Protective Role of α-Calcitonin Gene-Related Peptide in Cardiovascular Diseases

An-Gong-Niu-Huang-Wan (AGNHW) regulates cerebral blood flow by improving hypoperfusion, cerebrovascular reactivity and microcirculation disturbances after stroke

BACKGROUND

The restoration of cerebrovascular regulation and improvement of cerebral blood flow in ischaemic regions are crucial for improving the clinical prognosis after stroke. An-Gong-Niu-Huang-Wan (AGNHW) is a famous traditional compound Chinese medicine that has been used for over 220 years to treat acute ischaemic stroke; however, its role in the regulation of cerebral blood flow is still unclear. The aim of the present study was to investigate the regulatory effect of AGNHW on cerebral blood flow and microcirculation after ischaemic stroke and to elucidate the underlying mechanisms involved.

METHODS

Male C57BL/6 mice were subjected to distal middle cerebral artery occlusion (dMCAO) and randomly assigned to the sham, MCAO, or AGNHW groups. AGNHW was administered intragastrically 1 h after dMCAO. The rotarod test was utilized to evaluate behavioural function; TTC was used to determine the infarct volume; and ischaemic injury was assessed by detecting brain levels of SOD, MDA and NO. Then, cortical perfusion and acetazolamide-induced cerebrovascular reactivity were assessed using laser speckle contrast imaging, and the velocity and flux of red blood cells in cortical capillaries were detected using two-photon laser scanning microscopy. In addition, we employed RNA-Seq to identify variations in gene expression profiles and assessed endothelium-dependent changes in microcirculatory dysfunction by measuring vasoactive mediator levels.

RESULTS

AGNHW significantly increased cerebral blood flow, reduced the infarct volume, and promoted functional recovery after cerebral ischaemia. AGNHW increased the velocity and flux of red blood cells in capillaries and improved cerebrovascular reactivity in the ischaemic cortex. Furthermore, AGNHW regulated endothelium-dependent microcirculation, as evidenced by decreases in the expression of endothelins (Edn1, Edn3 and Ednrb) and the ratios of brain and serum TXB2/6-keto-PGF1α and ET-1/CGRP.

CONCLUSIONS

AGNHW improved cerebral hypoperfusion, regulated cerebrovascular reactivity and attenuated microcirculatory dysfunction within the ischaemic cortex after stroke. This outstanding effect was achieved by modulating the expression of genes related to vascular endothelial cell function and regulating endothelium-dependent vasoactive mediators.

Calcitonin Gene-Related Peptide Level in Cystic Fibrosis Patients

Calcitonin gene-related peptide (CGRP) has long been implicated in both the physiology and pathophysiology of the respiratory tract. The objective of our study was to determine the serum concentration of alpha CGRP (αCGRP) in cystic fibrosis (CF) that arises from mutations in the gene responsible for encoding the cystic fibrosis transmembrane conductance regulator (CFTR) protein. Currently, there are not many data in the literature about the role of CGRP in CF. The serum level of αCGRP was estimated using the enzyme-linked immunosorbent assay among 64 patients with CF and 31 healthy controls. The αCGRP concentration in the CF group was 62.51 ± 15.45 pg/mL, while in the control group it was 47.43 ± 8.06 pg/mL (p < 0.001). We also compared the level of αCGRP in CF patients according to the type of CFTR mutation. Homozygotes for ΔF508 had higher αCGRP levels than heterozygotes (67.9 ± 10.2 vs. 54.5 ± 18.3 pg/mL, p < 0.01). The level of this neuropeptide was statistically higher in patients with severe disease than in those with mild CF (p = 0.003) when patients were divided into three groups by spirometry results. αCGRP concentration was not correlated with age, sex, clinical parameters, and pulmonary function test results in the study participants. The results of our study suggest a significant increase in the concentration of αCGRP in the serum of patients with CF compared to the control group. This observation opens interesting possibilities for understanding the role of αCGRP in the context of CF pathophysiology.

CGRP attenuates pulmonary vascular remodeling by inhibiting the cGAS-STING-NFκB pathway in pulmonary arterial hypertension

BACKGROUND

Hyperproliferation, inflammation, and mitochondrial abnormalities in pulmonary artery smooth muscle cells (PASMCs) underlie the pathological mechanisms of vascular remodeling in pulmonary arterial hypertension (PAH). Cytoplasmic mtDNA activates the cGAS-STING-NFκB pathway and secretes pro-inflammatory cytokines that may be involved in the pathogenesis of PAH. Calcitonin gene-related peptide (CGRP) acts as a vasodilator to regulate patterns of cellular energy metabolism and has vasodilatory and anti-inflammatory effects.

METHODS

The role of the cGAS-STING-NFκB signaling pathway in PAH vascular remodeling and the regulation of CGRP in the cGAS-STING-NFκB signaling pathway were investigated by echocardiography, morphology, histology, enzyme immunoassay, and fluorometry.

RESULTS

Monocrotaline (MCT) could promote right heart hypertrophy, pulmonary artery intima thickening, and inflammatory cell infiltration in rats. Cinnamaldehyde (CA)-induced CGRP release alleviates MCT-induced vascular remodeling in PAH. CGRP reduces PDGF-BB-induced proliferation, and migration, and downregulates smooth muscle cell phenotypic proteins. In vivo and in vitro experiments confirm that the mitochondria of PASMCs were damaged during PAH, and the superoxide and mtDNA produced by injured mitochondria activate the cGAS-STING-NFκB pathway to promote PAH process, while CGRP could play an anti-PAH role by protecting the mitochondria and inhibiting the cGAS-STING-NFκB pathway through PKA.

CONCLUSION

This study identifies that CGRP attenuates cGAS-STING-NFκB axis-mediated vascular remodeling in PAH through PKA.

Activation of CGRP receptor-mediated signaling promotes tendon-bone healing

Calcitonin gene-related peptide (CGRP), an osteopromotive neurotransmitter with a short half-life, shows increase while calcitonin receptor-like (CALCRL) level is decreased at the early stage in bone fractures. Therefore, the activation of CALCRL-mediated signaling may be more critical to promote the tendon-bone healing. We found CGRP enhanced osteogenic differentiation of BMSCs through PKA/CREB/JUNB pathway, contributing to improved sonic hedgehog (SHH) expression, which was verified at the tendon-bone interface (TBI) in the mice with Calcrl overexpression. The osteoblast-derived SHH and slit guidance ligand 3 were reported to favor nerve regeneration and type H (CD31hiEMCNhi) vessel formation, respectively. Encouragingly, the activation or inactivation of CALCRL-mediated signaling significantly increased or decreased intensity of type H vessel and nerve fiber at the TBI, respectively. Simultaneously, improved gait characteristics and biomechanical performance were observed in the Calcrl overexpression group. Together, the gene therapy targeting CGRP receptor may be a therapeutic strategy in sports medicine.

