Endothelial and Neuronal Nitric Oxide Activate Distinct Pathways on Sympathetic Neurotransmission in Rat Tail and Mesenteric Arteries

Impact of Non-Pharmacological Interventions on the Mechanisms of Atherosclerosis

Atherosclerosis remains the leading cause of mortality and morbidity worldwide characterized by the deposition of lipids and fibrous elements in the form of atheroma plaques in vascular areas which are hemodynamically overloaded. The global burden of atherosclerotic cardiovascular disease is steadily increasing and is considered the largest known non-infectious pandemic. The management of atherosclerotic cardiovascular disease is increasing the cost of health care worldwide, which is a concern for researchers and physicians and has caused them to strive to find effective long-term strategies to improve the efficiency of treatments by managing conventional risk factors. Primary prevention of atherosclerotic cardiovascular disease is the preferred method to reduce cardiovascular risk. Fasting, a Mediterranean diet, and caloric restriction can be considered useful clinical tools. The protective impact of physical exercise over the cardiovascular system has been studied in recent years with the intention of explaining the mechanisms involved; the increase in heat shock proteins, antioxidant enzymes and regulators of cardiac myocyte proliferation concentration seem to be the molecular and biochemical shifts that are involved. Developing new therapeutic strategies such as vagus nerve stimulation, either to prevent or slow the disease’s onset and progression, will surely have a profound effect on the lives of millions of people.

Elevated Vascular Sympathetic Neurotransmission and Remodelling Is a Common Feature in a Rat Model of Foetal Programming of Hypertension and SHR

Hypertension is of unknown aetiology, with sympathetic nervous system hyperactivation being one of the possible contributors. Hypertension may have a developmental origin, owing to the exposure to adverse factors during the intrauterine period. Our hypothesis is that sympathetic hyperinnervation may be implicated in hypertension of developmental origins, being this is a common feature with essential hypertension. Two-animal models were used: spontaneously hypertensive rats (SHR-model of essential hypertension) and offspring from dams exposed to undernutrition (MUN-model of developmental hypertension), with their respective controls. In adult males, we assessed systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), sympathetic nerve function (3H-tritium release), sympathetic innervation (immunohistochemistry) and vascular remodelling (histology). MUN showed higher SBP/DBP, but not HR, while SHR exhibited higher SBP/DBP/HR. Regarding the mesenteric arteries, MUN and SHR showed reduced lumen, increased media and adventitial thickness and increased wall/lumen and connective tissue compared to respective controls. Regarding sympathetic nerve activation, MUN and SHR showed higher tritium release compared to controls. Total tritium tissue/tyrosine hydroxylase detection was higher in SHR and MUN adventitia arteries compared to respective controls. In conclusion, sympathetic hyperinnervation may be one of the contributors to vascular remodelling and hypertension in rats exposed to undernutrition during intrauterine life, which is a common feature with spontaneous hypertension.

Fetal Undernutrition Modifies Vascular RAS Balance Enhancing Oxidative Damage and Contributing to Remodeling

Fetal stress is known to increase susceptibility to cardiometabolic diseases and hypertension in adult age in a process known as fetal programming. This study investigated the relationship between vascular RAS, oxidative damage and remodeling in fetal programming. Six-month old Sprague-Dawley offspring from mothers that were fed ad libitum (CONTROL) or with 50% intake during the second half of gestation (maternal undernutrition, MUN) were used. qPCR or immunohistochemistry were used to obtain the expression of receptors and enzymes. Plasma levels of carbonyls were measured by spectrophotometry. In mesenteric arteries from MUN rats we detected an upregulation of ACE, ACE2, AT1 receptors and NADPH oxidase, and lower expression of AT2, Mas and MrgD receptors compared to CONTROL. Systolic and diastolic blood pressure and plasma levels of carbonyls were higher in MUN than in CONTROL. Vascular morphology evidenced an increased media/lumen ratio and adventitia/lumen ratio, and more connective tissue in MUN compared to CONTROL. In conclusion, fetal undernutrition indices RAS alterations and oxidative damage which may contribute to the remodeling of mesenteric arteries, and increase the risk of adverse cardiovascular events and hypertension.

