RESPONSES OF HUMAN FETAL SPLENOCYTES AND THYMOCYTES TO INTERLEUKIN-2: LAK ACTIVITY AND PROLIFERATION

Using cytotoxicity and thymidine uptake assays, we investigated the effects of human recombinant in-terleukin-2 (rIL-2) on the induction of lympholine-activated killer (LAK) activity and cellular proliferation in splenocytes and thymocytes from human fetuses (18-22 weeks). We observed that fetal splenocytes and thymocytes incubated with low doses of rIL-2 (10-100 U ml) developed broad antitumor activity (LAK activity) although the kinetics and magnitudes of the responses were different. It indicated the LAK precursors are present in fetal spleen and thymus. Further, rIL-2 induced a strong proliferative response in splenocytes, but not in thymocytes. On the basis of the findings, we conclude that the responses of fetal splenocytes and thymocytes to IL-2 are different.

Effects of elafibranor on liver fibrosis and gut barrier function in a mouse model of alcohol-associated liver disease

BACKGROUND Alcohol-associated liver disease(ALD)is a leading cause of liver-related morbidity and mortality,but there are no therapeutic targets and modalities to prevent ALD-related liver fibrosis.Peroxisome proliferator activated receptor(PPAR)α and δ play a key role in lipid metabolism and intestinal barrier homeostasis,which are major contributors to the pathological progression of ALD.Meanwhile,elafibranor(EFN),which is a dual PPARαand PPARδagonist,has reached a phase III clinical trial for the treatment of metabolic dysfunctionassociated steatotic liver disease and primary biliary cholangitis.However,the benefits of EFN for ALD treatment is unknown.AIM To evaluate the inhibitory effects of EFN on liver fibrosis and gut-intestinal barrier dysfunction in an ALD mouse model.METHODS ALD-related liver fibrosis was induced in female C57BL/6J mice by feeding a 2.5% ethanol(EtOH)-containing Lieber-DeCarli liquid diet and intraperitoneally injecting carbon tetrachloride thrice weekly(1 mL/kg)for 8 weeks.EFN(3 and 10 mg/kg/day)was orally administered during the experimental period.Histological and molecular analyses were performed to assess the effect of EFN on steatohepatitis,fibrosis,and intestinal barrier integrity.The EFN effects on HepG2 lipotoxicity and Caco-2 barrier function were evaluated by cell-based assays.RESULTS The hepatic steatosis,apoptosis,and fibrosis in the ALD mice model were significantly attenuated by EFN treatment.EFN promoted lipolysis and β-oxidation and enhanced autophagic and antioxidant capacities in EtOH-stimulated HepG2 cells,primarily through PPARαactivation.Moreover,EFN inhibited the Kupffer cell-mediated inflammatory response,with blunted hepatic exposure to lipopolysaccharide(LPS)and toll like receptor 4(TLR4)/nuclear factor kappa B(NF-κB)signaling.EFN improved intestinal hyperpermeability by restoring tight junction proteins and autophagy and by inhibiting apoptosis and proinflammatory responses.The protective effect on intestinal barrier function in the EtOH-stimulated Caco-2 cells was predominantly mediated by PPARδ activation.CONCLUSION EFN reduced ALD-related fibrosis by inhibiting lipid accumulation and apoptosis,enhancing hepatocyte autophagic and antioxidant capacities,and suppressing LPS/TLR4/NF-κB-mediated inflammatory responses by restoring intestinal barrier function.

Elafibranor:A promising treatment for alcoholic liver disease,metabolic-associated fatty liver disease,and cholestatic liver disease

Liver diseases pose a significant threat to human health.Although effective therapeutic agents exist for some liver diseases,there remains a critical need for advancements in research to address the gaps in treatment options and improve patient outcomes.This article reviews the assessment of Elafibranor's effects on liver fibrosis and intestinal barrier function in a mouse model of alcoholic liver disease(ALD),as reported by Koizumi et al in the World Journal of Gastroenterology.We summarize the impact and mechanisms of Elafibranor on ALD,metabolic-associated fatty liver disease,and cholestatic liver disease based on current research.We also explore its potential as a dual agonist of PPARα/δ,which is undergoing Phase III clinical trials for metabolic-associated steatohepatitis.Our goal is to stimulate further investigation into Elafibranor's use for preventing and treating these liver diseases and to provide insights for its clinical application.

