The involvement of P2X3 receptors of rat sympathetic ganglia in cardiac nociceptive transmission

The relevance of the superior cervical ganglion for cardiac autonomic innervation in health and disease: a systematic review

PURPOSE

The heart receives cervical and thoracic sympathetic contributions. Although the stellate ganglion is considered the main contributor to cardiac sympathetic innervation, the superior cervical ganglia (SCG) is used in many experimental studies. The clinical relevance of the SCG to cardiac innervation is controversial. We investigated current morphological and functional evidence as well as controversies on the contribution of the SCG to cardiac innervation.

METHODS

A systematic literature review was conducted in PubMed, Embase, Web of Science, and COCHRANE Library. Included studies received a full/text review and quality appraisal.

RESULTS

Seventy-six eligible studies performed between 1976 and 2023 were identified. In all species studied, morphological evidence of direct or indirect SCG contribution to cardiac innervation was found, but its contribution was limited. Morphologically, SCG sidedness may be relevant. There is indirect functional evidence that the SCG contributes to cardiac innervation as shown by its involvement in sympathetic overdrive reactions in cardiac disease states. A direct functional contribution was not found. Functional data on SCG sidedness was largely unavailable. Information about sex differences and pre- and postnatal differences was lacking.

CONCLUSION

Current literature mainly supports an indirect involvement of the SCG in cardiac innervation, via other structures and plexuses or via sympathetic overdrive in response to cardiac diseases. Morphological evidence of a direct involvement was found, but its contribution seems limited. The relevance of SCG sidedness, sex, and developmental stage in health and disease remains unclear and warrants further exploration.

Role of purinergic receptors in cardiac sympathetic nerve injury in diabetes mellitus

Diabetic cardiac autonomic neuropathy is a common and serious chronic complication of diabetes, which can lead to sympathetic and parasympathetic nerve imbalance and a relative excitation of the sympathetic nerve. Purinergic receptors play a crucial role in this process. Diabetic cardiac sympathetic nerve injury affects the expression of purinergic receptors, and activated purinergic receptors affect the phosphorylation of different signaling pathways and the regulation of inflammatory processes. This paper introduces the abnormal changes of sympathetic nerve in diabetes mellitus and summarizes the recently published studies on the role of several purinergic receptor subtypes in diabetic cardiac sympathetic nerve injury. These studies suggest that purinergic receptors as novel drug targets are of great significance for the treatment of diabetic autonomic neuropathy. This article is part of the Special Issue on "Purinergic Signaling: 50 years".

Glucokinase in stellate ganglia cooperates with P2X3 receptor to develop cardiac sympathetic neuropathy in type 2 diabetes rats

Glucokinase (GCK) may be involved in inflammatory pathological changes, while the P2X3 receptor in the stellate ganglia (SG) is related to diabetic cardiac autonomic neuropathy. In this study, we explored the relationship between the upregulated GCK in SG and diabetic cardiac sympathy. The expression and location of GCK and P2X3 in SG of type 2 diabetes mellitus (T2DM) rats were assessed. Changes in cardiac function were determined by measuring blood pressure, sympathetic nerve activity, heart rate, and heart rate variability. P2X3 agonist-activated currents in isolated stellate ganglion neurons and cultured human embryonic kidney 293 (HEK293) cells were recorded using whole-cell patch clamp techniques. The upregulated expression of GCK in SG of T2DM rats was decreased after treatment with GCK short hairpin RNA (shRNA). GCK shRNA treatment also improved the blood pressure, sympathetic nerve activity, heart rate, and heart rate variability in T2DM rats. By contrast, the expression of P2X3 and tumor necrosis factor α (TNF-α) was lessened by GCK shRNA treatment. In addition, adenosine triphosphate (ATP)-activated currents in stellate ganglion neurons and HEK293 cells co-transfected with GCK and P2X3 receptor plasmids were reduced after GCK shRNA treatment. In T2DM rats, knockdown of GCK relieved the diabetic cardiac sympathy mediated by P2X3 receptor-involved upregulation of GCK in SG.

