RESUMO
INTRODUCTION: We aimed to analyze the testicular histopathology of men who died with active COVID-19 infection. METHODS: We performed autopsy of eight consecutive men who died of COVID-19 pneumonia. Lung and testis tissue of all men were stained for SARS-CoV-2 nucleocapsid, angiotensin-converting enzyme 2 (ACE-2) receptor immunohistochemistry (IHC). H&E was performed to assess for spermatogenesis and evidence of testicle tissue damage. Reverse transcriptase polymerase chain reaction (RT-PCR) analysis for SARS-CoV-2 was performed on matched lung and bilateral testicular tissue samples from all men. RESULTS: Patient age ranged from 50-79 years. SARS-CoV-2 viral RNA was detected by RTPCR in testis tissue in one man. All eight testicle specimens that underwent IHC for ACE2 receptor showed uniformly strong immunoreactivity against all testicle cell populations. By H&E, all testis specimens showed no inflammation, vascular thrombosis, vasculitis, or morphological evidence of viral changes. One case showed diminished but not absent spermatogenesis, consistent with patient age. CONCLUSIONS: Our results suggest that SARS-CoV-2 is unlikely to affect male fertility. Contrary to all prior histological studies, our results showed no evidence of damage to reproductive tissues that might impair fertility.
RESUMO
It has been proposed that men hospitalised with COVID-19 be treated with oestrogen or progesterone to improve COVID-19 outcomes. Transgender women (male-to-female) are routinely treated with oestrogen or oestrogen +progesterone for feminisation which provides a model for the effect of feminising hormones on testicular tissue. Our goal was to analyse differences in ACE-2 expression in testicles of trans-women taking oestrogen or oestrogen +progesterone. Orchiectomy specimens were collected from trans-women undergoing gender-affirming surgery, who were taking oestrogen or oestrogen+progesterone preoperatively. For controls, we used benign orchiectomy specimens from cis-gender men. All specimens were stained with H&E, Trichrome (fibrosis), insulin-like 3 antibody (Leydig cell) and ACE-2 IHC. Cells per high-powered field were counted by cell type (Leydig, Sertoli and Germ). Stain intensity was rated on a 0-2 scale. On immunohistochemistry staining for Leydig cells and ACE-2 staining, the oestrogen+progesterone cohort had fewer Leydig cells compared with controls. The oestrogen+progesterone cohort also had greater degree of tissue fibrosis compared with controls and the oestrogen cohort. This work supports the hopeful possibility that a short course of progesterone (or oestrogen+progesterone) could downregulate ACE-2 to protect men from COVID-19 infection.
Assuntos
Enzima de Conversão de Angiotensina 2 , Estrogênios , Enzima de Conversão de Angiotensina 2/efeitos dos fármacos , Enzima de Conversão de Angiotensina 2/genética , COVID-19 , Estrogênios/farmacologia , Feminino , Humanos , Células Intersticiais do Testículo , Masculino , SARS-CoV-2 , TestículoRESUMO
COVID-19 pandemic has infected more than 154 million people worldwide and caused more than 3.2 million deaths. It is transmitted by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and affects the respiratory tract as well as extra-pulmonary systems, including the pancreas, that express the virus entry receptor, Angiotensin-Converting Enzyme 2 (ACE2) receptor. Importantly, the endocrine and exocrine pancreas, the latter composed of ductal and acinar cells, express high levels of ACE2, which correlates to impaired functionality characterized as acute pancreatitis observed in some cases presenting with COVID-19. Since acute pancreatitis is already one of the most frequent gastrointestinal causes of hospitalization in the U.S. and the majority of studies investigating the effects of SARS-CoV-2 on the pancreas are clinical and observational, we utilized human iPSC technology to investigate the potential deleterious effects of SARS-CoV-2 infection on iPSC-derived pancreatic cultures containing endocrine and exocrine cells. Interestingly, iPSC-derived pancreatic cultures allow SARS-CoV-2 entry and establish infection, thus perturbing their normal molecular and cellular phenotypes. The infection increased a key cytokine, CXCL12, known to be involved in inflammatory responses in the pancreas. Transcriptome analysis of infected pancreatic cultures confirmed that SARS-CoV-2 hijacks the ribosomal machinery in these cells. Notably, the SARS-CoV-2 infectivity of the pancreas was confirmed in post-mortem tissues from COVID-19 patients, which showed co-localization of SARS-CoV-2 in pancreatic endocrine and exocrine cells and increased the expression of some pancreatic ductal stress response genes. Thus, we demonstrate that SARS-CoV-2 can directly infect human iPSC-derived pancreatic cells with strong supporting evidence of presence of the virus in post-mortem pancreatic tissue of confirmed COVID-19 human cases. This novel model of iPSC-derived pancreatic cultures will open new avenues for the comprehension of the SARS-CoV-2 infection and potentially establish a platform for endocrine and exocrine pancreas-specific antiviral drug screening.