Novel intervention for alcohol-associated liver disease

A recently published article in the World Journal of Gastroenterology clarified that elafibranor,a dual peroxisome proliferator activated receptorα/δ(PPARα/δ)agonist,reduced inflammation and fibrosis in alcohol-associated liver disease(ALD).This letter aims to discuss the findings presented in that article.ALD is a global health problem,and no effective drugs has been approved by the Food and Drug Administration to cure it.Thus,finding targeted therapies is of great urgency.Herein,we focus on the pathogenesis of ALD and the role of PPARα/δin its development.Consistent with the conclusion of the article of interest,we think that elafibranor may be a promising therapeutic option for ALD,due to the pivotal involvement of PPARα/δin the pathogenesis of the disease.However,its treatment dose,timing,and side effects need to be further investigated in future studies.

Elafibranor:A promising treatment for alcohol-associated liver disease?

We comment on an article by Koizumi et al.Elafibranor(EFN)is a dual pero-xisome proliferator-activated receptorα/δagonist.The experimental results from Koizumi et al demonstrated that EFN significantly increases intestinal barrier function and ameliorates liver fibrosis.These positive outcomes suggest that EFN could be a promising therapeutic option for alcohol-associated liver disease(ALD).However,this study has limitations that necessitate further research to evaluate the efficacy of EFN.Future studies should consider the use of more appropriate animal models and cell types,optimize the administration routes and dosages of the drug,and conduct an in-depth investigation into the underlying mechanisms of action to determine the therapeutic effects of EFN in humans.With sustained and in-depth research,EFN has the potential to emerge as a novel therapeutic agent for the treatment of ALD.

Vitamin D 1,25-Dihydroxyvitamin D_(3) reduces lipid accumulation in hepatocytes by inhibiting M1 macrophage polarization

BACKGROUND Non-alcoholic fatty liver disease(NAFLD),which is a significant liver condition associated with metabolic syndrome,is the leading cause of liver diseases globally and its prevalence is on the rise in most nations.The protective impact of vitamin D on NAFLD and its specific mechanism remains unclear.AIM To examine the role of vitamin D in NAFLD and how vitamin D affects the polarization of hepatic macrophages in NAFLD through the vitamin D receptor(VDR)-peroxisome proliferator activated receptor(PPAR)γpathway.METHODS Wild-type C57BL/6 mice were provided with a high-fat diet to trigger NAFLD model and administered 1,25-dihydroxy-vitamin D[1,25(OH)_(2)D_(3)]supplementation.1,25(OH)_(2)D_(3) was given to RAW264.7 macrophages that had been treated with lipid,and a co-culture with AML12 hepatocytes was set up.Lipid accumulation,lipid metabolism enzymes,M1/M2 phenotype markers,proinflammatory cytokines and VDR-PPARγpathway were determined.RESULTS Supplementation with 1,25(OH)_(2)D_(3) relieved hepatic steatosis and decreased the proinflammatory M1 polarization of hepatic macrophages in NAFLD.Administration of 1,25(OH)_(2)D_(3) suppressed the proinflammatory M1 polarization of macrophages induced by fatty acids,thereby directly relieving lipid accumulation and metabolism in hepatocytes.The VDR-PPARγpathway had a notable impact on reversing lipid-induced proinflammatory M1 polarization of macrophages regulated by the administration of 1,25(OH)_(2)D_(3).CONCLUSION Supplementation with 1,25(OH)_(2)D_(3) improved hepatic steatosis and lipid metabolism in NAFLD,linked to its capacity to reverse the proinflammatory M1 polarization of hepatic macrophages,partially by regulating the VDRPPARγpathway.The involvement of 1,25(OH)_(2)D_(3) in inhibiting fatty-acid-induced proinflammatory M1 polarization of macrophages played a direct role in relieving lipid accumulation and metabolism in hepatocytes.

Study on Lymphocyte Activation and Proliferation Induced by Anti-CD3 McAb

T cell activation and proliferation via CD3-TCR complex were investigated by lymphocyte DNA synthesis in vitro.Several interfering factors were also discussed.The result indicated that lymphocyte activation and proliferation are calciumdependent.A rise of cytoplasmic free Ca2+ quickly following activation with CD3 McAb is mainly due to intracellular mobilization of Ca2+,while lymphocyte proliferation needs both intracellular mobilization of Ca2+ as well as influx of extracellular Ca2+, It was confirmed that CTX sensitive G protein plays a role in regulating T cell proliferation by pretreatment with CTX suppressing lymphocyte H-TdR incorporation obviously.PLC and PKC inhibitor neomycin and P.S.S could also decrease T cell proliferation.