Distribution and morphology of calcitonin gene-related peptide (CGRP) innervation in flat mounts of whole rat atria and ventricles

Calcitonin gene-related peptide (CGRP) is widely used as a marker for nociceptive afferent axons. However, the distribution of CGRP-IR axons has not been fully determined in the whole rat heart. Immunohistochemically labeled flat-mounts of the right and left atria and ventricles, and the interventricular septum (IVS) in rats for CGRP were assessed with a Zeiss imager to generate complete montages of the entire atria, ventricles, and septum, and a confocal microscope was used to acquire detailed images of selected regions. We found that 1) CGRP-IR axons extensively innervated all regions of the atrial walls including the sinoatrial node region, auricles, atrioventricular node region, superior/inferior vena cava, left pre-caval vein, and pulmonary veins. 2) CGRP-IR axons formed varicose terminals around individual neurons in some cardiac ganglia but passed through other ganglia without making appositions with cardiac neurons. 3) Varicose CGRP-IR axons innervated the walls of blood vessels. 4) CGRP-IR axons extensively innervated the right/left ventricular walls and IVS. Our data shows the rather ubiquitous distribution of CGRP-IR axons in the whole rat heart at single-cell/axon/varicosity resolution for the first time. This study lays the foundation for future studies to quantify the differences in CGRP-IR axon innervation between sexes, disease models, and species.

Role of cAMP in Cardiomyocyte Viability: Beneficial or Detrimental?

BACKGROUND

3', 5'-cyclic AMP (cAMP) regulates numerous cardiac functions. Various hormones and neurotransmitters elevate intracellular cAMP (i[cAMP]) in cardiomyocytes through activating GsPCRs (stimulatory-G-protein-coupled-receptors) and membrane-bound ACs (adenylyl cyclases). Increasing evidence has indicated that stimulating different GsPCRs and ACs exhibits distinct, even opposite effects, on cardiomyocyte viability. However, the underlying mechanisms are not fully understood.

METHODS

We used molecular and pharmacological approaches to investigate how different GsPCR/cAMP signaling differentially regulate cardiomyocyte viability with in vitro, ex vivo, and in vivo models.

RESULTS

For prodeath GsPCRs, we explored β1AR (beta1-adrenergic receptor) and H2R (histamine-H2-receptor). We found that their prodeath effects were similarly dependent on AC5 activation, ATP release to the extracellular space via PANX1 (pannexin-1) channel, and extracellular ATP (e[ATP])-mediated signaling involving in P2X7R (P2X purinoceptor 7) and CaMKII (Ca2+/calmodulin-dependent protein kinase II). PANX1 phosphorylation at Serine 206 by cAMP-dependent-PKA (protein-kinase-A) promoted PANX1 activation, which was critical in β1AR- or H2R-induced cardiomyocyte death in vitro and in vivo. β1AR or H2R was localized proximately to PANX1, which permits ATP release. For prosurvival GsPCRs, we explored adenosine-A2-receptor (A2R), CGRPR (calcitonin-gene-related-peptide-receptor), and RXFP1 (relaxin-family peptide-receptor 1). Their prosurvival effects were dependent on AC6 activation, cAMP efflux via MRP4 (multidrug resistance protein 4), extracellular cAMP metabolism to adenosine (e[cAMP]-to-e[ADO]), and e[ADO]-mediated signaling. A2R, CGRPR, or RXFP1 was localized proximately to MRP4, which enables cAMP efflux. Interestingly, exogenously increasing e[cAMP] levels by membrane-impermeable cAMP protected against cardiomyocyte death in vitro and in ex vivo and in vivo mouse hearts with ischemia-reperfusion injuries.

CONCLUSIONS

Our findings indicate that the functional diversity of different GsPCRs in cardiomyocyte viability could be achieved by their ability to form unique signaling complexes (signalosomes) that determine the fate of cAMP: either stimulate ATP release by activating PKA or directly efflux to be e[cAMP].

Decreased role of neuropeptides in the microvascular function in migraine patients with polycystic ovary syndrome

BACKGROUND AND AIMS

To understand pathophysiological mechanisms underlying migraine as a cardiovascular risk factor, we studied neuropeptide action and endothelial function as measures of peripheral microvascular function in middle-aged women with or without migraine.

METHODS

We included women with the endocrine disorder polycystic ovary syndrome (PCOS), a population with supposed elevated cardiovascular risk, with and without comorbid migraine. In 26 women without and 23 women with migraine in the interictal phase (mean age 50.8 ± 2.9 years) local thermal hyperemia (LTH) of the skin of the volar forearm was measured cross-sectionally under control conditions, after inhibition of neuropeptide release by 5% lidocaine/prilocaine (EMLA) cream application, and after inhibition of nitric oxide formation by iontophoresis of NG-monomethyl-l-arginine (L-NMMA). Hereafter, changes in the natural logarithm of the reactive hyperemia index (lnRHI) and augmentation index (AI) during reperfusion after occlusion-derived ischemia were measured.

RESULTS

While mean values under control conditions and L-NMMA conditions were similar, migraine patients had a significantly higher mean area of the curve (AUC) of the total LTH response after EMLA application than those without (86.7 ± 26.5% versus 67.9 ± 24.2%; p = 0.014). This was also reflected by a higher median AUC of the plateau phase under similar conditions in women with migraine compared to those without (83.2% (IQR[73.2-109.5]) versus 73.2% (IQR[54.3-92.0]); p = 0.039). Mean changes in lnRHI and AI scores were similar in both groups.

CONCLUSIONS

In PCOS patients with migraine, neuropeptide action was lower compared with those without migraine. While larger studies are warranted, these findings provide a potential mechanism supporting previous findings that migraine may be independent from traditional risk factors, including atherosclerosis.

Garlic prevents the oxidizing and inflammatory effects of sepsis induced by bacterial lipopolysaccharide at the systemic and aortic level in the rat. Role of trpv1

Garlic (Allium sativum) possesses healing properties for diseases like systemic arterial hypertension, cancer and diabetes, among others. Its main component, allicin, binds to the Transient Receptor Potential Vanilloid Type 1 (TRPV1). In this study, we investigated TRPV1's involvement in the regulation of various molecules at the systemic and aortic levels in Wistar rats treated with bacterial lipopolysaccharide (LPS) and garlic to activate the receptor. The experimental groups were as follows: 1) Control, 2) LPS, 3) Garlic, and 4) LPS + Garlic. Using Uv-visible spectrophotometry and capillary zone electrophoresis, we measured the levels of nitric oxide (NO), biopterins BH2 and BH4, total antioxidant capacity (TAC) and oxidizing capacity (OXCA). We also analyzed molecules related to vascular homeostasis such as angiotensin Ang 1-7 and Ang II, as well as endothelin ET-1. In addition, we assessed the inflammatory response by determining the levels of interleukin-6 (IL-6), tumor necrosis factor alpha (TNFα), and galectin-3 (GTN-3). For cell damage assessment, we measured levels of malondialdehyde (MDA), malonate (MTO) and 8-hydroxy-2-deoxyguanosine (8HO2dG). The results showed that LPS influenced the NO pathway at both systemic and aortic levels by increasing OXCA and reducing TAC. It also disrupted vascular homeostasis by increasing Ang-II and ET-1, while decreasing Ang1-7 levels. IL-6, TNFα, GTN-3, as well as MDA, MTO, and 8HO2dG were significantly elevated compared to the control group. The expression of iNOS was increased, but TRPV1 remained unaffected by LPS. However, garlic treatment effectively mitigated the effects of LPS and significantly increased TRPV1 expression. Furthermore, LPS caused a significant decrease in calcitonin gene-related peptide (CGRP) in the aorta, which was counteracted by garlic treatment. Overall, TRPV1 appears to play a crucial role in regulating oxidative stress and the molecules involved in damage and inflammation induced by LPS. Thus, studying TRPV1, CGRP, and allicin may offer a potential strategy for mitigating inflammatory and oxidative stress in sepsis.

