Features of Stress-Induced Changes in Heart Rate Variability During Blockade of Central and Stimulation of Peripheral Serotonin and Dopamine Receptors in Rats.

The dynamics of heart rate variability (HRV) during acute stress was studied in male nonlinear rats that received single injection of serotonin (200 μg/kg) or dopamine (60 μg/kg), regular (4-fold) injections of central serotonin receptor blockers (ketanserin and granisetron, 0.1 mg/kg each) or central dopamine receptor blockers (0.1 mg/kg SCH-23390 and 10 mg/kg sulpiride), as well as a combination of central receptor blockers with the administration of serotonin or dopamine, respectively. During stress against the background of serotonin receptors blockade, a weak tachycardia, low stress index, high rhythm variability, especially in the low-frequency range were recorded; against the background of dopamine receptors blockade, increased reactivity to stress at high HR, an initial increase in the stress index, and a decrease in rhythm variability, followed by an increase in the proportion of very low frequency waves in the spectrum were revealed. Serotonin and dopamine, by stimulating peripheral receptors, predominantly weakened stress-induced changes in HRV (especially serotonin), but in combination with blockade of the corresponding central receptors contributed to maintaining tachycardia, reduced rhythm variability, and potentiated the effects of blockers in relation to stress induced changes in the wave structure of the HRV spectrum. We believe that central and peripheral serotoninergic and dopaminergic structures are involved in the formation of HRV by modulating the activity of components of the autonomous and central circuits of HR regulation, respectively.