Long noncoding NONRATT021972 siRNA normalized abnormal sympathetic activity mediated by the upregulation of P2X7 receptor in superior cervical ganglia after myocardial ischemia

Previous studies showed that the upregulation of the P2X7 receptor in cervical sympathetic ganglia was involved in myocardial ischemic (MI) injury. The dysregulated expression of long noncoding RNAs (lncRNAs) participates in the onset and progression of many pathological conditions. The aim of this study was to investigate the effects of a small interfering RNA (siRNA) against the NONRATT021972 lncRNA on the abnormal changes of cardiac function mediated by the up-regulation of the P2X7 receptor in the superior cervical ganglia (SCG) after myocardial ischemia. When the MI rats were treated with NONRATT021972 siRNA, their increased systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), low-frequency (LF) power, and LF/HF ratio were reduced to normal levels. However, the decreased high-frequency (HF) power was increased. GAP43 and tyrosine hydroxylase (TH) are markers of nerve sprouting and sympathetic nerve fibers, respectively. We found that the TH/GAP43 value was significantly increased in the MI group. However, it was reduced after the MI rats were treated with NONRATT021972 siRNA. The serum norepinephrine (NE) and epinephrine (EPI) concentrations were decreased in the MI rats that were treated with NONRATT021972 siRNA. Meanwhile, the increased P2X7 mRNA and protein levels and the increased p-ERK1/2 expression in the SCG were also reduced. NONRATT021972 siRNA treatment inhibited the P2X7 agonist BzATP-activated currents in HEK293 cells transfected with pEGFP-P2X7. Our findings suggest that NONRATT021972 siRNA could decrease the upregulation of the P2X7 receptor and improve the abnormal changes in cardiac function after myocardial ischemia.

The effects of NONRATT021972 lncRNA siRNA on PC12 neuronal injury mediated by P2X7 receptor after exposure to oxygen-glucose deprivation

Adenosine triphosphate (ATP) participates in signal transmission by acting on P2X receptors, and the P2X7 receptor is involved in the pathophysiological changes of ischemic injury. The PC12 cell line is a popular model system to study sympathetic neuronal function. Long noncoding RNAs (lncRNAs) are highly expressed in the nervous system and serve as regulatory RNAs. In this study, the effects of NONRATT021972 lncRNA siRNA on P2X7-mediated PC12 neuronal injury after exposure to oxygen-glucose deprivation (OGD) were investigated. Our results showed that the viability of PC12 cells cultured with OGD or the P2X7 agonist BzATP was significantly decreased. Treatment with NONRATT021972 siRNA reversed the decreased viability of PC12 cells under OGD conditions. The upregulated P2X7 mRNA and protein levels in PC12 cells under OGD conditions or BzATP treatment were significantly decreased when pretreated with NONRATT021972 siRNA. Moreover, NONRATT021972 siRNA treatment effectively suppressed the increase in [Ca(2+)]i induced by OGD or P2X7 agonists (ATP or BzATP) in PC12 cells. Therefore, treatment with NONRATT021972 siRNA may decrease sympathetic neuronal injury induced by ischemia.

LncRNA NONRATT021972 involved the pathophysiologic processes mediated by P2X7 receptors in stellate ganglia after myocardial ischemic injury

Adenosine triphosphate (ATP) acts on P2X receptors to initiate signal transmission. P2X7 receptors play a role in the pathophysiological process of myocardial ischemic injury. Long noncoding RNAs (lncRNAs) participate in numerous biological functions independent of protein translation. LncRNAs are implicated in nervous system diseases. This study investigated the effects of NONRATT021972 small interference RNA (siRNA) on the pathophysiologic processes mediated by P2X7 receptors in stellate ganglia (SG) after myocardial ischemic injury. Our results demonstrated that the expression of NONRATT021972 in SG was significantly higher in the myocardial ischemic (MI) group than in the control group. Treatment of MI rats with NONRATT021972 siRNA, the P2X7 antagonist brilliant blue G (BBG), or P2X7 siRNA improved the histology of injured ischemic cardiac tissues and decreased the elevated concentrations of serum myocardial enzymes, creatine kinase (CK), CK isoform MB (CK-MB), lactate dehydrogenase (LDH) and aspartate aminotransferase (AST) compared to the MI rats. NONRATT021972 siRNA, BBG, or P2X7 siRNA treatment in MI rats decreased the expression levels of P2X7 immunoreactivity, P2X7 messenger RNA (mRNA), and P2X7 protein, interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and phosphorylated p38 mitogen-activated protein kinase (p38 MAPK) in the SG compared to MI rats. NONRATT021972 siRNA treatment prevented the pathophysiologic processes mediated by P2X7 receptors in the SG after myocardial ischemic injury.