Neurochemical alterations of intrinsic cardiac ganglionated nerve plexus caused by arterial hypertension developed during ageing in spontaneously hypertensive and Wistar Kyoto rats

The acknowledged hypothesis of the cause of arterial hypertension is the emerging disbalance in sympathetic and parasympathetic regulations of the cardiovascular system. This disbalance manifests in a disorder of sustainability of endogenous autonomic and sensory neural substances including calcitonin gene-related peptide (CGRP). This study aimed to examine neurochemical alterations of intrinsic cardiac ganglionated nerve plexus (GP) triggered by arterial hypertension during ageing in spontaneously hypertensive rats of juvenile (prehypertensive, 8-9 weeks), adult (early hypertensive, 12-18 weeks) and elderly (persistent hypertensive, 46-60 weeks) age in comparison with the age-matched Wistar-Kyoto rats as controls. Parasympathetic, sympathetic and sensory neural structures of GP were analysed and evaluated morphometrically in tissue sections and whole-mount cardiac preparations. Both the elevated blood pressure and the evident ultrasonic signs of heart failure were identified for spontaneously hypertensive rats and in part for the aged control rats. The amount of adrenergic and immunoreactive to CGRP neural structures was increased in the adult group of spontaneously hypertensive rats along with the significant alterations that occurred during ageing. In conclusion, the revealed chemical alterations of GP support the hypothesis about the possible disbalance of efferent and afferent heart innervation and may be considered as the basis for the emergence and progression of arterial hypertension and perhaps even as a consequence of hypertension in the aged spontaneously hypertensive rats. The determined anatomical changes in the ageing Wistar-Kyoto rats suggest this breed being as inappropriate for its use as control animals for hypertension studies in older animal age.

Serotonergic Modulation of Neurovascular Transmission: A Focus on Prejunctional 5-HT Receptors/Mechanisms

5-Hydroxytryptamine (5-HT), or serotonin, plays a crucial role as a neuromodulator and/or neurotransmitter of several nervous system functions. Its actions are complex, and depend on multiple factors, including the type of effector or receptor activated. Briefly, 5-HT can activate: (i) metabotropic (G-protein-coupled) receptors to promote inhibition (5-HT₁, 5-HT₅) or activation (5-HT₄, 5-HT₆, 5-HT₇) of adenylate cyclase, as well as activation (5-HT₂) of phospholipase C; and (ii) ionotropic receptor (5-HT₃), a ligand-gated Na⁺/K⁺ channel. Regarding blood pressure regulation (and beyond the intricacy of central 5-HT effects), this monoamine also exerts direct postjunctional (on vascular smooth muscle and endothelium) or indirect prejunctional (on autonomic and sensory perivascular nerves) effects. At the prejunctional level, 5-HT can facilitate or preclude the release of autonomic (e.g., noradrenaline and acetylcholine) or sensory (e.g., calcitonin gene-related peptide) neurotransmitters facilitating hypertensive or hypotensive effects. Hence, we cannot formulate a specific impact of 5-HT on blood pressure level, since an increase or decrease in neurotransmitter release would be favoured, depending on the type of prejunctional receptor involved. This review summarizes and discusses the current knowledge on the prejunctional mechanisms involved in blood pressure regulation by 5-HT and its impact on some vascular-related diseases.

Cardiac vagal afferent neurotransmission in health and disease: review and knowledge gaps

The meticulous control of cardiac sympathetic and parasympathetic tone regulates all facets of cardiac function. This precise calibration of cardiac efferent innervation is dependent on sensory information that is relayed from the heart to the central nervous system. The vagus nerve, which contains vagal cardiac afferent fibers, carries sensory information to the brainstem. Vagal afferent signaling has been predominantly shown to increase parasympathetic efferent response and vagal tone. However, cardiac vagal afferent signaling appears to change after cardiac injury, though much remains unknown. Even though subsequent cardiac autonomic imbalance is characterized by sympathoexcitation and parasympathetic dysfunction, it remains unclear if, and to what extent, vagal afferent dysfunction is involved in the development of vagal withdrawal. This review aims to summarize the current understanding of cardiac vagal afferent signaling under in health and in the setting of cardiovascular disease, especially after myocardial infarction, and to highlight the knowledge gaps that remain to be addressed.

Short histological kaleidoscope - recent findings in histology. Part III

The paper provides an overview of the current understanding of different cells' biology (e.g., keratinocytes, Paneth cells, myoepithelial cells, myofibroblasts, chondroclasts, monocytes, atrial cardiomyocytes), including their origin, structure, function, and role in disease pathogenesis, and of the latest findings in the medical literature concerning the brown adipose tissue and the juxtaoral organ of Chievitz.

Pharmacological Profile of the Purinergic P2Y Receptors That Modulate, in Response to ADPβS, the Vasodepressor Sensory CGRPergic Outflow in Pithed Rats

Calcitonin gene-related peptide (CGRP), an endogenous neuropeptide released from perivascular sensory nerves, exerts a powerful vasodilatation. Interestingly, adenosine triphosphate (ATP) stimulates the release of CGRP by activation of prejunctional P2X_2/3 receptors, and adenosine 5'-O-2-thiodiphosphate (ADPβS), a stable adenosine diphosphate (ADP) analogue, produces vasodilator/vasodepressor responses by endothelial P2Y₁ receptors. Since the role of ADP in the prejunctional modulation of the vasodepressor sensory CGRPergic drive and the receptors involved remain unknown, this study investigated whether ADPβS inhibits this CGRPergic drive. Accordingly, 132 male Wistar rats were pithed and subsequently divided into two sets. In set 1, ADPβS (5.6 and 10 µg/kg·min) inhibited the vasodepressor CGRPergic responses by electrical stimulation of the spinal T₉-T₁₂ segment. This inhibition by ADPβS (5.6 µg/kg·min) was reverted after i.v. administration of the purinergic antagonists MRS2500 (300 µg/kg; P2Y₁) or MRS2211 (3000 µg/kg; P2Y₁₃), but not by PSB0739 (300 µg/kg; P2Y₁₂), MRS2211 (1000 µg/kg; P2Y₁₃) or the K_ATP blocker glibenclamide (20 mg/kg). In set 2, ADPβS (5.6 µg/kg·min) failed to modify the vasodepressor responses to exogenous α-CGRP. These results suggest that ADPβS inhibits CGRP release in perivascular sensory nerves. This inhibition, apparently unrelated to activation of ATP-sensitive K⁺ channels, involves P2Y₁ and probably P2Y₁₃, but not P2Y₁₂ receptors.

