Role of substance P in the cardiovascular system

Nociceptor mechanisms underlying pain and bone remodeling via orthodontic forces: toward no pain, big gain

Orthodontic forces are strongly associated with pain, the primary complaint among patients wearing orthodontic braces. Compared to other side effects of orthodontic treatment, orthodontic pain is often overlooked, with limited clinical management. Orthodontic forces lead to inflammatory responses in the periodontium, which triggers bone remodeling and eventually induces tooth movement. Mechanical forces and subsequent inflammation in the periodontium activate and sensitize periodontal nociceptors and produce orthodontic pain. Nociceptive afferents expressing transient receptor potential vanilloid subtype 1 (TRPV1) play central roles in transducing nociceptive signals, leading to transcriptional changes in the trigeminal ganglia. Nociceptive molecules, such as TRPV1, transient receptor potential ankyrin subtype 1, acid-sensing ion channel 3, and the P2X3 receptor, are believed to mediate orthodontic pain. Neuropeptides such as calcitonin gene-related peptides and substance P can also regulate orthodontic pain. While periodontal nociceptors transmit nociceptive signals to the brain, they are also known to modulate alveolar bone remodeling in periodontitis. Therefore, periodontal nociceptors and nociceptive molecules may contribute to the modulation of orthodontic tooth movement, which currently remains undetermined. Future studies are needed to better understand the fundamental mechanisms underlying neuroskeletal interactions in orthodontics to improve orthodontic treatment by developing novel methods to reduce pain and accelerate orthodontic tooth movement-thereby achieving "big gains with no pain" in clinical orthodontics.

Evaluation of substance P as a biomarker for pain in equine colic

Equine colic is an important condition associated with acute abdominal pain and one of the leading causes of death in horses. As such, objectively evaluating pain is of interest for attending veterinarians. Pain scales for assessment are present, but no single pain-specific biomarker has been reported. The aim of this study was to determine if substance P (SP) could be a reliable biomarker to reflect pain and serve as a parameter to predict outcome in equine colic. The hypothesis was that horses displaying severe colic signs present with higher values of SP in contrast to those with mild colic signs. Thirty warmblood horses, aged between 3 and 20 years were recruited; evenly distributed (10 horses each) in three colic groups (mild, moderate, severe). To classify the colic signs, the horses were graded by the Equine Acute Abdominal Pain Scale (EAAPS). Clinical examination and EAAPS were performed at arrival in the hospital. Blood samples were collected four times in hourly intervals commencing from arrival. For comparison, already established parameters for prognosticating equine colic (heart rate, serum cortisol, and blood lactate concentration) were also measured. The assumption of increasing SP concentrations along with pain could not be confirmed. SP did not show any association with heart rate, cortisol, lactate, or EAAPS. Whereas the established parameters increased according to the EAAPS, SP remained stable in individual horses regardless of clinical signs, treatment, and disease progression. Consequently, SP was not a reliable parameter to reflect painful conditions or to predict outcome in equine colic.

An update on mechanisms of pruritus and their potential treatment in primary cutaneous T-cell lymphoma

Primary cutaneous T-cell lymphomas (CTCL), which include mycosis fungoides (MF) and Sézary syndrome (SS), are a group of lymphoproliferative disorders characterized by clonal accumulation of neoplastic T-lymphocytes in the skin. Severe pruritus, one of the most common and distressing symptoms in primary CTCL, can significantly impair emotional well-being, physical functioning, and interpersonal relationships, thus greatly reducing quality of life. Unfortunately, effectively managing pruritus remains challenging in CTCL patients as the underlying mechanisms are, as of yet, not fully understood. Previous studies investigating the mechanisms of itch in CTCL have identified several mediators and their corresponding antagonists used for treatment. However, a comprehensive overview of the mediators and receptors contributing to pruritus in primary CTCL is lacking in the current literature. Here, we summarize and review the mediators and receptors that may contribute to pruritus in primary CTCL to explore the mechanisms of CTCL pruritus and identify effective therapeutic targets using the PubMed and Web of Science databases. Studies were included if they described itch mediators and receptors in MF and SS. Overall, the available data suggest that proteases (mainly tryptase), and neuropeptides (particularly Substance P) may be of greatest interest. At the receptor level, cytokine receptors, MRGPRs, and TRP channels are most likely important. Future drug development efforts should concentrate on targeting these mediators and receptors for the treatment of CTCL pruritus.

The Role of Substance P Within Traumatic Brain Injury and Implications for Therapy

This review examines the role of the neuropeptide substance P within the neuroinflammation that follows traumatic brain injury. It examines it in reference to its preferential receptor, the neurokinin-1 receptor, and explores the evidence for antagonism of this receptor in traumatic brain injury with therapeutic intent. Expression of substance P increases following traumatic brain injury. Subsequent binding to the neurokinin-1 receptor results in neurogenic inflammation, a cause of deleterious secondary effects that include an increased intracranial pressure and poor clinical outcome. In several animal models of TBI, neurokinin-1 receptor antagonism has been shown to reduce brain edema and the resultant rise in intracranial pressure. A brief overview of the history of substance P is presented, alongside an exploration into the chemistry of the neuropeptide with a relevance to its functions within the central nervous system. This review summarizes the scientific and clinical rationale for substance P antagonism as a promising therapy for human TBI.

Substance P reversibly compromises the integrity and function of blood-brain barrier

BACKGROUND

Substance P (SP) plays a role in vasodilatation and tissue integrity through its receptor, neurokinin 1 (NK1R). However, its specific effect on blood-brain barrier (BBB) remains unknown.

METHODS

The impact of SP on the integrity/function of human BBB model in vitro, composed of brain microvascular endothelial cells (BMECs), astrocytes and pericytes, was assessed by measurements of transendothelial electrical resistance and paracellular flux of sodium fluorescein (NaF), respectively in the absence/presence of specific inhibitors targeting NK1R (CP96345), Rho-associated protein kinase (ROCK; Y27632) and nitric oxide synthase (NOS; N(G)-nitro-L-arginine methyl ester). Sodium nitroprusside (SNP), a NO donor, was employed as a positive control. The levels of tight junction proteins, zonula occludens-1, occludin and claudin-5 alongside RhoA/ROCK/myosin regulatory light chain-2 (MLC2) and extracellular signal‑regulated protein kinase (Erk1/2) proteins were detected by western analyses. Subcellular localisations of F-actin and tight junction proteins were visualized by immunocytochemistry. Flow cytometry was used to detect transient calcium release.

RESULTS

Exposure to SP increased RhoA, ROCK2 and phosphorylated serine-19 MLC2 protein levels and Erk1/2 phosphorylation in BMECs which were abolished by CP96345. These increases were independent of the changes in intracellular calcium availability. SP perturbed BBB in a time-dependent fashion through induction of stress fibres. Changes in tight junction protein dissolution or relocalisation were not involved in SP-mediated BBB breakdown. Inhibition of NOS, ROCK and NK1R mitigated the effect of SP on BBB characteristics and stress fibre formation.

CONCLUSION

SP promoted a reversible decline in BBB integrity independent of tight junction proteins expression or localisation.

