BACKGROUND: Currently, a significant number of miners are involved in mining operations at the Gejiu tin mine in Yunnan. This occupational setting is associated with exposure to dust particles, heavy metals, polycyclic aromatic hydrocarbons, and radioactive radon, thereby significantly elevating the risk of lung cancer. This study aims to investigate the involvement of leptin-mediated extracellular regulated protein kinase (ERK) signaling pathway in the malignant transformation of rat alveolar type II epithelial cells induced by Yunnan tin mine dust. METHODS: Immortalized rat alveolar cells type II (RLE-6TN) cells were infected with Yunnan tin mine dust at a concentration of 200 μg/mL for nine consecutive generations to establish the infected cell model, which was named R₂₀₀ cells. The cells were cultured normally, named as R cells. The expression of leptin receptor in both cell groups was detected using the Western blot method. The optimal concentration of leptin and mitogen-activated protein kinase kinase (MEK) inhibitor (U0126) on R₂₀₀ cells was determined using the MTT method. Starting from the 20th generation, the cells in the R group were co-cultured with leptin, while the cells in the R₂₀₀ group were co-cultured with the MEK inhibitor U0126. The morphological alterations of the cells in each group were visualized utilizing hematoxylin-eosin staining. Additionally, concanavalin A (ConA) was utilized to detect any morphological differences, and an anchorage-independent growth assay was conducted to assess the malignant transformation of the cells. The changes in the ERK signaling pathway in epithelial cells after the action of leptin were detected using the Western blot method. RESULTS: Both the cells in the R group and R₂₀₀ group express leptin receptor OB-R. Compared to the R₂₀₀ group, the concentration of leptin at 100 ng/mL shows the most significant pro-proliferation effect. The proliferation of R₂₀₀ cells infected with the virus is inhibited by 30 μmol/L U0126, and a statistically significant divergence was seen when compared to the control group (P<0.05). Starting from the 25th generation, the cell morphology of the leptin-induced R₂₀₀ group (R₂₀₀L group) underwent changes, leading to malignant transformation observed at the 30th generation. The characteristics of malignant transformation became evident by the 40th generation in the R₂₀₀L group. In contrast, the other groups showed agglutination of P40 cells, and the speed of cell aggregation increased with an increase in ConA concentration. Notably, the R₂₀₀L group exhibited faster cell aggregation compared to the U0126-induced R₂₀₀ (R₂₀₀LU) group. Additionally, the cells in the R₂₀₀L group were capable of forming clones starting from P30, with a colony formation rate of 2.25‰±0.5‰. However, no clonal colonies were observed in the R₂₀₀LU group and R₂₀₀ group. The expression of phosphorylated extracellular signal-regulated kinase (pERK) was enhanced in cells of the R₂₀₀L group. However, when the cells in the R₂₀₀L group were treated with U0126, a blocking agent, the phosphorylation level of pERK decreased. CONCLUSIONS Leptin can promote the malignant transformation of lung epithelial cells infected by mine dust, and the ERK signaling pathway may be necessary for the transformation of alveolar type II epithelial cells induced by Yunnan tin mine dust.
Rats ; Animals ; Alveolar Epithelial Cells/pathology* ; Dust ; Tin/adverse effects* ; Lung Neoplasms/pathology* ; Leptin/adverse effects* ; Receptors, Leptin ; China ; Signal Transduction ; Epithelial Cells/pathology* ; Mitogen-Activated Protein Kinase Kinases/adverse effects*

