Regulatory Peptides最新文献

Glucagon-like peptide 2 [GLP-2] is a 33-amino acid peptide released from the mucosal enteroendocrine L-cells of the intestine. The actions of GLP-2 are transduced by the GLP-2 receptor [GLP-2R], which is localized in the neurons of the enteric nervous system but not in the intestinal epithelium, indicating an indirect mechanism of action. GLP-2 is well known for its trophic role within the intestine and interest in GLP-2 is now reviving based on the approval of the GLP-2R agonist for treatment of short bowel syndrome [SBS]. Recently it also seems to be involved in glucose homeostasis.

The aim of this review is to outline the importance of neuroendocrine peptides, specifically of GLP-2 in the enteric modulation of the gastrointestinal function and to focus on new works in order to present an innovative picture of GLP-2.

To validate the potential anti-inflammatory and analgesic role of sita- and vildagliptin, five different experimental models were used in mice: i) mustard oil-induced ear edema, ii) neutrophil accumulation, iii) mechanical and iv) thermal touch sensitivity in complete Freund's adjuvant-induced arthritis and v) capsaicin-induced plasma extravasation in the urinary bladder. For the complete examination period in i) the dose of 10 mg sitagliptin as well as 1–10 mg vildagliptin was found to significantly decrease ear edema as compared to positive control (p < 0.05, n = 8/group). All doses of sitagliptin provided an anti-inflammatory effect p < 0.005 (n = 10/group) in test ii) and an analgesic effect in iii) except 3 mg. Vildagliptin was similarly effective in test ii) (p < 0.005, n = 10/group) as sitagliptin, but it failed to affect mechanical touch sensitivity. Unlike mechanical touch sensitivity, both gliptins could beneficially act on the thermal threshold (p < 0.05, n = 10/group). And only in tests v) could both gliptins reverse inflammation. Further studies are needed to support the suggestion that the utilization of these beneficial effects of gliptins may be considered in the treatment of Type 2 diabetic patients.

Resistin is an adipokine secreted from adipose tissue, which is likely involved in the development of obesity and insulin resistance via its interaction with other organs, as well as affecting adipose tissue function. The impact of resistin treatment on lipolysis and adiponectin secretion in human visceral adipose tissue is currently unknown. Mesenteric adipose tissue samples were obtained from 14 male subjects [age 54 ± 6 yr, body mass index (BMI) 23.59 ± 0.44 kg/m²] undergoing abdominal surgeries. Adipose tissues were cultured and treated with resistin (100 ng/mL, 24 h) in the absence or presence of different signaling inhibitors: H89 (1 μM), PD98059 (25 μM) and SB201290 (20 μM) for glycerol and non-esterified fatty acid (NEFA) measurement. Adiponectin level from media at 24 h was also measured via ELISA. Adipose tissue minces after resistin incubation (100 ng/mL, 24 h) were also collected for further Western blotting analysis.

Resistin resulted in significant induction of glycerol (3.62 ± 0.57 vs. 5.30 ± 1.11 mmol/L/g tissue, p < 0.05) and NEFA (5.99 ± 1.06 vs. 8.48 ± 1.57 mmol/L/g tissue, p < 0.05) release at 24 h. H89 and PD98059 partially inhibited resistin induced glycerol and NEFA release, while SB201290 has no such effect. Resistin induced the phosphorylation of p-HSL at serine 563, PKA at ~ 62 kDa and ERK1/2 as measured by Western blotting. Resistin led to significant reduction of the secretion of adiponectin (38.16 ± 10.43 vs. 21.81 ± 4.21 ng/mL/g tissue, p < 0.05). Our current findings implicate that resistin might play a significant role in obesity related pathologies in various tissues via its effect on adipose tissue function.

