Peptides最新文献

The neuropeptide phoenixin (PNX) may be involved in regulating the hypothalamic-pituitary-gonadal (HPG) axis and inflammatory responses. This study aims to investigate the role of PNX in the regulation of HPG axis function in ice hockey players and its impact on body composition. This cross-sectional study included 65 male ice hockey players aged 18-22, divided into untrained, non-elite athlete, and elite athlete groups. Body composition was assessed using bioelectrical impedance analysis, and plasma levels of PNX, gonadotropin-releasing hormone (GnRH), luteinizing hormone (LH), testosterone, tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-10 (IL-10) were measured by enzyme-linked immunosorbent assay. Elite ice hockey players exhibited significantly higher lower limb and core skeletal muscle mass, skeletal muscle index, and testosterone levels, aligning with the high-intensity intermittent nature of hockey training. Compared to the non-training group, ice hockey training groups showed elevated levels of PNX, GnRH, testosterone, and TNF-α, along with reduced levels of LH and IL-6. PNX concentration positively correlated with lean body mass, skeletal muscle mass, skeletal muscle index, serum GnRH, and testosterone levels, and negatively correlated with serum LH and IL-6 levels. In conclusion, PNX may enhance skeletal muscle mass in ice hockey players, particularly in the lower limbs and core muscles, by promoting HPG axis activity while inhibiting inflammatory responses and reducing HPG axis suppression. These findings provide new insights into the physiological adaptation mechanisms of ice hockey players, potentially aiding in the optimization of training strategies and improvement of athletic performance.

Delayed wound healing is a complication of diabetes mellitus and can lead to infection, sepsis, and amputation. Despite the currently available treatments, the global burden of diabetes-related wounds is growing; thus, more effective therapy for diabetic wounds is urgently needed. Ghrelin, an endogenous ligand for the growth hormone secretagogue receptor, is a 28-amino acid peptide hormone. Some reports have confirmed the therapeutic effects of ghrelin on diabetes mellitus and its complications. However, the effects and corresponding mechanisms of ghrelin on chronic diabetic wounds remain unknown. In this study, we explored the effect of ghrelin on diabetic wound healing and investigated the associated mechanisms. We showed that ghrelin accelerated wound healing in diabetic rats by promoting the proliferation and migration of keratinocytes. Re-epithelialization was accelerated in ghrelin-treated wounds, thicker and longer newly formed epidermis and more dividing keratinocytes were observed. We further confirmed that ghrelin regulated keratinocytes by activating the ERK1/2 pathway through its receptor growth hormone secretagogue receptor 1a (GHSR1a). Ghrelin also significantly reduced the levels of pro-inflammatory cytokines and increased the deposition of collagen in diabetic wounds. Our data provides preclinical evidence for the potential application of ghrelin as a compound to promote diabetic wound healing and clarifies the molecular mechanism.

Hormone replacement therapy (HRT) for postmenopausal syndrome (PMS) carries high risks of undesirable side effects. This study explores irisin as a potential alternative to HRT and investigates the underlying mechanisms. Ovariectomized (OVX) female mice was used as an animal model. The experimental mice were divided into sham, OVX, OVX + irisin (1, 3 μg/kg), OVX+ estradiol (0.5 mg/kg), and OVX + irisin + compound C (AMPK inhibitor) groups. Results showed that OVX induced depression, anxiety, and bodyweight growth in female mice. These OVX-induced abnormalities were reversed by irisin treatment, while AMPK inhibitor abolished irisin's function, indicating that irisin's therapeutic effects on OVX mice were achieved by activating AMPK. Moreover, irisin could increase pAMPK levels and ameliorate the overexpression of NF-κB and its downstream factors including inflammatory factors (IL-1β, IL-6, and TNF-α) and neurotoxic mediators (COX-2 and iNOS) in the hippocampus, frontal cortex, and serum of the OVX mice. However, irisin did not affect hypothalamus pAMPK level or food intake. These findings indicate that irisin's therapeutic effects on depression and anxiety may be linked to its inhibition of inflammatory factors and neurotoxic mediators in the serum and brain, occurring through the AMPK/NF-κB pathway. Additionally, irisin's effect of reducing bodyweight may be associated with an increase in serum pAMPK level, rather than a direct impact on food intake. Further mechanistic exploration revealed that the beneficial effects of irisin, including both the attenuation of bodyweight gain and the improvement of neurological deficits, are attributed to the activation of αVβ5 receptors.

