The odds of recent HIV infection were higher among those who used one type (aOR = 2.2, 95% CI: 1.5-3.0) or two types of RD (aOR=2.3, 95% CI: 1.0-5.2) in the previous 6 months compared to the odds among those who did not use RDs. CONCLUSION: The level and pattern of multiple RD use among Chinese MSM were different from high-income countries. MSM who used more RDs are more likely to engage in high-risk sexual behaviors, and these behaviors may be associated with increases in new HIV infections.

Performance Evaluation of Low-Cost Seismic Sensors for Dense Earthquake Early Warning: 2018⁻2019 Field Testing in Southwest China.

Earthquake Early Warning (EEW) was proved to be a potential means of disaster reduction. Unfortunately, the performance of the EEW system is largely determined by the density of EEW network. How to reduce the cost of sensors has become an urgent problem for building a dense EEW. A low-cost seismic sensor integrated with a Class C MEMS accelerometer was proposed in this paper. Based on minimal structure design, the sensor's reliability was enhanced, while the costs were cut down as well. To fully reveal the performance, ten of the seismic sensors were installed and tested in Sichuan Province, southwest of China from May 2018 to February 2019. The seismic records obtained by the MNSMSs were compared with those by the traditional strong motion seismographs. The records obtained by the MNSMSs have good consistency with the data obtained by the Etnas. The MNSMSs can obtain clear seismic phases that are enough to trigger earthquake detections for EEW. By noise analysis, different channels of the same sensor and different sensors have good consistency. The tested dynamic range (over 87 dB) and useful resolution (over 14.5 bits) are completely in conformity with the designed parameters. Through real field testing, small earthquakes (M 3.1-3.6) can be detected by all three components E-W, N-S, and U-D within 50 km. In all, the low-cost seismic sensor proposed as a high-performance Class C MEMS sensor can meet the needs of dense EEW in terms of noise, dynamic range, useful resolution, reliability, and detecting capabilities.

Crucial Roles of 5-HT and 5-HT2 Receptor in Diabetes-Related Lipid Accumulation and Pro-Inflammatory Cytokine Generation in Hepatocytes.

BACKGROUND/AIMS: Previously, we confirmed that liver-synthesized 5-HT rather than non-liver 5-HT, acting on the 5-HT2 receptor (5-HT2R), modulates lipid-induced excessive lipid synthesis (ELS). Here, we further revealed the effects of the hepatocellular 5-HT system in diabetes-related disorders. METHODS: Studies were conducted in male ICR mice, human HepG2 cells, and primary mouse hepatocytes (PMHs) under gene or chemical inhibition of the 5-HT system, key lipid metabolism, and inflammation-related factors. Protein and messenger RNA expression and levels of the factors were determined via western blotting, reverse transcription PCR, and quantitative assay kits, respectively. Hepatic steatosis with inflammation and fibrosis, intracellular lipid droplet accumulation (LDA), and reactive oxygen species (ROS) location were determined via hematoxylin and eosin, Masson's trichrome, Oil red O, and fluorescent-specific staining, respectively. RESULTS: Palmitic acid induced the activation of the 5-HT system: the activation of 5-HT2R, primarily 5-HT2AR, in addition to upregulating monoamine oxidase A (MAO-A) expression and 5-HT synthesis, by activating the G protein/ phospholipase C pathway modulated PKCε activation, resulting in ELS with LDA; the activation of NF-κB, which mediates the generation of pro-inflammatory cytokines, was primarily due to ROS generation in the mitochondria induced by MAO-A-catalyzed 5-HT degradation, and secondarily due to the activation of PKCε. These effects of the 5-HT system were also detected in palmitic acid- or high glucose-treated PMHs and regulated multiple inflammatory signaling pathways. In diabetic mice, co-treatment with antagonists of both 5-HT synthesis and 5-HT2R significantly abolished hepatic steatosis, inflammation, and fibrosis as well as hyperglycemia and dyslipidemia. CONCLUSION: Activation of the hepatocellular 5-HT system plays a crucial role in inducing diabetes-related hepatic dysfunction and is a potential therapeutic target.

High-risk behaviour and HIV infection risk among non-local men who have sex with men with less than a single year's residence in urban centres: a multicentre cross-sectional study from China.

