Blockade of Rostral Ventrolateral Medulla (RVLM) Bombesin Receptor Type 1 Decreases Blood Pressure and Sympathetic Activity in Anesthetized Spontaneously Hypertensive Rats.
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 (BB1) to the maintenance of hypertension in SHR. Urethane-anesthetized rats (1.2 g · kg(-1), 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; p < 0.05) and RSNA (97.8 ± 12.9 and 84.5 ± 18.1%, respectively; p < 0.05). In SHR, BBS also increased DIA burst amplitude (115.3 ± 22.7%; p < 0.05). BB1 receptors antagonist (BIM-23127; 3 mM) reduced MAP (-19.9 ± 4.4 mmHg; p < 0.05) and RSNA (-17.7 ± 3.8%; p < 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 BB1 receptors. This pathway might be involved in the maintenance of high levels of arterial blood pressure in SHR.
Department of Physiological Sciences, Center for Neuroscience and Cardiovascular Research, Biological Sciences Institute, Federal University of Goiás Goiânia, Brazil.
Izabella S
IS
Pinto
Department of Physiological Sciences, Center for Neuroscience and Cardiovascular Research, Biological Sciences Institute, Federal University of Goiás Goiânia, Brazil.
Aline A
AA
Mourão
Department of Physiological Sciences, Center for Neuroscience and Cardiovascular Research, Biological Sciences Institute, Federal University of Goiás Goiânia, Brazil.
Elaine F
EF
da Silva
Department of Physiological Sciences, Center for Neuroscience and Cardiovascular Research, Biological Sciences Institute, Federal University of Goiás Goiânia, Brazil.
Amanda S
AS
Camargo
Department of Physiological Sciences, Center for Neuroscience and Cardiovascular Research, Biological Sciences Institute, Federal University of Goiás Goiânia, Brazil.
Stefanne M
SM
Marques
Department of Physiological Sciences, Center for Neuroscience and Cardiovascular Research, Biological Sciences Institute, Federal University of Goiás Goiânia, Brazil.
Karina P
KP
Gomes
Postgraduate Programme in Pharmaceutical Sciences, Faculty of Pharmacy, Federal University of Goiás Goiânia, Brazil.
James O
JO
Fajemiroye
Department of Biochemistry and Molecular Biology, Biological Sciences Institute, Federal University of Goiás Goiânia, Brazil.
Angela A
AA
da Silva Reis
Department of Morphology, Biological Sciences Institute, Federal University of Goiás Goiânia, Brazil.
Ana C S
AC
Rebelo
Department of Physiology, College of Physical Education, Federal University of Uberlândia Uberlândia, Brazil.
Marcos L
ML
Ferreira-Neto
Department of Physiological Sciences, Center for Neuroscience and Cardiovascular Research, Biological Sciences Institute, Federal University of Goiás Goiânia, Brazil.
Daniel A
DA
Rosa
Department of Physiological Sciences, Center for Neuroscience and Cardiovascular Research, Biological Sciences Institute, Federal University of Goiás Goiânia, Brazil.
André H
AH
Freiria-Oliveira
Department of Physiological Sciences, Center for Neuroscience and Cardiovascular Research, Biological Sciences Institute, Federal University of Goiás Goiânia, Brazil.
Carlos H
CH
Castro
Department of Physiology and Pathology, School of Dentistry, São Paulo State University Araraquara, Brazil.
Eduardo
E
Colombari
Department of Physiological Sciences, Center for Neuroscience and Cardiovascular Research, Biological Sciences Institute, Federal University of Goiás Goiânia, Brazil.
Diego B
DB
Colugnati
Department of Physiological Sciences, Center for Neuroscience and Cardiovascular Research, Biological Sciences Institute, Federal University of Goiás Goiânia, Brazil.
Gustavo R
GR
Pedrino
BB1 receptors; BIM-23127; SHR; bombesin; rostral ventrolateral medulla