Orexin plays diverse roles in regulating behaviors, such as sleep and wake, reward processing, arousal, and stress and anxiety. The orexin system may accomplish these multiple tasks through its complex innervations throughout the brain. The emerging evidence indicates a role of orexin in emotional behaviors; however, most of the previous studies have investigated the function of orexin in naïve animals. Here, we examined a functional role of orexin in mice that had been exposed to repeated stress. Chronic social defeat stress produced differential social interaction behaviors in mice (susceptible versus resilient) and these two groups of mice displayed different levels of prepro-orexin in the hypothalamus. Exogenously added orexin A to the brain induced an antidepressant-like effect in only the susceptible mice but not in the resilient mice. In contrast, orexin A and orexin B infused together produced an anxiogenic effect in only the resilient mice and not in the susceptible mice. Furthermore, we found that the antidepressant-like effect of orexin A is mediated by the bed nucleus of the stria terminalis (BNST) after exposure to chronic restraint stress. These findings reveal a bimodal effect of the orexin system in regulating emotional behavior that depends on stress susceptibility.

Previous studies indicated that brain-derived neurotrophic factor (BDNF) is the main candidate to mediate the beneficial effects of exercise on cognitive function in sleep deprived male rats. In addition, our previous findings demonstrate that female rats are more vulnerable to the deleterious effects of sleep deprivation on cognitive performance and synaptic plasticity.

Therefore, the current study was designed to investigate the effects of treadmill exercise and/or sleep deprivation (SD) on the levels of BDNF mRNA and protein in the hippocampus of female rats.

Intact and ovariectomized (OVX) female Wistar rats were used in the present experiment. The exercise protocol was four weeks treadmill running and sleep deprivation was accomplished using the multiple platform method. Quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) and immunoblot analysis were used to evaluate the level of BDNF mRNA and protein in the rat hippocampus respectively.

Our results showed that protein and mRNA expression of BDNF was significantly (p < 0.05) decreased after 72 h SD in OVX rats in compared with other groups. Furthermore, sleep deprived OVX rats under exercise conditions had a significant (p < 0.05) up-regulation of the BDNF protein and mRNA in the hippocampus.

These findings suggest that regular exercise can exert a protective effect against hippocampus-related functions and impairments induced by sleep deprivation probably by inducing BDNF expression.

In humans, we reported an association of a certain allele of carnosinase gene with reduced carnosinase activity and absence of nephropathy in diabetic patients. CN1 degrades histidine dipeptides such as carnosine and anserine. Further, we and others showed that treatment with carnosine improves renal function and wound healing in diabetic mice and rats. We now investigated the effects of carnosine treatment alone and in combination with ACE inhibition, a clinically established nephroprotective drug in diabetic nephropathy.

Male Sprague–Dawley rats were injected i.v. with streptozotocin (STZ) to induce diabetes. After 4 weeks, rats were unilaterally nephrectomized and randomized for 24 weeks of treatment with carnosine, lisinopril or both.

Renal CN1 protein concentrations were increased under diabetic conditions which correlated with decreased anserine levels. Carnosine treatment normalized CN1 abundance and reduced glucosuria, blood concentrations of glycosylated hemoglobin (HbA1c), carboxyl-methyl lysine (CML), N-acetylglucosamine (GlcNac; all p < 0.05 vs. non-treated STZ rats), reduced cataract formation (p < 0.05) and urinary albumin excretion (p < 0.05), preserved podocyte number (p < 0.05) and normalized the increased renal tissue CN1 protein concentration. Treatment with lisinopril had no effect on HbA1C, glucosuria, cataract formation and CN1 concentration, but reduced albumin excretion rate more effectively than carnosine treatment (p < 0.05). Treatment with both carnosine and lisinopril combined the effects of single treatment, albeit without additive effect on podocyte number or albuminuria.

Increased CN1 amount resulted in decreased anserine levels in the kidney. Both carnosine and lisinopril exert distinct beneficial effects in a standard model of diabetic nephropathy. Both drugs administered together combine the respective effects of single treatment, albeit without exerting additive nephroprotection.