Gel-forming antagonist provides a lasting effect on CGRP-induced vasodilation

Migraine affects ∼15% of the adult population, and the standard treatment includes the use of triptans, ergotamines, and analgesics. Recently, CGRP and its receptor, the CLR/RAMP1 receptor complex, have been targeted for migraine treatment due to their critical roles in mediating migraine headaches. The effort has led to the approval of several anti-CGRP antibodies for chronic migraine treatment. However, many patients still suffer continuous struggles with migraine, perhaps due to the limited ability of anti-CGRP therapeutics to fully reduce CGRP levels or reach target cells. An alternative anti-CGRP strategy may help address the medical need of patients who do not respond to existing therapeutics. By serendipity, we have recently found that several chimeric adrenomedullin/adrenomedullin 2 peptides are potent CLR/RAMP receptor antagonists and self-assemble to form liquid gels. Among these analogs, the ADE651 analog, which potently inhibits CLR/RAMP1 receptor signaling, forms gels at a 6-20% level. Screening of ADE651 variants indicated that residues at the junctional region of this chimeric peptide are important for gaining the gel-forming capability. Gel-formation significantly slowed the passage of ADE651 molecules through Centricon filters. Consistently, subcutaneous injection of ADE651 gel in rats led to the sustained presence of ADE651 in circulation for >1 week. In addition, analysis of vascular blood flow in rat hindlimbs showed ADE651 significantly reduces CGRP-induced vasodilation. Because gel-forming antagonists could have direct and sustained access to target cells, ADE651 and related antagonists for CLR/RAMP receptors may represent promising candidates for targeting CGRP- and/or adrenomedullin-mediated headaches in migraine patients.

Fasudil Ameliorates Osteoporosis Following Myocardial Infarction by Regulating Cardiac Calcitonin Secretion

We hypothesis that Rho kinase inhibitor fasudil ameliorates osteoporosis following myocardial infarction (MI) by regulating cardiac calcitonin secretion. A mice model of MI and cultured neonatal cardiomyocytes exposed to hypoxia and serum deprivation (H/SD), and fibroblasts exposed to TGF-β were used, respectively. Cardiac function in vivo was assessed with echocardiography. Osteoporosis in vivo was assessed with X-ray and micro-CT. In vivo and in vitro studies used histological and immunohistochemical techniques, along with western blots. In mice post-MI, fasudil ameliorates the microstructure and bone metabolism of the lumbar, improved cardiac function, and attenuated myocardial fibrosis. In vitro, fasudil or αCGRP could effectively inhibit the proliferation of primary fibroblasts treated with TGF-β. Moreover, fasudil ameliorates the cardiac calcitonin secretion induced by MI in vivo or by H/SD in vitro. Our findings suggest that fasudil improved MI-induced osteoporosis by promoting cardiac secreting calcitonin.

A novel peptide HSP-17 ameliorates oxidative stress injury and apoptosis in H9c2 cardiomyocytes by activating the PI3K/Akt pathway

Background

Oxidative stress and cell apoptosis play pivotal roles in the pathogenesis of doxorubicin (DOX)-induced myocardial injury. Heat shock protein-derived peptide (HSP-17) is a peptide which is low-expressed in DOX treated mouse heart tissue. It has high bioactivity and interspecies sequence consistency, and is predicted to have myocardial protective effect.

Methods

Firstly, we added 1 µM DOX to H9c2 cell culture medium for 24 hours to construct the myocardial cytotoxicity model. Then we detected the effect of HSP-17 on DOX induced H9c2 cardiomyocyte injury by measuring cell viability and lactate dehydrogenase (LDH) level. In addition, reactive oxygen species (ROS) and tetraethylbenzimidazolylcarbocyanine iodide kits are used to evaluate the effect of the HSP-17 peptide on DOX-induced oxidative stress injury to cardiomyocytes, and the detection of apoptosis related proteins and flow cytometry were applied to detect the level of apoptosis. Furthermore, the protein expression levels [phosphorylated Akt (p-Akt) and phosphorylated PI3K (p-PI3K)] of the PI3K/Akt pathway were also detected by western blotting.

Results

We found that the HSP-17 peptide can increase cell viability, protect mitochondrial potential, reduce LDH levels, and reduce ROS and cardiomyocyte apoptosis. In addition, we also observed that HSP-17 upregulated the expression level of p-Akt, and LY294002, a typical inhibitor of PI3K/Akt, was found to eliminate the protective roles of HSP-17.

Conclusions

In conclusion, this study demonstrated that the HSP-17 peptide protected H9c2 cells against oxidative stress and apoptosis via PI3K/Akt pathway activation, which provides a new idea for the treatment of DOX-induced myocardial injury.

Case report: Monoclonal CGRP-antibody treatment in a migraine patient with a mutation in the mitochondrial single-strand binding protein (SSBP1)

Background

There is a growing body of mitochondrial disorders that are associated with headaches, albeit only one of them is currently listed in the latest International Classification of Headache Disorders, 3rd edition (ICHD-3). Headache frequency and headache presentation can vary widely in this respective patient group. Acute and preventive migraine treatment can be quite challenging—the use of several established medications is often limited due to their side effects in the setting of mitochondrial dysfunction and multi-organ disease.

Case presentation

Along with a review of the literature on treatment options in patients with mitochondrial disorders and migraine headaches, we present the case of a 23-year-old male with a homozygous mutation in the mitochondrial single-strand binding protein (SSBP1) with chronic migraine with aura. After failing several standard of care prophylactics due to either side effects or inefficacy, he was successfully treated with a monoclonal anti-CGRP-antibody as a preventive migraine treatment. The monoclonal antibody was well tolerated and showed adequate efficacy with a sustained &gt; 50% reduction in monthly headache days after 3 years of treatment.

Conclusion

Migraine is often challenging to treat in patients with mitochondriopathy due to therapy-limiting comorbidities. Monoclonal CGRP-antibodies might be a safe treatment option in the prevention of migraine headaches in patients with a mitochondrial disorder.

