Intense Fear Induces Low‐Frequency Oscillation of Cerebral Blood Flow, Arterial Pressure, and Sympathetic Nerve Activity in Conscious Rats

Abstract

A traumatic event, such as disaster, causes intense fear, which potentially leads to an increase in occurrence of cerebrovascular diseases. Little information is available regarding why intense fear causes cerebrovascular diseases. The present study aimed to measure cerebral blood flow, arterial pressure, and sympathetic nerve activity during intense fear conditioning in conscious rats. Wistar rats were chronically instrumented with a probe made with glass fiber for measuring hippocampal cerebral blood flow. Electrodes for measurements of renal (RSNA) and lumbar sympathetic nerve activity (LSNA) were inserted, as well as for an electroencephalogram, electromyogram, and electrocardiogram. A catheter was inserted for measuring systemic arterial pressure. Standard fear‐conditioning trials, in which a tone was paired with a brief electrical shock (5 mA, 2 s), were performed in rats two times per day over 3 days. Oscillation of arterial pressure with an amplitude of 15.7 mmHg and frequency of 0.075 Hz was induced by exposing a tone without electrical shock in fear‐conditioned rats. Arterial pressure oscillation was associated with synchronized oscillation of hippocampal cerebral blood flow, RSNA, and LSNA. Coherence between arterial pressure and hippocampal cerebral blood flow, RSNA, and LSNA was significantly increased at low frequency (0–1 Hz) compared with naive rats. These data suggest that intense fear can trigger disorder of sympathetic regulation of arterial pressure, causing low‐frequency oscillation of arterial pressure and synchronized changes in cerebral blood flow. This may be one of the causes of cerebrovascular disease induced by intense fear.Support or Funding InformationJSPS GrantThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.