Assuntos
COVID-19 , Pancreatite , Doença Aguda , Humanos , Pâncreas , Pandemias , SARS-CoV-2RESUMO
RATIONALE: Biobanks of patient tissues have emerged as essential resources in biomedical research. Optimal cutting temperature compound (OCT) blends have shown to provide stability to the embedded tissue and are compatible with spectroscopic methods, such as infrared (IR) and Raman spectroscopy. Data derived from omics-methods are only useful if tissue damage caused by storage in OCT blends is minimal and well understood. In this context, we investigated the suitability of OCT storage for heart tissue destined for liquid chromatography/tandem mass spectrometry (LC/MS/MS) lipidomic studies. METHODS: To determine the compatibility of OCT storage with LC/MS/MS lipidomics studies. The lipid profiles of macaque heart tissue snap-frozen in liquid nitrogen or stored in an OCT blend were evaluated. RESULTS: We have evaluated a lipid extraction protocol suitable for OCT-embedded tissue that is compatible with LC/MS/MS. We annotated and evaluated the profiles of 306 lipid species from tissues stored in OCT or liquid nitrogen. For most of the lipid species (95.4%), the profiles were independent of the storage conditions. However, 4.6% of the lipid species; mainly plasmalogens, were affected by the storage method. CONCLUSIONS: This study shows that OCT storage is compatible with LC-MS/MS lipidomics of heart tissue, facilitating the use of biobanked tissue samples for future studies.
Assuntos
Cromatografia Líquida/métodos , Lipidômica/métodos , Lipídeos/química , Miocárdio/química , Miocárdio/metabolismo , Preservação Biológica/métodos , Espectrometria de Massas em Tandem/métodos , Animais , Coração , Macaca , Polímeros/química , Inclusão do TecidoRESUMO
CONTEXT.: Myocardial fibrosis underpins a number of cardiovascular conditions and is difficult to identify with standard histologic techniques. Challenges include imaging, defining an objective threshold for classifying fibrosis as mild or severe, and understanding the molecular basis for these changes. OBJECTIVE.: To develop a novel, rapid, label-free approach to accurately measure and quantify the extent of fibrosis in cardiac tissue using infrared spectroscopic imaging. DESIGN.: We performed infrared spectroscopic imaging and combined that with advanced machine learning-based algorithms to assess fibrosis in 15 samples from patients belonging to the following 3 classes: (1) patients with nonpathologic (control) donor hearts, (2) patients undergoing transplant, and (3) patients undergoing implantation of a ventricular assist device. RESULTS.: Our results show excellent sensitivity and accuracy for detecting myocardial fibrosis, as demonstrated by a high area under the curve of 0.998 in the receiver operating characteristic curve measured from infrared imaging. Fibrosis of various morphologic subtypes were demonstrated with virtually generated picrosirius red images, which showed good visual and quantitative agreement (correlation coefficient = 0.92, ρ = 7.76 × 10-15) with stained images of the same sections. Underlying molecular composition of the different subtypes was investigated with infrared spectra showing reproducible differences presumably arising from differences in collagen subtypes and/or crosslinking. CONCLUSIONS.: Infrared imaging can be a powerful tool in studying myocardial fibrosis and gleaning insights into the underlying chemical changes that accompany it. Emerging methods suggest that the proposed approach is compatible with conventional optical microscopy, and its consistency makes it translatable to the clinical setting for real-time diagnoses as well as for objective and quantitative research.
Assuntos
Transplante de Coração , Corantes , Fibrose , Humanos , Microscopia , Doadores de TecidosRESUMO
OBJECTIVE: We sought to determine the extent of SARS-CoV-2 seroprevalence and the factors associated with seroprevalence across a diverse cohort of healthcare workers. DESIGN: Observational cohort study of healthcare workers, including SARS-CoV-2 serology testing and participant questionnaires. SETTINGS: A multisite healthcare delivery system located in Los Angeles County. PARTICIPANTS: A diverse and unselected population of adults (n=6062) employed in a multisite healthcare delivery system located in Los Angeles County, including individuals with direct patient contact and others with non-patient-oriented work functions. MAIN OUTCOMES: Using Bayesian and multivariate analyses, we estimated seroprevalence and factors associated with seropositivity and antibody levels, including pre-existing demographic and clinical characteristics; potential COVID-19 illness-related exposures; and symptoms consistent with COVID-19 infection. RESULTS: We observed a seroprevalence rate of 4.1%, with anosmia as the most prominently associated self-reported symptom (OR 11.04, p<0.001) in addition to fever (OR 2.02, p=0.002) and myalgias (OR 1.65, p=0.035). After adjusting for potential confounders, seroprevalence was also associated with Hispanic ethnicity (OR 1.98, p=0.001) and African-American race (OR 2.02, p=0.027) as well as contact with a COVID-19-diagnosed individual in the household (OR 5.73, p<0.001) or clinical work setting (OR 1.76, p=0.002). Importantly, African-American race and Hispanic ethnicity were associated with antibody positivity even after adjusting for personal COVID-19 diagnosis status, suggesting the contribution of unmeasured structural or societal factors. CONCLUSION AND RELEVANCE: The demographic factors associated with SARS-CoV-2 seroprevalence among our healthcare workers underscore the importance of exposure sources beyond the workplace. The size and diversity of our study population, combined with robust survey and modelling techniques, provide a vibrant picture of the demographic factors, exposures and symptoms that can identify individuals with susceptibility as well as potential to mount an immune response to COVID-19.