Study of baicalin on sympathoexcitation induced by myocardial ischemia via P2X3 receptor in superior cervical ganglia

After the myocardial ischemia, injured myocardial tissues released large quantity of ATP, which activated P2X3 receptor in superior cervical ganglia and made the SCG postganglionic neurons excited. Excitatory of sympathetic postganglionic efferent neurons increased the blood pressure and heart rates, which aggravated the myocardial ischemic injury. Baicalin has anti-inflammatory and anti-oxidant properties. Our study showed that baicalin reduced the incremental concentration of serum CK-MB, cTn-T, epinephrine and ATP, decreased the up-regulated expression levels of P2X3 mRNA and protein in SCG after MI, and then inhibited the sympathetic excitatory activity triggered by MI injury. These results indicated that baicalin acted on P2X3 receptor was involved in the transmission of sympathetic excitation after the myocardial ischemic injury. Baicalin might decrease sympathetic activity via inhibiting P2X3 receptor in rat SCG to protect the myocardium.

The role of P2X7 receptor in PC12 cells after exposure to oxygen-glucose deprivation

Adenosine triphosphate (ATP) plays an important role in signal transmission via acting on P2X receptors. P2X7 receptor is involved in pathophysiological changes of ischemic diseases. The PC12 cell line is a popular model system to study sympathetic neuronal function. In this study, the effects of P2X7 on the viability or [Ca(2+)]i in PC12 cells after exposure to oxygen-glucose deprivation (OGD) were investigated. The results showed that the viability of PC12 cells was decreased under the condition of OGD. BzATP, a P2X7 agonist, decreased the viability, while P2X7 antagonist oxATP or P2X7 siRNA reversed the viability of PC12 cells under the condition of OGD. The expression levels of P2X7 mRNA and protein in PC12 cells were up-regulated under the condition of OGD or BzATP treatment. The expression levels of P2X7 mRNA and protein were significantly decreased in OGD PC12 cells, which were pretreated with oxATP or P2X7 siRNA. It was also found that oxATP or P2X7 siRNA effectively suppressed the increase of [Ca(2+)]i induced by OGD. P2X7 agonist ATP or BzATP enhanced the [Ca(2+)]i rise induced by OGD in PC12 cells. The [Ca(2+)]i peak induced by ATP or BzATP in OGD group was decreased by ERK inhibitor U0126. Therefore, P2X7 antagonists or P2X7 siRNA could depress the sympathetic neuronal damage induced by ischemia.

Puerarin blocks the signaling transmission mediated by P2X3 in SG and DRG to relieve myocardial ischemic damage

P2X₃ receptors in stellate ganglia (SG) and cervical dorsal root ganglia (DRG) neurons are involved in sympathoexcitatory reflex induced by myocardial ischemic damage. Puerarin, a major active ingredient extracted from the traditional Chinese plant medicine Ge-gen, has been widely used in treatment of myocardial and cerebral ischemia. The present study is aimed to observe the effects of puerarin on the signaling transmission mediated by P2X₃ receptor in SG and DRG after myocardial ischemic damage. Our results showed that systolic blood pressure and heart rate increased, and the expression levels of P2X₃ mRNA and protein in SG and DRG were up-regulated after myocardial ischemic damage. Puerarin reduced systolic blood pressure and heart rate, relieved pain and decreased up-regulated expression of P2X₃ mRNA and protein in SG and DRG after myocardial ischemia. Puerarin inhibited the up-regulated ATP-activated currents in DRG neurons after myocardial ischemia. Thus, puerarin can relieve myocardial ischemic damage through blocking the P2X₃ signaling transmission and then depressed the aggravated sympathoexcitatory reflex.