5-HT/CGRP pathway and Sumatriptan role in Covid-19

Coronavirus disease 2019 (Covid-19) is a pandemic caused by severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2). In Covid-19, there is uncontrolled activation of immune cells with a massive release of pro-inflammatory cytokines and the development of cytokine storm. These inflammatory changes induce impairment of different organ functions, including the central nervous system (CNS), leading to acute brain injury and substantial changes in the neurotransmitters, including serotonin (5-HT) and calcitonin gene-related peptide (CGRP), which have immunomodulatory properties through modulation of central and peripheral immune responses. In Covid-19, 5-HT neurotransmitters and CGRP could contribute to abnormal and atypical vascular reactivity. Sumatriptan is a pre-synaptic 5-HT (5-HT1D and 5-HT1B) agonist and inhibits the release of CGRP. Both 5-HT and CGRP seem to be augmented in Covid-19 due to underlying activation of inflammatory signaling pathways and hyperinflammation. In virtue of its anti-inflammatory and antioxidant properties with inhibition release of 5-HT and CGRP, Sumatriptan may reduce Covid-19 hyperinflammation. Therefore, Sumatriptan might be a novel potential therapeutic strategy in managing Covid-19. In conclusion, Sumatriptan could be an effective therapeutic strategy in managing Covid-19 through modulation of 5-HT neurotransmitters and inhibiting CGRP.

Genome-wide Meta-analysis Reveals New Gene Signatures and Potential Drug Targets of Hypertension

The prevalence of hypertension reported around the world is increasing and is an important public health challenge. This study was designed to explore the disease's genetic variations and to identify new hypertension-related genes and target proteins. We analyzed 22 publicly available Affymetrix cDNA datasets of hypertension using an integrated system-level framework involving differential expression genetic (DEG) analysis, data mining, gene enrichment, protein-protein interaction, microRNA analysis, toxicogenomics, gene regulation, molecular docking, and simulation studies. We found potential DEGs after screening out the extracellular proteins. We studied the functional role of seven shortlisted DEGs (ADM, EDN1, ANGPTL4, NFIL3, MSR1, CEBPD, and USP8) in hypertension after disease gene curation analysis. The expression profiling and cluster analysis showed significant variations and enriched GO terms. hsa-miR-365a-3p, hsa-miR-2052, hsa-miR-3065-3p, hsa-miR-603, hsa-miR-7113-3p, hsa-miR-3923, and hsa-miR-524-5p were identified as hypertension-associated miRNA targets for each gene using computational algorithms. We found functional interactions of source DEGs with target and important gene signatures including EGFR, AGT, AVP, APOE, RHOA, SRC, APOB, STAT3, UBC, LPL, APOA1, and AKT1 associated with the disease. These DEGs are mainly involved in fatty acid metabolism, myometrial pathways, MAPK, and G-alpha signaling pathways linked with hypertension pathogenesis. We predicted significantly disordered regions of 71.2, 48.8, and 45.4% representing the mutation in the sequence of NFIL3, USP8, and ADM, respectively. Regulation of gene expression was performed to find upregulated genes. Molecular docking analysis was used to evaluate Food and Drug Administration-approved medicines against the four DEGs that were overexpressed. For each elevated target protein, the three best drug candidates were chosen. Furthermore, molecular dynamics (MD) simulation using the target's active sites for 100 ns was used to validate these 12 complexes after docking. This investigation establishes the worth of systems genetics for finding four possible genes as potential drug targets for hypertension. These network-based approaches are significant for finding genetic variant data, which will advance the understanding of how to hasten the identification of drug targets and improve the understanding regarding the treatment of hypertension.

The Vascular-Dependent and -Independent Actions of Calcitonin Gene-Related Peptide in Cardiovascular Disease

The treatment of hypertension and heart failure remains a major challenge to healthcare providers. Despite therapeutic advances, heart failure affects more than 26 million people worldwide and is increasing in prevalence due to an ageing population. Similarly, despite an improvement in blood pressure management, largely due to pharmacological interventions, hypertension remains a silent killer. This is in part due to its ability to contribute to heart failure. Development of novel therapies will likely be at the forefront of future cardiovascular studies to address these unmet needs. Calcitonin gene-related peptide (CGRP) is a 37 amino acid potent vasodilator with positive-ionotropic and -chronotropic effects. It has been reported to have beneficial effects in hypertensive and heart failure patients. Interestingly, changes in plasma CGRP concentration in patients after myocardial infarction, heart failure, and in some forms of hypertension, also support a role for CGRP on hemodynamic functions. Rodent studies have played an important role thus far in delineating mechanisms involved in CGRP-induced cardioprotection. However, due to the short plasma half-life of CGRP, these well documented beneficial effects have often proven to be acute and transient. Recent development of longer lasting CGRP agonists may therefore offer a practical solution to investigating CGRP further in cardiovascular disease in vivo. Furthermore, pre-clinical murine studies have hinted at the prospect of cardioprotective mechanisms of CGRP which is independent of its hypotensive effect. Here, we discuss past and present evidence of vascular-dependent and -independent processes by which CGRP could protect the vasculature and myocardium against cardiovascular dysfunction.

Alpha-Calcitonin Gene Related Peptide: New Therapeutic Strategies for the Treatment and Prevention of Cardiovascular Disease and Migraine

Alpha-calcitonin gene-related peptide (α-CGRP) is a vasodilator neuropeptide of the calcitonin gene family. Pharmacological and gene knock-out studies have established a significant role of α-CGRP in normal and pathophysiological states, particularly in cardiovascular disease and migraines. α-CGRP knock-out mice with transverse aortic constriction (TAC)-induced pressure-overload heart failure have higher mortality rates and exhibit higher levels of cardiac fibrosis, inflammation, oxidative stress, and cell death compared to the wild-type TAC-mice. However, administration of α-CGRP, either in its native- or modified-form, improves cardiac function at the pathophysiological level, and significantly protects the heart from the adverse effects of heart failure and hypertension. Similar cardioprotective effects of the peptide were demonstrated in pressure-overload heart failure mice when α-CGRP was delivered using an alginate microcapsules-based drug delivery system. In contrast to cardiovascular disease, an elevated level of α-CGRP causes migraine-related headaches, thus the use of α-CGRP antagonists that block the interaction of the peptide to its receptor are beneficial in reducing chronic and episodic migraine headaches. Currently, several α-CGRP antagonists are being used as migraine treatments or in clinical trials for migraine pain management. Overall, agonists and antagonists of α-CGRP are clinically relevant to treat and prevent cardiovascular disease and migraine pain, respectively. This review focuses on the pharmacological and therapeutic significance of α-CGRP-agonists and -antagonists in various diseases, particularly in cardiac diseases and migraine pain.

Myocardial infarction reduces cardiac nociceptive neurotransmission through the vagal ganglia

Myocardial infarction causes pathological changes in the autonomic nervous system, which exacerbate heart failure and predispose to fatal ventricular arrhythmias and sudden death. These changes are characterized by sympathetic activation and parasympathetic dysfunction (reduced vagal tone). Reasons for the central vagal withdrawal and, specifically, whether myocardial infarction causes changes in cardiac vagal afferent neurotransmission that then affect efferent tone, remain unknown. The objective of this study was to evaluate whether myocardial infarction causes changes in vagal neuronal afferent signaling. Using in vivo neural recordings from the inferior vagal (nodose) ganglia and immunohistochemical analyses, structural and functional alterations in vagal sensory neurons were characterized in a chronic porcine infarct model and compared with normal animals. Myocardial infarction caused an increase in the number of nociceptive neurons but a paradoxical decrease in functional nociceptive signaling. No changes in mechanosensitive neurons were observed. Notably, nociceptive neurons demonstrated an increase in GABAergic expression. Given that nociceptive signaling through the vagal ganglia increases efferent vagal tone, the results of this study suggest that a decrease in functional nociception, possibly due to an increase in expression of inhibitory neurotransmitters, may contribute to vagal withdrawal after myocardial infarction.