Assuntos
Anticorpos Antivirais/sangue , COVID-19/diagnóstico , Pessoal de Saúde , Estudos Soroepidemiológicos , Adulto , Teorema de Bayes , COVID-19/imunologia , Teste Sorológico para COVID-19 , Estudos de Coortes , Estudos Transversais , Feminino , Humanos , Los Angeles/epidemiologia , Masculino , Pessoa de Meia-Idade , SARS-CoV-2/imunologiaRESUMO
BACKGROUND: The relationship between physical heart failure (HF) symptoms and pathophysiological mechanisms is unclear. OBJECTIVE: To quantify the relationship between plasma ß-adrenergic receptor kinase-1 (ßARK1) and physical symptoms among adults with HF. METHODS: We performed a secondary analysis of data collected from two studies of adults with HF. Plasma ßARK1 was quantified using an enzyme-linked immunosorbent assay. Physical symptoms were measured with the HF Somatic Perception Scale (HFSPS). Generalized linear modeling was used to quantify the relationship between ßARK1 and HFSPS scores. RESULTS: The average age (n = 94) was 54.5 ± 13.1 years, 76.6% were male, and a majority (83.0%) had Class III or IV HF. ßARK1 was significantly associated with HFSPS scores (ß = 0.22 ± 0.10, p = 0.038), adjusting for other predictors of physical symptoms (model R2 = 0.250, F(7, 70) = 3.34, p = 0.004). CONCLUSIONS: Higher ßARK1 is associated with worse physical HF symptoms, pinpointing a potential pathophysiologic underpinning.
Assuntos
Quinase 2 de Receptor Acoplado a Proteína G/sangue , Insuficiência Cardíaca/fisiopatologia , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
Platelet apheresis units are transfused into patients to mitigate or prevent bleeding. In a hospital, platelet apheresis units are transported from the transfusion service to the healthcare teams via two methods: a pneumatic tubing system (PTS) or ambulatory transport. Whether PTS transport affects the activity and utility of platelet apheresis units is unclear. We quantified the gravitational forces and transport time associated with PTS and ambulatory transport within our hospital. Washed platelets and supernatants were prepared from platelet apheresis units prior to transport as well as following ambulatory or PTS transport. For each group, we compared resting and agonist-induced platelet activity and platelet aggregate formation on collagen or von Willebrand factor (VWF) under shear, platelet VWF-receptor expression and VWF multimer levels. Subjection of platelet apheresis units to rapid acceleration/deceleration forces during PTS transport did not pre-activate platelets or their ability to activate in response to platelet agonists as compared to ambulatory transport. Platelets within platelet apheresis units transported via PTS retained their ability to adhere to surfaces of VWF and collagen under shear, although platelet aggregation on collagen and VWF was diminished as compared to ambulatory transport. VWF multimer levels and platelet GPIb receptor expression was unaffected by PTS transport as compared to ambulatory transport. Subjection of platelet apheresis units to PTS transport did not significantly affect the baseline or agonist-induced levels of platelet activation as compared to ambulatory transport. Our case study suggests that PTS transport may not significantly affect the hemostatic potential of platelets within platelet apheresis units.
Assuntos
Remoção de Componentes Sanguíneos , Plaquetas/metabolismo , Unidades Hospitalares , Ativação Plaquetária , Transfusão de Plaquetas , Meios de Transporte/métodos , Aceleração , Desaceleração , Desenho de Equipamento , Gravitação , Humanos , Agregação Plaquetária , Testes de Função Plaquetária , Complexo Glicoproteico GPIb-IX de Plaquetas/metabolismo , Fator de von Willebrand/metabolismoRESUMO
Patients with heart failure have been traditionally treated with a pharmacology-based approach, diet, exercise, and rehabilitation for reducing symptoms, hospitalizations, and mortality. We have developed a solid conceptual framework for music listening-based protocols, showing how music may have a broad range of positive effects on cardiovascular health through psychoneuroimmunoendocrinological pathways.