Sensory-sympathetic coupling in superior cervical ganglia after myocardial ischemic injury facilitates sympathoexcitatory action via P2X7 receptor

P2X receptors participate in cardiovascular regulation and disease. After myocardial ischemic injury, sensory-sympathetic coupling between rat cervical DRG nerves and superior cervical ganglia (SCG) facilitated sympathoexcitatory action via P2X7 receptor. The results showed that after myocardial ischemic injury, the systolic blood pressure, heart rate, serum cardiac enzymes, IL-6, and TNF-α were increased, while the levels of P2X7 mRNA and protein in SCG were also upregulated. However, these alterations diminished after treatment of myocardial ischemic (MI) rats with the P2X7 antagonist oxATP. After siRNA P2X7 in MI rats, the systolic blood pressure, heart rate, serum cardiac enzymes, the expression levels of the satellite glial cell (SGC) or P2X7 were significantly lower than those in MI group. The phosphorylation of ERK 1/2 in SCG participated in the molecular mechanism of the sympathoexcitatory action induced by the myocardial ischemic injury. Retrograde tracing test revealed the sprouting of CGRP or SP sensory nerves (the markers of sensory afferent fibers) from DRG to SCG neurons. The upregulated P2X7 receptor promoted the activation of SGCs in SCG, resulting in the formation of sensory-sympathetic coupling which facilitated the sympathoexcitatory action. P2X7 antagonist oxATP could inhibit the activation of SGCs and interrupt the formation of sensory-sympathetic coupling in SCG after the myocardial ischemic injury. Our findings may benefit the treatment of coronary heart disease and other cardiovascular diseases.

P2X(7) inhibition in stellate ganglia prevents the increased sympathoexcitatory reflex via sensory-sympathetic coupling induced by myocardial ischemic injury

Purinergic signaling has been found to participate in the regulation of cardiovascular function. In this study, using a rat myocardial ischemic injury model, the sympathoexcitatory reflex mediated by P2X7 receptor via sensory-sympathetic coupling between cervical dorsal root ganglia (DRG) nerves and stellate ganglia (SG) nerves was explored. Our results showed that the systolic blood pressure, heart rate, serum cardiac enzymes concentrations, interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) concentrations were increased, and the expression levels of P2X7 mRNA and protein in DRG and SG were up-regulated after myocardial ischemic injury. Administration of brilliant blue G (BBG), a selective P2X7 antagonist, decreased the elevation of systolic blood pressure, heart rate, serum cardiac enzyme, IL-6 and TNF-α, and inhibited the up-regulated expression of P2X7 mRNA and protein in DRG and SG after myocardial ischemic injury. Retrograde tracing test showed that there were calcitonin gene-related peptide sensory nerves and substance P sensory nerves sprouting from DRG to SG, which played an important role in the development of myocardial ischemic injury. The up-regulated P2X7 receptor expression levels on the surface membrane of satellite glial cells contributed to the activation of sensory-sympathetic coupling, which in turn facilitated the sympathoexcitatory reflex. BBG can inhibit the activation of satellite glial cells and interrupt the generation of sensory-sympathetic coupling in the cervical sympathetic ganglia after the myocardial ischemic injury. Taken together, these findings may provide a new therapeutic approach for treating coronary heart disease, hypertension and other cardiovascular diseases.

Vatalanib decrease the positive interaction of VEGF receptor-2 and P2X2/3 receptor in chronic constriction injury rats