Renal hemodynamics damage, an important driving mechanism of diabetic nephropathy (DN), is related to many abnormal endothelial released molecules, such as endothelial nitrogen monoxide synthase (eNOS) and endothelin-1 (ET-1), caused by glomerular endothelial cells dysfunction. Apelin, as the endogenous ligand for APJ, was reported to be associated with endothelial cell dysfunction in diabetes. Therefore, it is hypothesized that apelin/APJ increased renal perfusion in DN through regulating endothelial released molecules. Diabetic models were replicated via injecting STZ intraperitoneally (40 mg/kg/day) for 5 consecutive days. Apelin-13 was infused with micro-osmotic pump at 30 μg/kg/day for 4 weeks. The results showed that apelin increased renal blood flow by increasing phosphorylated eNOS and decreasing ET-1 in diabetic mice, which were cancelled in endothelial-specific APJ knockout mice or whole-body large conductance Ca^2 +-activated K⁺ (BKCa) channel knockout rats. Additionally, apelin/APJ activated BKCa channel via increasing expression of BKCa subunits through PI3K/AKT/GSK-3β/Nrf2 pathway but not increasing intracellular Ca²⁺ concentration under high glucose conditions. In conclusion, this study revealed that apelin/APJ increased renal blood flow in early phase of DN via increasing p-eNOS and decreasing ET-1 in glomerular endothelial cells dependent on PI3K/AKT/GSK-3β/Nrf2 pathway induced expression of BKCa subunits.

Migration is an essential characteristic of cells that occurs during many physiological and pathological processes. Astrocytes represent the most abundant cell type in the adult central nervous system (CNS), that play a crucial role in various functions such as guiding and supporting neuronal migration during development and maintaining brain homeostasis at adulthood. Astrocytes specifically synthesize and release endozepines, a family of regulatory peptides, including the octadecaneuropeptide (ODN). ODN is an endogenous ligand for both central-type benzodiazepine receptors and a metabotropic receptor. ODN promotes proliferation and prevents oxidative damage induced apoptosis on both neurons and astrocytes. However, little is known regarding the effect of ODN on cell migration. The purpose of the present study was to investigate the potential effect of ODN on astrocytes migration. Our results show that ODN stimulates astrocytes proliferation and migration at very low concentrations in wound healing assays, that was mimicked by the metabotropic ODN receptor agonist cyclo_1-8 octapeptide (cyclo_1-8OP, 10^-14 M to 10^-10 M). The effect of ODN on astrocyte migration was abrogated by the metabotropic receptor antagonist, cyclo_1-8[DLeu⁵] OP. Moreover, we have shown that ODN activates the calcium signaling pathway and increases the mammalian target of rapamycin (mTOR) gene transcription, which are both known to promote astrocyte migration. Therefore, the present results suggest that ODN regulates astroglial cell migration through the calcium/mTOR signaling pathway and provide new insight regarding the role of ODN on brain remodling after injury.

Increasing evidence has demonstrated that sPRR [a truncated soluble form of (pro)renin receptor] levels may reflect the severity of several diseases, including kidney disease, hypertension, and heart failure (HF). Although previous studies using cohorts primarily consisting of HF patients with reduced ejection fraction revealed that increased plasma sPRR levels may be a promising evaluative indicator for HF, definitive information on the relationship between plasma sPRR levels and HF patients with preserved ejection fraction (HFpEF) is still insufficient and scarce. In the present study, we further clarified the status of plasma sPRR levels in HF patients by meta-analysis. We enrolled a cohort primarily consisting of HFpEF patients (87.8 %) to further determine the relationships between plasma sPRR levels and HFpEF. Meta-analysis showed a significant increase in plasma sPRR levels in HF patients, with substantial statistical heterogeneity. In our observational study, plasma sPRR levels were significantly higher in the HF group than in the non-HF group (17.4 ± 9.8 vs. 10.4 ± 3.4 ng/ml, p < 0.001) and positively correlated with age, B-type natriuretic peptide, creatine, urea nitrogen, plasma renin activity, angiotensin II, and left atrial diameter and negatively correlated with estimated glomerular filtration rate. Plasma sPRR levels (The average value ≥ 16.1 ± 7.2 ng/ml) and the diagnostic values (reflected by the area under the receiver operating characteristic curves ≥ 0.749) of sPRR were comparable for all subtypes of HF patients. Overall, plasma sPRR levels were significantly elevated in HF patients. Elevated plasma sPRR levels may be one of the underlying indicators for HF.