OBJECTIVES: Traditionally, subjects' migration status has usually been defined on the basis of their registered residency status. We attempted to redefine migration based on the duration of residency in their cities of migration and to explore more precisely the impact of migration on HIV infection risk in men who have sex with men (MSM). METHODS: A multisite cross-sectional study was conducted during 2012-2013 in seven Chinese cities. Questionnaire surveys were conducted and blood was drawn to test for antibodies to HIV, syphilis and herpes simplex virus-2 (HSV-2). MSM who were unregistered local residents and had resided in their cities of migration for ≤1 or >1 year were defined as migrant MSM, or transitional MSM, respectively. RESULTS: Compared with transitional MSM and local MSM, migrant MSM had poorer HIV knowledge and higher rates of high-risk behaviour, including earlier sexual debut, multiple sexual partners, participation in commercial sex and recreational drug use. Multivariate logistic regression analysis showed that HIV prevalence among migrant MSM was higher than local MSM (p<0.05). This relationship, however, did not hold for transitional MSM and local MSM (p>0.05). Male sex work, recreational drug use, syphilis infection and HSV-2 infection were independently associated with HIV infection among migrant MSM. CONCLUSIONS: Non-local MSM with shorter residence were at greater risk of HIV acquisition. More focus should be placed on HIV behavioural interventions targeting non-local MSM with temporary residence.

A Cost-Effective Geodetic Strainmeter Based on Dual Coaxial Cable Bragg Gratings.

Observations of surface deformation are essential for understanding a wide range of geophysical problems, including earthquakes, volcanoes, landslides, and glaciers. Current geodetic technologies, such as global positioning system (GPS), interferometric synthetic aperture radar (InSAR), borehole and laser strainmeters, are costly and limited in their temporal or spatial resolutions. Here we present a new type of strainmeters based on the coaxial cable Bragg grating (CCBG) sensing technology that provides cost-effective strain measurements. Two CCBGs are introduced into the geodetic strainmeter: one serves as a sensor to measure the strain applied on it, and the other acts as a reference to detect environmental noises. By integrating the sensor and reference signals in a mixer, the environmental noises are minimized and a lower mixed frequency is obtained. The lower mixed frequency allows for measurements to be taken with a portable spectrum analyzer, rather than an expensive spectrum analyzer or a vector network analyzer (VNA). Analysis of laboratory experiments shows that the strain can be measured by the CCBG sensor, and the portable spectrum analyzer can make measurements with the accuracy similar to the expensive spectrum analyzer, whose relative error to the spectrum analyzer R3272 is less than ±0.4%. The outputs of the geodetic strainmeter show a linear relationship with the strains that the CCBG sensor experienced. The measured sensitivity of the geodetic strainmeter is about -0.082 kHz/µÎµ; it can cover a large dynamic measuring range up to 2%, and its nonlinear errors can be less than 5.3%.

Commercial sex and risk of HIV, syphilis, and herpes simplex virus-2 among men who have sex with men in six Chinese cities.

BACKGROUND: Men who have sex with men (MSM) are at high risk of HIV and sexually transmitted infections (STIs) in China and globally. Engaging in commercial sex put them at even greater risk. This study estimated the prevalence of HIV/STIs among three subgroups of MSM: MSM who sold sex (MSM-selling), MSM who bought sex (MSM-buying), and non-commercial MSM (NC-MSM) and evaluated the relationship between commercial sex and HIV/STIs. METHODS: We conducted a cross-sectional survey among MSM in six Chinese cities (Shenyang, Ji'nan, Changsha, Zhengzhou, Nanjing, and Kunming) from 2012 to 2013. Data on socio-demographics and sexual behaviors were collected. Serological tests were conducted to detect HIV, syphilis, and human simplex virus type 2 (HSV-2). RESULTS: Of 3717 MSM, 6.8% were engaged in commercial sex. The overall prevalence of HIV, syphilis and HSV-2 infections was 11.1, 8.8 and 12.1%, respectively. MSM-selling had higher prevalence of HIV (13.4%), syphilis (12.1%) and HSV-2 (17.9%) than NC-MSM (10.9, 8.7 and 11.9% for HIV, syphilis and HSV-2, respectively), though the differences are not statistically significant. Among MSM-selling, HIV prevalence was significantly higher for those who found sex partners via Internet than those did not (19.4% vs. 8.1%, P = 0.04). Compared to NC-MSM, MSM-selling were more likely to use recreation drugs (59.3% vs. 26.3%), have unprotected anal intercourse (77.9% vs. 61.7%), and have ≥10 male sex partners (46.2% vs. 6.2%) in the past 6 months (each P < 0.05). CONCLUSIONS: All three subgroups of MSM in six large Chinese cities have high prevalence of HIV/STIs. Those who sell sex only have a particularly high risk of acquiring and transmitting disease, and therefore, they should be considered as a priority group in HIV/STIs surveillance and intervention programs.