Neuropathic pain can arise from a lesion affecting the peripheral nervous system. Selective P2X(3) and P2X(2/3) receptors' antagonists effectively reduce neuropathic pain. VEGF inhibitors are effective for pain relief. The present study investigated the effects of Vatalanib (VEGF receptor-2 (VEGFR-2) inhibitor) on the neuropathic pain to address the interaction of VEGFR-2 and P2X(2/3) receptor in dorsal root ganglia of chronic constriction injury (CCI) rats. Neuropathic pain symptoms following CCI are similar to most peripheral lesions as assessed by the Neuropathic Pain Symptom Inventory. Sprague-Dawley rats were randomly divided into sham group, CCI group and CCI rats treated with Vatalanib group. Mechanical withdrawal threshold and thermal withdrawal latency were measured. Co-expression of VEGFR-2 and P2X(2) or P2X(3) in L4-6 dorsal root ganglia (DRG) was detected by double-label immunofluorescence. The modulation effect of VEGF on P2X(2/3) receptor agonist-activated currents in freshly isolated DRG neurons of rats both of sham and CCI rats was recorded by whole-cell patch-clamp technique. The mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) in CCI group were lower than those in sham group (p<0.05). MWT and TWL in CCI rats treated with Vatalanib group were increased compared with those in CCI group (p<0.05). VEGFR-2 and P2X(2) or P2X(3) receptors were co-expressed in the cytoplasm and surface membranes of DRG. The co-expression of VEGFR-2 and P2X(2) or P2X(3) receptor in CCI group exhibited more intense staining than those in sham group and CCI rats treated with Vatalanib group, respectively. VEGF enhanced the amplitude of ATP and α,β-meATP -activated currents of both sham and CCI rats. Increment effects of VEGF on ATP and α,β-meATP -activated currents in CCI rats were higher than those in sham rats. Both ATP (100 μM) and α,β-meATP (10 μM)- activated currents enhanced by VEGF ( 1nM) were significantly blocked by Vatalanib (1 μM, an inhibitor of VEGF receptors). The stain values of VEGFR-2, P2X(2) and P2X(3) protein expression in L4/5 DRG of CCI treated with Vatalanib group were significantly decreased compared with those in CCI group (p<0.01). Vatalanib can alleviate chronic neuropathic pain by decreasing the activation of VEGF on VEGFR-2 and the positive interaction between the up-regulated VEGFR-2 and P2X(2/3) receptors in the neuropathic pain signaling.

Increased sympathoexcitatory reflex induced by myocardial ischemic nociceptive signaling via P2X2/3 receptor in rat superior cervical ganglia

The restructuring of cardiac innervation after myocardial ischemic injury, which is often associated with an increased sympathoexcitatory reflex characterized by an increase in blood pressure and sympathetic nerve activity. This study observed whether P2X(2/3) receptor in rat superior cervical ganglion (SCG) played a role in the increased sympathoexcitatory reflex induced by myocardial ischemic nociceptive signaling. The findings showed that the systolic blood pressure, heart rate and respiration in the myocardial ischemic rats were higher than those in control rats. The content of adenosine 5'-triphosphate (ATP) from myocardial ischemic group was higher than that from control group. After myocardial ischemic rats were treated with selective P2X(2/3) receptor antagonist A-317491, the content of ATP in SCG was reduced. Coexpression value of P2X(2), P2X(3) and tyrosine hydroxylase (TH) in the SCG and myocardial tissues of myocardial ischemic group was increased significantly, compared with that in the SCG and myocardial tissues of control group. The expression value of P2X(2), P2X(3) and TH in the SCG and myocardial tissues of myocardial ischemic rats treated with A-317491 was decreased. The amplitude of the currents was much larger in myocardial ischemic group than that obtained in control group after administration of ATP with the same concentration. After the myocardial ischemic rats were treated with A-317491, ATP-activated currents were reduced. The myocardial ischemic injury induced an increase in the expression of P2X(2/3) receptor colocalization with TH and a hypersensitivity state of SCG neurons to ATP, which led to the increased sympathoexcitatory reflex.

Expressions of P2X2 and P2X3 receptors in rat nodose neurons after myocardial ischemia injury

The role of ATP is as a functional neurotransmitter and local intercellular signaling molecule. The nodose neurons express both P2X(2) and P2X(3) subunits in their plasma membrane. This study wants to observe the expression of P2X(2) receptor and the expression relationship between P2X(2) and P2X(3) in nodose neurons after myocardial ischemic injury. The expressions of P2X(3) immunoreactivity, mRNA and protein were analyzed by immunohistochemistry, in situ hybridization and western blotting. P2X(2) and P2X(3) immunoreactivity, mRNA expression had been increased after myocardial ischemia in nodose neurons. Myocardial ischemia enhanced P2X(2) and P2X(3) protein level in nodose ganglia after myocardial ischemia. P2X(2) receptor in nodose neurons participated in the transmission of cardiac pain. The changes of P2X(2) and P2X(3) immunoreactivities, mRNA and protein that occurred following myocardial ischemic injury in the nodose ganglia showed that a correlation existed between P2X(2) and P2X(3) expression. It suggests that P2X(2) receptor subtype in company with P2X(3) receptor subtype plays the important role in cardiac vagal sensory nociceptors with a sensitivity to ATP.