Native CGRP Neuropeptide and Its Stable Analogue SAX, But Not CGRP Peptide Fragments, Inhibit Mucosal HIV-1 Transmission

Background

The vasodilator neuropeptide calcitonin gene-related peptide (CGRP) plays both detrimental and protective roles in different pathologies. CGRP is also an essential component of the neuro-immune dialogue between nociceptors and mucosal immune cells. We previously discovered that CGRP is endowed with anti-viral activity and strongly inhibits human immunodeficiency virus type 1 (HIV-1) infection, by suppressing Langerhans cells (LCs)-mediated HIV-1 trans-infection in-vitro and mucosal HIV-1 transmission ex-vivo. This inhibition is mediated via activation of the CGRP receptor non-canonical NFκB/STAT4 signaling pathway that induces a variety of cooperative mechanisms. These include CGRP-mediated increase in the expression of the LC-specific pathogen recognition C-type lectin langerin and decrease in LC-T-cell conjugates formation. The clinical utility of CGRP and modalities of CGRP receptor activation, for inhibition of mucosal HIV-1 transmission, remain elusive.

Methods

We tested the capacity of CGRP to inhibit HIV-1 infection in-vivo in humanized mice. We further compared the anti-HIV-1 activities of full-length native CGRP, its metabolically stable analogue SAX, and several CGRP peptide fragments containing its binding C-terminal and activating N-terminal regions. These agonists were evaluated for their capacity to inhibit LCs-mediated HIV-1 trans-infection in-vitro and mucosal HIV-1 transmission in human mucosal tissues ex-vivo.

Results

A single CGRP intravaginal topical treatment of humanized mice, followed by HIV-1 vaginal challenge, transiently restricts the increase in HIV-1 plasma viral loads but maintains long-lasting higher CD4+ T-cell counts. Similarly to CGRP, SAX inhibits LCs-mediated HIV-1 trans-infection in-vitro, but with lower potency. This inhibition is mediated via CGRP receptor activation, leading to increased expression of both langerin and STAT4 in LCs. In contrast, several N-terminal and N+C-terminal bivalent CGRP peptide fragments fail to increase langerin and STAT4, and accordingly lack anti-HIV-1 activities. Finally, like CGRP, treatment of human inner foreskin tissue explants with SAX, followed by polarized inoculation with cell-associated HIV-1, completely blocks formation of LC-T-cell conjugates and HIV-1 infection of T-cells.

Conclusion

Our results show that CGRP receptor activation by full-length CGRP or SAX is required for efficient inhibition of LCs-mediated mucosal HIV-1 transmission. These findings suggest that formulations containing CGRP, SAX and/or their optimized agonists/analogues could be harnessed for HIV-1 prevention.

LncRNA MIAT promotes hypoxia-induced H9C2 cell pyroptosis via binding to SF1 to inhibit CGRP transcription

NEW FINDINGS

What is the central question of this study? How does long non-coding RNA myocardial infarction-associated transcript (lncRNA MIAT) function in hypoxia-induced H9C2 cells? What is the main finding and its importance? LncRNA MIAT inhibited transcription of calcitonin gene-related peptide by binding to splicing factor 1, thereby promoting hypoxia-induced H9C2 cell pyroptosis. This study provides a new theoretical basis for the treatment of acute myocardial infarction by using lncRNA MIAT as a molecular target to mediate cardiomyocyte pyrodeath.

ABSTRACT

Hypoxia induces severe cardiomyocyte pyroptosis, contributing to acute myocardial infarction. The aim of this study was to analyse the molecular mechanism of long non-coding RNA myocardial infarction-associated transcript (lncRNA MIAT) in hypoxia-induced H9C2 cell pyroptosis. A hypoxic H9C2 cell model was established. Cell viability was detected via the Cell Counting Kit-8 method. Levels of lactate dehydrogenase, malondialdehyde and superoxide dismutase and expressions of pyroptotic markers, lncRNA MIAT, splicing factor 1 (SF1) and calcitonin gene-related peptide (CGRP) were detected via qRT-PCR. The subcellular localization of lncRNA MIAT was predicted and confirmed via LncATLAS and nuclear/cytosol fractionation assay. The binding relationships between lncRNA MIAT and SF1 and between SF1 and the CGRP promotor were verified via RNA immunoprecipitation. Rescue experiments were designed to confirm the role of lncRNA MIAT/SF1/CGRP in H9C2 cell pyroptosis. LncRNA MIAT was overexpressed in hypoxia-induced H9C2 cells. Hypoxia induced pyroptosis in H9C2 cells. Silencing of lncRNA MIAT enhanced cell viability and alleviated pyroptosis. LncRNA MIAT inhibited CGRP transcription via binding to SF1. Overexpression of SF1 promoted CGRP transcription and relieved H9C2 cell pyroptosis. Downregulation of CGRP reversed the role of silencing lncRNA MIAT in H9C2 cell pyroptosis. Overall, lncRNA MIAT inhibited CGRP transcription via binding to SF1, thereby promoting hypoxia-induced H9C2 cell pyroptosis.

The locus of Action of CGRPergic Monoclonal Antibodies Against Migraine: Peripheral Over Central Mechanisms

Migraine is a complex neurovascular disorder characterized by attacks of moderate to severe unilateral headache, accompanied by photophobia among other neurological signs. Although an arsenal of antimigraine agents is currently available in the market, not all patients respond to them. As Calcitonin Gene-Related Peptide (CGRP) plays a key role in the pathophysiology of migraine, CGRP receptor antagonists (gepants) have been developed. Unfortunately, further pharmaceutical development (for olcegepant and telcagepant) was interrupted due to pharmacokinetic issues observed during the Randomized Clinical Trials (RCT). On this basis, the use of monoclonal antibodies (mAbs; immunoglobulins) against CGRP or its receptor has recently emerged as a novel pharmacotherapy to treat migraines. RCT showed that these mAbs are effective against migraines producing fewer adverse events. Presently, the U.S. Food and Drug Administration approved four mAbs, namely: (i) erenumab; (ii) fremanezumab; (iii) galcanezumab; and (iv) eptinezumab. In general, specific antimigraine compounds exert their action in the trigeminovascular system, but the locus of action (peripheral vs. central) of the mAbs remains elusive. Since these mAbs have a molecular weight of ∼150 kDa, some studies rule out the relevance of their central actions as they seem unlikely to cross the Blood-Brain Barrier (BBB). Considering the therapeutic relevance of this new class of antimigraine compounds, the present review has attempted to summarize and discuss the current evidence on the probable sites of action of these mAbs.

