Vesicular glutamate transporter 1‐immunoreactive sensory neurons in the rat intrinsic cardiac ganglia

Abstract

Sensory neurons that reside in intrinsic cardiac ganglia (ICG) have an important role in monitoring the cardiac milieu for regional cardiac dynamic control. We recently described sensory neurons in ICG that project to the cardiac ventricular wall and currently are evaluating their neurochemical phenotype. Since many primary sensory neurons are glutamatergic, we hypothesized that ICG sensory neurons are glutamatergic, utilizing vesicular glutamate transporter 1 (VGLUT1) to package glutamate into synaptic vesicles. In the present study, the rat ventricle wall was injected (retro‐diaphragmatic, 8μl) with the retrograde tracer wheat germ agglutinin‐horseradish peroxidase (WGA‐HRP). After 72h, rats were euthanized and transcardially perfused with fixative. ICG were processed for immunohistochemistry studies. Our results demonstrated that: (1) VGLUT1‐immunoreactive (ir) neurons were present in ICG; (2) Some VGLUT1‐ir neurons were labeled from the ventricles with WGA‐HRP. Our previous studies indicated that sensory ICG neurons contain glutaminase, the synthetic enzyme for glutamate. These and the current results indicate that ICG sensory neurons are glutamatergic in neurochemical phenotype. Further investigation of VGLUTs during cardiac physiological and pathological conditions will help in deciphering the function of glutamate as a neurotransmitter in the ICG. Supported by NIH AR47410 (KEM).Grant Funding Source: NIH AR47410