Luigi F. Rodella

CARDIOVASCULAR DISEASES: PROTECTIVE EFFECTS OF MELATONIN

Abstract:  This brief review considers some of the cardiac diseases and conditions where free radicals and related reactants are believed to be causative. The report also describes the beneficial actions of melatonin against oxidative cardiovascular disorders. Based on the data available, melatonin seems to have cardioprotective properties via its direct free radical scavenger and its indirect antioxidant activity. Melatonin efficiently interacts with various reactive oxygen and reactive nitrogen species (receptor independent actions) and it also upregulates antioxidant enzymes and downregulates pro‐oxidant enzymes (receptor‐dependent actions). Moreover, melatonin enters all cells and subcellular compartments and crosses morphophysiologic barriers. These findings have implications for the protective effects of melatonin against cardiac diseases induced by oxidative stress. Melatonin attenuates molecular and cellular damages resulting from cardiac ischemia/reperfusion in which destructive free radicals are involved. Anti‐inflammatory and antioxidative properties of melatonin are also involved in the protection against a chronic vascular disease, atherosclerosis. The administration of melatonin, as a result of its antioxidant features, has been reported to reduce hypertension and cardiotoxicity induced by clinically used drugs. The results described herein help to clarify the beneficial effects of melatonin against these conditions and define the potential clinical applicability of melatonin in cardiovascular diseases.

Structural Alterations in Subcutaneous Small Arteries of Normotensive and Hypertensive Patients With Non–Insulin-Dependent Diabetes Mellitus

Background — It is not presently known whether non–insulin-dependent diabetes mellitus (NIDDM) is associated with the presence of structural alterations in small arteries or whether the combination of hypertension and NIDDM may have an additive effect on endothelial dysfunction. Therefore, we investigated subcutaneous small arteries in 12 normotensive subjects (NT group), 18 patients with essential hypertension (EH group), 13 patients with NIDDM, and 11 patients with NIDDM and EH (NIDDM+EH group). Methods and Results — Subcutaneous small arteries were evaluated by a micromyographic technique. The internal diameter, the media-to-lumen ratio, remodeling and growth indices, and the collagen-to-elastin ratio were calculated. Concentration-response curves to acetylcholine, bradykinin, the endothelium-independent vasodilator sodium nitroprusside, and endothelin-1 were performed. The media-to-lumen ratio was higher in the EH, NIDDM, and NIDDM+EH groups compared with the NT group. EH patients showed the presence of eutrophic remodeling, whereas NIDDM and NIDDM+EH patients showed 40% to 46% cell growth. The collagen-to-elastin ratio was significantly increased in the EH and NIDDM+EH groups compared with the NT group. The vasodilatation to acetylcholine and bradykinin was similarly reduced in EH, NIDDM, and NIDDM+EH groups compared with the NT group. The contractile responses to endothelin-1 were similarly reduced in EH, NIDDM, and NIDDM+EH patients. Conclusions — Our data suggest that the effects of NIDDM and EH on small artery morphology are quantitatively similar but qualitatively different and that the presence of hypertension in diabetic patients has little additive effect on small artery morphology and none on endothelial dysfunction.

Treatment of Obese Diabetic Mice With a Heme Oxygenase Inducer Reduces Visceral and Subcutaneous Adiposity, Increases Adiponectin Levels, and Improves Insulin Sensitivity and Glucose Tolerance