Assuntos
Fenômenos Bioquímicos , Insuficiência Cardíaca/terapia , Musicoterapia/normas , Humanos , Musicoterapia/métodosRESUMO
Thromboembolic complications are a significant cause of mortality and re-hospitalization in heart failure (HF) patients. One source of thrombi is the ventricular endocardial surface that becomes increasingly pro-thrombotic as HF progresses. Anticoagulation comes with bleeding risks so identifying therapeutic agents for improving cardiac endothelial health are of critical clinical importance. Endocardial endothelial cells are closely apposed to cardiac sympathetic nerves. In HF, cardiac sympathetic nerves are dysregulated and promote disease progression. Whether endocardial endothelial health and function is impacted by sympathetic dysregulation in HF is unknown. Also unexplored is the impact of neuropeptides, such as galanin and neuropeptide Y (NPY), co-released from sympathetic nerve terminals, on endothelial health. In this study we examined the effect of sympathetic nerve-released neurotransmitters and neuropeptides on the procoagulant phenotype of cultured human endocardial endothelial cells from HF patients. As a functional readout of procoagulant state we examined thrombin-mediated von Willebrand factor (vWF) extrusion and multimer expression. We demonstrate that vWF extrusion and multimer expression is promoted by thrombin, that isoproterenol (a beta-adrenergic receptor agonist) augments this effect, whereas co-treatment with the beta-blockers propranolol and carvedilol blocks this effect. We also show that vWF extrusion and multimer expression is attenuated by treatment with the neuropeptide galanin, but not with NPY. Our results are consistent with a protective role of beta-blockers and galanin on endocardial endothelial health in heart failure. Improving endothelial health through galanin therapy is a future clinical application of this study.
Assuntos
Células Endoteliais/metabolismo , Galanina/metabolismo , Insuficiência Cardíaca/metabolismo , Ventrículos do Coração/metabolismo , Agonistas Adrenérgicos beta/farmacologia , Antagonistas Adrenérgicos beta/farmacologia , Adulto , Idoso , Antitrombinas/administração & dosagem , Antitrombinas/metabolismo , Carbazóis/farmacologia , Carvedilol , Células Cultivadas , Células Endoteliais/efeitos dos fármacos , Células Endoteliais/patologia , Galanina/administração & dosagem , Insuficiência Cardíaca/tratamento farmacológico , Insuficiência Cardíaca/patologia , Ventrículos do Coração/efeitos dos fármacos , Ventrículos do Coração/patologia , Humanos , Isoproterenol/farmacologia , Masculino , Pessoa de Meia-Idade , Neuropeptídeo Y/administração & dosagem , Neuropeptídeo Y/metabolismo , Fenótipo , Propanolaminas/farmacologia , Propranolol/farmacologia , Multimerização Proteica , Trombina/administração & dosagem , Trombina/metabolismoRESUMO
AIMS: To describe a conceptual framework and to test the effectiveness of a recorded music-listening protocol on symptom burden and quality of life in heart failure (HF) patients. BACKGROUND: Heart failure is an important public health problem. Many HF patients experience symptoms burden and poor quality of life, even with current improvements in pharmacological treatments. Recorded music listening has been shown to improve outcomes in cardiovascular patients, but it has never been tested on HF patients and with a specific music protocol and a randomized controlled trial methodology. METHODS: This study is a multicenter blinded randomized controlled trial that will involve 150 patients. Eligible patients will have a diagnosis of HF, in New York Heart Association functional classification of I to III, and will be recruited from 3 large hospitals in Northern Italy. Patients will be randomly allocated in a 1:1 ratio to receive recorded music-listening intervention with or without standard care for 3 months. Data will be collected at baseline and at the end of the first, second, and third month during the intervention, and at 6 months for follow-up. The following variables will be collected from HF patients with validated protocols: quality of life (primary endpoint), use of emergency services, rehospitalization rates, all cause mortality, self-care, somatic symptoms, quality of sleep, anxiety and depression symptoms, and cognitive function. DISCUSSION: This study will examine the effect of recorded music listening on HF patients and will inform clinical practice. If the findings are found to be positive, the protocol could be used as a tool for evidence-based applications of recorded music in HF patients. The framework developed in this study may be helpful for future research focused on the effects of music in HF patients.