Although enhanced appetite and weight gain are potential side effects of treatment with antipsychotic agents, particularly olanzapine and clozapine, the mechanisms underlying these side effects are poorly understood. Leptin and ghrelin were recently identified as hormones that play crucial roles in the regulation of energy balance and glucose metabolism. To elucidate relationships between weight change and plasma levels of ghrelin and leptin, we investigated the circulating ghrelin and leptin levels and body weight during olanzapine treatment. Twenty-four patients with schizophrenia were examined during 6-month administration of olanzapine. Ghrelin, leptin, weight and body mass index (BMI) were measured before and after 2, 4, 8, 12, 16, and 24 weeks of olanzapine treatment. The concentration of glucose and various lipid metabolic parameters were measured at baseline and at 24 weeks. Significant increases in weight, BMI and leptin were observed at week 24. On the other hand, the serum levels of ghrelin decreased significantly after olanzapine treatment. In addition, the level of ghrelin was negatively correlated with the leptin level, BMI and weight. The leptin level was positively correlated with both BMI and weight. Ghrelin is associated with metabolic changes, in combination with leptin, during olanzapine treatment. However, further large-scale and longitudinal studies are warranted to elucidate the metabolic changes involving ghrelin, leptin and insulin during treatment with antipsychotics.
Antipsychotic Agents/*adverse effects ; Benzodiazepines/*adverse effects ; Body Mass Index ; Body Weight/*drug effects ; Ghrelin/*blood ; Humans ; Leptin/*blood ; Male ; Schizophrenia/blood/*drug therapy

OBJECTIVETo investigate whether exogenous hydrogen sulfide (H2S) inhibits the high-glucose (HG)-induced injury by modulating leptin/leptin receptor (LEPR) signal pathway in human umbilical vein endothelial cells (HUVECs).

METHODSHUVECs were treated with 40 mmol/L glucose for 3-24 h, and the cell viability was examined by CCK-8 assay. The changes of cell morphology and the number of apoptotic cells were assessed by Hoechst 33258 nuclear staining followed by photofluorography. The intracellular levels of reactive oxygen species (ROS) was detected by DCFH-DA staining followed by photofluorography. Mitochondrial membrane potential (MMP) was determined by Rhodamine 123 (Rh123) staining and photofluorography. The expression levels of leptin and LEPR protein were measured by Western blotting.

RESULTSs The expression of leptin and LERP in HUVECs began to significantly increase at 3 h after HG exposure and reached the peak levels at 9 h (P<0.01). Pretreatment of HUVECs with 400 µmol/L sodium hydrosulfide (H2S donor) for 30 min inhibited HG-induced increase in leptin and leptin receptor expressions in HUVECs (P<0.01). Pretreatment of HUVECs with 400 µmol/L NaHS for 30 min or 50 ng/mL leptin antagonists (LA) for 1 h obviously alleviated HG-induced injury by increasing cell viability, decreasing cell apoptosis and lowering accumulation of intracellular ROS and MMP loss (P<0.01).

CONCLUSIONExogenous H2S protects against HG-induced injury by inhibiting leptin/LEPR pathway in HUVECs.

Apoptosis ; Cell Survival ; Cells, Cultured ; Glucose ; adverse effects ; Human Umbilical Vein Endothelial Cells ; drug effects ; metabolism ; Humans ; Hydrogen Sulfide ; pharmacology ; Leptin ; metabolism ; Membrane Potential, Mitochondrial ; Reactive Oxygen Species ; metabolism ; Receptors, Leptin ; metabolism ; Signal Transduction

Accumulating evidence suggests that obesity is associated with chronic pain. However, whether obesity is associated with acute inflammatory pain is unknown. Using a well-established obese mouse model induced by a high-fat diet, we found that: (1) the acute thermal pain sensory threshold did not change in obese mice; (2) the model obese mice had fewer nociceptive responses in formalin-induced inflammatory pain tests; restoring the obese mice to a chow diet for three weeks partly recovered their pain sensation; (3) leptin injection induced significant phosphorylation of STAT3 in control mice but not in obese mice, indicating the dysmodulation of topical leptin-leptin receptor signaling in these mice; and (4) leptin-leptin receptor signaling-deficient mice (ob/ob and db/db) or leptin-leptin receptor pathway blockade with a leptin receptor antagonist and the JAK2 inhibitor AG 490 in wild-type mice reduced their nociceptive responses in formalin tests. These results indicate that leptin plays a role in nociception induced by acute inflammation and that interference in the leptin-leptin receptor pathway could be a peripheral target against acute inflammatory pain.
Animals ; Diet, High-Fat ; adverse effects ; Inflammation ; chemically induced ; metabolism ; Leptin ; metabolism ; pharmacology ; Male ; Mice ; Mice, Inbred C57BL ; Nociception ; drug effects ; physiology ; Nociceptive Pain ; etiology ; metabolism ; Obesity ; complications ; metabolism ; Pain Measurement ; Pain Threshold ; drug effects ; physiology ; Receptors, Leptin ; metabolism ; Signal Transduction ; drug effects ; physiology

OBJECTIVETo investigate the effects of Chang-Chul-Eui-Ee-In-Tang ([see text], CCEET), modififi ed CCEET (MCCEET), and Semen Coicis (SC, a major component of CCEET) on energy and glucose homeostasis. The possible mechanism of action of CCEET was also determined.

