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 P2X(7) receptor. The results showed that after myocardial ischemic injury, the systolic blood pressure, heart rate, serum cardiac enzymes, IL-6, and TNF-alpha were increased, while the levels of P2X(7) mRNA and protein in SCG were also upregulated. However, these alterations diminished after treatment of myocardial ischemic (MI) rats with the P2X(7) antagonist oxATP. After siRNA P2X(7) in MI rats, the systolic blood pressure, heart rate, serum cardiac enzymes, the expression levels of the satellite glial cell (SGC) or P2X(7) 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 P2X(7) receptor promoted the activation of SGCs in SCG, resulting in the formation of sensory-sympathetic coupling which facilitated the sympathoexcitatory action. P2X(7) 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.