FOREBRAIN PARASYMPATHETIC CONTROL OF HEART ACTIVITY - RETROGRADE TRANSNEURONAL VIRAL LABELING IN RATS

Dysfunction of parasympathetic command neurons may be a cause of cardi ac autonomic imbalance, which has been implicated as a pathogenic mech anism of lethal arrhythmias. The locations in the brain of these comma nd neurons are not known. The aim of this investigation is to identify selectively the parasympathetic command neurons in the forebrain. Mal e Wistar rats were inoculated in the left ventricular myocardium with 2 mi of a 3 x 10(6) plaque-forming units/ml of a pseudorabies virus (P RV)-Bartha solution. Eighteen hours after the infection the spinal cor d was transected at T-1. Six of fourteen rats showed PRV-immunoreactiv e cells in the forebrain after 6 postoperative survival days. Bilatera lly, the infections were located in the prelimbic, anterior cingulate, frontal, and insular cortexes, various hypothalamic and midbrain nucl ei, the nucleus of the solitary tract, the dorsal motor vagus, and per iambiguus nuclei. Control animals receiving intravenous PRV-Bartha inj ections were not infected. Using transneuronal retrograde viral labeli ng and spinal cord transection, we were able to localize the forebrain parasympathetic command neurons that maintain cardiac autonomic balan ce. The virus-infected cells were localized in regions that previously showed susceptibility for immune activation-mediated selective cerebr al endothelial leakage. We hypothesize that such selective endothelial leakage could induce autonomic imbalance after myocardial infarction.