Identification of hypothalamic neuron-derived neurotrophic factor as a novel factor modulating appetite.

Disruption of finely coordinated neuropeptide signals in the hypothalamus can result in altered food intake and body weight. We identified neuron-derived neurotrophic factor (NENF) as a novel secreted protein through a large-scale screen aimed at identifying novel secreted hypothalamic proteins that regulate food intake. We observed robust Nenf expression in hypothalamic nuclei known to regulate food intake, and its expression was altered under the diet-induced obese (DIO) condition relative to the fed state. Hypothalamic Nenf mRNA was regulated by brain-derived neurotrophic factor (BDNF) signaling, itself an important regulator of appetite. Delivery of purified recombinant BDNF into the lateral cerebral ventricle decreased hypothalamic Nenf expression, while pharmacological inhibition of trkB signaling increased Nenf mRNA expression. Furthermore, recombinant NENF administered via an intracerebroventricular cannula decreased food intake and body weight and increased hypothalamic Pomc and Mc4r mRNA expression. Importantly, the appetite-suppressing effect of NENF was abrogated in obese mice fed a high-fat diet, demonstrating a diet-dependent modulation of NENF function. We propose the existence of a regulatory circuit involving BDNF, NENF, and melanocortin signaling. Our study validates the power of using an integrated experimental and bioinformatic approach to identify novel CNS-derived proteins with appetite-modulating function and reveals NENF as an important central modulator of food intake.

Closed Incision Negative-Pressure Therapy Is Associated with Decreased Surgical-Site Infections: A Meta-Analysis.

BACKGROUND: Negative-pressure therapy has recently been used over closed incisions to decrease surgical-site occurrences, including infection and dehiscence. A meta-analysis was performed to evaluate the effectiveness of closed incision negative-pressure therapy in lowering the incidence of surgical-site infections compared with standard dressings. METHODS: A literature search was conducted to find publications comparing closed incision negative-pressure therapy to standard incisional care. A fixed-effects model was used to assess between-study and between-incision location subgroup heterogeneity and effect size. Funnel plots were used to assess publication bias. RESULTS: The overall weighted average rates of surgical-site infection in the closed incision negative-pressure therapy and control groups were 6.61 percent and 9.36 percent, respectively. This reflects a relative reduction in surgical site infection rate of 29.4 percent. A decreased likelihood of surgical-site infection was evident in the closed incision negative-pressure therapy group compared with the control group across all studies, and across all four incision location subgroups. Across all studies, odds of surgical-site infections decreased 0.564 (p < 0.00001). After excluding groin incision studies because of heterogeneity following sensitivity analysis, the odds of surgical-site infection decrease was still 0.496 (p < 0.00001). In addition, overall rates of dehiscence in closed incision negative-pressure therapy and control groups were 5.32 percent and 10.68 percent, respectively. CONCLUSIONS: The results of this meta-analysis suggest that closed incision negative-pressure therapy is a potentially effective method for reducing surgical-site infections. It also appears that closed incision negative-pressure therapy may be associated with a decreased incidence of dehiscence, but the published data available were too heterogeneous to perform meta-analysis.

GnRH-(1-5) transactivates EGFR in Ishikawa human endometrial cells via an orphan G protein-coupled receptor.

The decapeptide GnRH is known for its central role in the regulation of the hypothalamo-pituitary-gonadal axis. In addition, it is also known to have local effects within peripheral tissues. The zinc metalloendopeptidase, EC 3.4.24.15 (EP24.15), can cleave GnRH at the Tyr(5)-Gly(6) bond to form the pentapeptide, GnRH-(1-5). The central and peripheral effect of GnRH-(1-5) is different from its parent peptide, GnRH. In the current study, we examined the effect of GnRH-(1-5) on epidermal growth factor receptor (EGFR) phosphorylation and cellular migration. Using the Ishikawa cell line as a model of endometrial cancer, we demonstrate that GnRH-(1-5) stimulates epidermal growth factor release, increases the phosphorylation of EGFR (P < .05) at three tyrosine sites (992, 1045, 1068), and promotes cellular migration. In addition, we also demonstrate that these actions of GnRH-(1-5) are mediated by the orphan G protein-coupled receptor 101 (GPR101). Down-regulation of GPR101 expression blocked the GnRH-(1-5)-mediated release of epidermal growth factor and the subsequent phosphorylation of EGFR and cellular migration. These results suggest that GPR101 is a critical requirement for GnRH-(1-5) transactivation of EGFR in Ishikawa cells.

ß-Arrestin 2 is a mediator of GnRH-(1-5) signaling in immortalized GnRH neurons.

We have previously demonstrated that the cleavage product of the full-length GnRH, GnRH-(1-5), is biologically active, binds G protein-coupled receptor 173 (GPR173), and inhibits the migration of cells in the immortalized GnRH-secreting GN11 cell. In this study, we attempted to characterize the GnRH-(1-5) intracellular signaling mechanism. To determine whether the signaling pathway mediating GnRH-(1-5) regulation of migration involves a G protein-dependent mechanism, cells were treated with a generic G protein antagonist in the presence and absence of GnRH-(1-5), and a wound-healing assay was conducted to measure migration. G Protein antagonist 2 treatment abolished the GnRH-(1-5) inhibition of migration, indicating that the mechanism of GnRH-(1-5) is G protein coupled. To identify the potential Gα-subunit recruited by GnRH-(1-5) binding GPR173, we measured the second messengers cAMP and inositol triphosphate levels. GnRH-(1-5) treatment did not alter cAMP levels relative to cells treated with vehicle or forskolin, suggesting that GnRH-(1-5) does not couple to the Gαs or Gαi subunits. Similarly, inositol triphosphate levels remained unchanged with GnRH-(1-5) treatment, indicating a mechanism not mediated by the Gαq/11 subunit. Therefore, we also examined whether GnRH-(1-5) activating GPR173 deviated from the canonical G protein-coupled receptor signaling pathway by coupling to ß-arrestin 1/2 to regulate migration. Our coimmunoprecipitation studies indicate that GnRH-(1-5) induces the rapid interaction between GPR173 and ß-arrestin 2 in GN11 cells. Furthermore, we demonstrate that this association recruits phosphatase and tensin homolog to mediate the downstream action of GnRH-(1-5). These findings suggest that the GnRH-(1-5) mechanism deviates from the canonical G protein-coupled receptor pathway to regulate cell migration in immortalized GnRH neurons.