Neurophysiologic implications of neuronal nitric oxide synthase

The molecular and chemical properties of neuronal nitric oxide synthase (nNOS) have made it a key mediator in many physiological functions and signaling transduction. The NOS monomer is inactive, but the dimer form is active. There are three forms of NOS, which are neuronal (nNOS), inducible (iNOS), and endothelial (eNOS) nitric oxide synthase. nNOS regulates nitric oxide (NO) synthesis which is the mechanism used mostly by neurons to produce NO. nNOS expression and activation is regulated by some important signaling proteins, such as cyclic adenosine monophosphate (cAMP) response element-binding protein (CREB), calmodulin (CaM), heat shock protein 90 (HSP90)/HSP70. nNOS-derived NO has been implicated in modulating many physiological functions, such as synaptic plasticity, learning, memory, neurogenesis, etc. In this review, we have summarized recent studies that have characterized structural features, subcellular localization, and factors that regulate nNOS function. Finally, we have discussed the role of nNOS in the developing brain under a wide range of physiological conditions, especially long-term potentiation and depression.

Sympathetic and Sensory-Motor Nerves in Peripheral Small Arteries

Small arteries, which play important roles in controlling blood flow, blood pressure, and capillary pressure, are under nervous influence. Their innervation is predominantly sympathetic and sensory motor in nature, and while some arteries are densely innervated, others are only sparsely so. Innervation of small arteries is a key mechanism in regulating vascular resistance. In the second half of the previous century, the physiology and pharmacology of this innervation were very actively investigated. In the past 10-20 yr, the activity in this field was more limited. With this review we highlight what has been learned during recent years with respect to development of small arteries and their innervation, some aspects of excitation-release coupling, interaction between sympathetic and sensory-motor nerves, cross talk between endothelium and vascular nerves, and some aspects of their role in vascular inflammation and hypertension. We also highlight what remains to be investigated to further increase our understanding of this fundamental aspect of vascular physiology.

Nitrergic perivascular innervation in health and diseases: Focus on vascular tone regulation

For a long time, the vascular tone was considered to be regulated exclusively by tonic innervation of vasoconstrictor adrenergic nerves. However, accumulating experimental evidence has revealed the existence of nerves mediating vasodilatation, including perivascular nitrergic nerves (PNN), in a wide variety of mammalian species. Functioning of nitrergic vasodilator nerves is evidenced in several territories, including cerebral, mesenteric, pulmonary, renal, penile, uterine and cutaneous arteries. Nitric oxide (NO) is the main neurogenic vasodilator in cerebral arteries and acts as a counter-regulatory mechanism for adrenergic vasoconstriction in other vascular territories. In the penis, NO relaxes the vascular and cavernous smooth muscles leading to penile erection. Furthermore, when interacting with other perivascular nerves, NO can act as a neuromodulator. PNN dysfunction is involved in the genesis and maintenance of vascular disorders associated with arterial and portal hypertension, diabetes, ageing, obesity, cirrhosis and hormonal changes. For example defective nitrergic function contributes to enhanced sympathetic neurotransmission, vasoconstriction and blood pressure in some animal models of hypertension. In diabetic animals and humans, dysfunctional nitrergic neurotransmission in the corpus cavernosum is associated with erectile dysfunction. However, in some vascular beds of hypertensive and diabetic animals, an increased PNN function has been described as a compensatory mechanism to the increased vascular resistance. The present review summarizes current understanding on the role of PNN in control of vascular tone, its alterations under different conditions and the associated mechanisms. The knowledge of these changes can serve to better understand the mechanisms involved in these disorders and help in planning new treatments.

Prolonged caffeine intake decreases alveolar bone damage induced by binge-like ethanol consumption in adolescent female rats

Ethanol consumption has been reported to negatively impact on periodontal disease. In particular, oral cavity disorders occur upon ethanol exposure during adolescence, a life period associated with particular patterns of short and intense ('binge-like') ethanol consumption that is most deleterious to oral health. The hazardous central effects of ethanol have been linked to the overfunction of adenosine receptors, which are antagonized by caffeine, a bioactive substance present in numerous natural nutrients, which can also modify bone metabolism. The aim of this study was to investigate the effects of caffeine on alveolar bone damage induced by an ethanol binge drinking paradigm during adolescence. Female Wistar rats (35 days old; n = 30) were allocated to six groups: control (vehicle), ethanol (3 g/kg/day; 3 days On-4 days Off challenge), caffeine (10 mg/kg/day), caffeine plus ethanol, SCH58261 (0.1 mg/kg/day, an antagonist of A_2A receptors), and SCH58261 plus ethanol. Bone micromorphology and vertical bone loss were analyzed by computed microtomography. Our data showed that ethanol binge drinking reduced alveolar bone quality, with repercussion on alveolar bone size. This ethanol-induced alveolar bone deterioration was abrogated upon treatment with caffeine, but not with SCH58261. This shows that caffeine prevented the periodontal disorder caused by ethanol binge drinking during adolescence, an effect that was not mediated by adenosine A_2A receptor blockade.