The Src1-PGC1α-AP1 complex-dependent secretion of substance P induces inflammation and apoptosis in encephalomyocarditis virus-infected mice

Substance P (SP), a neuropeptide consisting of 11 amino acid residues, is involved in the pathogenesis of encephalomyocarditis virus (EMCV)-induced myocarditis by stimulating the production of proinflammatory cytokines. However, the underlying mechanism that regulates SP production is still unknown. In this study, we report the transcriptional regulation of the Tachykinin Precursor 1 (TAC1) gene that encodes SP by a transcriptional complex composed of Steroid Receptor Coactivator 1 (Src1), Peroxisome proliferator-activated receptor-gamma coactivator 1 (PGC1α), and Activator Protein 1 (AP1) transcription factor. Infection of mice with EMCV induced the accumulation of PGC1α and increased TAC1 expression, thereby promoting the secretion of SP, initiating apoptosis, and elevating proinflammatory cytokine levels. In vitro overexpression of the Src1-PGC1α-AP1 members also induced TAC1 expression, increased the SP concentration, initiated apoptosis, and elevated proinflammatory cytokine concentrations. Depletion or inhibition of the Src1-PGC1α-AP1 complex reversed these effects. The administration of gossypol, an Src1 inhibitor, or SR1892, a PGC1α inhibitor, to EMCV-infected mice attenuated myocarditis. Taken together, our results reveal that the upregulation of TAC1 and the secretion of SP in EMCV-induced myocarditis are dependent on the Src1-PGC1α-AP1 complex. Targeting the Src1-PGC1α-AP1 complex may represent a new therapeutic strategy for myocarditis.

Integrated LC-MS/MS and network pharmacology approach for predictingactive ingredients and pharmacological mechanisms of Tribulus terrestris L. against cardiac diseases

Tribulus terrestris L. (Gokshura) is a medicinal herb used for treating cardiac diseases and several other diseases. However, the active ingredients and the possible mechanism of action for treating cardiac diseases remain unclear. Hence, the study was designed to identify the active ingredients and to explore the potential mechanism of action of Tribulus terrestris L. for treating cardiac diseases by an integrated approach of metabolomics and network pharmacology. We performed HPLC-QTOF-MS/MS analysis to identify putative compounds and network pharmacology approach for predictive key targets and pathways. Using molecular docking and molecular dynamics simulation, we identified the active ingredients in Tribulus terrestris L. that can act as putative lead compounds to treat cardiac diseases. A total of 55 putative compounds were identified using methanolic extract of Tribulus terrestris L. using HPLC-QTOF-MS/MS analysis. Network pharmacology analysis predicted 32 human protein targets from 25 secondary metabolites, which have shown direct interaction with cardiac diseases. Based on the degrees of interaction, the hub targets such as TACR1, F2, F2R, ADRA1B, CHRM5, ADRA1A, ADRA1D, HTR2B, and AVPR1A were identified. In silico molecular docking and simulation resulted in the identification of active ingredients such as Kaempferol 3-rutinoside 7-glucuronide, Keioside, rutin, moupinamide, aurantiamide, quercetin-3-o-α-rhamnoside, tribuloside, and 3'',6''- Di-O-p-coumaroyltrifolin against hub protein targets. Hence, these compounds could be potential lead compounds for treating cardiac diseases. A further assessment of its efficacy can be made based on in vivo and in vitro studies for better understanding and strong assertion.Communicated by Ramaswamy H. Sarma.

MME+ fibro-adipogenic progenitors are the dominant adipogenic population during fatty infiltration in human skeletal muscle

Fatty infiltration, the ectopic deposition of adipose tissue within skeletal muscle, is mediated via the adipogenic differentiation of fibro-adipogenic progenitors (FAPs). We used single-nuclei and single-cell RNA sequencing to characterize FAP heterogeneity in patients with fatty infiltration. We identified an MME⁺ FAP subpopulation which, based on ex vivo characterization as well as transplantation experiments, exhibits high adipogenic potential. MME⁺ FAPs are characterized by low activity of WNT, known to control adipogenic commitment, and are refractory to the inhibitory role of WNT activators. Using preclinical models for muscle damage versus fatty infiltration, we show that many MME⁺ FAPs undergo apoptosis during muscle regeneration and differentiate into adipocytes under pathological conditions, leading to a reduction in their abundance. Finally, we utilized the varying fat infiltration levels in human hip muscles and found less MME⁺ FAPs in fatty infiltrated human muscle. Altogether, we have identified the dominant adipogenic FAP subpopulation in skeletal muscle.

Hunting for Genes Underlying Emotionality in the Laboratory Rat: Maps, Tools and Traps

Scientists have systematically investigated the hereditary bases of behaviors since the 19th century, moved by either evolutionary questions or clinically-motivated purposes. The pioneer studies on the genetic selection of laboratory animals had already indicated, one hundred years ago, the immense complexity of analyzing behaviors that were influenced by a large number of small-effect genes and an incalculable amount of environmental factors. Merging Mendelian, quantitative and molecular approaches in the 1990s made it possible to map specific rodent behaviors to known chromosome regions. From that point on, Quantitative Trait Locus (QTL) analyses coupled with behavioral and molecular techniques, which involved in vivo isolation of relevant blocks of genes, opened new avenues for gene mapping and characterization. This review examines the QTL strategy applied to the behavioral study of emotionality, with a focus on the laboratory rat. We discuss the challenges, advances and limitations of the search for Quantitative Trait Genes (QTG) playing a role in regulating emotionality. For the past 25 years, we have marched the long journey from emotionality-related behaviors to genes. In this context, our experiences are used to illustrate why and how one should move forward in the molecular understanding of complex psychiatric illnesses. The promise of exploring genetic links between immunological and emotional responses are also discussed. New strategies based on humans, rodents and other animals (such as zebrafish) are also acknowledged, as they are likely to allow substantial progress to be made in the near future.

Involvement of neurokinin-1 receptors in the autonomic nervous system in colorectal distension-induced cardiovascular suppression in rats

Situational syncope, which includes rectally mediated reflexes, is defined as syncope induced by a specific situation. Its pathogenesis generally involves disorders of the autonomic nervous system. However, the mechanisms and preventive strategies are not yet well understood. Therefore, we hypothesized that a tachykinin neurokinin-1 receptor might be involved in the autonomic nervous system, and that a neurokinin-1 receptor antagonist could mitigate reflex syncope. This study used a rat model in which the reflex was induced by afferent vagal stimulation with colorectal distension (CRD). In the study, the rats were divided into three groups: non-CRD, CRD, and CRD with a neurokinin-1 receptor antagonist. First, we examined the effect of fosaprepitant, a neurokinin-1 receptor antagonist, on the circulatory response in this model. We then determined the brain regions that showed increased numbers of c-Fos immunoreactive cells in the respective groups. Our results suggest that the colorectal distension procedure reduced blood pressure and that fosaprepitant lowered this response. In addition, the number of c-Fos immunoreactive cells was increased in the caudal ventrolateral medullary region with colorectal distension, and this number was decreased by the administration of fosaprepitant. In conclusion, fosaprepitant might be involved in the vagal reflex pathway and potentially suppress the circulatory response to colorectal distension.

Effects of substance P on human cerebral microvascular endothelial cell line hCMEC/D3 are mediated exclusively through a truncated NK-1 receptor and depend on cell confluence

The neuropeptide substance P (SP) mediates pain transmission, immune modulation, vasodilation and neurogenic inflammation. Its role in the peripheral nervous system has been well characterised. However, its actions on the blood-brain barrier (BBB) are less clear and warrant further study. The aim of this study was to characterise the effect of SP on the brain microvascular endothelial cells using the immortalized human brain microvascular endothelial cell line hCMEC/D3. As part of our studies, we have evaluated changes in expression, at mRNA and protein levels, of genes involved in the function of the blood-brain barrier such as occludin, induced by exposure to SP. We show that the effect of SP is dependent on cell confluence status. Thus, at low confluence but not at full confluence, SP treatment reduced occludin expression. The expression of the SP receptor, neurokinin-1 receptor (NK-1R) (the truncated form of the receptor expressed exclusively in this cell line) was also modulated in a similar pattern. SP treatment stimulated extracellular signal-regulated kinase (Erk2) phosphorylation which was not associated to changes in Interleukin-6 (IL-6), Interleukin-8 (IL-8), or Intercellular Adhesion Molecule 1 (ICAM-1) protein expression. In addition, SP treatment effectively recovered nitric oxide production on cells exposed to tumour necrosis factor alpha (TNF-α). SP did not trigger intracellular calcium release in hCMEC/D3 cells. We conclude that hCMEC/D3 cells are partially responsive to SP, that the effects are mediated through the truncated form of the receptor and are dependent on the confluence status of these cells.