Recreational drug use and risks of HIV and sexually transmitted infections among Chinese men who have sex with men: Mediation through multiple sexual partnerships.

BACKGROUND: Recreational drug use (RDU) may result in sexual disinhibition and higher risk for HIV and other sexually transmitted infections (STIs) among men who have sex with men (MSM) in China. We assessed whether RDU was associated with HIV, syphilis, and herpes simplex virus type 2 (HSV-2) within the context of multiple sexual partnerships and unprotected sex. METHODS: We conducted a cross-sectional study among sexually-active MSM in six Chinese cities (Kunming, Jinan, Changsha, Zhengzhou, Nanjing, and Shanghai) in 2012-2013. We interviewed participants regarding RDU and sexual activity and drew blood for HIV, syphilis, and HSV-2. We fit multiple logistic regression models to assess associations of drug use and HIV, syphilis and HSV-2 infections, controlling for number of sexual partners and unprotected sex. RESULTS: Of 3830 participants, 28% reported ever using ≥1 of these drugs in the past 6 months: popper (alkyl nitrites), ecstasy, ice (methamphetamine), amphetamine, tramadol, and ketamine. In the past six months, 62% of MSM reported ≥2 sexual partners and 76% did not use condoms at last sexual encounter. HIV, syphilis and HSV-2 prevalences were 9.2%, 12.2%, and 10.3%, respectively.RDU was associated with HIV infection (aOR = 1.67; 95% CI, 1.31-2.13). Men with RDU were more likely to report multiple sexual partners (OR = 1.69; 95% CI, 1.44-1.98) and unprotected sex (aOR = 1.25; 95% CI, 1.05-1.49). The RDU-HIV association persisted (aOR = 1.58; 95% CI = 1.23-2.02) after adjusting for numbers of partners. CONCLUSIONS: RDU was associated with multiple sexual partnerships, unprotected sex, and HIV among Chinese MSM. It is plausible that RDU is a driver of increased sexual/HIV risk and/or may be an associated behavior with sexually risky lifestyles. Community engagement is needed.

Myocardial ischemia-reperfusion injury is probably due to the excessive production of mitochondrial ROS caused by the activation of 5-HT degradation system mediated by PAF receptor.

AIM: Previously, we revealed a crucial role of 5-HT degradation system (5DS), consisting of 5-HT2A receptor (5-HT2AR), 5-HT synthases and monoamine oxidase A (MAO-A), in ischemia-reperfusion (IR)-caused organ injury. Whereas, platelet activating factor receptor (PAFR) also mediates myocardial ischemia-reperfusion injury (MIRI). Here, we try to clarify the relationship between 5DS and PAFR in mediating MIRI. METHODS: H9c2 cell injury and rat MIRI were caused by hypoxia/reoxygenation (H/R) or PAF, and by ligating the left anterior descending coronary artery then untying, respectively. 5-HT2AR and PAFR antagonists [sarpogrelate hydrochloride (SH) and BN52021], MAO-A, AKT, mTOR and 5-HT synthase inhibitors (clorgyline, perifosine, rapamycin and carbidopa), and gene-silencing PKCε were used in experiments RESULTS: The mitochondrial ROS production, respiratory chain damage, inflammation, apoptosis and myocardial infarction were significantly prevented by BN52021, SH and clorgyline in H/R and PAF-treated cells and in IR myocardium. BN52021 also significantly suppressed the upregulation of PAFR, 5-HT2AR, 5-HT synthases and MAO-A expression (mRNA and protein), and Gαq and PKCε (in plasmalemma) expression induced by H/R, PAF or IR; the effects of SH were similar to that of BN52021 except for no affecting the expression of PAFR and 5-HT2AR. Gene-silencing PKCε suppressed H/R and PAF-induced upregulation of 5-HT synthases and MAO-A expression in cells; perifosine and rapamycin had not such effects; however, clorgyline suppressed H/R and PAF-induced phosphorylation of AKT and mTOR. CONCLUSION: MIRI is probably due to PAFR-mediated 5-HT2AR activation, which further activates PKCε-mediated 5-HT synthesis and degradation, leading to mitochondrial ROS production.