OBJECTIVE—We hypothesized that the induction of heme oxygenase (HO)-1 and increased HO activity, which induces arterial antioxidative enzymes and vasoprotection in a mouse and a rat model of diabetes, would ameliorate insulin resistance, obesity, and diabetes in the ob mouse model of type 2 diabetes. RESEARCH DESIGN AND METHODS—Lean and ob mice were intraperitoneally administered the HO-1 inducer cobalt protoporphyrin (3 mg/kg CoPP) with and without the HO inhibitor stannous mesoporphyrin (2 mg/100 g SnMP) once a week for 6 weeks. Body weight, blood glucose, and serum cytokines and adiponectin were measured. Aorta, adipose tissue, bone marrow, and mesenchymal stem cells (MSCs) were isolated and assessed for HO expression and adipogenesis. RESULTS—HO activity was reduced in ob mice compared with age-matched lean mice. Administration of CoPP caused a sustained increase in HO-1 protein, prevented weight gain, decreased visceral and subcutaneous fat content (P < 0.03 and 0.01, respectively, compared with vehicle animals), increased serum adiponectin, and decreased plasma tumor necrosis factor-α (TNF-α), interleukin (IL)-6, and IL-1β levels (P < 0.05). HO-1 induction improved insulin sensitivity and glucose tolerance and decreased insulin levels. Upregulation of HO-1 decreased adipogenesis in bone marrow in vivo and in cultured MSCs and increased adiponectin levels in the culture media. Inhibition of HO activity decreased adiponectin and increased secretion of TNF-α, IL-6, and IL-1β levels in ob mice. CONCLUSIONS—This study provides strong evidence for the existence of an HO-1–adiponectin regulatory axis that can be manipulated to ameliorate the deleterious effects of obesity and the metabolic syndrome associated with cardiovascular disease and diabetes.

Role of Caveolar Compartmentation in Endothelium-Derived Hyperpolarizing Factor–Mediated Relaxation Ca2+ Signals and Gap Junction Function Are Regulated by Caveolin in Endothelial Cells

Background— In endothelial cells, caveolin-1, the structural protein of caveolae, acts as a scaffolding protein to cluster lipids and signaling molecules within caveolae and, in some instances, regulates the activity of proteins targeted to caveolae. Specifically, different putative mediators of the endothelium-derived hyperpolarizing factor (EDHF)–mediated relaxation are located in caveolae and/or regulated by the structural protein caveolin-1, such as potassium channels, calcium regulatory proteins, and connexin 43, a molecular component of gap junctions. Methods and Results— Comparing relaxation in vessels from caveolin-1 knockout mice and their wild-type littermates, we observed a complete absence of EDHF-mediated vasodilation in isolated mesenteric arteries from caveolin-1 knockout mice. The absence of caveolin-1 is associated with an impairment of calcium homeostasis in endothelial cells, notably, a decreased activity of Ca2+-permeable TRPV4 cation channels that participate in nitric oxide– and EDHF-mediated relaxation. Moreover, morphological characterization of caveolin-1 knockout and wild-type arteries showed fewer gap junctions in vessels from knockout animals associated with a lower expression of connexins 37, 40, and 43 and altered myoendothelial communication. Finally, we showed that TRPV4 channels and connexins colocalize with caveolin-1 in the caveolar compartment of the plasma membrane. Conclusions— We demonstrated that expression of caveolin-1 is required for EDHF-related relaxation by modulating membrane location and activity of TRPV4 channels and connexins, which are both implicated at different steps in the EDHF-signaling pathway.

Metabolic Syndrome, Aging and Involvement of Oxidative Stress

The prevalence of the metabolic syndrome, a cluster of cardiovascular risk factors associated with obesity and insulin resistance, is dramatically increasing in Western and developing countries. This disorder consists of a cluster of metabolic conditions, such as hypertriglyceridemia, hyper-low-density lipoproteins, hypo-high-density lipoproteins, insulin resistance, abnormal glucose tolerance and hypertension, that-in combination with genetic susceptibility and abdominal obesity-are risk factors for type 2 diabetes, vascular inflammation, atherosclerosis, and renal, liver and heart diseases. One of the defects in metabolic syndrome and its associated diseases is excess of reactive oxygen species. Reactive oxygen species generated by mitochondria, or from other sites within or outside the cell, cause damage to mitochondrial components and initiate degradative processes. Such toxic reactions contribute significantly to the aging process. In this article we review current understandings of oxidative stress in metabolic syndrome related disease and its possible contribution to accelerated senescence.