Cell-To-Cell Communication in the Resistance Vasculature

The arterial vasculature can be divided into large conduit arteries, intermediate contractile arteries, resistance arteries, arterioles, and capillaries. Resistance arteries and arterioles primarily function to control systemic blood pressure. The resistance arteries are composed of a layer of endothelial cells oriented parallel to the direction of blood flow, which are separated by a matrix layer termed the internal elastic lamina from several layers of smooth muscle cells oriented perpendicular to the direction of blood flow. Cells within the vessel walls communicate in a homocellular and heterocellular fashion to govern luminal diameter, arterial resistance, and blood pressure. At rest, potassium currents govern the basal state of endothelial and smooth muscle cells. Multiple stimuli can elicit rises in intracellular calcium levels in either endothelial cells or smooth muscle cells, sourced from intracellular stores such as the endoplasmic reticulum or the extracellular space. In general, activation of endothelial cells results in the production of a vasodilatory signal, usually in the form of nitric oxide or endothelial-derived hyperpolarization. Conversely, activation of smooth muscle cells results in a vasoconstriction response through smooth muscle cell contraction. © 2022 American Physiological Society. Compr Physiol 12: 1-35, 2022.

Modulating the tachykinin: Role of substance P and neurokinin receptor expression in ocular surface disorders

Substance P (SP) is a tachykinin expressed by various cells in the nervous and immune systems. SP is predominantly released by neurons and exerts its biological and immunological effects through the neurokinin receptors, primarily the neurokinin-1 receptor (NK1R). SP is essential for maintaining ocular surface homeostasis, and its reduced levels in disorders like diabetic neuropathy disrupt the corneal tissue. It also plays an essential role in promoting corneal wound healing by promoting the migration of keratocytes. In this review, we briefly discuss the structure, expression, and function of SP and its principal receptor NK1R. In addition, SP induces pro-inflammatory effects through autocrine or paracrine action on the immune cells in various ocular surface pathologies, including dry eye disease, herpes simplex virus keratitis, and Pseudomonas keratitis. We provide an in-depth review of the pathogenic role of SP in various ocular surface diseases and several new approaches developed to counter the immune-mediated effects of SP either through modulating its production or blocking its target receptor.

The Role of KLF2 in the Regulation of Atherosclerosis Development and Potential Use of KLF2-Targeted Therapy

Kruppel like factor 2 (KLF2) is a mechanosensitive transcription factor participating in the regulation of vascular endothelial cells metabolism. Activating KLF2 in endothelial cells induces eNOS (endothelial nitric oxide synthase) expression, subsequent NO (nitric oxide) release, and vasodilatory effect. In addition, many KLF2-regulated genes participate in the anti-thrombotic, antioxidant, and anti-inflammatory activities, thereby preventing atherosclerosis development and progression. In this review, we summarise recent evidence suggesting that KLF2 plays a major role in regulating atheroprotective effects in endothelial cells. We also discuss several recently identified repurposed drugs and natural plant-based bioactive compounds with KLF2-mediated atheroprotective activities. Herein, we present a comprehensive overview of the role of KLF2 in atherosclerosis and as a pharmacological target for different drugs and natural compounds and highlight the potential application of these phytochemicals for the treatment of atherosclerosis.

Molecular mechanism in trigeminal nerve and treatment methods related to orthodontic pain

BACKGROUND

Orthodontic treatment is the main treatment approach for malocclusion. Orthodontic pain is an inevitable undesirable adverse reaction during orthodontic treatment. It is reported orthodontic pain has become one of the most common reason that patients withdraw from orthodontic treatment. Therefore, understanding the underlying mechanism and finding treatment of orthodontic pain are in urgent need.

AIMS

This article aims to sort out the mechanisms and treatments of orthodontic pain, hoping to provide some ideas for future orthodontic pain relief.

MATERIALS

Tooth movement will cause local inflammation. Certain inflammatory factors and cytokines stimulating the trigeminal nerve and further generating pain perception, as well as drugs and molecular targeted therapy blocking nerve conduction pathways, will be reviewed in this article.

METHOD

We review and summaries current studies related to molecular mechanisms and treatment approaches in orthodontic pain control.

RESULTS

Orthodontics pain related influencing factors and molecular mechanisms has been introduced. Commonly used clinical methods in orthodontic pain control has been evaluated.

DISCUSSION

With the clarification of more molecular mechanisms, the direction of orthodontic pain treatment will shift to targeted drugs.

Neurokinin-1 Receptor as a potential drug target for COVID-19 treatment

Novel Coronavirus infection (COVID-19) has become a pandemic in these days. It is an acute respiratory and infectious disease with no known etiology and treatment. It is continuously causing losses of precious lives and economy at a global scale on daily basis. It is the need of the hour to find more treatment strategies by either developing a drug or to boost the immune system. This opinion article aims to provide Substance P (SP) as a possible cause of the initiation of cytokine storm developed in COVID-19 infection and to suggest Neurokinin-1 Receptor (NK-1R) antagonist, Aprepitant, as a drug to be used for its treatment. This perspective will provide directions to the Biomedical scientists to explore SP and NK-1R and prepare a drug to alleviate the symptoms and cure the disease. It is very important to work on this perspective at earliest to reach to some conclusion regarding the therapeutic intervention. Clinical studies may also be conducted if proven successful. SP is a neurotransmitter and neuromodulator, released from the trigeminal nerve of brainstem as a result of nociception. It is directly related to the respiratory illness as in COVID-19 infection. It is responsible for the increased inflammation and the signature symptoms associated with this disease. It is the main switch that needs to be switched off by administering Aprepitant along with glucocorticosteroid, dexamethasone.

Characterization of putative tachykinin peptides in Caenorhabditis elegans

Tachykinin-like peptides, such as substance P, neurokinin A, and neurokinin B, are among the earliest discovered and best-studied neuropeptide families, and research on them has contributed greatly to our understanding of the endocrine control of many physiological processes. However, there are still many orphan tachykinin receptor homologs for which cognate ligands have not yet been identified, especially in small invertebrates, such as the nematode Caenorhabditis elegans (C. elegans). We here show that the C. elegans nlp-58 gene encodes putative ligands for the orphan G protein-coupled receptor (GPCR) TKR-1, which is a worm ortholog of tachykinin receptors. We first determine, through an unbiased biochemical screen, that a peptide derived from the NLP-58 preprotein stimulates TKR-1. Three mature peptides that are predicted to be generated from NLP-58 show potent agonist activity against TKR-1. We designate these peptides as C. elegans tachykinin (CeTK)-1, -2, and -3. The CeTK peptides contain the C-terminal sequence GLR-amide, which is shared by tachykinin-like peptides in other invertebrate species. nlp-58 exhibits a strongly restricted expression pattern in several neurons, implying that CeTKs behave as neuropeptides. The discovery of CeTKs provides important information to aid our understanding of tachykinin-like peptides and their functional interaction with GPCRs.

Neprilysin inhibition does not alter dynamic of proenkephalin-A 119-159 and pro-substance P in heart failure

AIMS

As NEP degrades many substrates, the specific therapeutic mechanism of NEP inhibition with angiotensin receptor neprilysin inhibitor (ARNi) in heart failure with reduced ejection fraction (HFrEF) is not entirely evident. The aim of this study was to investigate the response of two substrates of NEP-the tachykinin and enkephalin systems-to the initiation of ARNi therapy in HFrEF.