Profile of 5-HT2A receptor involved in signaling cascades associated to intracellular inflammation and apoptosis in hepatocytes and its role in carbon tetrachloride-induced hepatotoxicity.

Previously, we found that the 5-HT2A receptor plays a key role in cell injury. However, the mechanism by which the 5-HT2A receptor mediates intracellular processes remains unclear. In this study, we aimed to clarify this intracellular process in hepatocyte LO2 cells and evaluate its role in CCl4-induced hepatotoxicity in mice. In vitro, both the agonist and overexpression of 5-HT2A receptor could promote 5-HT degradation by upregulating the expression of 5-HT synthases and monoamine oxidase-A (MAO-A) to cause overproduction of ROS in mitochondria. We refer to this as the activation of the 5-HT degradation system (5DS) axis, which leads to the phosphorylation of JNK, p38 MAPK, STAT3, and NF-κB; upregulation of Bax, cleaved-caspase3, and cleaved-caspase9; and downregulation of Bcl-2, followed by apoptosis and oversecretion of TNF-α and IL-1ß in cells. This phenomenon could be markedly blocked by the 5-HT2A receptor antagonist, MAO-A inhibitor, or gene-silencing MAO-A. Through protein kinases C epsilon (PKCε) agonist treatment and gene silencing of the PKCε and 5-HT2A receptor, we demonstrated that the 5-HT2A receptor controls 5-HT synthases and MAO-A expression via the PKCε pathway in cells. Unexpectedly, we discovered that PKCε-mediated phosphorylation of the AKT/mTOR pathway is also a consequence of the activation of the 5DS axis. Furthermore, we confirmed that the inhibition of the 5DS axis using the 5-HT2A receptor antagonist could prevent hepatotoxicity induced by CCl4 both in vitro and in vivo, inhibiting the aforementioned signaling cascades, inflammation, and apoptosis, and that the 5DS activation area overlapped the necrotic area of mouse liver. Taken together, we revealed a 5DS axis in hepatocytes that controls the signaling cascades associated with inflammation and apoptosis and confirmed its role in CCl4-induced hepatotoxicity.

5-HT2A Receptor and 5-HT Degradation Play a Crucial Role in Atherosclerosis by Modulating Macrophage Foam Cell Formation, Vascular Endothelial Cell Inflammation, and Hepatic Steatosis.

AIM: Previously, we found that diabetes-related liver dysfunction is due to activation of the 5-HT2A receptor (5-HT2AR) and increased synthesis and degradation of 5-HT. Here, we investigated the role of 5-HT in the development of atherosclerosis. METHODS: The study was conducted using high-fat diet-fed male ApoE-/- mice, THP-1 cell-derived macrophages, and HUVECs. Protein expression and biochemical indexes were determined by Western blotting and quantitative analysis kit, respectively. The following staining methods were used: oil red O staining (showing atherosclerotic plaques and intracellular lipid droplets), immunohistochemistry (showing the expression of 5-HT2AR, 5-HT synthase, and CD68 in the aortic wall), and fluorescent probe staining (showing intracellular ROS). RESULTS: In addition to improving hepatic steatosis, insulin resistance, and dyslipidemia, co-treatment with a 5-HT synthesis inhibitor and a 5-HT2AR antagonist significantly suppressed the formation of atherosclerotic plaques and macrophage infiltration in the aorta of ApoE-/- mice in a synergistic manner. Macrophages and HUVECs exposed to oxLDL or palmitic acid in vitro showed that activated 5-HT2AR regulated TG synthesis and oxLDL uptake by activating PKCε, resulting in formation of lipid droplets and even foam cells; ROS production was due to the increase of both intracellular 5-HT synthesis and mitochondrial MAO-A-catalyzed 5-HT degradation, which leads to the activation of NF-κB and the release of the inflammatory cytokines TNF-α and IL-1ß from macrophages and HUVECs as well as MCP-1 release from HUVECs. CONCLUSION: Similar to hepatic steatosis, the pathogenesis of lipid-induced atherosclerosis is associated with activation of intracellular 5-HT2AR, 5-HT synthesis, and 5-HT degradation.

Syphilis and methamphetamine use among female sex workers in Shandong Province, China.

A study of female sex workers in China, found alarmingly high prevalence of methamphetamine use. Methamphetamine users were more likely to be single, younger, inconsistent condom users, and have syphilis.

