Background Little is known about the impact of type 2 diabetes mellitus (DM) on coronary arteriole remodeling. The aim of this study was to determine the mechanisms that underlie coronary arteriole structural remodeling in type 2 diabetic (db/db) mice. Methods and Results Passive structural properties of septal coronary arterioles isolated from 12- and 16-wk-old diabetic db/db and control mice were assessed by pressure myography. Coronary arterioles from 12-wk-old db/db mice were structurally similar to age-matched controls. By 16-wks of age, coronary wall thickness was increased in db/db arterioles (p < 0.01), while luminal diameter was reduced (Control: 118±5μm; db/db: 102±4μm, p < 0.05), augmenting the wall-to-lumen ratio by 58% (Control: 5.9±0.6; db/db: 9.5±0.4, p < 0.001). Inward hypertrophic remodeling was accompanied by a 56% decrease in elastic modulus (p < 0.05, indicating decreased vessel coronary wall stiffness) and a ~30% reduction in coronary flow reserve in diabetic mice. Interestingly, aortic pulse wave velocity and femoral artery incremental modulus were increased (p < 0.05) in db/db mice, indicating macrovascular stiffness. Molecular tissue analysis revealed increased elastin-to-collagen ratio in diabetic coronaries when compared to control and a decrease in the same ratio in the diabetic aortas. Conclusions These data show that coronary arterioles isolated from type 2 diabetic mice undergo inward hypertrophic remodeling associated with decreased stiffness and increased elastin-to-collagen ratio which results in a decreased coronary flow reserve. This study suggests that coronary microvessels undergo a different pattern of remodeling from macrovessels in type 2 DM.

Traumatic brain injury (TBI) is an increasingly frequent and poorly understood condition lacking effective therapeutic strategies. Inflammation and oxidative stress (OS) are critical components of injury, and targeted interventions to reduce their contribution to injury should improve neurobehavioral recovery and outcomes. Recent evidence reveals potential protective, yet short-lived, effects of the endocannabinoids (ECs), 2-arachidonoyl glycerol (2-AG) and N-arachidonoylethanolamine (AEA), on neuroinflammatory and OS processes after TBI. The aim of this study was to determine whether EC degradation inhibition after TBI would improve neurobehavioral recovery by reducing inflammatory and oxidative damage. Adult male Sprague-Dawley rats underwent a 5-mm left lateral craniotomy, and TBI was induced by lateral fluid percussion. TBI produced apnea (17 -5 sec) and a delayed righting reflex (479 -21 sec). Thirty minutes post-TBI, rats were randomized to receive intraperitoneal injections of vehicle (alcohol, emulphor, and saline; 1:1:18) or a selective inhibitor of 2-AG ( JZL184, 16 mg/kg) or AEA (URB597, 0.3 mg/kg) degradation. At 24 h post-TBI, animals showed significant neurological and -behavioral impairment as well as disruption of blood-brain barrier (BBB) integrity. Improved neurological and -behavioral function was observed in JZL184-treated animals. BBB integrity was protected in both JZL184-and URB597-treated animals. No significant differences in ipsilateral cortex messenger RNA expression of interleukin (IL)-1b, IL-6, chemokine (C-C motif) ligand 2, tumor necrosis factor alpha, cyclooxygenase 2 (COX2), or nicotinamide adenine dinucleotide phosphate oxidase (NOX2) and protein expression of COX2 or NOX2 were observed across experimental groups. Astrocyte and microglia activation was significantly increased post-TBI, and treatment with JZL184 or URB597 blocked activation of both cell types. These findings suggest that EC degradation inhibition post-TBI exerts neuroprotective effects. Whether repeated dosing would achieve greater protection remains to be examined.

Objective Mitochondrial depolarization following ATP-sensitive potassium (mitoKATP) channel activation has been shown to induce cerebral vasodilation by the generation of ‘calcium sparks’ in smooth muscle. It is unclear, however, if mitochondrial depolarization in endothelial cells is capable of promoting vasodilation by releasing vasoactive factors. Therefore, we studied the effect of endothelial mitochondrial depolarization by mitoKATP channel activators, BMS-191095 (BMS) and diazoxide, on endothelium-dependent vasodilation. Methods and Results Diameter studies in isolated rat cerebral arteries showed BMS and diazoxide induced vasodilations that were diminished by endothelial denudation. Mitochondrial depolarization-induced vasodilation was reduced by inhibition of mitoKATP channels, phosphoinositide-3 kinase (PI3K) or nitric oxide synthase (NOS). Scavenging of reactive oxygen species (ROS), however, diminished vasodilation induced by diazoxide but not by BMS. Fluorescence studies in cultured rat brain microvascular endothelial cells (CMVECs) showed that BMS elicited mitochondrial depolarization, and enhanced nitric oxide (NO) production; diazoxide exhibited largely similar effects, but unlike BMS, increased mitochondrial ROS production. Measurements of intracellular calcium ([Ca2+]i) in CMVECs and arteries showed that both diazoxide and BMS increased endothelial [Ca2+]i. Western blot analyses revealed increased phosphorylation of Akt and endothelial NOS (eNOS) by BMS and diazoxide. Increased phosphorylation of eNOS by diazoxide was abolished by PI3K inhibition. Electron spin resonance spectroscopy confirmed vascular NO generation in response to diazoxide and BMS. Conclusions Pharmacological depolarization of endothelial mitochondria promotes activation of eNOS by dual pathways involving increased [Ca2+]i as well as by PI3K-Akt-induced eNOS phosphorylation. Both mitochondrial ROS-dependent and –independent mechanisms mediate activation of eNOS by endothelial mitochondrial depolarization.