Nuclear receptors and pathogenesis of pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease with a median overall survival time of 5 mo and the five years survival less than 5%, a rate essentially unchanged over the course of the years. A well defined progression model of accumulation of genetic alterations ranging from single point mutations to gross chromosomal abnormalities has been introduced to describe the origin of this disease. However, due to the its subtle nature and concurring events PDAC cure remains elusive. Nuclear receptors (NR) are members of a large superfamily of evolutionarily conserved ligand-regulated DNA-binding transcription factors functionally involved in important cellular functions ranging from regulation of metabolism, to growth and development. Given the nature of their ligands, NR are very tempting drug targets and their pharmacological modulation has been widely exploited for the treatment of metabolic and inflammatory diseases. There are now clear evidences that both classical ligand-activated and orphan NR are involved in the pathogenesis of PDAC from its very early stages; nonetheless many aspects of their role are not fully understood. The purpose of this review is to highlight the striking connections that link peroxisome proliferator activated receptors, retinoic acid receptors, retinoid X receptor, androgen receptor, estrogen receptors and the orphan NR Nur, chicken ovalbumin upstream promoter transcription factor II and the liver receptor homologue-1 receptor to PDAC development, connections that could lead to the identification of novel therapies for this disease.

emerging role of the β-catenin-PPARγ axis in the pathogenesis of colorectal cancer

Multiple lines of evidence indicate that Wnt/β-catenin signaling plays a fundamental role in colorectal cancer (CRC) initiation and progression. Recent genome-wide data have confirmed that in CRC this pathway is one of the most frequently modified by genetic or epigenetic alterations affecting almost 90% of Wnt/β-catenin gene members. A major challenge is thus learning how the corrupted coordination of this pathway is tied to other signalings to enhance cell growth. Peroxisome proliferator activated receptor γ (PPARγ) is emerging as a growth-limiting and differentiation-promoting factor. In tumorigenesis it exerts a tumor suppressor role and is potentially linked with the Wnt/β-catenin pathway. Based on these results, the identification of new selective PPARγ modulators with inhibitory effects on the Wnt/β-catenin pathway is becoming an interesting perspective. Should, in fact, these molecules display such properties, new research avenues would be opened aimed at developing new molecular targeted drugs. Herein, we review the basic principles and present new hypotheses underlying the crosstalk between Wnt/β-catenin and PPARγ signaling. Furthermore, we discuss the advances in our understanding as to how their altered regulation can culminate in colon cancer and the efforts aimed at designing novel PPARγ agonists endowed with Wnt/β-catenin inhibitory effects to be used as therapeutic and/or preventive agents.

Association of β3 Adrenergic Receptor and Peroxisome Proliferator-activated Receptor Gamma 2 Polymorphisms With Insulin Sensitivity:A Twin Study

Objective To study the effect of β3 adrenergic receptor （β3AR） Trp64Arg and peroxisome proliferator activated receptor gamma 2 （PPAR72） Prol2Ala polymorphisms on insulin resistance. Methods One hundred and eight dizygotic twin pairs were enrolled in this study. Microsatellite polymorphism was used to diagnose zygosity of twins. Insulin sensitivity was estimated with logarithm transformed homeostasis model assessment （HOMA）. PCR-RFLP analysis was performed to detect the variants. As a supplement to the sib-pair method, identity by state （IBS） was used to analyze the association of polymorphisms with insulin sensitivity. Results The genotype frequencies of Trp64Trg, Trp64Arg, and Arg64Arg were 72.3%, 23.8%, and 3.9%, respectively, while the genotype frequencies of Pro12Pro, Pro12Ala, and Ala12Ala were 89.9%, 9.6%, and 0.5%, respectively. For β3AR Trp64Arg the interclass co-twin correlations of Waist-to-hip ratio （WHR）, blood glucose （GLU）, and insulin （INS）, homeostasis model assessment insulin resistance index （HOMA-IR） of the twin pairs sharing 2 alleles of IBS were greater than those sharing 0-1 allele of IBS, and HOMA4R had statistic significance. For PPAR3t2 Prol2Ala most traits of twin pairs sharing 2 alleles of IBS had greater correlations and statistic significance in body mass index （BMI）, WHR, percent of body fat （PBF） and GLU, but there were low correlations of either insulin or HOMA-IR of twin pairs sharing 1 or 2 alleles of IBS. The combined effects of the two variations showed less squared significant twin-pair differences of INS and HOMA-IR among twins sharing 4 alleles of IBS. Condusions β3AR Trp64Arg and PPAR）,2 Pro 12Ala polymorphisms might be associated with insulin resistance and obesity, and there might be slight synergistic effects between this two gene loci, and further studies are necessary to confirm this finding.

