title: Cardiovascular and single-unit responses to microinjection of angiotensin II into the bed nucleus of the stria terminalis in rat.
abstract: 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 angiotensin II (Ang II) receptor, AT1, was found in the BST, however its effects on the cardiovascular system and on single-unit responses have not been studied yet. In the present study, Ang II was microinjected into the BST of anesthetized rats and cardiovascular and single-unit responses were recorded simultaneously. Furthermore the responses were re-tested after the microinjection of a blocker of the AT1 receptor, losartan, into the BST. We found that microinjection of Ang II into the BST produced a pressor response of 11±1mmHg for a duration of 2-8min. Ang II had no consistent effect on heart rate. It also produced two types of single-unit responses in the BST, short excitatory and long inhibitory. Blockade of AT1 receptors abolished both the cardiovascular and single-unit responses, indicating that the responses were mediated through AT1 receptors. These findings imply that Ang II may be utilized as a neurotransmitter and may play a role in returning blood pressure toward normal during hypotension.
authors.affiliation: Department of Physiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: M
authors.initials: M
authors.lastname: Kafami
authors.affiliation: Department of Physiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran. Electronic address: nasimi@med.mui.ac.ir.
authors.forename: A
authors.initials: A
authors.lastname: Nasimi
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology*; D047228:Angiotensin II Type 1 Receptor Blockers / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects* / Q000502:physiology; D006339:Heart Rate / Q000187:drug effects* / Q000502:physiology; D019808:Losartan / Q000494:pharmacology; D008297:Male; D008839:Microelectrodes; D008845:Microinjections; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D017208:Rats, Wistar; D044140:Receptor, Angiotensin, Type 1 / Q000378:metabolism; D012686:Septal Nuclei / Q000187:drug effects* / Q000502:physiology; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
chemical_list: D047228:Angiotensin II Type 1 Receptor Blockers; D044140:Receptor, Angiotensin, Type 1; D014662:Vasoconstrictor Agents; D000804:Angiotensin II; D019808:Losartan
keywords: BST; angiotensin II; bed nucleus of the stria terminalis; blood pressure; single-unit responses