Piezoelectric surgery: twenty years of use.

The use of ultrasonic vibrations for the cutting of bone was first introduced two decades ago. Piezoelectric surgery is a minimally invasive technique that lessens the risk of damage to surrounding soft tissues and important structures such as nerves, vessels, and mucosa. It also reduces damage to osteocytes and permits good survival of bony cells during harvesting of bone. Piezoelectric surgery was first used by oral and maxillofacial surgeons for osteotomies, but recently some specific applications in neurosurgery and orthopaedics have been proposed. We review the different applications of piezoelectric surgery.

Heme Oxygenase-1 Induction Remodels Adipose Tissue and Improves Insulin Sensitivity in Obesity-Induced Diabetic Rats

Obesity-associated inflammation causes insulin resistance. Obese adipose tissue displays hypertrophied adipocytes and increased expression of the cannabinoid-1 receptor. Cobalt protoporphyrin (CoPP) increases heme oxygenase-1 (HO-1) activity, increasing adiponectin and reducing inflammatory cytokines. We hypothesize that CoPP administration to Zucker diabetic fat (ZDF) rats would improve insulin sensitivity and remodel adipose tissue. Twelve-week-old Zucker lean and ZDF rats were divided into 4 groups: Zucker lean, Zucker lean–CoPP, ZDF, and ZDF–CoPP. Control groups received vehicle and treatment groups received CoPP (2 mg/kg body weight) once weekly for 6 weeks. Serum insulin levels and glucose response to insulin injection were measured. At 18 weeks of age, rats were euthanized, and aorta, kidney, and subcutaneous and visceral adipose tissues were harvested. HO-1 expression was measured by Western blot analysis and HO-1 activity by serum carbon monoxide content. Adipocyte size and cannabinoid-1 expression were measured. Adipose tissue volumes were determined using MRI. CoPP significantly increased HO-1 activity, phosphorylated AKT and phosphorylated AMP kinase, and serum adiponectin in ZDF rats. HO-1 induction improved hyperinsulinemia and insulin sensitivity in ZDF rats. Subcutaneous and visceral adipose tissue volumes were significantly decreased in ZDF rats. Adipocyte size and cannabinoid-1 expression were both significantly reduced in ZDF–CoPP rats in subcutaneous and visceral adipose tissues. This study demonstrates that HO-1 induction improves insulin sensitivity, downregulates the peripheral endocannabinoid system, reduces adipose tissue volume, and causes adipose tissue remodeling in a model of obesity-induced insulin resistance. These findings suggest HO-1 as a potential therapeutic target for obesity and its associated health risks.

The purinergic antagonist PPADS reduces pain related behaviours and interleukin-1β, interleukin-6, iNOS and nNOS overproduction in central and peripheral nervous system after peripheral neuropathy in mice

&NA; Neuropathic pain consequent to peripheral injury is associated with local inflammation and overexpression of nitric oxide synthases (NOS) and inflammatory cytokines in locally recruited macrophages, Schwann and glial cells. We investigated the time course and localization of nitric oxide synthases (NOS) and cytokines in the central (spinal cord and thalamus) and peripheral nervous system (nerve and dorsal root ganglia), in a mouse model of mononeuropathy induced by sciatic nerve chronic constriction injury. ATP is recognized as an endogenous pain mediator. Therefore we also evaluated the role of purinergic signalling in pain hypersensitivity employing the P2 receptor antagonist, pyridoxalphosphate‐6‐azophenyl‐2′,4′‐disulphonic acid (PPADS), on pain behaviour, NOS and cytokines. The PPADS daily administration starting on day 3 after injury dose‐ and time‐dependently decreased both tactile allodynia and thermal hyperalgesia. PPADS (25 mg/kg) completely reversed nociceptive hypersensitivity and simultaneously reduced the increased NO/NOS system and IL‐1β in both peripheral (injured sciatic nerve and L4–L6 ipsilateral dorsal root ganglia) and central steps of nervous system (L4–L6 spinal cord and thalamus) involved in pain signalling. IL‐6 was overexpressed only in the peripheral nervous system and PPADS prolonged administration reduced it in sciatic nerve. In conclusion, we hypothesize that NO/NOS and IL‐1β have a pronociceptive role in this neuropathy model, and that purinergic antagonism reduces pain hypersensitivity by inhibiting their overactivity.