Down-regulated expressions of PPAR_γ and its coactivator PGC-1 are related to gastric carcinogenesis and Lauren's classification in gastric carcinoma

Objective： To explore the relationship between peroxisome proliferator activated receptor-gamma （PPARγ） and peroxisome proliferator-activated receptor-gamma coactivator-1 （PGC-1） expression in gastric carcinoma （GC）, and analyze their correlations with clinicopathological features and clinical outcomes of patients. Methods：The two-step immunohistochemical method was used to detect the expression of PPARγ and PGC-1 in 179 cases of GC, and 108 cases of matched normal gastric mucosa. Besides, 16 cases of fresh GC specimens and corresponding normal gastric mucosa were detected for PGC-1 expression with Western blotting. Results： The positive rates of PPART and PGC-1 expression were significantly lower in GC （54.75%, 49.16%） than in normal gastric mucosa （70.37%, 71.30%）, respectively （P〈0.05）. The decreased expression of PGC-1 in GC was confirmed ha our Western blot analysis （P=0.004）. PPAR7 and PGC-1 expressions were related to Lauren＇s types ofGC （P〈0.05）. Positive correlation was found between PPART and PGC-1 expression in GC （rk=0.422, P〈0.001）. The survival time of PPART negative and positive patients was 36.6±3.0 vs. 38.5_＋2.7 months, and no statistical difference was found between the 5-year survival rates of two groups （34.4% vs. 44.1%, P=0.522, log-rank test）; the survival time of PGC-1 negative and positive patients was 36.2±2.8 vs. 39.9±2.9 months, while no statistical difference was found between the 5-year survival rates of the two groups （32.0% vs. 48.2%, P=0.462, log-rank test） Conclusions＇. Decreased expression of PPARγand PGC-1 in GC was related to the Lauren＇s classification. Their expressions in GC were positively correlated, indicating that their fimctions in gastric carcinogenesis may be closely related.

Influence of Ciglitazone on A549 Cells Growth in vitro and in vivo and Mechanism

The effect and mechanism of the ciglitazone on lung cancer cells A549 growth in vitro and in vivo were studied. Various concentrations of ciglitazone were added to the cultured A549 line, and the proliferation and differentiation of A549 cells were examined by MTT and cytometry analysis. A549 cells （1 × 10^6/mouse） were inoculated subcutaneously into 20 nude mice, which were randomly divided into two groups., the control group, the ciglitazone treated group. The weights of subcutaneous tumors were measured, The expression of cyclin D1 and P21 in the lung was detected by immohistochemistry and Western blot respectively. The results showed that the proliferation of A549 was inhibited significantly by ciglitazone in a dose- and time-dependent manner. There were more ceils arrested in G1/G0 phase and the expression of PPARγ was markedly upregulated in ciglitazone-treated group. Direct injection of ciglitazone into A549-induced tumors could suppress tumor growth in nude mice and the growth inhibitory rate was 36 %. The expression of cyclin D1 was decreased and P21 increased significantly in ciglitazone-treated group as compared with control group. It was concluded that ciglitazone could inhibit A549 proliferation dose-dependently and time-dependently and induce differentiation, ,which might be related to the modulation of cell cycle interfered by PPARγ.

Dual therapy of rosiglitazone/pioglitazone with glimepiride on diabetic nephropathy in experimentally induced type 2 diabetes rats

Diabetic nephropathy is a major cause of end-stage renal disease （ESRD） in the general population. It is estimated that diabetic nephropathy will eventually develop in about 40% of all patients with diabetes; therefore, prevention is critical for delaying the development and progression of diabetic kidney disease. Despite extensive efforts, medical advances are still not successful enough to prevent the progression of the disease. In the present study, we focused on the comparison of combination therapies and whether they offered additional renoprotection. Type 2 diabetes mellitus was induced by intraperitoneally administering streptozotocin （90 mg/kg） in neonatal rats and then these rats were treated with rosiglitazone （1.0 mg/kg） in combination with glimepiride （0.5 mg/kg） or with pioglitazone （2.5 mg/kg） in combination with glimepiride （0.5 mg/kg）. Diabetic nephropathy markers were evaluated by biochemical and ELISA kits and renal structural changes were examined by light microscopy and transmission electron microscopy. Results show that the combination of pioglitazone with glimepiride is more effective in amelioration of diabetic nephropathy than rosiglitazone with glimepiride drug therapy due to glycemic control, suppressing albumin excretion rate, total protein excretion rate and augmented TNF-α signaling during the development of streptozotocin induced type 2 diabetic nephropathy.

