AUTHOR=Pinto Izabella S. , Mourão Aline A. , da Silva Elaine F. , Camargo Amanda S. , Marques Stefanne M. , Gomes Karina P. , Fajemiroye James O. , da Silva Reis Angela A. , Rebelo Ana C. S. , Ferreira-Neto Marcos L. , Rosa Daniel A. , Freiria-Oliveira André H. , Castro Carlos H. , Colombari Eduardo , Colugnati Diego B. , Pedrino Gustavo R. 

TITLE=Blockade of Rostral Ventrolateral Medulla (RVLM) Bombesin Receptor Type 1 Decreases Blood Pressure and Sympathetic Activity in Anesthetized Spontaneously Hypertensive Rats

JOURNAL=Frontiers in Physiology

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2016.00205

DOI=10.3389/fphys.2016.00205

ISSN=1664-042X

ABSTRACT=<p>Intrathecal injection of bombesin (BBS) promoted hypertensive and sympathoexcitatory effects in normotensive (NT) rats. However, the involvement of rostral ventrolateral medulla (RVLM) in these responses is still unclear. In the present study, we investigated: (1) the effects of BBS injected bilaterally into RVLM on cardiorespiratory and sympathetic activity in NT and spontaneously hypertensive rats (SHR); (2) the contribution of RVLM BBS type 1 receptors (BB<sub>1</sub>) to the maintenance of hypertension in SHR. Urethane-anesthetized rats (1.2 g · kg<sup>−1</sup>, i.v.) were instrumented to record mean arterial pressure (MAP), diaphragm (DIA) motor, and renal sympathetic nerve activity (RSNA). In NT rats and SHR, BBS (0.3 mM) nanoinjected into RVLM increased MAP (33.9 ± 6.6 and 37.1 ± 4.5 mmHg, respectively; <italic>p</italic> &lt; 0.05) and RSNA (97.8 ± 12.9 and 84.5 ± 18.1%, respectively; <italic>p</italic> &lt; 0.05). In SHR, BBS also increased DIA burst amplitude (115.3 ± 22.7%; <italic>p</italic> &lt; 0.05). BB<sub>1</sub> receptors antagonist (BIM-23127; 3 mM) reduced MAP (–19.9 ± 4.4 mmHg; <italic>p</italic> &lt; 0.05) and RSNA (−17.7 ± 3.8%; <italic>p</italic> &lt; 0.05) in SHR, but not in NT rats (−2.5 ± 2.8 mmHg; −2.7 ± 5.6%, respectively). These results show that BBS can evoke sympathoexcitatory and pressor responses by activating RVLM BB<sub>1</sub> receptors. This pathway might be involved in the maintenance of high levels of arterial blood pressure in SHR.</p>