Injection of brain-derived neurotrophic factor in the rostral ventrolateral medulla increases arterial blood pressure in anaesthetized rats

The purpose of the present investigation was to determine if gamma-aminobutyric acid (GABA) mediates the baroreceptor-induced inhibition of sympathetic nerve discharge (SND) in dialurethan-anesthetized cats. The GABA antagonists picrotoxin and bicuculline produced marked elevations in arterial blood pressure and inferior cardiac SND. The inhibition of SND observed during pressor responses was occasionally slightly depressed after picrotoxin or bicuculline. Midcollicullar transection blocked or reversed the increase in blood pressure and SND produced by GABA antagonists. Under these conditions, baroreceptor inhibition of SND was not affected by picrotoxin. Microinjections of picrotoxin into the rostral ventrolateral medulla produced increases in arterial blood pressure and SND but failed to affect baroreceptor-induced sympathoinhibition. GABA antagonists given intravenously also failed to affect the baroreceptor-induced inhibition of sympathetically related neurons recorded in the rostral ventrolateral medulla. However, intravenous picrotoxin did antagonize the inhibitory affect of microiontophoretically applied GABA on these neurons. These data provide no evidence to support the contention that GABA mediates the baroreceptor-induced inhibition of SND. The role of GABA in regulating SND is discussed.

Download Full-text

REGULATION OF ARTERIAL BLOOD PRESSURE BY THE ROSTRAL VENTROLATERAL MEDULLA

Behavioral Aspects of Cardiovascular Disease ◽

10.4324/9781315827568-19 ◽

2014 ◽

pp. 177-218

Keyword(s):

Blood Pressure ◽

Arterial Blood Pressure ◽

Rostral Ventrolateral Medulla ◽

Ventrolateral Medulla ◽

Arterial Blood

Download Full-text

Role of the medulla oblongata in normal and high arterial blood pressure regulation: the contribution of Escola Paulista de Medicina - UNIFESP

Anais da Academia Brasileira de Ciências ◽

10.1590/s0001-37652009000300021 ◽

2009 ◽

Vol 81 (3) ◽

pp. 589-603 ◽

Cited By ~ 3

Author(s):

Sergio L. Cravo ◽

Ruy R. Campos ◽

Eduardo Colombari ◽

Mônica A. Sato ◽

Cássia M. Bergamaschi ◽

...

Keyword(s):

Blood Pressure ◽

Arterial Blood Pressure ◽

Medulla Oblongata ◽

Neural Circuits ◽

Ventrolateral Medulla ◽

Vasomotor Tone ◽

Arterial Blood ◽

Pathological Conditions ◽

De Medicina

Several forms of experimental evidence gathered in the last 37 years have unequivocally established that the medulla oblongata harbors the main neural circuits responsible for generating the vasomotor tone and regulating arterial blood pressure. Our current understanding of this circuitry derives mainly from the studies of Pedro Guertzenstein, a former student who became Professor of Physiology at UNIFESP later, and his colleagues. In this review, we have summarized the main findings as well as our collaboration to a further understanding of the ventrolateral medulla and the control of arterial blood pressure under normal and pathological conditions.

Download Full-text

Rostral ventral medulla 5-HT1A receptors selectively inhibit the somatosympathetic reflex

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.2001.280.5.r1261 ◽

2001 ◽

Vol 280 (5) ◽

pp. R1261-R1268 ◽

Cited By ~ 25

Author(s):

Takashi Miyawaki ◽

Ann K. Goodchild ◽

Paul M. Pilowsky

Keyword(s):

Blood Pressure ◽

Arterial Blood Pressure ◽

Sympathetic Nerve Activity ◽

Selective Inhibition ◽

Inhibitory Effect ◽

Ventrolateral Medulla ◽

Arterial Blood ◽

Potent Inhibition ◽

Somatosympathetic Reflex

The role of the 5-hydroxytryptamine (5-HT1A) receptors in the rostral ventrolateral medulla (RVLM) on somatosympathetic, baroreceptor, and chemoreceptor reflexes was examined in anesthetized rats. Microinjection of the selective 5-HT1A agonist 8-hydroxy-di- n-propylamino tetralin (8-OH-DPAT) decreased arterial blood pressure and splanchnic sympathetic nerve activity (SNA). Electrical stimulation of the hindlimb evoked early and late excitatory sympathetic responses. Bilateral microinjection in the RVLM of 8-OH-DPAT markedly attenuated both the early and late responses. This potent inhibition of the somatosympathetic reflex persisted even after SNA and arterial blood pressure returned to preinjection levels. Preinjection of the selective 5-HT1A antagonist NAN-190 in the RVLM blocked the sympathoinhibitory effect of 8-OH-DPAT and attenuated the inhibitory effect on the somatosympathetic reflex. 8-OH-DPAT injected in the RVLM did not affect baroreceptor or chemoreceptor reflexes. Our findings suggest that activation of 5-HT1A receptors in the RVLM exerts a potent, selective inhibition on the somatosympathetic reflex.

