Cardiac regulation in the socially monogamous prairie vole

Abstract

Social experiences, both positive and negative, may influence cardiovascular regulation. Prairie voles (Microtus ochrogaster) are socially monogamous rodents that form social bonds similar to those seen in primates, and this species may provide a useful model for investigating neural and social regulation of cardiac function. Cardiac regulation has not been studied previously in the prairie vole. Radiotelemetry transmitters were implanted into adult female prairie voles under anesthesia, and electrocardiographic parameters were recorded. Autonomic blockade was performed using atenolol (8 mg/kg ip) and atropine methyl nitrate (4 mg/kg ip). Several variables were evaluated, including heart rate (HR), HR variability and the amplitude of respiratory sinus arrhythmia. Sympathetic blockade significantly reduced HR. Parasympathetic blockade significantly increased HR, and reduced HR variability and the amplitude of respiratory sinus arrhythmia. Combined autonomic blockade significantly increased HR, and reduced HR variability and respiratory sinus arrhythmia amplitude. The data indicate that autonomic function in prairie voles shares similarities with primates, with a predominant vagal influence on cardiac regulation. The current results provide a foundation for studying neural and social regulation of cardiac function during different behavioral states in this socially monogamous rodent model.

Social Isolation Disrupts Autonomic Regulation of the Heart and Influences Negative Affective Behaviors

“…In this species, social isolation induced anhedonia and increased neuroendocrine responsiveness to an acute residentintruder paradigm (15). Our laboratory also described for the first time autonomic regulation of the heart in prairie voles, including high parasympathetic (vagal) cardiac tone, similar to humans (40). The high levels of social behaviors (relative to small mammals), coupled with a parasympathetic nervous system influence regulating resting cardiac function, suggest that prairie voles can provide a translational model for studying the integration of social behavior and cardiac function.…”

“…Transmitter implantation was similar to procedures described elsewhere (50,51). Animals were housed for 5 days in custom-designed divided cages (40) to permit adequate healing of suture wounds, and then were returned to the home cages (with the sibling) to recover for an additional 5-7 days.…”

“…, and (c) dual blockade (both drugs). These doses were chosen for their ability to completely block the respective autonomic inputs to the heart according to previously published results from voles (40,55) and preliminary analyses conducted by our laboratory. Drugs were administered in a counterbalanced fashion over a 6-day period (48 hours between each drug).…”

“…Quantification of Telemetric Variables-Quantification of telemetric variables was conducted according to procedures described previously (40). Multiple segments of 1-5 minutes of stable, continuous data were used to evaluate HR, HR variability and activity.…”

“…Data segments were matched across subjects and time points, and were used to calculate all cardiac and activity variables. Resting Cardiac Parameters-Activity level is high in prairie voles and occurs in short bouts throughout the light and dark periods (40), therefore resting cardiac parameters were derived from ECG data sampled during a period of at least 1 hour of minimal activity [5 counts/ minute (cpm) or lower], and included the average of 2-5 minute intervals of continuous ECG data collected every 30 minutes (4-15 minutes of accumulated data from each animal).…”