METHODS AND RESULTS

Between 2016 and 2018, 141 consecutive patients with stable HFrEF [74 with initiation of ARNi and 67 controls on continuous angiotensin converting enzyme inhibitor (ACEi) or angiotensin receptor blocker (ARB) therapy] were prospectively enrolled. Plasma proenkephalin-A 119-159 (PENK) and pro-substance P (pro-SP) were serially determined. Proenkephalin-A 119-159 and pro-SP correlated strongly with each other (r_s  = 0.67, P < 0.001) and kidney function (r_s  = -0.66, P < 0.001 and r_s  = -0.54, P < 0.001) and modestly with NT-proBNP (r_s  = 0.32, P < 0.001 and r_s  = 0.24, P = 0.006, respectively). Concentrations of circulating PENK were slightly elevated after 1 and 2 year follow-up compared with baseline (BL) [BL median: 67.4 pmol/L (IQR: 57.3-89.8), 1 year: 83.5 pmol/L (IQR: 62.4-111.6), 2 years: 92.3 pmol/L (IQR: 63.1-101.9); BL vs. 1 year: P = 0.017 and BL vs. 2 years: P = 0.019] in the overall analysis, but lost significance at 2 year follow-up when assessed in paired subanalysis (P = 0.116). Plasma pro-SP levels remained comparable during the entire follow-up [BL median: 78.3 pmol/L (IQR: 67.9-90.6), 1 year: 75.9 pmol/L (IQR: 58.6-96.3), 2 years: 79.7 pmol/L (IQR: 59.9-105.3); P = ns for both timepoints]. Biomarker patterns of ARNi patients were independent from baseline therapy, that is, ACEi or ARB (P > 0.05 between groups).

CONCLUSIONS

Although enkephalins and SP are known substrates of NEP, NEP inhibition by ARNi does not clearly affect the circulating precursors PENK and pro-SP in HFrEF.

Changes Caused by Low Doses of Bisphenol A (BPA) in the Neuro-Chemistry of Nerves Located in the Porcine Heart

Simple Summary

Bisphenol A (BPA) is a substance commonly used in the plastics industry, which is a part of many everyday items. It may leach from plastics and penetrate food, water, soil and air. It is known that BPA negatively affects living organisms. It impairs the functions of the intestine, neurons, reproductive organs, endocrine glands and immune cells. Previous studies have also reported that BPA negatively influences the cardiovascular system, leading to heart arrhythmia, intensification of atherosclerosis, blood hypertension and increased risk of a heart attack. However, many aspects of the influence of BPA on the heart are still poorly understood. One of these aspects is the BPA impact on heart innervation. Therefore, this article aimed to investigate the influence of low doses of BPA on the number of nerves containing selected active substances taking part in neuronal stimuli conduction located in the porcine heart apex. The results indicate that even relatively low doses of BPA are not neutral to the cardiovascular system, because they affect the neurochemical characterization of nerves in the heart. These changes may underlie the negative effects of BPA on the heart.

Abstract

Bisphenol A (BPA) contained in plastics used in the production of various everyday objects may leach from these items and contaminate food, water and air. As an endocrine disruptor, BPA negatively affects many internal organs and systems. Exposure to BPA also contributes to heart and cardiovascular system dysfunction, but many aspects connected with this activity remain unknown. Therefore, this study aimed to investigate the impact of BPA in a dose of 0.05 mg/kg body weight/day (in many countries such a dose is regarded as a tolerable daily intake–TDI dose of BPA–completely safe for living organisms) on the neurochemical characterization of nerves located in the heart wall using the immunofluorescence technique. The obtained results indicate that BPA (even in such a relatively low dose) increases the number of nerves immunoreactive to neuropeptide Y, substance P and tyrosine hydroxylase (used here as a marker of sympathetic innervation). However, BPA did not change the number of nerves immunoreactive to vesicular acetylcholine transporter (used here as a marker of cholinergic structures). These observations suggest that changes in the heart innervation may be at the root of BPA-induced circulatory disturbances, as well as arrhythmogenic and/or proinflammatory effects of this endocrine disruptor. Moreover, changes in the neurochemical characterization of nerves in the heart wall may be the first sign of exposure to BPA.

Neuropathological explanation of minimal COVID-19 infection rate in newborns, infants and children - a mystery so far. New insight into the role of Substance P

Sars-Cov-2 or Novel coronavirus infection (COVID-19) has become a global challenge, affecting elderly population at large, causing a burden on hospitals. It has been affecting the world from a health and economic perspective after its emergence since October 2019 at Wuhan province of China. Later on it became a pandemic, with aged people most affected. Surprisingly, the infants and children were not severely infected and mortality among them was reported infrequently. If they died it was due to some comorbidity or congenital heart problems. Why the rate of infection varies in different age groups around the world and what is the protective mechanism in children remains a mystery.

Based on our neuropathological experience at the “Lino Rossi Research Center for the study and prevention of the unexpected perinatal death and Sudden Infant Death Syndrome (SIDS)” of the University of Milan, Italy, we hypothesize that the decreased severity of the disease in infants compared to the elderly may be due to alteration at neurotransmitter levels especially of the Substance P (SP) and of the spinal trigeminal nucleus in the brainstem that is responsible for its secretion.

This neurotransmitter may be directly related to the respiratory illness as is in COVID-19 infection. It is responsible for the increased inflammation and the characteristic symptoms associated with this disease. It is the main switch that must be urgently turned off using the NK-1R antagonist which is the receptor of SP and responsible for its functionality, especially in the elderly.

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COVID-19 is the biggest public health crisis of recent times.

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Children are not significantly affected in the same way as adults by COVID-19.

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The infant's immune system might protect from the ‘cytokine storm’ of adults.

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Increased expression of substance P in brains is here proposed as a possible cause.

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Aprepitant could be a promising therapeutic approach to COVID-19 infection in adults.

Specific Frequency Electroacupuncture Stimulation Transiently Enhances the Permeability of the Blood-Brain Barrier and Induces Tight Junction Changes

The blood-brain barrier (BBB) plays an important role in both the physiological state and pharmacological state of the brain. Transiently enhancing the permeability of the BBB may allow the use of more types of medications for neuropsychiatric diseases. Our previous research revealed that electroacupuncture (EA) stimulation at certain parameters can enhance the permeability of the BBB in Sprague-Dawley rats, but this phenomenon is not well characterized. We propose that specific frequency EA can transiently open the BBB and may be related to the change of tight junctions (TJ). To find the best EA frequency among commonly used frequencies, preliminarily explore the mechanism, we detected BBB permeability by measuring the intensity of Evans Blue and 20 kDa FITC-dextran fluorescence in the cerebral cortex. Then, we used a laser spectrometer, immunofluorescence, western blotting, and transmission electron microscopy to detect the mechanism of BBB opening. Finally, measured brain water content, AQP4, GFAP, Iba1, and used the DeadEnd^TM Fluorometric TUNEL System to clear whether the stimulation caused obvious negative effects. The results show that EA stimulation at 2/100 Hz maximally increased BBB permeability, and the BBB closed within 12 h after EA stimulation was removed. EA stimulation increased blood perfusion, c-fos levels, and Substance P expression in the cerebral cortex, decreased ZO-1 and occludin levels and induced ultrastructural changes in TJ morphology. EA stimulation at specific parameters did not cause brain edema, activation of glial cells, or cell apoptosis. This study shows that EA stimulation induces a reversible, frequency-dependent alteration of BBB permeability and proposes a hypothetical mechanism of BBB opening related to vasodilation and TJ disruption. Transiently enhancing the permeability of the BBB with EA at specific parameters may be a new strategies for delivering therapeutics to the central nervous system. Further study of this technology is needed.