METHODSA total of 100 Sprague Dawley female rats were randomly assigned to 5 groups, with 20 in each group. Rats in 4 groups were fed with a high fat diet supplementation (2 g/kg body weight), and water extracts of CCEET, MCCEET, SC, and cellulose (negative control), respectively. The last group was fed with a low-fat diet as a positive control.

RESULTSCCEET and MCCEET decreased body weight and body fat (mesenteric and retroperitoneal fat) more than SC. This decrease was due to decreased energy intake and increased energy expenditure and fat oxidation. The improvement in energy homeostasis was associated with the enhancement of the hypothalamic leptin signalling pathway involving potentiating the phosphorylation of the signal transducer and activator of transcription-3, as well as attenuating the phosphorylation of 5' adenosine monophosphate-activated protein kinase (AMPK). Both CCEET and MCCEET improved glucose tolerance without changing serum insulin levels during an oral glucose tolerance test but MCCEET had a better effect than CCEET.

CONCLUSIONSBoth CCEET and MCCEET safely exerted anti-obesity effects by enhancing energy balance in female rats with diet-induced obesity; MCCEET showed a better effect on glucose homeostasis.

Adenylate Kinase ; metabolism ; Adipose Tissue ; drug effects ; Animals ; Anti-Obesity Agents ; adverse effects ; pharmacology ; therapeutic use ; Blood Glucose ; metabolism ; Body Weight ; drug effects ; Calorimetry ; Diet ; Drugs, Chinese Herbal ; adverse effects ; pharmacology ; therapeutic use ; Energy Metabolism ; drug effects ; Female ; Glucose Tolerance Test ; Homeostasis ; drug effects ; Hypothalamus ; drug effects ; enzymology ; Leptin ; metabolism ; Motor Activity ; drug effects ; Obesity ; blood ; drug therapy ; pathology ; physiopathology ; Phosphorylation ; drug effects ; Rats ; Rats, Sprague-Dawley ; STAT3 Transcription Factor ; metabolism ; Signal Transduction ; drug effects

OBJECTIVE: To investigate the effect of high-fat (HF) diet on the body weight and the mRNA expression of melanin concentrating hormone receptor 1 (MCHR1) and leptin receptor (OB-Rb) in the adipose tissue in rats, the two important and opposite factors in regulating the body weight. METHODS: Post-weaning rats were divided into 3 groups: the NC group were fed a normal-chow diet (NC) (13% calories from fat), the HF group with a HF-diet (47% calories from fat) and the PHF group pair-fed a HF-diet (47% calories from fat). At the end of 8th week, the gained bodyweight, the plasma melanin concentrating hormone (MCH) and leptin, and the expression levels of MCHR1 and OB-Rb in the adipose tissue were measured. RESULTS: Both the HF-diet and pair-fed HF-diet enhanced the body weight (P<0.01), plasma MCH (P<0.01) and leptin concentrations (P<0.05). In the adipose tissue, HF-diet resulted in significant increase in MCHR1 (PHF group,P<0.05) and decrease in OB-Rb mRNA levels (HF group,P<0.01; PHF group,P<0.05). No statistical difference was found between the HF group and the PHF group in terms of the aforementioned data (P>0.05). CONCLUSION Chronic intake of iso-caloric HF-diet and ad libitum HF-diet obviously results in increase in the body weight, serum leptin, and MCH concentration. Diet-induced obesity and related metabolic disorders are possibly correlated with up-regulated expression of MCHR1 and down-regulated expression of OB-Rb in the adipose tissue.
Adipose Tissue ; metabolism ; Animals ; Animals, Newborn ; Diet, High-Fat ; adverse effects ; Dietary Fats ; administration & dosage ; Hypothalamic Hormones ; blood ; Leptin ; blood ; Male ; Melanins ; blood ; Obesity ; etiology ; metabolism ; Pituitary Hormones ; blood ; RNA, Messenger ; genetics ; metabolism ; Rats ; Rats, Sprague-Dawley ; Receptors, Leptin ; genetics ; metabolism ; Receptors, Somatostatin ; genetics ; metabolism