Assuntos
Insuficiência Cardíaca/terapia , Estudos Multicêntricos como Assunto , Musicoterapia , Ensaios Clínicos Controlados Aleatórios como Assunto , Humanos , Qualidade de VidaRESUMO
OBJECTIVE: An experimental model of endocardial thrombosis has not been developed and endocardial endothelial dysfunction in heart failure (HF) is understudied. We sought to determine whether disruption of the endothelial anti-coagulant activated protein C (APC) pathway in CREBA133 HF mice promotes endocardial thrombosis in the acute decompensated phase of the disease, and whether alterations in von Willebrand factor (vWF) secretion from HF endocardium reduces thrombus formation as HF stabilizes. APPROACH AND RESULTS: Echocardiography was used to follow HF development and to detect endocardial thrombi in CREBA133 mice. Endocardial thrombi incidence was confirmed with immunohistochemistry and histology. In early and acute decompensated phases of HF, CREBA133 mice had the highest incidence of endocardial thrombi and these mice also had a shorter tail-bleeding index consistent with a pro-thrombotic milieu. Both APC generation, and expression of receptors that promote APC function (thrombomodulin, endothelial protein C receptor, protein S), were suppressed in the endocardium of acute decompensated HF mice. However, in stable compensated HF mice, an attenuation occurred for vWF protein content and secretion from endocardial endothelial cells, vWF-dependent platelet agglutination (by ristocetin), and thrombin generation on the endocardial surface. CONCLUSIONS: CREBA133 mice develop HF and endocardial endothelial dysfunction. Attenuation of the anti-coagulant APC pathway promotes endocardial thrombosis in early and acute decompensated phases of HF. However, in stable compensated HF mice, disruptions in endothelial vWF expression and extrusion may actually reduce the incidence of endocardial thrombosis.
Assuntos
Endocárdio/metabolismo , Cardiopatias/fisiopatologia , Insuficiência Cardíaca/fisiopatologia , Proteína C/metabolismo , Trombose/fisiopatologia , Fator de von Willebrand/metabolismo , Animais , Anticoagulantes/química , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/genética , Modelos Animais de Doenças , Ecocardiografia , Células Endoteliais/citologia , Feminino , Hemodinâmica , Imuno-Histoquímica , Masculino , Camundongos , Camundongos Transgênicos , Fenótipo , Agregação Plaquetária , Trombina/metabolismo , Trombose/metabolismoRESUMO
This chapter addresses the role of neurotrophins in the development of the heart, blood vessels, and neural circuits that control cardiovascular function, as well as the role of neurotrophins in the mature cardiovascular system. The cardiovascular system includes the heart and vasculature whose functions are tightly controlled by the nervous system. Neurons, cardiomyocytes, endothelial cells, vascular smooth muscle cells, and pericytes are all targets for neurotrophin action during development. Neurotrophin expression continues throughout life, and several common pathologies that impact cardiovascular function involve changes in the expression or activity of neurotrophins. These include atherosclerosis, hypertension, diabetes, acute myocardial infarction, and heart failure. In many of these conditions, altered expression of neurotrophins and/or neurotrophin receptors has direct effects on vascular endothelial and smooth muscle cells in addition to effects on nerves that modulate vascular resistance and cardiac function. This chapter summarizes the effects of neurotrophins in cardiovascular physiology and pathophysiology.
Assuntos
Fenômenos Fisiológicos Cardiovasculares , Fatores de Crescimento Neural/fisiologia , Animais , Diabetes Mellitus/fisiopatologia , Insuficiência Cardíaca/fisiopatologia , Humanos , Hipertensão/fisiopatologia , Isquemia Miocárdica/fisiopatologia , Neovascularização FisiológicaRESUMO
Postganglionic cardiac parasympathetic and sympathetic nerves are physically proximate in atrial cardiac tissue allowing reciprocal inhibition of neurotransmitter release, depending on demands from central cardiovascular centers or reflex pathways. Parasympathetic cardiac ganglion (CG) neurons synthesize and release the sympathetic neurotrophin nerve growth factor (NGF), which may serve to maintain these close connections. In this study we investigated whether NGF synthesis by CG neurons is altered in heart failure, and whether norepinephrine from sympathetic neurons promotes NGF synthesis. NGF and proNGF immunoreactivity in CG neurons in heart failure rats following chronic coronary artery ligation was investigated. NGF immunoreactivity was decreased significantly in heart failure rats compared to sham-operated animals, whereas proNGF expression was unchanged. Changes in neurochemistry of CG neurons included attenuated expression of the cholinergic marker vesicular acetylcholine transporter, and increased expression of the neuropeptide vasoactive intestinal polypeptide. To further investigate norepinephrine's role in promoting NGF synthesis, we cultured CG neurons treated with adrenergic receptor (AR) agonists. An 82% increase in NGF mRNA levels was detected after 1h of isoproterenol (ß-AR agonist) treatment, which increased an additional 22% at 24h. Antagonist treatment blocked isoproterenol-induced increases in NGF transcripts. In contrast, the α-AR agonist phenylephrine did not alter NGF mRNA expression. These results are consistent with ß-AR mediated maintenance of NGF synthesis in CG neurons. In heart failure, a decrease in NGF synthesis by CG neurons may potentially contribute to reduced connections with adjacent sympathetic nerves.