Elevated plasma levels of fat-derived signaling molecules are associated with obesity, vascular endothelial dysfunction, and coronary heart disease; however, little is known about their direct coronary vascular effects. Accordingly, we examined mechanisms by which one adipokine, resistin, affects coronary vascular tone and endothelial function. Studies were conducted in anesthetized dogs and isolated coronary artery rings. Resistin did not change coronary blood flow, mean arterial pressure, or heart rate. Resistin had no effect on acetylcholine-induced relaxation of artery rings; however, resistin did impair bradykinin-induced relaxation. Selective impairment was also observed in vivo, as resistin attenuated vasodilation to bradykinin but not to acetylcholine. Resistin had no effect on dihydroethidium fluorescence, an indicator of superoxide (O 2 Ϫ ) production, and the inhibitory effect of resistin on bradykinininduced relaxation persisted in the presence of Tempol, a superoxide dismutase mimetic. To determine whether resistin impaired production of and/or responses to nitric oxide (NO) or prostaglandins (e.g., prostacyclin; PGI2), we performed experiments with N -nitro-L-arginine methyl ester (L-NAME) and indomethacin. The effect of resistin to attenuate bradykinin-induced vasodilation persisted in the presence of L-NAME or indomethacin, suggesting resistin may act at a cell signaling point upstream of NO or PGI2 production. Resistin-induced endothelial dysfunction is not generalized, and it is not consistent with effects mediated by O 2 Ϫ or interference with NO or PGI2 signaling.

Previous studies from our laboratory showed that coronary arterioles from type 2 diabetic mice undergo inward hypertrophic remodeling and reduced stiffness. The aim of the current study was to determine if coronary resistance microvessels (CRMs) in Ossabaw swine with metabolic syndrome (MetS) undergo remodeling distinct from coronary conduit arteries. Male Ossabaw swine were fed normal (n = 7, Lean) or hypercaloric high-fat (n = 7, MetS) diets for 6 mo, and then CRMs were isolated and mounted on a pressure myograph. CRMs isolated from MetS swine exhibited decreased luminal diameters (126 ± 5 and 105 ± 9 μm in Lean and MetS, respectively, P < 0.05) with thicker walls (18 ± 3 and 31 ± 3 μm in Lean and MetS, respectively, P < 0.05), which doubled the wall-to-lumen ratio (14 ± 2 and 30 ± 2 in Lean and MetS, respectively, P < 0.01). Incremental modulus of elasticity (IME) and beta stiffness index (BSI) were reduced in CRMs isolated from MetS pigs (IME: 3.6 × 10(6) ± 0.7 × 10(6) and 1.1 × 10(6) ± 0.2 × 10(6) dyn/cm(2) in Lean and MetS, respectively, P < 0.001; BSI: 10.3 ± 0.4 and 7.3 ± 1.8 in Lean and MetS, respectively, P < 0.001). BSI in the left anterior descending coronary artery was augmented in pigs with MetS. Structural changes were associated with capillary rarefaction, decreased hyperemic-to-basal coronary flow velocity ratio, and augmented myogenic tone. MetS CRMs showed a reduced collagen-to-elastin ratio, while immunostaining for the receptor for advanced glycation end products was selectively increased in the left anterior descending coronary artery. These data suggest that MetS causes hypertrophic inward remodeling of CRMs and capillary rarefaction, which contribute to decreased coronary flow and myocardial ischemia. Moreover, our data demonstrate novel differential remodeling between coronary micro- and macrovessels in a clinically relevant model of MetS.