[The prevalence and evolution of HIV drug-resistant strains in people who live with HIV/AIDS during HIV antiretroviral therapy in Shandong province].

OBJECTIVE: To understand the prevalence and evolution of HIV drug-resistant strains in people who live with HIV/AIDS (PLWHA) during HIV antiretroviral therapy in Shandong province. METHODS: Viral load testing was performed by using fluorescence real-time quantitative PCR (NucliSens EasyQ system) on 324 patients who were under HIV antiretroviral therapy (ART) over 1 year in Shandong province. HIV resistance testing was conducted on the samples with more than 1000 copies/ml by using genotypic resistance testing method established in our lab. We tested the samples from drug-resistant patients before and after treatment to analyze the evolution of HIV resistant strains. RESULTS: The resistance rate for the patients under HIV ART over 1 year was 6.2% (20/324). The rate of drug-resistant mutation, but not resistant to ART was 0.6% (5/324). Nucleoside reverse transcriptase inhibitor (NRTIs) and non-NRTIs (NNRTIs) accounted for 93.1% (94/101) and protein inhibitors (PIs) accounted only 6.9% (7/101) of all mutations. M184V (48.0%, 12/25) and Y181C (32.0%, 8/25) were the most frequent mutations among 25 samples. Our research showed 20.0% (2/10) patients were resistant to primary ART and 1 patient was detected drug resistance in 6 months after ART treatment. HIV evolved from wild type to drug resistant virus, from low level to high level drug resistance, and from resistance to few to multiple drugs. In addition, interactions between mutations may influence the sensitivity of patients to other drug treatment. CONCLUSION: The prevalence of HIV drug-resistant strains in Shandong province is still at a low level, but its evolution is complex.

[Relationship between MnSOD polymorphisms and susceptibility of chronic poisoning exposed to manganism occupationally].

OBJECTIVE: To study the relationship between polymorphisms of MnSOD and the susceptibility of chronic poisoning exposed to manganism occupationally. METHODS: In a study of case-control, genotypes were determined by PCR-RFLP in 164 patients with chronic occupational mangamism poisoning and 328 controls with age- and sex-matched for MnSOD 9Ala-Val. RESULTS: There was a significant difference in the frequency of MnSOD 9Ala-Val at V locus mutant allele between cases and controls (χ(2) = 15.225, P < 0.01, 95%CI = 1.43 ∼ 3.00). Individuals with the genotype VV had a 1.30 of risk increase of occupational chronic manganism poisoning compared with the the genotype AV or AA (OR = 2.30, 95%CI = 1.52 ∼ 3.49, P < 0.05). CONCLUSION: The MnSOD polymorphisms may be related with the susceptibility to chronic occupational manganism poisoning, the risk of chronic occupational manganism poisoning increases in carriers with genotype VV at MnSOD 9Ala-Val locus.

Renal ischemia/reperfusion injury in rats is probably due to the activation of the 5-HT degradation system in proximal renal tubular epithelial cells.

AIMS: To explore the relationship between renal ischemia/reperfusion injury (RIRI) and the activation of the renal 5-HT degradation system, including 5-HT2A receptor (5-HT2AR), 5-HT synthases and monoamine oxidase-A (MAO-A). MAIN METHODS: Rat RIRI was induced by removing the right kidney, causing ischemia of the left kidney for 45 min and reperfusion for different times. RIRI model (ischemia for 45 min and reperfusion for 24 h) was pretreated with 5-HT2AR antagonist sarpogrelate hydrochloride (SH) and the 5-HT synthase inhibitor carbidopa. In HK-2 cells, cellular damage was induced by hypoxia (24 h)/reoxygenation (12 h) (H/R) and treated with SH, carbidopa or the MAO-A inhibitor clorgyline. Hematoxylin-eosin, immunohistochemistry, TUNEL and fluorescent probe staining, RT-qPCR, western blotting, ELISA, etc. were used in the tests. KEY FINDINGS: The development of RIRI and the emergence of the RIRI peak were consistent with renal 5-HT degradation system activation. The highest expression regions of the 5-HT degradation system overlapped with those of the most severe lesions in the kidney, which were in proximal renal tubules. Rat RIRI and HK-2 cell damage, including oxidative stress, inflammation and apoptosis, could be almost abolished by synergistic inhibition of SH and carbidopa. Clorgyline also abolished the cellular damage induced by H/R. H/R-induced production of mitochondrial ROS in HK-2 cells was due to MAO-A-catalyzed 5-HT degradation, and 5-HT2AR was involved by mediating the expression of 5-HT synthases and MAO-A. SIGNIFICANCE: These findings revealed a close association between RIRI and activation of the renal 5-HT degradation system.