Nonalcoholic steatohepatitis (NASH) is characterized by hepatocyte injury and inflammatory cell infiltration, which has been linked to peripheral insulin resistance and increased levels of triglycerides in the liver. The purposes of this study were to establish a mouse model of NASH by feeding mice a 60% high-fat diet (HFD) and to demonstrate the anti-fibrotic effects of oleuropein, which has been shown to have anti-oxidant and anti-inflammatory properties, in this HFD-induced mouse model of NASH. C57BL/6 mice were divided into three groups: a regular diet group (Chow), a HFD group and an oleuropein-supplemented HFD group (OSD), which was fed a 0.05% OSD for 6 months. The effects of oleuropein in this model were evaluated using biochemical, histological and molecular markers. The expression levels of alpha-smooth muscle actin (alpha-SMA)and collagen type I in the HFD and OSD groups were evaluated using real-time PCR and western blotting. The body weight, biochemical marker levels, nonalcoholic fatty liver disease activity score, homeostasis model of assessment-insulin resistance (HOMA-IR) and leptin levels observed in the HFD group at 9 and 12 months were higher than those observed in the Chow group. The HOMA-IR and leptin levels in the OSD group were decreased compared with the HFD group. In addition, alpha-SMA and collagen type I expression were decreased by oleuropein treatment. We established a NASH model induced by HFD and demonstrated that this model exhibits the histopathological features of NASH progressing to fibrosis. Our results suggest that oleuropein may be pharmacologically useful in preventing the progression of steatohepatitis and fibrosis and may be a promising agent for the treatment of NASH in humans.
Actins/genetics/metabolism ; Animals ; Antihypertensive Agents/*therapeutic use ; Collagen Type I/genetics/metabolism ; Diet, High-Fat/*adverse effects ; Fatty Liver/*drug therapy/etiology/metabolism ; Fibrosis/etiology/metabolism/prevention & control ; Iridoids/*therapeutic use ; Leptin/genetics/metabolism ; Liver/metabolism/pathology ; Mice ; Mice, Inbred C57BL

Leptin serves an important role in suppressing appetite in mice and is known to be elevated in chronic renal failure (CRF) patients. But clinical significance of leptin as an appetite-reducing uremic toxin, remains to be determined. So we studied the relationship between plasma leptin and nutritional status in 46 chronic hemodialysis (HD) patients. Pre HD leptin was measured and divided by body mass index (BMI) to give adjusted leptin levels. KT/Vurea (K, dialyzer urea clearance; T, duration of HD; V, volume of distribution of urea), C-reactive protein (CRP), plasma insulin and nutritional parameters such as serum albumin, normalized protein catabolic rate (nPCR), subjective global assessment (SGA), BMI and mid-arm muscle circumference (MAMC) were also measured. Mean plasma leptin levels were 8.13+/-2.91 ng/mL (male 3.15+/-0.70; female 14.07+/-6.14, p<0.05). Adjusted leptin levels were positively correlated with nPCR (male r=0.47, p<0.05; female r=0.46, p<0.05), SGA (male r=0.43, p<0.05; female r=0.51, p<0.05) and MAMC (male r=0.60, p<0.005; female r=0.61, p<0.05). They did not correlate with KT/Vurea, serum albumin, hematocrit, bicarbonate, insulin and CRP. Presence of DM and erythropoietin therapy had no effect on leptin levels. These results suggest that leptin is a marker of good nutritional status rather than a cause of protein energy malnutrition in chronic HD patients.
Adult ; Biological Markers/blood ; Cross-Sectional Studies ; Female ; Human ; Kidney Failure, Chronic/therapy ; Kidney Failure, Chronic/complications ; Kidney Failure, Chronic/blood* ; Leptin/blood* ; Male ; Middle Age ; Nutrition Disorders/etiology ; Nutrition Disorders/diagnosis ; Nutritional Status* ; Obesity/metabolism ; Obesity/etiology ; Renal Dialysis*/adverse effects ; Sex Factors

OBJECTIVETo observe the difference in fatty degree, glucose-lipid disorder and adipose-hormones between diet induced obesity (DIO) rats and diet induced obesity resistance (DIO-R) rats, and to explore the effect and acting mechanism of Chinese drugs for strengthening Pi (CD-SP) and those for both strengthening Pi and dissolving phlegm (CD-SPDP) in inhibiting obesity.