A Homozygous Truncating Mutation in NALCN Causing IHPRF1: Detailed Clinical Manifestations and a Review of Literature

Infantile hypotonia, with psychomotor retardation and characteristic facies 1 (IHPRF1), is a rare disorder characterized by global developmental delay and dysmorphic features. This syndrome is caused by genetic anomalies within the NALCN gene. The current report examines a 9-year-old female IHPRF1 patient. Our objective was to contribute to the delineation of the underlying factors influencing this rare condition. Whole exome sequencing (WES) was utilized to identify the disease-causing mutation in the affected individual. Subsequently, Sanger sequencing was performed for the patient, her parents, and two close relatives in order to confirm the detected mutation. Moreover, detailed clinical examinations including EEG, echocardiography, and biochemical/physical tests were carried out to elucidate the effects of the mutation. WES identified a homozygous nonsense mutation in the NALCN gene (c.2563C>T p.R855X). This mutation was confirmed by Sanger sequencing in the patient and her family members and segregated with the autosomal recessive inheritance pattern of IHPRF1. Moreover, genotype-phenotype correlation analysis confirmed the disease-causing nature of this mutation. The current report provides the first detailed description of a patient with this homozygous nonsense mutation (c.2563C>T p.R855X) and expands the clinical spectrum of IHPRF1 disease. Possible influences of sex and other factors on this disease are discussed and a review of the literature is also provided.

The potential role of TRPV1 in pulmonary hypertension: Angel or demon?

Pulmonary hypertension (PH) is a pathological state defined by increased pulmonary artery pressure, the pathogenesis of which is related to genetic mutations, intracellular calcium ([Ca²⁺]_i), inflammation and proliferation. Transient receptor potential vanilloid subfamily member 1 (TRPV1) is a nonselective cation channel expressed in neural and nonneural cells, including pulmonary vessels and nerves. As a calcium channel, TRPV1 can make vessels contracted, and promote smooth muscle cells proliferation through calcium-dependent transcription factors. Activation of TRPV1 in sensory nerves can release neuropeptides, including calcitonin gene-related peptide (CGRP), substance P (SP), and somatostatin (SST), which can regulate inflammation via transcription factor NF-kB. Considering the increased level of [Ca²⁺]_i and inflammation in the pathogenesis of PH, our review summarizes the role of TRPV1 in PH with regard to [Ca²⁺]_i, neuropeptides, and inflammation. In view of the limited research illustrating the relationship between TRPV1 and PH directly, our review also considers the role of TRPV1 in other types of vascular inflammation. Through this review, we hope to raise awareness about the function of TRPV1 in PH.

Potential role of serum substance P as a favorable biomarker of functional outcome in acute spontaneous intracerebral hemorrhage

BACKGROUND

Substance P (SP) is implicated in brain inflammation. We clarified relationship between serum SP concentrations and functional outcome of acute intracerebral hemorrhage (ICH).

METHODS

We quantified admission serum SP concentrations in 106 ICH patients. The primary outcome measure was a poor outcome at 90 days (modified Rankin Scale score ≥ 3) after onset.

RESULTS

Patients with a poor outcome compared with the rest had substantially higher serum SP concentrations. The area under the curve for serum SP concentrations with regard to discriminating a poor outcome was 0.795 (95% CI, 0.706 to 0.867). Serum SP concentrations >449 pg/ml predicted the risk of a poor outcome with 63.0% sensitivity and 78.9% specificity, and were independently associated with a poor outcome (odds ratio, 5.437; 95% CI, 2.156 to 13.715). There were the positive associations between serum SP concentrations, National Institutes of Health Stroke Scale score (r = 0.480), hematoma volume (r = 0.464) and serum C-reactive protein concentrations (r = 0.398).

CONCLUSIONS

Higher serum SP concentrations in the acute phase of ICH were intimately associated with aggravated inflammation response, rising severity and increased risk of a poor functional outcome, suggesting that serum SP could be an inflammatory prognostic factor for ICH.

Detection of neurokinin-1 receptor by immunohistochemistry in canine mammary gland tumours

Canine mammary gland tumour (cMGT) is the most common tumour in intact female dogs. Surgery is the only effective treatment for cMGT, and dogs with metastasis at the time of diagnosis or those diagnosed at an advanced stage have poorer prognosis. Thus, novel diagnostic biomarkers and therapeutic targets are needed. Neurokinin‐1 receptor (NK‐1 receptor) is involved in cancer progression and has been detected in various malignant tumours including breast cancer in humans. Furthermore, NK‐1 receptor antagonists inhibit cancer progression. We evaluated NK‐1 receptor expression in malignant and benign cMGT compared with that in normal mammary gland tissues and analysed the relationship between the expression of NK‐1 receptor and histopathological type or malignancy grade. Specimens from 34 malignant MGT and 35 benign MGT cases were used for immunohistochemistry and scored according to intensity and percentage. Healthy margins from each tumour were used as internal controls. The scores for NK‐1 receptor intensity, percentage of positive cells and overall immunohistochemistry were higher in malignant MGT than in benign MGT and normal tissue (p < .000). NK‐1 receptor expression was not correlated with either malignancy grade or histopathological type. Expression of the NK‐1 receptor in malignant MGT was higher than that in benign MGT and normal tissues. Thus, NK‐1 receptor could be considered a novel therapeutic target for cMGT. Further studies using other quantitative tests such as western blotting or PCR and the evaluation of substance P in patient tumour tissue or serum are needed.

Molecular basis of the therapeutic properties of hemorphins

Hemorphins are endogenous peptides, 4-10 amino acids long, belonging to the family of atypical opioid peptides released during the sequential cleavage of hemoglobin protein. Hemorphins have been shown to exhibit diverse therapeutic effects in both human and animal models. However, the precise cellular and molecular mechanisms involved in such effects remain elusive. In this review, we summarize and propose potential mechanisms based on studies that investigated the biological activity of hemorphins of different lengths on multiple therapeutic targets. Special emphasis is given to molecular events related to renin-angiotensin system (RAS), opioid receptors and insulin-regulated aminopeptidase receptor (IRAP). This review provides a comprehensive coverage of the molecular mechanisms that underpin the therapeutic potential of hemorphins. Furthermore, it highlights the role of various hemorphin residues in pathological conditions, which could be explored further for therapeutic purposes.

Sensory neurons directly promote angiogenesis in response to inflammation via substance P signaling

Blood vessels and nerves travel together to supply most tissues in the body. However, there is a knowledge gap in the mechanisms underlying the direct regulation of angiogenesis by nerves. In the current study, we examined the regulation of angiogenesis by sensory nerves in response to inflammation using the cornea, a normally avascular and densely innervated ocular tissue, as a model. We used desiccating stress as an inflammatory stimulus in vivo and found that sub-basal and epithelial nerve densities in the cornea were reduced in dry eye disease (DED). We established a co-culture system of trigeminal ganglion sensory neurons and vascular endothelial cells (VEC) and found that neurons isolated from mice with DED directly promoted VEC proliferation and tube formation compared with normal controls. In addition, these neurons expressed and secreted higher levels of substance P (SP), a proinflammatory neuropeptide. SP potently promoted VEC activation in vitro and blockade of SP signaling with spantide I, an antagonist of SP receptor Neurokinin-1, significantly reduced corneal neovascularization in vivo. Spantide I and siRNA knockdown of SP abolished the promotion of VEC activation by DED neurons in vitro. Taken together, our data suggested that sensory neurons directly promote angiogenesis via SP signaling in response to inflammation in the cornea.

Tibetan medicine Ru-yi-Zhen-bao Pills exhibits anti-migraine effect through mediating PAG anti-nociceptive channel

ETHNOPHARMACOLOGICAL RELEVANCE

Migraine is a disabling neurovascular disorder, which increases risk of cardiovascular events and is a social burden worldwide. The present first-line anti-migraine medications can cause overwhelming side-effects, of which one includes the onset of cardiovascular disease. As one of the marketed Tibetan drugs, Ru-yi-Zhen-bao Pills (RYZBP) have been clinically used to treat cardiovascular disorders and as anti-migraine medication. However, there is currently no research exploring the anti-migraine actions of RYZBP.

