Bidirectional cardiovascular responses evoked by microstimulation of the amygdala in rats

• Published in: The journal of physiological sciences 2018-05, Vol.68 (3), p.233-242
• Main Authors: Yamanaka, Ko, Takagishi, Miwa, Kim, Jimmy, Gouraud, Sabine S., Waki, Hidefumi
• Format: Article
• Language: English
• Subjects: Amygdala; Amygdala - drug effects; Amygdala - physiopathology; Animals; Arterial pressure; Arterial Pressure - drug effects; Arterial Pressure - physiology; Autonomic nervous system; Baroreceptor reflex; Baroreflex - drug effects; Baroreflex - physiology; Blood pressure; Cardiovascular system; Cardiovascular System - drug effects; Cardiovascular System - physiopathology; Electric Stimulation - methods; GABA; GABA-A Receptor Antagonists - pharmacology; Heart beat; Heart rate; Heart Rate - drug effects; Heart Rate - physiology; Lesion; Male; Microinjection; Original Paper; Pressoreceptors - metabolism; Rats; Rats, Wistar; Reflex - drug effects; Reflex - physiology; Rodents; γ-Aminobutyric acid A receptors
• ISSN: 1880-6546; 1880-6562
• DOI: 10.1007/s12576-017-0523-2

Although the amygdala is known as a negative emotion center for coordinating defensive behaviors, its functions in autonomic control remain unclear. To resolve this issue, we examined effects on cardiovascular responses induced by stimulation and lesions of the amygdala in anesthetized and free-moving rats. Electrical microstimulation of the central nucleus of the amygdala (CeA) induced a gradual increase in arterial pressure (AP) and heart rate (HR), whereas stimulation of adjacent nuclei evoked a phasic AP decrease. The gain of the baroreceptor reflex was not altered by CeA stimulation, suggesting that CeA activity increases both AP and HR by resetting baroreceptor reflex function. Disinhibition of GABAergic input by amygdalar microinjection of the GABAA receptor antagonist induced robust increases in AP and HR. Furthermore, bilateral electrolytic lesions of CeA evoked consistent AP increases over the light/dark cycle. These results suggest that the amygdala exerts ‘bidirectional’ autonomic control over the cardiovascular system.