Assuntos
Insuficiência Cardíaca/metabolismo , Coração/inervação , Fator de Crescimento Neural/biossíntese , Neurônios/metabolismo , Sistema Nervoso Parassimpático/metabolismo , Receptores Adrenérgicos/metabolismo , Antagonistas Adrenérgicos/farmacologia , Agonistas alfa-Adrenérgicos/farmacologia , Agonistas Adrenérgicos beta/farmacologia , Animais , Células Cultivadas , Insuficiência Cardíaca/tratamento farmacológico , Isoproterenol/farmacologia , Masculino , Fatores de Crescimento Neural/biossíntese , Neurônios/efeitos dos fármacos , Sistema Nervoso Parassimpático/efeitos dos fármacos , Fenilefrina/farmacologia , Precursores de Proteínas/biossíntese , RNA Mensageiro/metabolismo , Ratos , Ratos Sprague-Dawley , Fatores de Tempo , Peptídeo Intestinal Vasoativo/metabolismo , Proteínas Vesiculares de Transporte de Acetilcolina/metabolismoRESUMO
Obesity increases the risk of arrhythmias and sudden cardiac death, but the mechanisms are unknown. This study tested the hypothesis that obesity-induced cardiac sympathetic outgrowth and hyperinnervation promotes the development of arrhythmic events. Male Sprague-Dawley rats (250-275 g), fed a high-fat diet (33% kcal/fat), diverged into obesity-resistant (OR) and obesity-prone (OP) groups and were compared with rats fed normal chow (13% kcal/fat; CON). In vitro experiments showed that both OR and OP rats exhibited hyperinnervation of the heart and high sympathetic outgrowth compared with CON rats, even though OR rats are not obese. Despite the hyperinnervation and outgrowth, we showed that, in vivo, OR rats were less susceptible to arrhythmic events after an intravenous epinephrine challenge compared with OP rats. On examining total and stimulus-evoked neurotransmitter levels in an ex vivo system, we demonstrate that atrial acetylcholine content and release were attenuated in OP compared with OR and CON groups. OP rats also expressed elevated atrial norepinephrine content, while norepinephrine release was suppressed. These findings suggest that the consumption of a high-fat diet, even in the absence of overt obesity, stimulates sympathetic outgrowth and hyperinnervation of the heart. However, normalized cardiac parasympathetic nervous system control may protect the heart from arrhythmic events.
Assuntos
Arritmias Cardíacas/etiologia , Dieta Hiperlipídica , Coração/inervação , Obesidade/etiologia , Sistema Nervoso Simpático/fisiopatologia , Acetilcolina/metabolismo , Animais , Arritmias Cardíacas/metabolismo , Arritmias Cardíacas/fisiopatologia , Arritmias Cardíacas/prevenção & controle , Modelos Animais de Doenças , Epinefrina , Átrios do Coração/inervação , Masculino , Norepinefrina/metabolismo , Obesidade/complicações , Obesidade/metabolismo , Obesidade/fisiopatologia , Sistema Nervoso Parassimpático/metabolismo , Sistema Nervoso Parassimpático/fisiopatologia , Ratos , Ratos Sprague-Dawley , Sistema Nervoso Simpático/crescimento & desenvolvimento , Sistema Nervoso Simpático/metabolismoRESUMO
Autonomic cardiac neurons have a common origin in the neural crest but undergo distinct developmental differentiation as they mature toward their adult phenotype. Progenitor cells respond to repulsive cues during migration, followed by differentiation cues from paracrine sources that promote neurochemistry and differentiation. When autonomic axons start to innervate cardiac tissue, neurotrophic factors from vascular tissue are essential for maintenance of neurons before they reach their targets, upon which target-derived trophic factors take over final maturation, synaptic strength and postnatal survival. Although target-derived neurotrophins have a central role to play in development, alternative sources of neurotrophins may also modulate innervation. Both developing and adult sympathetic neurons express proNGF, and adult parasympathetic cardiac ganglion neurons also synthesize and release NGF. The physiological function of these "non-classical" cardiac sources of neurotrophins remains to be determined, especially in relation to autocrine/paracrine sustenance during development. Cardiac autonomic nerves are closely spatially associated in cardiac plexuses, ganglia and pacemaker regions and so are sensitive to release of neurotransmitter, neuropeptides and trophic factors from adjacent nerves. As such, in many cardiac pathologies, it is an imbalance within the two arms of the autonomic system that is critical for disease progression. Although this crosstalk between sympathetic and parasympathetic nerves has been well established for adult nerves, it is unclear whether a degree of paracrine regulation occurs across the autonomic limbs during development. Aberrant nerve remodeling is a common occurrence in many adult cardiovascular pathologies, and the mechanisms regulating outgrowth or denervation are disparate. However, autonomic neurons display considerable plasticity in this regard with neurotrophins and inflammatory cytokines having a central regulatory function, including in possible neurotransmitter changes. Certainly, neurotrophins and cytokines regulate transcriptional factors in adult autonomic neurons that have vital differentiation roles in development. Particularly for parasympathetic cardiac ganglion neurons, additional examinations of developmental regulatory mechanisms will potentially aid in understanding attenuated parasympathetic function in a number of conditions, including heart failure.