The PLGA nanoparticles for sustainable release of CGRP to ameliorate the inflammatory and vascular disorders in the lung of CGRP-deficient rats

The calcitonin gene-related peptide (CGRP) has been demonstrated relating to vascular and inflammatory regulations not only the nerve systems. As the anti-inflammation factor and the most potent vasodilator, the CGRP holds therapeutic potentials for the treatment of cardiovascular diseases which was, however, limited by its peptide nature and short half-life. With advantages in improving the stability, circulation time and protection from degradation, the nanoparticles were promising as delivery carriers for the peptide. Nevertheless, few nanoparticulate systems were developed to deliver the CGRP peptide for the modulation of vascular or inflammatory functions instead of neural regulation. In this study, the CGRP was encapsulated into the poly (lactic-co-glycolic acid) (PLGA) nanoparticle for sustained release of CGRP in vivo. The nanoparticles recovered the systemic level of CGRP and the vascular inflammatory factors in the CGRP^+/− rats comparing to the administration of (Dulbecco's Phosphate Buffered Saline) DPBS or peptide only. With the decrease of vascular wall thickness and the attenuation of the T cell infiltration in the lung, the polymer based CGRP delivery system showed potentials to facilitate the therapeutic effects of the CGRP which may help for the development of CGRP-based therapy in vascular and inflammatory disorder related diseases.

Npas4 impairs fear memory via phosphorylated HDAC5 induced by CGRP administration in mice

The relationships among neuropeptide, calcitonin gene-related peptide (CGRP), and memory formation remain unclear. Here, we showed that the intracerebroventricular administration of CGRP impaired the traumatic fear memories, in a widely studied animal model of post-traumatic stress disorder. We found that CGRP administration suppressed fear memory by increasing neuronal PAS domain protein 4 (Npas4), phosphorylated histone deacetylase 5 (HDAC5), and protein kinase D (PKD). We also discovered that Npas4 knockdown inhibited CGRP-mediated fear memory. CGRP decreased the binding between HDAC5 and the Npas4 enhancer site and increased the binding between acetylated histone H3 and the Npas4 enhancer site. The pharmacological inhibition or knockdown of PKD attenuated the CGRP-mediated impairment of fear memory and the increased phosphorylation of HDAC5 and Npas4 expression. Our findings demonstrated that the CGRP-PKD pathway was associated with the histone H3 acetylation-Npas4 pathway. These results suggested a novel function for CGRP on fear memory, through epigenetic regulation.

Autocrine Signaling in Cardiac Remodeling: A Rich Source of Therapeutic Targets

The myocardium consists of different cell types, of which endothelial cells, cardiomyocytes, and fibroblasts are the most abundant. Communication between these different cell types, also called paracrine signaling, is essential for normal cardiac function, but also important in cardiac remodeling and heart failure. Systematic studies on the expression of ligands and their corresponding receptors in different cell types showed that for 60% of the expressed ligands in a particular cell, the receptor is also expressed. The fact that many ligand-receptor pairs are present in most cells, including the major cell types in the heart, indicates that autocrine signaling is a widespread phenomenon. Autocrine signaling in cardiac remodeling and heart failure is involved in all pathophysiological mechanisms generally observed: hypertrophy, fibrosis, angiogenesis, cell survival, and inflammation. Herein, we review ligand-receptor pairs present in the major cardiac cell types based on RNA-sequencing expression databases, and we review current literature on extracellular signaling proteins with an autocrine function in the heart; these include C-type natriuretic peptide, fibroblast growth factors 2, F21, and 23, macrophage migration inhibitory factor, heparin binding-epidermal growth factor, angiopoietin-like protein 2, leptin, adiponectin, follistatin-like 1, apelin, neuregulin 1, vascular endothelial growth factor, transforming growth factor β, wingless-type integration site family, member 1-induced secreted protein-1, interleukin 11, connective tissue growth factor/cellular communication network factor, and calcitonin gene‒related peptide. The large number of autocrine signaling factors that have been studied in the literature supports the concept that autocrine signaling is an essential part of myocardial biology and disease.

A Novel Alginate-Based Delivery System for the Prevention and Treatment of Pressure-Overload Induced Heart Failure

Background: α-CGRP (alpha-calcitonin gene related peptide) is a cardioprotective neuropeptide. Our recent study demonstrated that the administration of native α-CGRP, using osmotic mini-pumps, protected against transverse aortic constriction (TAC) pressure-induced heart failure in mice. However, the short half-life of peptides and the non-applicability of osmotic pumps in humans limits the use of α-CGRP as a therapeutic agent for heart failure (HF). Here, we sought to comprehensively study a novel α-CGRP delivery system using alginate microcapsules to determine its bioavailability in vivo and to test for cardioprotective effects in HF mice.

Methods: Native α-CGRP filled alginate microcapsules (200 µm diameter) were prepared using an electrospray method. The prepared alginate-α-CGRP microcapsules were incubated with rat cardiac H9c2 cells, mouse cardiac HL-1 cells, and human umbilical vein endothelial cells (HUVECs), and the cytotoxicity of the alginate-α-CGRP microcapsules was measured by a trypan-blue cell viability assay and a calcium dye fluorescent based assay. The efficacy of the alginate-α-CGRP microcapsules was tested in a TAC-pressure overload mouse model of heart failure. Male C57BL6 mice were divided into four groups: sham, sham-alginate-α-CGRP, TAC-only, and TAC-alginate-α-CGRP, and the TAC procedure was performed in the TAC-only and TAC-alginate-α-CGRP groups of mice to induce pressure-overload heart failure. After 2 or 15 days post-TAC, alginate-α-CGRP microcapsules (containing an α-CGRP dose of 6 mg/kg/mouse) were administered subcutaneously on alternate days, for 28 days, and echocardiography was performed weekly. After 28 days of peptide delivery, the mice were sacrificed and their hearts were collected for histological and biochemical analyses.

Results: Our in vitro cell culture assays showed that alginate-α-CGRP microcapsules did not affect the viability of the cell lines tested. The alginate-α-CGRP microcapsules released their peptides for an extended period of time. Our echocardiography, biochemical, and histology data from HF mice demonstrated that the administration of alginate-α-CGRP microcapsules significantly improved all cardiac parameters examined in TAC-mice. When compared to sham mice, TAC significantly decreased cardiac functions (as determined by fraction shortening and ejection fraction) and markedly increased heart and lung weight, left ventricle (LV) cardiac cell size, cardiac apoptosis, and oxidative stress. In contrast, the administration of alginate-α-CGRP microcapsules significantly attenuated the increased heart and lung weight, LV cardiac cell size, apoptosis, and oxidative stress in TAC mice.

