Contribution of amygdala to the pressor response elicited by microinjection of angiotensin II into the bed nucleus of the stria terminalis

• Injection of Ang II into the BST produced a pressor response.
• Blockade of central nucleus of amygdala (CeA) attenuated this pressor response.
• Injection of Ang II into BST produced a short excitatory single unit response in 45% of neurons of CeA.
• BST and CeA may cooperate in their cardiovascular responses.

The bed nucleus of the stria terminalis (BST) is part of the limbic system located in the rostral forebrain. BST is involved in behavioral, neuroendocrine and autonomic functions, including cardiovascular regulation. The amygdala, plays an important role in mediating the behavioral and physiological responses associated with fear and anxiety, including cardiovascular responses. In a previous study, we showed that microinjection of AngII into the BST produced a pressor and two types of single-unit responses in the BST, short excitatory and long inhibitory. This study was performed to find possible involvement of amygdala in cardiovascular responses elicited by microinjection of AngII into the BST, using blockade of the central nucleus of amygdala (CeA) and single unit recording from the CeA, while injecting AngII into the BST in anesthetized rat. Blockade of CeA attenuated the pressor response to microinjection of AngII into the BST. Eighty-six AngII microinjections were given into the BST and 198 single unit responses were recorded from CeA simultaneously, from which 89 showed a short duration excitatory response and 109 showed no responses. In conclusion, microinjection of AngII into the BST produces a short excitatory single unit response in the CeA, resulting in contribution of amygdala to the resulted pressor response. Taken together, our study and previous studies suggest a plausible hypothesis that these two nuclei perform their cardiovascular functions in cooperation with each other.