Download Full-text

Electrical stimulation of cervical vagal afferents. II. Central relays for behavioral antinociception and arterial blood pressure decreases

Journal of Neurophysiology ◽

10.1152/jn.1990.64.4.1115 ◽

1990 ◽

Vol 64 (4) ◽

pp. 1115-1124 ◽

Cited By ~ 60

Author(s):

A. Randich ◽

K. Ren ◽

G. F. Gebhart

Keyword(s):

Blood Pressure ◽

Arterial Blood Pressure ◽

Nucleus Tractus Solitarius ◽

Cardiovascular Response ◽

Ibotenic Acid ◽

Vagal Afferents ◽

Ventrolateral Medulla ◽

Tail Flick ◽

Threshold Intensity ◽

Arterial Blood

1. Supraspinal substrates mediating vagal afferent stimulation (VAS)-induced inhibition of the nociceptive tail-flick reflex were examined by the use of the soma-selective neurotoxin ibotenic acid and the nonselective local anesthetic lidocaine. Fifty rats were studied in the lightly anesthetized state maintained with pentobarbital sodium. 2. The threshold intensity of VAS required to inhibit the tail-flick reflex to a cut-off latency of 10 s was established in all rats. Ibotenic acid (5 or 10 micrograms, 0.5 microliter) or lidocaine (4%, 0.5 microliter) was then microinjected into various regions of the brain stem followed by reestablishment of the intensity of VAS required to produce inhibition of the tail-flick reflex. 3. Microinjections of ibotenic acid into the ipsilateral nucleus tractus solitarius (NTS), medial rostroventral medulla (principally the nucleus raphe magnus; NRM), or bilaterally into the dorsolateral pons (principally the locus coeruleus/subcoeruleus; LC/SC), significantly increased the threshold intensity of VAS required to inhibit the tail-flick reflex. Microinjections of ibotenic acid into either the rostral or caudal ventrolateral medulla (RVLM or CVLM, respectively) ipsilateral to the vagus nerve stimulated or ipsilateral LC/SC did not significantly affect the inhibition produced by VAS. Arterial blood pressure decreases produced by VAS were significantly attenuated or eliminated after microinjections of ibotenic acid into the NTS, RVLM, CVLM, or NRM. Lidocaine microinjected into the ipsilateral CVLM also significantly increased the intensity of VAS required to inhibit the tail-flick reflex. 4. These outcomes obtained with behavioral measures are consistent with the outcomes of the preceding study using electrophysiological measures in establishing that cells in the NTS, LC/SC, and NRM regions and fibers of passage in the CVLM are important in mediating the inhibitory effects of VAS. The present studies confirm previous reports of the importance of the RVLM and CVLM in VAS-produced depressor responses but also demonstrate that the NRM is critical for this cardiovascular response.

Download Full-text

Methane, a gut bacteria-produced gas, does not affect arterial blood pressure in normotensive anaesthetized rats.

10.1101/2021.03.31.437828 ◽

2021 ◽

Author(s):

Ewelina Zaorska ◽

Marta Gawrys-Kopczynska ◽

Ryszard Ostaszewski ◽

Dominik Koszelewski ◽

Marcin Ufnal

Keyword(s):

Blood Pressure ◽

Heart Rate ◽

Arterial Blood Pressure ◽

Acute Administration ◽

Hemodynamic Effects ◽

Arterial Blood ◽

Anaesthetized Rats ◽

Carbohydrate Fermentation ◽

Oxidative Effects ◽

Lines Of Evidence

Methane is produced by carbohydrate fermentation in the gastrointestinal tract through the metabolism of methanogenic microbiota. Several lines of evidence suggest that methane exerts anti-inflammatory, anti-apoptotic and anti-oxidative effects. The effect of methane on cardiovascular system is obscure. The objective of the present study was to evaluate the hemodynamic response to methane. A vehicle or methane-rich saline were administered intravenously or intraperitoneally in normotensive anaesthetized rats. We have found no significant effect of the acute administration of methane-rich saline on arterial blood pressure and heart rate in anaesthetized rats. Our study suggests that methane does not influence the control of arterial blood pressure. However, further chronic studies may be needed to fully understand hemodynamic effects of the gas.

Download Full-text