Curcumin inhibits beta-amyloid protein 40/42 expression in the brain in a concentration-and time-dependent manner

Several studies have demonstrated that the amount of beta-amyloid （Aβ） protein in the brain can be lowered by down-regulating Aβ production, promoting Aβ degradation, reducing Aβ oligomerization or deposition, thereby alleviating symptoms of Alzheimer＇s disease. Curcumin has been known to be a peroxisome proliferator activated receptor gamma （PPARy） agonist and can obviously inhibit Aβ production and oligomerization. This study investigated the effects of curcumin on the G-site APP cleaving enzyme 1 （BACE1） activity and PPARy expression in human neuroblastoma SH-SY5Y cells, and validated the inhibitory effects of curcumin on Aβ40/42 expression in the brain. Results revealed that PPARy mRNA and protein expression in the human neuroblastoma SH-SY5Y cells significantly increased with increasing curcumin concentration and time course （P 〈 0.05）; BACE1 mRNA and protein expression and Aβ40/42 production significantly decreased with increasing curcumin concentration and time course （P 〈 0.05）. The changes in PPARy and BACE1 expression during Aβ production could be reversed by the PPARy antagonist GW9662. These findings indicate that curcumin reduced Aβ production by activating PPARy expression and inhibiting BACE1 expression in a concentration- and time-dependent manner.

Neuronal PPARαdeficiency-induced axonal mitochondrial transport defects underly isch⁃emic stroke pathology

OBJECTIVE Peroxisome proliferator activated receptor alpha(PPARα)is an important protective factor in neurovascular diseases such as ischemic stroke.Although PPARαexpression is higher in neurons than astrocytes and microglia,the pathophysiological functions of neuronal specific-PPARαin isch⁃emic stroke remains unknown.Here,we report that neuronal PPARαdeficiency is a key factor of neuronal injury.PPARαexpression markedly decreased in neurons after ischemic stroke.METHODS AND RESULTS Neuronal-specific PPARαknockout(NCKO)exacerbates neuronal damage and brain ischemic injury.PPARαdefi⁃ciency disrupts axonal microtubule organization and mitochondrial transport by decreasing the expression of dynein light chain Tctex-type 1(Dynlt1),which is implicated in cytoprotective role with damaged neurons.Furthermore,resto⁃ration of Dynlt1 expression in neurons of NCKO mice rescue mitochondrial transport disorder,cognitive deficits and brain ischemic injury asso⁃ciated with PPARαdeletion.CONCLUSION These results reveal a critical role for neuronal PPARαin ischemic brain injury by modulating axonal mitochondrial transportation.

Identification and Expression of PPAR in Sinonovacula constricta and Their Potential Regulatory Effects on Δ6 Fad Transcription

Peroxisome proliferator activated receptors(PPAR)are kinds of key transcriptional factors in regulating LC-PUFA biosynthesis.Until now,little is known about PPAR in marine molluscs as well as in other invertebrates.Sinonovacula constricta is the first marine mollusc that is proved to possess the complete LC-PUFA biosynthetic pathway,and it can be a perfect representative to clarify this situation.In this study,the molecular properties of S.constricta PPAR were characterized,and corresponding potential regulatory roles in S.constrictaΔ6 fatty acyl desaturase(Fad)transcription were estimated by dual luciferase assay.Results showed that two PPAR homologs(PPAR_a and_b)were identified in S.constricta.They both contain typical features of vertebrate PPAR,suggesting highly conserved functional regions in PPAR.By phylogenetic comparison,they are clearly different with vertebrate PPAR and can be divided into two distinctive sub-groups.Moreover,they show a high expression level in gill,labial palps,mantle and intestine.Their down-regulated expressions in trochophore larva and veliger larva might be attributed to food-deprivation.Additionally,the transcriptional activity of S.constrictaΔ6 Fad promoter was significantly activated by both PPAR_a and_b,indicating that S.constricta PPAR might play a role in the regulation of LC-PUFA biosynthesis.To our knowledge,this is the first systematic analysis of PPAR in a marine mollusc.The results will provide a valuable reference for further researches on the function of marine molluscan PPAR and their underlying mechanisms in regulating LC-PUFA biosynthesis.