Experimental and Clinical Evidence of Endothelial Dysfunction in Inflammatory Bowel Disease

The endothelium has a crucial role in proper hemodynamics. Inflammatory bowel disease (IBD) is mainly a chronic inflammatory condition of the gastrointestinal tract. However, considerable evidence points to high cardiovascular risk in patients with IBD. This review positions the basic mechanisms of endothelial dysfunction in the IBD setting (both clinical and experimental). Furthermore, we review the main effects of drugs used to treat IBD in endothelial (dys)function. Moreover, we leave challenging points for enlarging the therapeutic arsenal for IBD with new or repurposed drugs that target endothelial dysfunction besides inflammation.

Review of a Potential Novel Approach for Erectile Dysfunction: Light-Controllable Nitric Oxide Donors and Nanoformulations

INTRODUCTION

Nitric oxide (NO) is known as the key factor involved in initiating and maintaining an erection. Therefore, NO supplementation may be a target for erectile dysfunction. However, the use of NO donors carries the risk of systemic side effects. Recently, novel NO donors, such as a light-controllable NO donor or NO donor in nanoparticles, have been developed. In this review, we introduce such novel compounds and methods.

AIM

To review light-controllable and nanotechnological NO donors for the treatment of erectile dysfunction.

METHODS

We conducted a review of relevant articles via PubMed in December 2018.

MAIN OUTCOME MEASURES

In this study, we reviewed novel NO donors, such as light-controllable NO donors and nanotechnological NO donors.

RESULTS

Some light-controllable NO donors have been already reported. A light-controllable NO donor without metal has also been recently developed. Light-controllable NO donors and light irradiation can control the release of NO spatiotemporally. In an isometric tension study, a relaxing response of the aortic tissue and penile corpus cavernosum was observed under light irradiation with a light-controllable NO donor. In addition, the effects of nanoparticles and nanoemulsions containing sodium nitrate on erectile function have been reported. The nanoformulation containing an NO donor can likely be absorbed percutaneously and, thus, enhance erectile function.

CONCLUSIONS

A light-controllable NO donor might be useful for treating erectile dysfunction because light irradiation is a convenient method to be applied for patients. However, light permeability might be an issue that needs to be solved. Nanoformulation is also likely to be a useful, non-invasive approach. The application of these procedures and compounds may help in the development of future treatments for erectile dysfunction. Hotta Y, Kataoka T, Taiki Mori T, et al. Review of a Potential Novel Approach for Erectile Dysfunction: Light-Controllable Nitric Oxide Donors and Nanoformulations. Sex Med Rev 2020;8:297-302.

The Adenosinergic System as a Therapeutic Target in the Vasculature: New Ligands and Challenges

Adenosine is an adenine base purine with actions as a modulator of neurotransmission, smooth muscle contraction, and immune response in several systems of the human body, including the cardiovascular system. In the vasculature, four P1-receptors or adenosine receptors—A₁, A_2A, A_2B and A₃—have been identified. Adenosine receptors are membrane G-protein receptors that trigger their actions through several signaling pathways and present differential affinity requirements. Adenosine is an endogenous ligand whose extracellular levels can reach concentrations high enough to activate the adenosine receptors. This nucleoside is a product of enzymatic breakdown of extra and intracellular adenine nucleotides and also of S-adenosylhomocysteine. Adenosine availability is also dependent on the activity of nucleoside transporters (NTs). The interplay between NTs and adenosine receptors’ activities are debated and a particular attention is given to the paramount importance of the disruption of this interplay in vascular pathophysiology, namely in hypertension., The integration of important functional aspects of individual adenosine receptor pharmacology (such as in vasoconstriction/vasodilation) and morphological features (within the three vascular layers) in vessels will be discussed, hopefully clarifying the importance of adenosine receptors/NTs for modulating peripheral mesenteric vascular resistance. In recent years, an increase interest in purine physiology/pharmacology has led to the development of new ligands for adenosine receptors. Some of them have been patented as having promising therapeutic activities and some have been chosen to undergo on clinical trials. Increased levels of endogenous adenosine near a specific subtype can lead to its activation, constituting an indirect receptor targeting approach either by inhibition of NT or, alternatively, by increasing the activity of enzymes responsible for ATP breakdown. These findings highlight the putative role of adenosinergic players as attractive therapeutic targets for cardiovascular pathologies, namely hypertension, heart failure or stroke. Nevertheless, several aspects are still to be explored, creating new challenges to be addressed in future studies, particularly the development of strategies able to circumvent the predicted side effects of these therapies.