Nephrotoxicity induced by cisplatin is primarily due to the activation of the 5-hydroxytryptamine degradation system in proximal renal tubules.

As a widely used anticancer drug in the clinic, cisplatin has obvious side effects, especially nephrotoxicity. Previous studies have suggested that the accumulation of intracellular reactive oxygen species (ROS) is a hallmark of cisplatin-induced acute kidney injury. This study aimed to investigate the relationship between ROS accumulation induced by cisplatin and 5-HT degradation. In vivo, by HE and TUNEL staining, we found that cisplatin-induced renal lesions and apoptotic regions, which were located in proximal tubular epithelial cells, were also the regions in which tryptophan hydroxylase 1 (Tph1), aromatic l-amino acid decarboxylase (AADC), 5-HT2A receptor (5-HT2AR) and monoamine oxidase A (MAO-A) were overexpressed, as determined by immunohistochemistry. Notably, the 5-HT2AR antagonist sarpogrelate hydrochloride (SH) and the AADC inhibitor carbidopa (CDP) significantly attenuated cisplatin-induced increases in serum creatinine and blood urea nitrogen levels, renal ROS levels, oxidative stress (SOD activity and MDA), proinflammatory cytokine levels (NF-κB, TNF-α and IL-1ß), proapoptotic factor levels (Bax, Bcl-2, C-caspase 3 and C-caspase 9) and the phosphorylation of p38 and STAT3, as well as renal lesions and apoptosis. The combination of SH and CDP could almost abolish the effects of cisplatin challenge. In vitro, the effects of cisplatin challenge and the inhibitory effects of SH and CDP were also observed in HK-2 cells. Additionally, similar to the combination of SH and CDP, the MAO-A inhibitor clorgyline could also abolish the effects of cisplatin challenge. More importantly, by western blotting, we detected that the upregulation of Tph1, AADC and MAO-A expression induced by cisplatin both in vivo and in vitro could be obviously suppressed by SH to decrease 5-HT synthesis and mitochondrial 5-HT degradation. Altogether, these findings suggested that cisplatin-induced nephrotoxicity is due to the activation of the 5-HT degradation system in proximal tubular epithelial cells, including 5-HT2AR and 5-HT synthesis and degradation. 5-HT2AR plays a role by mediating the expression of MAO-A and the 5-HT synthases Tph1 and AADC.

Role of 5-HT degradation in acute liver injury induced by carbon tetrachloride.

5-hydroxytryptamine (5-HT) is involved in the pathological processes of several liver diseases. Acute liver injury underlies the development of many liver diseases, but the mechanism remains unclear. We aimed to investigate the role of 5-HT in carbon tetrachloride (CCl4)-induced acute liver injury. Acute liver injury was induced with CCl4 (10 mg/kg) in mice pretreated with the 5-HT2A receptor antagonist sarpogrelate hydrochloride (SH) and the 5-HT synthesis inhibitor carbidopa (CDP). LO2 cells were treated with CCl4, 5-HT or 2,5-dimethoxy-4-idopametamine and pretreated with SH, CDP or the monoamine oxidase A (MAO-A) inhibitor clorgyline. Hematoxylin-eosin staining, immunohistochemistry, Real-time quantitative PCR, western blotting, fluorescent probe and biochemical markers were used to evaluate liver compromise. 5-HT2A receptor, 5-HT synthetase and MAO-A were expressed in hepatocytes; their gene and protein expression were upregulated by CCl4, which led to the degradation of mitochondrial 5-HT and overproduction of reactive oxygen species (ROS). Hepatic injury may be aggravated by ROS, which induce oxidative stress and the phosphorylation of p38 mitogen-activated protein kinase, Jun N-terminal kinase, extracellular regulated protein kinase, signal transducer and activator of transcription 3 and nuclear factor kappa-B. 5-HT2A receptor may contribute to acute liver injury by modulating 5-HT synthase and MAO-A expression. The synergistic action of SH and CDP treatment may inhibit CCl4-induced acute liver injury in a dose-dependent manner. Hence, CCl4-induced acute liver injury is due to an increase in mitochondrial ROS production caused by increased 5-HT degradation and probably involves increases in 5-HT2A receptor expression and 5-HT synthesis.