The neuropeptides vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) act in arcuate (ARC) and paraventricular (PVN) hypothalamic nuclei, reducing food intake and changing plasma parameters. Estrogens (E) also regulate energy homeostasis, and loss of ovarian function leads to hyperphagia and body weight gain. This study aimed to evaluate the effects of estradiol (E) in a postmenopausal rat model, ovariectomy (OVX), on PAC1 and VPAC2 receptors in the PVN and ARC, as well as on food intake, plasma parameters, and PVN and ARC cell activation in response to intracerebroventricular microinjection of VIP and PACAP. For this, the rats underwent intracerebroventricular and OVX surgeries, being treated daily with subcutaneous injections of 0.2 mL of corn oil or 10 μg/0.2 mL of estradiol cypionate, comprising the OVX+O and OVX+E groups, respectively. OVX+E showed reduced VPAC2 mRNA expression in the PVN. PACAP reduced food intake in both groups, and VIP-induced hypophagia was not observed in OVX+E. VIP increased plasma glucose in both groups, and PACAP increased plasma glucose only in OVX+O. VIP decreased free fatty acids in OVX+E. Furthermore, PACAP increased ARC cell activation in both groups, and in the PVN only in OVX+O. Cell activation induced by VIP in ARC and PVN was blocked by estradiol. Therefore, estrogens disrupted the hypophagia induced by VIP, but not by PACAP, and these differences seem to be, at least in part, due to an impairment of the activation of the ARC-PVN pathway.

Expression of prokineticin 2 (PK2) mRNA in the suprachiasmatic nucleus (SCN), also known as the brain's clock, exhibits circadian oscillations with peak levels midday, zeitgeber time (ZT) 4, and almost undetectable levels during night. This circadian expression profile has substantially contributed to the suggested role of PK2 as an SCN output molecule involved in transmitting circadian rhythm of behavior and physiology. Due to unreliable specificity of PK2 antibodies, the 81 amino acid protein has primarily been studied at the mRNA level and correlation between circadian oscillating mRNAs and protein products are infrequent. Hence, data on PK2 protein expression in the SCN is lacking. In this study a thorough validation of a commercial PK2 antibody for immunohistochemistry (IHC) was performed followed by fluorescence IHC on SCN mouse brain sections at six consecutive ZTs over a 24-h cycle (12:12 light-dark, ZT0 =light ON whereas ZT12 =light OFF). Data were visualized and processed using confocal microscopy. Results showed that PK2 protein expression diurnally oscillates with calculated peak expression ZT5:40 ± 1:40 h. Opposite than described for PK2 mRNA, PK2 immunoreactivity was detectable at all times during the 24-h cycle. PK2 was primarily located in neurons of the shell compartment and > 80 % of these neurons co-expressed the core clock protein PER2. In conclusion, PK2 protein expression oscillates as the mRNA, supporting the suggested role of PK2 as a SCN molecule involved in circadian rhythm regulation.

Obesity is a worldwide health issue. Effective and safe methods for obesity management are highly desirable. In the current study, hyperbaric oxygen (HBO) treatment was investigated as a potential treatment against obesity-associated hyperphagia and hyperenergy intake. Diet induced obesity (DIO) mice model was established with high fat diet (HFD) feeding, HBO was then co-administered. Food and energy intake were assessed with nocturnal food intake assay. Immunohistochemistry for c-Fos was performed for neuronal activation in arcuate nucleus (ARC), paraventricular nucleus of hypothalamus (PVN) and lateral parabrachial nucleus (LPBN) of brain. Additionally, enzyme-linked immunosorbent assay (ELISA) in serum and immunofluorescence in LPBN were performed. Results indicated that HBO co-treatment effectively decreased food and energy intake in DIO mice, reverted the abnormal neuronal activation in the ARC and PVN, and enhanced both peripheral and central nesfatin-1 peptide levels without affecting serum leptin levels. While SHU9119 microinjection in LPBN effectively abolished the beneficial effects of HBO on body weight, visceral fat, nocturnal feeding and energy intake in DIO mice. In conclusion, HBO treatment could effectively protect against HFD-induced increase of food and energy intake, which is associated with its central effects against abnormal neuronal activation in ARC and PVN and enhanced peptide levels of nesfatin-1 both centrally and peripherally. The melanocortin system downstream of nesfatin-1 may exert a potential effect in this process.