Assuntos
Sistema Nervoso Autônomo , Vias Autônomas , Coração , Plasticidade Neuronal , Animais , Coração/inervação , Coração/fisiologia , Humanos , Camundongos , Fatores de Crescimento Neural , Coelhos , RatosRESUMO
Heart rate is controlled by stimulatory sympathetic and inhibitory parasympathetic nerves innervating the sino-atrial node and cardiac conduction system. Sympathetic release of norepinephrine (NE) and parasympathetic release of acetylcholine (ACh) are controlled by the central nervous system, and by pre-synaptic inhibition of transmitter release within the atria. An increase in cardiac sympathetic transmission relative to parasympathetic transmission is pathological as it can lead to disturbances in heart rhythm, catecholaminergic toxicity and development of arrhythmias or fibrillation. Mice lacking the p75 neurotrophin receptor (p75(-/-)) have elevated atrial NE but a low heart rate suggesting autonomic dysregulation. Similarly, mice whose sympathetic neurons lack the gp130 cytokine receptor (gp130 KO) have a normal heart rate but enhanced bradycardia after vagal nerve stimulation. What is unclear is whether cardiac autonomic disturbances in these animals reflect systemic alterations in nerve activity or whether localized defects in neurotransmitter stores or release are involved. To examine local stimulus-evoked release of neurotransmitters, we have developed a novel method for simultaneous quantification of both NE and ACh after ex vivo atrial field stimulation. Using HPLC with electrochemical detection for NE, and HPLC with mass spectrometry for ACh, we found that following field stimulation NE release was impaired in p75(-/-) atria while ACh content and release was elevated in gp130 KO atria. Thus, alterations in localized transmitter release from atrial explants are consistent with in vivo deficits in heart rate control, suggesting peripheral alterations in autonomic transmission in these mice.
Assuntos
Acetilcolina/metabolismo , Receptor gp130 de Citocina/metabolismo , Átrios do Coração/metabolismo , Sistema de Condução Cardíaco/metabolismo , Neurotransmissores/metabolismo , Norepinefrina/metabolismo , Receptores de Fator de Crescimento Neural/metabolismo , Animais , Camundongos , Camundongos Knockout , Camundongos Transgênicos , Receptores de Fator de Crescimento Neural/genética , Transmissão Sináptica/fisiologiaRESUMO
Cardiac function is regulated by a balance of sympathetic and parasympathetic transmission. Neuropeptide Y (NPY) and galanin (GAL) released from cardiac sympathetic neurons inhibits parasympathetic transmission in the heart. Sympathetic peptides may contribute to autonomic imbalance, which is characterized by increased sympathetic and decreased parasympathetic transmission and contributes to life threatening cardiovascular pathologies. Several gp130 cytokines are increased in the heart after myocardial infarction (MI), and these cytokines stimulate neuropeptide expression in sympathetic neurons. We used mice whose sympathetic neurons lack the gp130 receptor (gp130(DBH-Cre/lox) mice) to ask if cytokine activation of gp130 regulated neuropeptide expression in cardiac sympathetic nerves after MI. Myocardial infarction decreased NPY mRNA through a gp130 independent mechanism and increased VIP and PACAP mRNA via gp130, while GAL mRNA was unchanged. Immunohistochemistry revealed a gp130-dependent increase in PACAP38 in cells of the stellate ganglion after MI, and PACAP was detected in pre-ganglionic fibers of all genotypes and surgical groups. VIP was identified in a few sympathetic nerve fibers in all genotypes and surgical groups. GAL and PACAP38 were not detected in sham hearts, but peptide immunoreactivity was high in the infarct three days after MI. Surprisingly, peptides were abundant in cells that co-labeled with macrophage markers F4/80 and MAC2, but were not detected in sympathetic axons. PACAP protects cardiac myocytes from apoptosis, and GAL stimulates axon regeneration in addition to inhibiting parasympathetic transmission. Thus, these peptides may play an important role in cardiac and neuronal remodeling after ischemia-reperfusion.
