The effect of electrical stimulation of the orbitofrontal cortex on the circulatory system of an anesthetized rat

Abstract

One of the urgent problems of integrative physiology is the determination of the role of the cerebral cortex various areas in the autonomic control. It has been established that two areas of the prefrontal cortex are directly involved in the control of autonomic functions: medial (infralimbic) and lateral (insular). At the same time, it could be supposed that other areas of the prefrontal cortex can be involved in the autonomic functions, in particular, the fields located on the orbitofrontal surface of the cerebral hemispheres. To test this hypothesis, the effect of microstimulation of the lateral orbital and ventral orbital fields on arterial pressure and heart rate was investigated. Experiments had been performed on laboratory rats (males Wistar, weight 250-300 g, n = 12) anesthetized with urethane (1600 mg/kg, i.p.). Arterial pressure was recorded directly through a catheter inserted into the femoral vein. The cortex was stimulated with a 10 s trains of rectangular pulses of current (150-200 μA, 50 Hz) through a monopolar electrode, which was immersed at the desired point with a stereotaxic apparatus. It had been found that blood pressure and heart rate remained stable throughout the experiment. The predominant effect of the orbitofrontal cortex stimulation was a short-term drop in arterial pressure, which was not accompanied by changes in heart rate. The results obtained confirm the hypothesis put forward. A promising direction for further research may be the study of neurophysiological mechanisms of interaction of the orbitofrontal cortex with the fields of the autonomic cortex.