Neuromedin B, a peptide highly expressed at the pituitary, has been shown to act as autocrine/paracrine inhibitor of thyrotropin (TSH) release. Here we studied the thyroid axis of adult female mice lacking neuromedin B receptor (NBR-KO), compared to wild type (WT) littermates. They exhibited slight increase in serum TSH (18%), with normal pituitary expression of mRNA coding for α-glycoprotein subunit (Cga), but reduced TSH β-subunit mRNA (Tshb, 41%), lower intra-pituitary TSH content (24%) and increased thyroid hormone transporter MCT-8 (Slc16a2, 44%) and thyroid hormone receptor β mRNA expression (Thrb, 39%). NBR-KO mice exhibited normal thyroxine (T4) and reduced triiodothyronine (T3) (30%), with no alterations in the intra-thyroidal content of T4 and T3 or thyroid morphological changes. Hypothalamic thyrotropin-releasing hormone (TRH) mRNA (Trh) was increased (68%), concomitant with a reduction in type 2 deiodinase mRNA (Dio2, 30%) and no changes in MCT-8 and thyroid hormone receptor mRNA expression. NBR-KO mice exhibited a 56% higher increase in serum TSH in response to an acute single intraperitoneal injection of TRH concomitant with a non-significant increase in pituitary TRH receptor (Trhr) mRNA at basal state. The phenotype of female NBR-KO mice at the hypothalamus–pituitary axis revealed alterations in pituitary and hypothalamic gene expression, associated with reduced serum T3, and higher TSH response to TRH, with apparently normal thyroid morphology and hormonal production. Thus, results confirm that neuromedin B pathways are importantly involved in secretory pathways of TSH and revealed its participation in the in vivo regulation of gene expression of TSH β-subunit and pituitary MCT8 and Thrb and hypothalamic TRH and type 2 deiodinase.

Pseudhymenochirin-1Pb (Ps-1Pb) and pseudhymenochirin-2Pa (Ps-2Pa) are host-defense peptides, first isolated from skin secretions of the frog Pseudhymenochirus merlini (Pipidae). Ps-1Pb and Ps-2Pa are highly cytotoxic (LC₅₀ < 12 μM) against non-small cell lung adenocarcinoma A549 cells, breast adenocarcinoma MDA-MB-231 cells, and colorectal adenocarcinoma HT-29 cells but are also hemolytic against human erythrocytes (LC₅₀ = 28 ± 2 μM for Ps-1Pb and LC₅₀ = 6 ± 1 μM for Ps-2Pa). Ps-2Pa shows selective cytotoxicity for tumor cells (LC₅₀ against non-neoplastic human umbilical vein (HUVEC) cells = 68 ± 2 μM). Ps-1Pb and Ps-2Pa (5 μg/mL) significantly inhibit production of the anti-inflammatory cytokine IL-10 and the multifunctional cytokine IL-6 from lipopolysaccharide (LPS)-stimulated peritoneal macrophages from C57BL/6 mice and enhance the production of the pro-inflammatory cytokine IL-23 from both unstimulated and LPS-stimulated macrophages. Ps-1Pb potently (MIC ≤ 10 μM) inhibits growth of multidrug-resistant clinical isolates of the Gram-positive bacteria methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis, and the Gram-negative bacteria Acinetobacter baumannii and Stenotrophomonas maltophilia.

Ps-2Pa shows the same high potency (MIC ≤ 10 μM) against the Gram-positive bacteria but is 2–4 fold less potent against the Gram-negative isolates. Ps-1Pb at 4 × MIC kills 99.9% of Escherichia coli within 30 min and 99.9% of S. aureus within 180 min. In conclusion, cytotoxicity against tumor cells, cytokine-mediated immunomodulatory properties, and broad-spectrum antimicrobial activity suggest that the Ps-1Pb and Ps-2Pa represent templates for design of non-hemolytic analogs for tumor therapy and for treatment of infections in cancer patients produced by multidrug-resistant pathogens.