Abstract-Vascular dysfunction is a major complication of metabolic disorders such as diabetes and obesity. The current studies were undertaken to determine whether inflammatory responses are activated in the vasculature of mice with diet-induced obesity, and if so, whether Toll-Like Receptor-4 (TLR4), a key mediator of innate immunity, contributes to these responses. Mice lacking TLR4 (TLR4 Ϫ/Ϫ ) and wild-type (WT) controls were fed either a low fat (LF) control diet or a diet high in saturated fat (HF) for 8 weeks. In response to HF feeding, both genotypes displayed similar increases of body weight, body fat content, and serum insulin and free fatty acid (FFA) levels compared with mice on a LF diet. In lysates of thoracic aorta from WT mice maintained on a HF diet, markers of vascular inflammation both upstream (IKK␤ activity) and downstream of the transcriptional regulator, NF-B (ICAM protein and IL-6 mRNA expression), were increased and this effect was associated with cellular insulin resistance and impaired insulin stimulation of eNOS. In contrast, vascular inflammation and impaired insulin responsiveness were not evident in aortic samples taken from TLR4 Ϫ/Ϫ mice fed the same HF diet, despite comparable increases of body fat mass. Incubation of either aortic explants from WT mice or cultured human microvascular endothelial cells with the saturated FFA, palmitate (100 mol/L), similarly activated IKK␤, inhibited insulin signal transduction and blocked insulin-stimulated NO production. Each of these effects was subsequently shown to be dependent on both TLR4 and NF-B activation. These findings identify the TLR4 signaling pathway as a key mediator of the deleterious effects of palmitate on endothelial NO signaling, and are the first to document a key role for TLR4 in the mechanism whereby diet-induced obesity induces vascular inflammation and insulin resistance.

To investigate the full range of molecular changes associated with erectile dysfunction (ED) in Type 1 diabetes, we examined alterations in penile gene expression in streptozotocin-induced diabetic rats and littermate controls. With the use of Affymetrix GeneChip arrays and statistical filtering, 529 genes/transcripts were considered to be differentially expressed in the diabetic rat cavernosum compared with control. Gene Ontology (GO) classification indicated that there was a decrease in numerous extracellular matrix genes (e.g., collagen and elastin related) and an increase in oxidative stress-associated genes in the diabetic rat cavernosum. In addition, PubMatrix literature mining identified differentially expressed genes previously shown to mediate vascular dysfunction [e.g., ceruloplasmin (Cp), lipoprotein lipase, and Cd36] as well as genes involved in the modulation of the smooth muscle phenotype (e.g., Kruppel-like factor 5 and chemokine C-X3-C motif ligand 1). Real-time PCR was used to confirm changes in expression for 23 relevant genes. Further validation of Cp expression in the diabetic rat cavernosum demonstrated increased mRNA levels of the secreted and anchored splice variants of Cp. CP protein levels showed a 1.9-fold increase in tissues from diabetic rats versus controls. Immunohistochemistry demonstrated localization of CP protein in cavernosal sinusoids of control and diabetic animals, including endothelial and smooth muscle layers. Overall, this study broadens the scope of candidate genes and pathways that may be relevant to the pathophysiology of diabetes-induced ED as well as highlights the potential complexity of this disorder.

Luttrell IP, Swee M, Starcher B, Parks WC, Chitaley K. Erectile dysfunction in the type II diabetic db/db mouse: impaired venoocclusion with altered cavernosal vasoreactivity and matrix. Am J Physiol Heart Circ Physiol 294: H2204-H2211, 2008. First published March 7, 2008 doi:10.1152/ajpheart.00027.2008.-The number of men with type II diabetes-associated erectile dysfunction (ED) continues to grow rapidly; however, the majority of basic science studies has examined mechanisms of ED in animal models of type I diabetes. In this study, we first establish an in vivo mouse model of type II diabetic ED using the leptin receptor mutated db/db and wild-type control BKS mouse. Furthermore, we hypothesized that dual mechanistic impairments contribute to the impaired erectile function in the type II diabetic mouse, altered vasoreactivity, and venoocclusive disorder. In vivo erectile function was measured as intracavernosal pressure (ICP) normalized to mean arterial pressure (MAP) following electrical stimulation of the cavernosal nerve. Venoocclusion was assessed by the maintenance of elevated in vivo ICP following intracorporal saline infusion. Vasoreactivity of isolated cavernosum in response to contractile and dilatory stimulation was examined in vitro by myography. Collagen and elastin content were evaluated by quantification of hydroxyproline and desmosine, respectively, as well as by quantitative PCR and histological analysis of isolated cavernosum. Erectile function was significantly decreased in db/db vs. BKS mice in a manner consistent with impairments in venoocclusive ability and decreased inflow. Heightened vasoconstriction and attenuated dilation in cavernosum of db/db vs. BKS mice suggest an overall lowered relaxation ability and thus impaired filling of the cavernosal spaces. A decrease in desmosine and hydroxyproline as well as lowered mRNA levels for tropoelastin, fibrillin-1, and ␣1(I) collagen were detected. These vasoreactive and sinusoidal matrix alterations may alter tissue compliance dispensability, preventing the normal expansion necessary for erection. matrix; elastin; collagen; penis IN TYPE II DIABETIC patients, erectile dysfunction (ED) is associated with risk factors such as neuropathy, vascular disease, smoking, and poor lifestyle conditions such as inactivity and obesity, which are components of the metabolic syndrome (1,8). Although many studies have examined ED associated with type I diabetes, few studies have examined underlying mechanisms of decreased erectile function in animal models of type II diabetes.The penile circulation is unique in that it is composed of arterioles that supply a network of collagenous sinusoidal cavities lined with endothelial and smooth muscle cells. During sexual arousal or nocturnal tumescence, the synthesis of nitric oxide (NO) by the neuronal NO synthase, located in nonadrenergic/noncholinergic nerves, initiates cavernosal smooth muscle relaxation (2, 3). The dilation of the cavernosal arteriolar and sinusoidal smooth muscle permits increased penile blood fl...