METHODSExcepting eight rats allocated in the blank control group, the other 54 rats were fed with high-lipid forage for 12 weeks to establish models of obesity. Finally, 30 DIO rats and 8 DIO-R rats (shown by their body weight) were obtained. The DIO rats were divided into three groups, which were given gastric perfusion, respectively, with normal saline (Group A), CD-SP (Group B), and CD-SPDP (Group C). Fourteen weeks later, the animals' body weight (BW), length (BL), blood levels of fasting insulin (FIn), fasting glucose (FBG), triglyceride (TG), cholesterol (TC), leptin (LP), neuropeptide Y (NPY), C-reactive protein (CRP), tumor necrosis factor-alpha(TNF-alpha), adiponectin (AN), and resistin (RS) were measured; insulin resistance index (IRI) was calculated, and the degree of obesity and lipid content in abdominal cavity of rats were estimated. Moreover, the levels of LP, CRP, TNF-alpha, AN and RS in homogenate of rats' adipose tissues (ATH) were determined.

RESULTSAfter 12 weeks of high-lipid diet, the BW of DIO rats was higher than that of normal or DIO-R rats. After a 14-week continuous high-lipid diet feeding, in DIO rats, BW, lipid coefficient (LC), and IRI were significantly increased (P<0.01); serum levels of TNF-alpha, LP and AN were lower, NPY was higher, while the ATH levels of LP and AN were lower and TNF-alpha was higher in DIO rats than in DIO-R rats (P<0.05 or P<0.01); blood levels of FBG and lipids in DIO rats showed an increasing trend but was statistically insignificant (P>0.05); no significant difference was found in serum levels of CRP and RS due to the overly high data dispersion. Comparisons of the 3 DIO groups showed that BW, body weight index (BWI), LC and IRI were significantly lowered after treatment (P<0.01) in Group C, while these indexes were not significantly different between Group A and B; the serum levels of TNF-alpha, LP, and AN increased, NPY decreased in Group B and C, ATH levels of LP and AN increased, and TNF-alpha decreased in the two groups; but NPY, LP, and AN in blood and ATH were higher in Group C than those in Group B (P<0.05 or P<0.01).

CONCLUSIONCD-SPDP could inhibit DIO and IR, showing that the effect is better than that of CD-SP, and its mechanism is related to promotion of LP and AN secretion and elevation of serum NPY.

Adipokines ; blood ; Animals ; Blood Glucose ; analysis ; C-Reactive Protein ; analysis ; Diet, Atherogenic ; Dietary Fats ; adverse effects ; Drug Evaluation, Preclinical ; Drugs, Chinese Herbal ; pharmacology ; therapeutic use ; Leptin ; blood ; Male ; Neuropeptide Y ; blood ; Obesity ; blood ; etiology ; pathology ; prevention & control ; Random Allocation ; Rats ; Rats, Wistar ; Syndrome ; Tumor Necrosis Factor-alpha ; blood