Effect of Treatment With Candesartan or Enalapril on Subcutaneous Small Artery Structure in Hypertensive Patients With Noninsulin-Dependent Diabetes Mellitus

Structural alterations of subcutaneous small resistance arteries are associated with a worse clinical prognosis in hypertension and noninsulin-dependent diabetes mellitus (NIDDM). However, no data are presently available about the effects of antihypertensive therapy on vascular structure in hypertensive patients with NIDDM. Therefore, we have investigated the effect of an angiotensin-converting enzyme inhibitor, enalapril, and a highly selective angiotensin receptor blocker, candesartan cilexetil, on indices of subcutaneous small resistance artery structure in 15 patients with mild hypertension and NIDDM. Eight patients were treated with candesartan (8 to 16 mg per day) and 7 with enalapril (10 to 20 mg per day) for 1 year. Each patient underwent a biopsy of the subcutaneous fat from the gluteal region at baseline and after 1 year of treatment. Small arteries were dissected and mounted on a micromyograph and the media-to-internal lumen ratio was evaluated; moreover, endothelium-dependent vasodilation to acetylcholine was assessed. A similar blood pressure-lowering effect and a similar reduction of the media-to-lumen ratio of small arteries was observed with the 2 drugs. Vascular collagen content was reduced and metalloproteinase-9 was increased by candesartan, but not by enalapril. Changes of circulating indices of collagen turnover and circulating matrix metalloproteinase paralleled those of vascular collagen. The 2 drugs equally improved endothelial function. In conclusion, antihypertensive treatment with drugs that inhibit the renin-angiotensin-aldosterone system activity is able to correct, at least in part, alterations in small resistance artery structure in hypertensive patients with NIDDM. Candesartan may be more effective than enalapril in reducing collagen content in the vasculature.

The L-4F mimetic peptide prevents insulin resistance through increased levels of HO-1, pAMPK, and pAKT in obese mice

We examined mechanisms by which L-4F reduces obesity and diabetes in obese (ob) diabetic mice. We hypothesized that L-4F reduces adiposity via increased pAMPK, pAKT, HO-1, and increased insulin receptor phosphorylation in ob mice. Obese and lean mice were divided into five groups: lean, lean-L-4F-treated, ob, ob-L-4F-treated, and ob-L-4F-LY294002. Food intake, insulin, glucose adipocyte stem cells, pAMPK, pAKT, CB1, and insulin receptor phosphorylation were determined. Subcutaneous (SAT) and visceral adipose tissue (VAT) were determined by MRI and hepatic lipid content by magnetic resonance spectroscopy. SAT and VAT volumes decreased in ob-L-4F-treated animals compared with control. L-4F treatment decreased hepatic lipid content and increased the numbers of small adipocytes (P < 0.05) and phosphorylation of insulin receptors. L-4F decreased CB1 in SAT and VAT and increased pAKT and pAMPK in endothelium. L-4F-mediated improvement in endothelium was prevented by LY294002. Inhibition of pAKT and pAMPK by LY294002 was associated with an increase in glucose levels. Upregulation of HO-1 by L-4F produced adipose remodeling and increased the number of small differentiated adipocytes. The anti-obesity effects of L-4F are manifested by a decrease in visceral fat content with reciprocal increases in adiponectin, pAMPK, pAKT, and phosphorylation of insulin receptors with improved insulin sensitivity.