AIM OF THE STUDY

The current research was designed to assess the anti-migraine roles of RYZBP and explore the underlying mechanisms in a nitroglycerin (NTG)-induced migraine rat model trial.

MATERIALS AND METHODS

120 rats were randomly divided into the following six groups of 20 rats each: normal control group, model control group, positive control group, and RYZBP high/medium/low-dose groups (Ru-yi-Zhen-bao Pills; TH 1.00 g/kg, TM 0.50 g/kg and TL 0.25 g/kg). All rats were administered intragastrically for 7 consecutive days, which were subcutaneously injected with the NTG (10 mg/kg) after the last gavage (except in the normal control group). 3min after NTG treatment, 30 rats (5 rats from each group) were anesthetized and devoted to electroencephalogram(EEG) testing, which was used to evaluate the analgesic effect of RYZBP. One hour after NTG treatment, the rest of the 90 rats (15 rats from each group) were anesthetized and midbrain tissue sample was dissected. The dissection was then washed with physiological saline and collected. The histopathological changes in the periaqueductal gray(PAG) of 5 tissue samples were determined by aematoxylin-eosin (H&E) staining, as well as an estimation of substance P (SP) and neurokinin 1 receptor (NK1R) expression through immunohistochemically staining(IHC). Another 5 midbrain preparations were carried out to evaluate calcitonin gene-related peptide (CGRP), proenkephalin (PENK), SP, and cholecystokinin (CCK) expressions by real-time quantitative polymerase chain reaction (RT-qPCR). The rest of the 5 brainstem tissues were then used to measure CCK, CGRP, and opioid peptide receptor (DORR) levels by western blotting(WB).

RESULTS

In the EEG test, RYZBP (TM 0.50 g / kg) treatment transformed the EEG pain-wave of the NTG-induced migraine model rats in different time period. In the mechanism assay, compared with the model control group, RYZBP pretreatment reduced inflammatory cell infiltration, fibrosis and vacuolation of neuronal cells of PAG tissue seen by HE staining. IHC experiments further showed that RYZBPTM up-regulated SP expression levels and enhanced NK1R levels in the NTG-induced migraine rats (P < 0.05). Therapeutic administration of RYZBP also increased PENK mRNA expression and DORR protein level. Both RT-qPCR and western blotting trials indicated that RYZBP treatment significantly decreased CCK and CGRP expression levels (P < 0.01 or P < 0.05) in the NTG-induced migraine rats.

CONCLUSIONS

RYZBP has the potential to be an effective anti-migraine treatment through suppressing the EEG pain-wave, increasing the levels of SP, PENK, DORR and reducing expression of CCK and CGRP. Mediating the PAG anti-nociceptive channel and inhibiting central sensitization were the two potential mechanisms, which offers further evidence for clinical therapy.

[Neurobiological aspects of venous pelvic pain]

Mechanisms of the development of pain in chronic venous diseases (CVD), including pelvic congestion syndrome (PCS), are understudied. The existing hypotheses of the occurrence of venous pelvic pain (VVP) do not allow to answer the question why some patients have no pain syndrome while others have very pronounced pain despite the same morphofunctional changes in the pelvic veins. This review presents current hypotheses of the VPP development, data on some vasoactive neuropeptides (endothelin, calcitonin gene-related peptide, and substance P), their role in the modulation of vascular tone and sensation of pain, possible association between neurogenic inflammation and VPP and provides a rationale for studying the activity of these neurotransmitters in the treatment of PCS and pelvic pain.

Pilot study for risk assessment of aspiration pneumonia based on oral bacteria levels and serum biomarkers

Background

Aspiration pneumonia is a serious problem among elderly patients; it is caused by many risk factors including dysphagia, poor oral hygiene, malnutrition, and sedative medications. The aim of this study was to define a convenient procedure to objectively evaluate the risk of aspiration pneumonia in the clinical setting.

Methods

This prospective study included an aspiration pneumonia (AP) group, a community-acquired pneumonia (CAP) group, and a control (Con) group (patients hospitalized for lung cancer chemotherapy). We used the Oral Health Assessment Tool (OHAT), which assesses oral hygiene, and evaluated performance status, body mass index, serum albumin levels, substance P values in plasma, and oral bacterial counts.

Results

The oral health as assessed by the OHAT of the aspiration pneumonia group was significantly impaired compared with that of the CAP group and the control (5.13 ± 0.18, 4.40 ± 0.26, 3.90 ± 0.22, respectively; p < 0.05). The oral bacterial count in the aspiration pneumonia group (7.20 ± 0.11) was significantly higher than that in the CAP group (6.89 ± 0.12), consistent with the OHAT scores. Oral bacterial count was significantly reduced by oral care.

Conclusions

OHAT and oral bacterial counts can be a tool to assess the requirement of taking oral care and other preventive procedures in patients at high risk of aspiration pneumonia.

The role of vasoactive neuropeptides in the genesis of venous pelvic pain: A review

Mechanisms of the development of pain in chronic venous diseases, including pelvic congestion syndrome, are not studied in detail so far. The existing hypotheses of the occurrence of venous pelvic pain do not allow to answer the question why some patients have no pain syndrome, while others have very pronounced pain despite the same morphofunctional changes in the pelvic veins. This review presents current hypotheses of the venous pelvic pain development, data on some vasoactive neuropeptides (endothelin, calcitonin gene-related peptide, and substance P), their role in the modulation of vascular tone and sensation of pain, and possible association between neurogenic inflammation and venous pelvic pain, as well as provides rationale for studying the activity of these neurotransmitters in the treatment of pelvic congestion syndrome and pelvic pain.

Evaluation of serum level of substance P and tissue distribution of NK-1 receptor in breast cancer

Breast cancer is the second leading cause of cancer death in women with increasing incidence. Hence, finding a diagnostic factor and/or potential drug target could lead to an earlier diagnosis or a more effective therapeutic protocol. It is shown that substance P (SP) through its receptor neurokinin-1 (NK1R) could initiate tumor cell proliferation, angiogenesis, and migration. This was a case-control study on 41 women with breast cancer and 34 healthy controls. Serum level of SP was measured using an ELISA method, and immunohistochemistry staining was performed to study NK1R expression in different cell compartments. Assessing serum SP values of patients showed significantly higher levels than those of healthy individuals. However, no significant correlation was found between SP levels and tumor criteria, but between SP and HER-2. Moreover, the percentage, intensity of staining as well as tissue distribution of NK1R were significantly higher in tumor tissues as compared with controls. Increased serum SP levels and NK1R tissue distribution were observed in patients with breast cancer as compared with their controls, highlighting the involvement of SP/NK1R complex in breast cancer incidence. NK1R profound expression in tumor cell cytoplasm and its significant correlation with the majority of cancer features can be of importance to be taken into consideration as a possible potential therapeutic target in future targeted therapeutic strategies. Furthermore, cytoplasmic expression of NK1R can be suggested as a potent prognostic factor as it has shown significant correlation with TNM and tumor grade.

Neurokinin-3 receptor activation selectively prolongs atrial refractoriness by inhibition of a background K+ channel

The cardiac autonomic nervous system (ANS) controls normal atrial electrical function. The cardiac ANS produces various neuropeptides, among which the neurokinins, whose actions on atrial electrophysiology are largely unknown. We here demonstrate that the neurokinin substance-P (Sub-P) activates a neurokinin-3 receptor (NK-3R) in rabbit, prolonging action potential (AP) duration through inhibition of a background potassium current. In contrast, ventricular AP duration was unaffected by NK-3R activation. NK-3R stimulation lengthened atrial repolarization in intact rabbit hearts and consequently suppressed arrhythmia duration and occurrence in a rabbit isolated heart model of atrial fibrillation (AF). In human atrial appendages, the phenomenon of NK-3R mediated lengthening of atrial repolarization was also observed. Our findings thus uncover a pathway to selectively modulate atrial AP duration by activation of a hitherto unidentified neurokinin-3 receptor in the membrane of atrial myocytes. NK-3R stimulation may therefore represent an anti-arrhythmic concept to suppress re-entry-based atrial tachyarrhythmias, including AF.