OBJECTIVES: Acute kidney injury (AKI) can be caused by ischemia/reperfusion (I/R), nephrotoxin, and sepsis, with poor prognosis and high mortality. Leptin is a protein molecule that regulates the body's energy metabolism and reproductive activities via binding to its specific receptor. Leptin can inhibit cardiomyocyte apoptosis caused by I/R, but its effect on I/R kidney injury and the underlying mechanisms are still unclear. This study aims to investigate the effect and mechanisms of leptin on renal function, renal histopathology, apoptosis, and autophagy during acute I/R kidney injury. METHODS: Healthy adult male mice were randomly divided into 4 groups: a sham+wild-type mice (ob/+) group, a sham+leptin gene-deficient mice (ob/ob) group, an I/R+ob/+ group, and an I/R+ob/ob group (n=8 per group). For sham operation, a longitudinal incision was made on the back of the mice to expose and separate the bilateral kidneys and renal arteries, and no subsequent treatment was performed. I/R treatment was ischemia for 30 min and reperfusion for 48 h. The levels of BUN and SCr were detected to evaluate renal function; HE staining was used to observe the pathological changes of renal tissue; TUNEL staining was used to observe cell apoptosis, and apoptosis-positive cells were counted; Western blotting was used to detect levels of apoptosis-related proteins (caspase 3, caspase 9), autophagy-related proteins [mammalian target of rapamycin (mTOR), phosphorylated mTOR (p-mTOR), LC3 I, LC3 II], mTOR-dependent signaling pathway proteins [phosphate and tension homology (PTEN), adenosine monophosphate-activated protein kinase (AMPK), protein kinase B (AKT), extracellular regulated protein kinase (ERK), phosphorylated PTEN (p-PTEN), phosphorylated AMPK (p-AMPK), phosphorylated AKT (p-AKT), phosphorylated ERK (p-ERK)]. RESULTS: There was no significant difference in the levels of BUN and SCr between the sham+ob/+ group and the sham+ob/ob group (both P>0.05). The levels of BUN and SCr in the I/R+ob/+ group were significantly higher than those in the sham+ob/+ group (both P<0.05). Compared with the mice in the sham+ob/ob group or the I/R+ob/+ group, the levels of BUN and SCr in the I/R+ob/ob group were significantly increased (all P<0.05). There was no obvious damage to the renal tubules in the sham+ob/+ group and the sham+ob/ob group. Compared with sham+ob/+ group and sham+ob/ob group, both the I/R+ob/+ group and the I/R+ob/ob group had cell damage such as brush border shedding, vacuolar degeneration, and cast formation. Compared with the I/R+ob/+ group, the renal tubules of the mice in the I/R+ob/ob group were more severely damaged. The pathological score of renal tubular injury showed that the renal tubular injury was the most serious in the I/R+ob/ob group (P<0.05). Compared with the sham+ob/+ group, the protein levels of caspase 3, caspase 9, PTEN, and LC3 II were significantly up-regulated, the ratio of LC3 II to LC3 I was significantly increased, and the protein levels of p-mTOR, p-PTEN, p-AMPK, p-AKT, and p-ERK were significantly down-regulated in the I/R+ob/+ group (all P<0.05). Compared with the sham+ob/ob group, the protein levels of caspase 3, caspase 9, PTEN, and LC3 II were significantly up-regulated, and the ratio of LC3 II to LC3 I was significantly increased, while the protein levels of p-mTOR, p-PTEN, p-AMPK, p-AKT, and p-ERK were significantly down-regulated in the I/R+ob/ob group (all P<0.05). Compared with the I/R+ob/+ group, the levels of p-mTOR, p-PTEN, p-AMPK, p-AKT were more significantly down-regulated, while the levels of caspase 3, caspase 9, PTEN, and LC3 II were more significantly up-regulated, and the ratio of LC3 II to LC3 I was more significantly increase in the I/R+ob/ob group (all P<0.05). CONCLUSIONS Renal function and tubular damage, and elevated levels of apoptosis and autophagy are observed in mice kidneys after acute I/R. Leptin might relieve I/R induced AKI by inhibiting apoptosis and autophagy that through a complex network of interactions between mTOR-dependent signaling pathways.
AMP-Activated Protein Kinases/metabolism* ; Acute Kidney Injury/pathology* ; Animals ; Apoptosis ; Apoptosis Regulatory Proteins/pharmacology* ; Autophagy ; Caspase 3/metabolism* ; Caspase 9/metabolism* ; Female ; Humans ; Ischemia ; Kidney/pathology* ; Leptin/pharmacology* ; Male ; Mammals/metabolism* ; Mice ; Proto-Oncogene Proteins c-akt/metabolism* ; Reperfusion/adverse effects* ; Reperfusion Injury/metabolism* ; TOR Serine-Threonine Kinases/metabolism*