Assuntos
Receptor gp130 de Citocina/metabolismo , Isquemia Miocárdica/metabolismo , Neuropeptídeos/metabolismo , Traumatismo por Reperfusão/metabolismo , Sistema Nervoso Simpático/metabolismo , Animais , Receptor gp130 de Citocina/genética , Galanina/genética , Galanina/metabolismo , Coração/inervação , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Miocárdio/citologia , Miocárdio/metabolismo , Neuropeptídeo Y/genética , Neuropeptídeo Y/metabolismo , Neuropeptídeos/genética , Polipeptídeo Hipofisário Ativador de Adenilato Ciclase/metabolismo , Peptídeo Intestinal Vasoativo/genética , Peptídeo Intestinal Vasoativo/metabolismoRESUMO
ß-Adrenoceptor antagonists are used widely to reduce cardiovascular sympathetic tone, but withdrawal is accompanied by sympathetic hyperactivity. Receptor supersensitivity accounts for some but not all aspects of this withdrawal syndrome. Therefore, we investigated effects of ß-blockers on sympathetic innervation. Rats received infusions of adrenergic receptor blockers or saline for 1 week. The nonselective ß-blocker propranolol and the ß(1)-antagonist metoprolol both increased myocardial sympathetic axon density. At 2 d after propranolol discontinuation, ß-receptor sensitivity and responsiveness to isoproterenol were similar to controls. However, tyramine-induced mobilization of norepinephrine stores produced elevated ventricular contractility consistent with enhanced sympathetic neuroeffector properties. In addition, rats undergoing discontinuation showed exaggerated increases in mean arterial pressure in response to air puff or noise startle. In sympathetic neuronal cell cultures, both propranolol and metoprolol increased axon outgrowth but the ß(2)-blocker ICI 118551 did not. Norepinephrine synthesis suppression by α-methyl-p-tyrosine also increased sprouting and concurrent dobutamine administration reduced it, confirming that locally synthesized norepinephrine inhibits outgrowth via ß(1)-adrenoceptors. Immunohistochemistry revealed ß(1)-adrenoceptor protein on sympathetic axon terminations. In rats with coronary artery ligation, propranolol reversed heart failure-induced ventricular myocardial sympathetic axon depletion, but did not affect infarct-associated sympathetic hyperinnervation. We conclude that sympathetic neurons possess ß(1)-autoreceptors that negatively regulate axon outgrowth. Chronic ß-adrenoceptor blockade disrupts this feedback system, leading to ventricular sympathetic axon proliferation and increased neuroeffector gain, which are likely to contribute to ß-blocker withdrawal syndrome.
Assuntos
Antagonistas Adrenérgicos beta/farmacologia , Autorreceptores/antagonistas & inibidores , Autorreceptores/fisiologia , Axônios/fisiologia , Cones de Crescimento/fisiologia , Inibidores do Crescimento/fisiologia , Coração/inervação , Inibição Neural/fisiologia , Fibras Simpáticas Pós-Ganglionares/crescimento & desenvolvimento , Animais , Animais Recém-Nascidos , Células Cultivadas , Modelos Animais de Doenças , Regulação para Baixo/efeitos dos fármacos , Regulação para Baixo/fisiologia , Feminino , Cones de Crescimento/efeitos dos fármacos , Inibidores do Crescimento/antagonistas & inibidores , Coração/efeitos dos fármacos , Inibição Neural/efeitos dos fármacos , Ratos , Ratos Sprague-Dawley , Fibras Simpáticas Pós-Ganglionares/citologia , Fibras Simpáticas Pós-Ganglionares/efeitos dos fármacos , Regulação para Cima/efeitos dos fármacos , Regulação para Cima/fisiologiaRESUMO
Myocardial infarction induces sympathetic axon sprouting adjacent to the necrotic region, and this has been implicated in the etiology of arrhythmias resulting in sudden cardiac death. Previous studies show that nerve growth factor (NGF) is essential for enhanced post-infarct sympathetic sprouting, but the cell types necessary to supply this neurotrophic protein are unknown. The objective of the present study was to determine whether macrophages, which are known to synthesize NGF, are necessary for post-infarct cardiac sympathetic sprouting. Ovariectomized female rats received left coronary artery ligation or sham operation, followed by intravenous injection of liposomes containing saline vehicle or clodronate, which kills macrophages. Sham-operated myocardium contained some sympathetic axons, few myofibroblasts and T cells and no CD-68-positive macrophages. In rats receiving saline liposomes through 7 days post-ligation, the posterolateral infarct border contained numerous myofibroblasts, macrophages and T cells, and sympathetic innervation was increased twofold. Treatment with clodronate liposomes reduced macrophage numbers by 69%, while myofibroblast area was reduced by 23% and T cell number was unaffected. Clodronate liposome treatment reduced sympathetic axon density to levels comparable to the uninfarcted heart. NGF protein content measured in western blots was reduced to 33% of that present in infarcts where rats received saline-containing liposomes. Tissue morphometry confirmed that NGF immunostaining was dramatically reduced, and this was attributable primarily to reduced macrophage content. These results show that macrophage destruction markedly reduces post-infarction levels of NGF and that the presence of elevated numbers of macrophages is obligatory for development of sympathetic hyperinnervation following myocardial infarction.