The cardiac autonomic nervous system produces various neuropeptides, such as neurokinin substance-P (Sub-P), whose function remains largely unclear. Here, authors show that Sub-P causes a receptor-mediated prolongation of the atrial action potential through a reduced background potassium current, and prevents atrial fibrillation.

The Neurokinins: Peptidomimetic Ligand Design and Therapeutic Applications

The neurokinins are indisputably essential neurotransmitters in numerous pathoand physiological events. Being widely distributed in the Central Nervous System (CNS) and peripheral tissues, their discovery rapidly promoted them to drugs targets. As a necessity for molecular tools to understand the biological role of this class, endogenous peptides and their receptors prompted the scientific community to design ligands displaying either agonist and antagonist activity at the three main neurokinin receptors, called NK1, NK2 and NK3. Several strategies were implemented for this purpose. With a preference to small non-peptidic ligands, many research groups invested efforts in synthesizing and evaluating a wide range of scaffolds, but only the NK1 antagonist Aprepitant (EMENDT) and its prodrug Fosaprepitant (IVEMENDT) have been approved by the Food Drug Administration (FDA) for the treatment of Chemotherapy-Induced and Post-Operative Nausea and Vomiting (CINV and PONV, respectively). While non-peptidic drugs showed limitations, especially in side effect control, peptidic and pseudopeptidic compounds progressively regained attention. Various strategies were implemented to modulate affinity, selectivity and activity of the newly designed ligands. Replacement of canonical amino acids, incorporation of conformational constraints, and fusion with non-peptidic moieties gave rise to families of ligands displaying individual or dual NK1, NK2 and NK3 antagonism, that ultimately were combined with non-neurokinin ligands (such as opioids) to target enhanced biological impact.

Distribution and Neurochemistry of the Porcine Ileocaecal Valve Projecting Sensory Neurons in the Dorsal Root Ganglia and the Influence of Lipopolysaccharide from Different Serotypes of Salmonella spp. on the Chemical Coding of DRG Neurons in the Cell Cultures

The ileocecal valve (ICV)—a sphincter muscle between small and large intestine—plays important roles in the physiology of the gastrointestinal (GI) tract, but many aspects connected with the innervation of the ICV remain unknown. Thus, the aim of this study was to investigate the localization and neurochemical characterization of neurons located in the dorsal root ganglia and supplying the ICV of the domestic pig. The results have shown that such neurons mainly located in the dorsal root ganglia (DRG) of thoracic and lumbar neuromers show the presence of substance P (SP), calcitonin gene-related peptide (CGRP), and galanin (GAL). The second part of the experiment consisted of a study on the influence of a low dose of lipopolysaccharide (LPS) from Salmonella serotypes Enteritidis Minnesota and Typhimurium on DRG neurons. It has been shown that the LPS of these serotypes in studied doses does not change the number of DRG neurons in the cell cultures, but influences the immunoreactivity to SP and GAL. The observed changes in neurochemical characterization depend on the bacterial serotype. The results show that DRG neurons take part in the innervation of the ICV and may change their neurochemical characterization under the impact of LPS, which is probably connected with direct actions of this substance on the nervous tissue and/or its pro-inflammatory activity.

Comparison of Angiogenic Activities of Three Neuropeptides, Substance P, Secretoneurin, and Neuropeptide Y Using Myocardial Infarction

BACKGROUND

The interplay between neurogenesis and angiogenesis is crucial during the development mediated by neuro-angiogenic morphogens. In particular, the angiogenic activity of neuropeptides and their role in tissue regeneration have long been investigated for better understanding of their biological mechanisms and further applications. However, there have been few studies for direct comparison of angiogenic activities of neuropeptides for in vitro and in vivo models. In this study, we report that direct comparison of the angiogenic activities of neuropeptide Y, secretoneurin, and substance P (SP) immobilized on hydrogels in in vitro and in vivo experiments.

METHODS

A hyaluronic acid-based hydrogel is prepared by utilizing acrylated hyaluronic acid and thiolated peptides as a crosslinker and angiogenic factors, respectively. Angiogenic activities of three neuropeptides are evaluated not only by in vitro angiogenic and gene expression assays, but also by an in vivo chronic myocardial infarction model.

RESULTS

The comparison of in vitro angiogenic activities of three peptides demonstrates that the SP-immobilized hydrogel shows a higher degree of cell network formation and angiogenic-specific genes than those of the other peptides and the control case. In addition, a three-dimensional angiogenic assay illustrates that more sprouting is observable in the SP group. Evaluation of regenerative activity in the chronic myocardial infarction model reveals that all three peptide-immobilized hydrogels induce increased cardiac function as well as structural regeneration. Among all the cases, the SP group provided the highest regenerative activity both in vitro and in vivo.

CONCLUSION

In our comparison study, the SP-immobilized hydrogel shows the highest angiogenic activity and tissue regeneration among the test groups. This result suggests that nerve regeneration factors help angiogenesis in damaged tissues, which also highlights the importance of the neuro-angiogenic peptides as an element of tissue regeneration.

The potential role of substance P in brainstem homeostatic control in the pathogenesis of sudden infant death syndrome (SIDS)

Victims of sudden infant death syndrome (SIDS) are believed to have an underlying dysfunction in medullary homeostatic control that impairs critical responses to life threatening challenges such as hypoxia, hypercarbia and asphyxia, often during a sleep period. This failure is thought to result from abnormalities in a network of neural pathways in the medulla oblongata that control respiration, chemosensitivity, autonomic function and arousal. Studies have mainly focused on the role of serotonin, 5-hydroxytyptamine (5HT), although the neuropeptide substance P (SP) has also been shown to play an integral role in the modulation of medullary homeostatic function, often in conjunction with 5-HT. Actions of SP include regulation of respiratory rhythm generation, integration of cardiovascular control, modulation of the baroreceptor reflex and mediation of the chemoreceptor reflex in response to hypoxia. Abnormalities in SP neurotransmission may, therefore, also play a significant role in homeostatic dysfunction of the neurotransmitter network in SIDS. This review focuses on the pathways within the medulla involving SP and its tachykinin NK1 receptor, their potential relationship with the medullary 5-HT system, and possible involvement in the pathogenesis of SIDS.

Substance P Receptor in the Rat Heart and Regulation of Its Expression in Long-Term Diabetes

Substance P (SP) is a neuropeptide engaged in the signal transmission of neural C fibers afferents in the myocardium. The actions of SP in the heart are extensive and they are mediated by the neurokinin 1 receptor (NK1R), a member of the tachykinin subfamily of G-protein coupled receptors. The receptors have been found in the heart, but to our knowledge, their exact localization in the heart has not been described yet. Here, we investigated the presence of NK1R protein in separate rat heart compartments by means of western blot and its tissue distribution by means of immunofluorescence. Specificity of NK1R immunolabeling was controlled by preabsorption of the antiserum with its corresponding peptide. Additionally, we investigated abundance of gene for NK1R in separated heart chambers by means of quantitative real-time PCR (RT-PCR). Relative abundance of NK1R mRNA was expressed as a ratio of target gene Cq value to Cq value of control gene - beta-actin. Finally, we studied abundance of NK1R mRNA in different cell types of heart isolated by laser capture microdissection. Immunofluorescence showed NK1R immunoreactivity on the surface of some intracardiac neurons and smooth muscle cells of coronary vessels. The results of quantitative RT-PCR indicate abundance of mRNA for NK1R in all heart chambers with highest level in the left atrium. The presence of NK1R mRNA was detected in some samples of dissected intracardiac neurons, but not in cardiomyocytes or smooth muscle cells of coronary vessels. In the course of long-term diabetes, a significant downregulation of the NK1R mRNA was seen in the right atrium and upregulation in the right ventricle 53 weeks after the induction of diabetes. Our results indicate localization of NK1R in some intracardiac neurons and smooth muscle cells. Impaired transcription of the NK1R gene in the diabetic heart may be induced by unidentified genes or factors involved in the development of diabetic cardiomyopathy.