Background Traumatic brain injury (TBI) affects millions of people each year and is characterized by direct tissue injury followed by a neuroinflammatory response. The post-TBI recovery period can be associated with a negative emotional state characterized by alterations in affective behaviors implicated in the development of Alcohol Use Disorder in humans. The aim of this study was to test the hypothesis that post-TBI neuroinflammation is associated with behavioral dysfunction, including escalated alcohol intake. Methods Adult male Wistar rats were trained to self-administer alcohol prior to counterbalanced assignment into naïve, craniotomy, and TBI groups by baseline drinking. TBI was produced by lateral fluid percussion (LFP; >2 ATM; 25 ms). Alcohol drinking and neurobehavioral function were measured at baseline and following TBI in all experimental groups. Markers of neuroinflammation (GFAP & ED1) and neurodegeneration (FJC) were determined by fluorescence histochemistry in brains excised at sacrifice 19 days post-TBI. Results The cumulative increase in alcohol intake over the 15 days post-TBI was greater in TBI animals compared to naïve controls. A higher rate of pre-injury alcohol intake was associated with a greater increase in post-injury alcohol intake in both TBI and craniotomy animals. Immediately following TBI, both TBI and craniotomy animals exhibited greater neurobehavioral dysfunction compared to naïve animals. GFAP, IBA-1, ED1, and FJC immunoreactivity at 19 days post-TBI was significantly higher in brains from TBI animals compared to both craniotomy and naïve animals. Conclusions These results show an association between post-TBI escalation of alcohol drinking and marked localized neuroinflammation at the site of injury. Moreover, these results highlight the relevance of baseline alcohol preference in determining post-TBI alcohol drinking. Further investigation to determine the contribution of neuroinflammation to increased alcohol drinking post-TBI is warranted.

ObjectiveResistance vessel remodeling is controlled by myriad of hemodynamic and neurohormonal factors. This study characterized structural and molecular remodeling in mesenteric resistance arteries (MRAs) in diabetic (db/db) and control (Db/db) mice.MethodsStructural properties were assessed in isolated MRAs from 12 and 16 wk-old db/db and Db/db mice by pressure myography. Matrix regulatory proteins were measured by Western blot analysis. Mean arterial pressure and superior mesenteric blood flow were measured in 12 wk-old mice by telemetry and a Doppler flow nanoprobe, respectively.ResultsBlood pressure was similar between groups. Lumen diameter and medial cross-sectional area were significantly increased in 16 wk-old db/db MRA compared to control, indicating outward hypertrophic remodeling. Moreover, wall stress and cross-sectional compliance were significantly larger in diabetic arteries. These remodeling indices were associated with increased expression of matrix regulatory proteins matrix metalloproteinase (MMP)-9, MMP-12, tissue inhibitors of matrix metalloproteinase (TIMP)-1, TIMP-2, and plasminogen activator inhibitor-1 (PAI-1) in db/db arteries. Finally, superior mesenteric artery blood flow was increased by 46% in 12 wk-old db/db mice, a finding that preceded mesenteric resistance artery remodeling.ConclusionsThese data suggest that flow-induced hemodynamic changes may supersede the local neurohormonal and metabolic milieu to culminate in hypertrophic outward remodeling of type 2 DM mesenteric resistance arteries.

Traumatic brain injury (TBI) is an increasingly prevalent condition affecting soldiers, athletes, and motor vehicle accident victims. Unfortunately, it currently lacks effective therapeutic interventions. TBI is defined as a primary mechanical insult followed by a secondary cascade involving inflammation, apoptosis, release of reactive oxygen species, and excitotoxicity, all of which can cause synaptic changes, altered neuronal signaling, and, ultimately, behavioral changes. Previously we showed that preventing degradation of the endocannabinoid (EC) 2-acylglycerol (2-AG) with JZL184 after mild TBI attenuated neuroinflammation and improved recovery of neurobehavioral function during the early 24 h post-TBI period. The aim of this study was to extend the timeline of observations to 2 weeks post-injury and to investigate JZL184's impact on synaptic transmission, which we view as a potential mechanism for TBI-induced cellular and behavioral pathology. Adult male rats underwent mild TBI (mTBI) followed by a single intraperitoneal injection of JZL184 or vehicle 30 min post-injury. JZL184 administered-TBI animals showed improved neurobehavioral recovery compared with vehicle-injected TBI animals beginning 24 h post-injury and persisting for 2 weeks. JZL184-treated animals had significantly diminished gray and white matter astrocyte activation when compared with vehicle-treated animals at day 7 post-TBI. JZL184 administration significantly attenuated the increased pGluR1/GluR1 and pERK 1/2/ERK and the increases in miniature excitatory postsynaptic potential (mEPSC) frequency and amplitude observed in layer 5 pyramidal neurons at 10 days post-TBI. These results suggest a neuroprotective role for ECs in ameliorating the TBI-induced neurobehavioral, neuroinflammatory, and glutamate dyshomeostasis from mTBI. Further studies elucidating the cellular mechanisms involved are warranted.