Gut-brain crosstalk regulates craving for fatty food

Patients undergoing Roux-en-Y gastric bypass(RYGB)surgery elicit striking loss of body weight. Anatomical restructuring of the gastrointestinal(GI) tract, leading to reduced caloric intake and changes in food preference, are thought to be the primary drivers of weight loss in bariatric surgery patients. However, the mechanisms by which RYGB surgery causes a reduced preference for fatty foods remain elusive. In a recent report, Hankir et al described how RYGB surgery modulated lipid nutrient signals in the intestine of rats to blunt their craving for fatty food. The authors reported that RYGB surgery restored an endogenous fat-satiety signaling pathway, mediated via oleoylethanolamide(OEA), that was greatly blunted in obese animals. In RYGB rats, high fat diet(HFD) led to increased production of OEA that activated the intestinal peroxisome proliferation activator receptors-α(PPARα). In RYGB rats, activation of PPARα by OEA was accompanied by enhanced dopamine neurotransmission in the dorsal striatum and reduced preference for HFD. The authors showed that OEA-mediated signals to the midbrain were transmitted via the vagus nerve. Interfering with either the production of OEA in enterocytes, or blocking of vagal and striatal D1 receptors signals eliminated the decreased craving for fat in RYGB rats. These studies demonstrated that bariatric surgery led to alterations in the reward circuitry of the brain in RYGB rats and reduced their preference for HFD.

Studies on mechanism of cis9,trans11-CLA and trans10,cis12-CLA inducing apoptosis of human breast cancer cell line MCF-7

Objective： The aim of the study was to explore the activities of cis9, trans11-CLA （C9, t11-CLA） and transl0, cis12-CLA （t10, c12-CLA） inhibiting tumor, and investigate their relationships with PPARy and apoptotic proteins, and mechanism of anti-cancer. Methods： The inhibitory rate, cell growth curve and apoptotic morphological observation of MCF-7 cells were obtained by MTT assay, trypan blue staining and Hoechst33342 fluorescence staining. The apoptotic rate and cell cycle were detected with flow cytometry. Transcriptional level of genes was detected with RT-PCR semi-quantitative method, and Western blot was performed to detect proteins levels. Results： The two CLA isomers could reduce cell proliferation （P 〈 0.05）, increase apoptotic rate （P 〈 0.05）, and increase obviously the transcriptional and protein levels of PPARy （P 〈 0.01）. The synchronism and correlation between the effects of CLA to PPARy and apoptotic proteins Bax, Bcl-2, Caspase 3 changes were found with the dose- and time-dependent manners. There was cooperative relation between the levels of PPARy and the rates of Bax/Bcl-2, Caspase 3 （small fragment） by experiments of PPARy inhibitor GW9662 and ligand Rosiglitazone. Conclusion： The apoptotic pathway of PPARy-Bcl-2-Caspase 3 signaling was found. The C9, t11-CLA and tl0, c12-CLA could inhibit MCF-7 cell proliferation and promote apoptosis via activating PPARy-Bcl-2-Caspase 3 pathway. CLA may be a kind of activator of PPARv.

Species differences in regulation of renal proximal tubule transport by certain molecules

Renal proximal tubules （PTs） play important roles in the regulation of acid/base, plasma volume and blood pressure. Recent studies suggest that there are substantial species differences in the regulation of PT transport. For example, thiazolidinediones （TZDs） are widely used for the treatment of type 2 diabetes mellitus, but the use of TZDs is associated with fluid overload. In addition to the transcriptional enhancement of sodium transport in distal nephrons, TZDs rapidly stimulate PT sodium transport via a non-genomic mechanism depending onperoxisome proliferator activated receptor g/Src/epidermal growth factor receptor （EGFR）/MEK/ERK. In mouse PTs, however, TZDs fail to stimulate PT transport probably due to constitutive activation of Src/EGFR/ERK pathway. This unique activation of Src/ERK may also affect the effect of high concentrations of insulin on mouse PT transport. On the other hand, the effect of angiotensin Ⅱ （Ang Ⅱ） on PT transport is known to be biphasic in rabbits, rats, and mice. However, Ang Ⅱ induces a concentration-dependent, monophasic transport stimulation in human PTs. The contrasting responses to nitric oxide/guanosine 3’,5’-cyclic monophosphate pathway may largely explain these different effects of Ang Ⅱ on PT transport. In this review, we focus on the recent fndings on the species differences in the regulation of PT transport, which may help understand the species-specific mechanisms underlying edema formation and/or hypertension occurrence.