Direct activation of tachykinin receptors within baroreflex afferent pathway and neurocontrol of blood pressure regulation

AIM

Substance P (SP) causes vasodilation and blood pressure (BP) reduction. However, the involvement of tachykinin receptors (NKRs) within baroreflex afferent pathway in SP-mediated BP regulation is largely unknown.

METHODS

Under control and hypertensive condition, NKRs' expressions were evaluated in nodose (NG) and nucleus of tractus solitary (NTS) of male, female, and ovariectomized (OVX) rats; BP was recorded after microinjection of SP and NKRs agonists into NG; Baroreceptor sensitivity (BRS) was tested as well.

RESULTS

Immunostaining and immunoblotting data showed that NK1R and NK2R were estrogen-dependently expressed on myelinated and unmyelinated afferents in NG. A functional study showed that BP was reduced dose-dependently by SP microinjection, which was more dramatic in males and can be mimicked by NK1R and NK2R agonists. Notably, further BP elevation and BRS dysfunction were confirmed in desoxycorticosterone acetate (DOCA)-salt model in OVX compared with DOCA-salt model in intact female rats. Additionally, similar changes in NKRs' expression in NG were also detected using DOCA-salt and SHR. Compared with NG, inversed expression profiles of NKRs were also found in NTS with either gender.

CONCLUSION

The estrogen-dependent NKRs' expression in baroreflex afferent pathway participates at least partially in sexual-dimorphic and SP-mediated BP regulation under physiological and hypertensive conditions.

Occurrence of substance P and neurokinin receptors during the early phase of spinal fusion

Spinal fusion is widely used for patients with spinal disorders; however, patients often suffer from back pain following fusion surgery. Substance P (SP) acts as a pain neurotransmitter via the sensory nerve afferent fibres up to the spinal cord, and is involved in the conduction and modulation of pain. The use of specific SP neurokinin receptor (NKR) antagonists may decrease postoperative pain. In the present study, the effects of alterations in the quantity of SP and NKRs in the early spinal fusion process were investigated. The results of the present study revealed that SP and NKRs began to appear 1 week post‑surgery in fibrous tissues. The abundance of SP and NKRs peaked at 3 weeks post‑surgery; the majority of SP and NKRs were distributed around the allograft and the new microvessels. In conclusion, SP and NKRs are involved in early spinal fusion, a finding that may facilitate the development of novel strategies to promote spinal fusion from a neurogenesis perspective.

Cardiovascular and Diabetic Medications That Cause Bradykinin-Mediated Angioedema

Medication-induced angioedema is a bradykinin-mediated process that results from increased production or decreased degradation of bradykinin. These reactions are documented for several cardiac medications including blockers of the renin-angiotensin-aldosterone system (RAAS). Other cardiovascular and diabetes medications further increase the risk of medication-induced angioedema, particularly with concomitant use of RAAS inhibitors. Dipeptidyl peptidase IV inhibitors are a class of oral diabetic agents that affect bradykinin and substance P degradation and therefore can lead to angioedema. Neprilysin inhibitors are a separate class of cardiac medications, which includes sacubitril, and can lead to drug-induced angioedema especially when used in combination with RAAS inhibitors. This article discusses the proposed mechanisms by which these medications cause angioedema and how medication-induced angioedema differs from mast cell-mediated angioedema. It also details how to recognize medication-induced angioedema and the treatment options available.

Thioamide Substitution Selectively Modulates Proteolysis and Receptor Activity of Therapeutic Peptide Hormones

Peptide hormones are attractive as injectable therapeutics and imaging agents, but they often require extensive modification by mutagenesis and/or chemical synthesis to prevent rapid in vivo degradation. Alternatively, the single-atom, O-to-S modification of peptide backbone thioamidation has the potential to selectively perturb interactions with proteases while preserving interactions with other proteins, such as target receptors. Here, we use the validated diabetes therapeutic, glucagon-like peptide-1 (GLP-1), and the target of clinical investigation, gastric inhibitory polypeptide (GIP), as proof-of-principle peptides to demonstrate the value of thioamide substitution. In GLP-1 and GIP, a single thioamide near the scissile bond renders these peptides up to 750-fold more stable than the corresponding oxopeptides toward cleavage by dipeptidyl peptidase 4, the principal regulator of their in vivo stability. These stabilized analogues are nearly equipotent with their parent peptide in cyclic AMP activation assays, but the GLP-1 thiopeptides have much lower β-arrestin potency, making them novel agonists with altered signaling bias. Initial tests show that a thioamide GLP-1 analogue is biologically active in rats, with an in vivo potency for glycemic control surpassing that of native GLP-1. Taken together, these experiments demonstrate the potential for thioamides to modulate specific protein interactions to increase proteolytic stability or tune activation of different signaling pathways.

Pathogenesis of Lethal Aspiration Pneumonia in Mecp2-null Mouse Model for Rett Syndrome

Rett syndrome (RTT) is a neurodevelopmental disorder mainly caused by mutations in the gene encoding the transcriptional regulator Methyl-CpG-binding protein 2 (MeCP2), located on the X chromosome. Many RTT patients have breathing abnormalities, such as apnea and breathing irregularity, and respiratory infection is the most common cause of death in these individuals. Previous studies showed that MeCP2 is highly expressed in the lung, but its role in pulmonary function remains unknown. In this study, we found that MeCP2 deficiency affects pulmonary gene expression and structures. We also found that Mecp2-null mice, which also have breathing problems, often exhibit inflammatory lung injury. These injuries occurred in specific sites in the lung lobes. In addition, polarizable foreign materials were identified in the injured lungs of Mecp2-null mice. These results indicated that aspiration might be a cause of inflammatory lung injury in Mecp2-null mice. On the other hand, MeCP2 deficiency affected the expression of several neuromodulator genes in the lower brainstem. Among them, neuropeptide substance P (SP) immunostaining was reduced in Mecp2-null brainstem. These findings suggest that alteration of SP expression in brainstem may be involved in autonomic dysregulation, and may be one of the causes of aspiration in Mecp2-null mice.

Substance P Regulation in Epilepsy

Background:

Epilepsy is a common neurological disease characterized by abnormal temporary discharge of neurons in the central nervous system. In recent years, studies have revealed the localization and changes in the density of neuropeptides, such as substance P (SP) in the pathogenesis of epilepsy. This review is a concise overview of SP and their physiologic and pathologic functions on regulating epilepsy, and the underline mechanisms.

Methods:

We research and collect relative online content for reviewing the effects of SP in Epilepsy.

Results:

The SP/NK-1 receptor system may induce seizures and play an important role in status epilepticus and in experimental animal models of epilepsy. Newest studies show that several mechanisms may explain the excitatory effects of the SP/NK-1 receptor signaling pathway in epilepsy. By binding to the NK-1 receptor, NK-1 receptor antagonists may block the pathophysiological effects of SP, and further studies are needed to confirm the possible anti-epileptic activity of NK-1 receptor antagonists.

Conclusion:

SP plays crucial roles on through binding with NK-1 receptor during epilepsy pathologic processing, and the NK-1 receptor is receiving a great attention as a therapeutic target for treating epilepsy. Thus, the use of NK-1 receptor antagonists for the treatment of epilepsy should be investigated in further studies.