AT(2) and MAS (but not AT(1)) angiotensinergic receptors in the medial amygdaloid nucleus modulate the baroreflex activity in rats

Author(s)

Costa-Ferreira, Willian ^{[1, 2]} ; Gomes-de-Souza, Lucas ^{[1, 2]} ; Crestani, Carlos C. ^{[1, 2]}

Affiliation

^[1] Joint UFSCar UNESP Grad Program Physiol Sci, Sao Carlos, SP - Brazil

^[2] Sao Paulo State Univ UNESP, Sch Pharmaceut Sci, Pharmacol Lab, Rodovia Araraquara Jau Km 01 Campus Univ, BR-14800903 Araraquara, SP - Brazil

• Document type: Journal article
• Source: PFLUGERS ARCHIV-EUROPEAN JOURNAL OF PHYSIOLOGY; v. 471, n. 9, p. 1173-1182, SEP 2019.
• Web of Science Citations: 0

Abstract

The medial amygdaloid nucleus (MeA) is a limbic structure that has been demonstrated to be part of the central circuitry regulating baroreflex function. However, the local neurochemical mechanisms involved in baroreflex control by this forebrain structure is poorly understood. Thus, in the present study, we investigated the specific role of AT(1), AT(2), and MAS angiotensinergic receptors within the MeA in baroreflex responses in unanesthetized rats. For this, the baroreflex function was assessed using both the pharmacological approach via intravenous infusion of vasoactive agents and the sequence analysis technique. Using the pharmacological approach, we observed that bilateral microinjection of the selective AT(2) receptor antagonist PD123319 into the MeA increased the tachycardia evoked by blood pressure decrease, but without affecting the reflex bradycardia caused by blood pressure increase. Besides, bilateral microinjection of the selective MAS receptor antagonist A-779 decreased both tachycardic and bradycardic responses of the baroreflex. The sequence analysis technique indicated that PD123319 into the MeA increased baroreflex effectiveness index while A-779 had an opposite effect. Treatment of the MeA with the selective AT(1) receptor antagonist losartan did not affect baroreflex function assessed by either the pharmacological approach or sequence analysis technique. Overall, these findings provide evidence that MAS receptor within the MeA plays a facilitatory role in baroreflex function, whereas local AT(2) receptor inhibits cardiac baroreflex responses. Results also indicate that AT(1) receptor within the MeA is not involved in the control of baroreflex function. (AU)

• FAPESP's process: 15/05922-9 - Study of the participation of CRF neurotransmission in the bed nucleus of the stria terminalis in cardiovascular changes evoked by stress: interaction with the NMDA receptor/nitric oxide / guanilil cycles / protein kinase g signaling pathway?
• Grantee: Carlos Cesar Crestani
• Support Opportunities: Regular Research Grants
• FAPESP's process: 16/05218-2 - Involvement of the Angiotensin II / AT1 receptor angiotensin 1-7 / Mas receptor signaling in the medial nucleus of the amygdala in the cardiovascular and anxiogenic responses to stress in rats
• Grantee: Willian Costa Ferreira
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 17/19249-0 - Involvement of angiotensinergic neurotransmissions of medial amygdaloid nucleus in control of cardiovascular and anxiogenic responses to stress in rats.
• Grantee: Carlos Cesar Crestani
• Support Opportunities: Regular Research Grants