Conclusion: Our results demonstrate that the encapsulation of α-CGRP in an alginate polymer is an effective strategy to improve peptide bioavailability in plasma and increase the duration of the therapeutic effect of the peptide throughout the treatment period. Furthermore, alginate mediates α-CGRP delivery, either prior to the onset or after the initiation of the symptom progression of pressure-overload, improves cardiac function, and protects hearts against pressure-induced HF.

Cannabidiol selectively inhibits the contraction of rat small resistance arteries: Possible role for CGRP and voltage-gated calcium channels

The pharmacology of cannabidiol, the non-psychoactive major component of Cannabis sativa, is of growing interest as it becomes more widely prescribed. This study aimed to examine the effects of cannabidiol on a wide range of contractile agents in rat small resistance arteries, in comparison with large arteries, and to explore its mechanism of action. The vascular actions of cannabidiol were also contrasted with effects on the contractions of bronchial, urogenital, cardiac and skeletal muscles. Isolated small or large arteries were incubated with cannabidiol (0.3-3 μM) or vehicle and concentration-contraction response curves were completed to various agents, including endothelin-1, arginine vasopressin, methoxamine, 5-HT, α-methyl 5-HT and U46619. In small arteries, the effects of cannabidiol were tested in the presence of antagonists of CB1 or CB2 receptors, calcitonin gene-related peptide (CGRP), nitric oxide synthase, cyclooxygenase, PPARγ or a combination. The role of L-type voltage-operated calcium channels was also assessed. Cannabidiol 1-3 μM significantly inhibited the contraction of small resistance arteries to all tested agents through a combination of mechanisms that include CGRP and L-type calcium channels. However, large arteries were insensitive to cannabidiol. Cannabidiol (10-100 μM) was largely without effect in bronchi, atria and hemidiaphragm, but 100 μM attenuated maximum contractions in vasa deferentia. Cannabidiol's effects in the clinical range (1-3 μM) appear to be specific to small resistance arteries. This high sensitivity of the resistance arterial circulation to cannabidiol may offer a therapeutic opportunity in peripheral vascular disease that excludes off-target sites such as the heart and non-vascular smooth muscle.

Effect of Chinese Medicine Xinmaitong on Blood Pressure in Spontaneously Hypertensive Rats

Objective

To investigate the effect of traditional Chinese antihypertensive compound Xinmaitong on blood pressure and vasoactive factors of vasoconstrictor endothelin-1 (ET-1) and vasodilator calcitonin gene related peptide (CGRP) in spontaneously hypertensive rats (SHRs) with early stage hypertension.

Methods

Twenty male SHRs were randomly divided into two groups: 10 for hypertensive control group and 10 for hypertensive treatment group. In addition, 10 Wistar rats were used as the normal control group without any intervention. SHRs of hypertensive treatment group were orally treated with Xinmaitong, while the hypertensive control group was treated with the normal saline (NS) for a total of eight weeks. The blood pressure in SHRs was examined before and after the end of the eight-week study. After treatment, the rats were killed and the blood samples were collected to measure plasma levels of ET-1 and CGRP by ELISA method, respectively. Meanwhile, the aorta rings were isolated for measuring the mRNA expression of ET-1 and CGRP by PCR. Moreover, the protein levels of ET-1 and CGRP were studied by immunohistochemical.

Results

Daily oral administration of Xinmaitong resulted in significant fall in the SHRs' blood pressure, including systolic and diastolic blood pressures (SBP and DBP), mean blood pressure (MBP), and pulse pressure (PP). The plasma ET-1 levels were reduced and CGRP increased. In parallel, the mRNA and protein expression of ET-1 were decreased, whereas the mRNA and protein expression of CGRP were enhanced in SHRs treated with Xinmaitong.

Conclusion

The present study demonstrated for the first time that Xinmaitong leads to the fall in blood pressure of SHRs and that this antihypertensive effect is, at least in part, due to improvement of arterial tone.

Natriuretic Peptides as the Basis of Peptide Drug Discovery for Cardiovascular Diseases

Cardiovascular diseases (CVDs) are the leading global cause of death, accounting for more than 17.6 million deaths per year in 2016, a number that is expected to grow to more than 23.6 million by 2030. While many technologies are currently under investigation to improve the therapeutic outcome of CVD complications, only a few medications have been approved. Therefore, new approaches to treat CVD are urgently required. Peptides regulate numerous physiological processes, mainly by binding to specific receptors and inducing a series of signals, neurotransmissions or the release of growth factors. Importantly, peptides have also been shown to play an important role in the circulatory system both in physiological and pathological conditions. Peptides, such as angiotensin II, endothelin, urotensin-II, urocortins, adrenomedullin and natriuretic peptides have been implicated in the control of vascular tone and blood pressure as well as in CVDs such as congestive heart failure, atherosclerosis, coronary artery disease, and pulmonary and systemic hypertension. Hence it is not surprising that peptides are becoming important therapeutic leads in CVDs. This article will review the current knowledge on peptides and their role in the circulatory system, focusing on the physiological roles of natriuretic peptides in the cardiovascular system and their implications in CVDs.

Afferent renal innervation in anti-Thy1.1 nephritis in rats

Afferent renal nerves exhibit a dual function controlling central sympathetic outflow via afferent electrical activity and influencing intrarenal immunological processes by releasing peptides such as calcitonin gene-related peptide (CGRP). We tested the hypothesis that increased afferent and efferent renal nerve activity occur with augmented release of CGRP in anti-Thy1.1 nephritis, in which enhanced CGRP release exacerbates inflammation. Nephritis was induced in Sprague-Dawley rats by intravenous injection of OX-7 antibody (1.75 mg/kg), and animals were investigated neurophysiologically, electrophysiologically, and pathomorphologically 6 days later. Nephritic rats exhibited proteinuria (169.3 ± 10.2 mg/24 h) with increased efferent renal nerve activity (14.7 ± 0.9 bursts/s vs. control 11.5 ± 0.9 bursts/s, n = 11, P < 0.05). However, afferent renal nerve activity (in spikes/s) decreased in nephritis (8.0 ± 1.8 Hz vs. control 27.4 ± 4.1 Hz, n = 11, P < 0.05). In patch-clamp recordings, neurons with renal afferents from nephritic rats showed a lower frequency of high activity following electrical stimulation (43.4% vs. 66.4% in controls, P < 0.05). In vitro assays showed that renal tissue from nephritic rats exhibited increased CGRP release via spontaneous (14 ± 3 pg/mL vs. 6.8 ± 2.8 pg/ml in controls, n = 7, P < 0.05) and stimulated mechanisms. In nephritic animals, marked infiltration of macrophages in the interstitium (26 ± 4 cells/mm²) and glomeruli (3.7 ± 0.6 cells/glomerular cross-section) occurred. Pretreatment with the CGRP receptor antagonist CGRP_8-37 reduced proteinuria, infiltration, and proliferation. In nephritic rats, it can be speculated that afferent renal nerves lose their ability to properly control efferent sympathetic nerve activity while influencing renal inflammation through increased CGRP release.