Role of GABA and glycine in the formation of somato-sympathetic reflexes

1976 ◽  
Vol 82 (5) ◽  
pp. 1677-1680
Author(s):  
G. V. Kovalev ◽  
I. S. Morozov ◽  
V. I. Petrov
Keyword(s):  
Sympathetic Reflexes

Intrathecal melanin-concentrating hormone reduces sympathetic tone and blocks cardiovascular reflexes

2012 ◽  
Vol 303 (6) ◽  
pp. R624-R632 ◽  
Author(s):  
Eyitemi J. Egwuenu ◽  
Angelina Y. Fong ◽  
Paul M. Pilowsky
Keyword(s):  
Intrathecal Injection ◽  
Sympathetic Tone ◽  
Cardiovascular Reflexes ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Melanin Concentrating Hormone ◽  
Somatosympathetic Reflex ◽  
Sympathetic Reflexes ◽  
Two Peaks

Melanin-concentrating hormone (MCH) is a neuropeptide that acts to increase feeding behavior and decrease energy expenditure. The role of MCH in central cardiorespiratory regulation is still poorly understood. Experiments were conducted on urethane-anesthetized, vagotomized, and artificially ventilated male Sprague-Dawley rats ( n = 22) to ascertain whether MCH modulates sympathetic vasomotor tone, as well as barosympathetic, chemosympathetic, and somatosympathetic reflexes at the level of the spinal cord. Intrathecal injection of 10 μl of MCH produced a dose-dependent hypotension, bradycardia, and sympathoinhibition. Peak response was observed following administration of 1 mM MCH, causing a decrease in mean arterial pressure of 39 ± 2 mmHg ( P < 0.001), splanchnic sympathetic nerve activity of 78 ± 11% ( P < 0.001), and heart rate of 87 ± 11 beats per minute (bpm) ( P < 0.01). The two peaks of the somatosympathetic reflex were decreased by intrathecal MCH, 7 ± 3% ( P < 0.01) and 31 ± 6% ( P < 0.01), respectively, and the spinal component of the reflex was accentuated 96 ± 23% ( P < 0.05), with respect to the baseline for MCH, compared with the two peaks and spinal component of the somatosympathetic reflex elicited following saline injection with respect to the baseline for saline. MCH decreased the sympathetic gain to 120 s of hyperoxic hypercapnea (10% CO2 in 90% O2) and to 10–12 s poikilocapneic anoxia (100% N2) from 0.74 ± 0.14%/s to 0.23 ± 0.04%/s ( P < 0.05) and 16.47 ± 3.2% to 4.35 ± 1.56% ( P < 0.05), respectively. There was a 34% decrease in gain and a 62% decrease in range of the sympathetic baroreflex with intrathecal MCH. These data demonstrate that spinal MCH blunts the central regulation of sympathetic tone and adaptive sympathetic reflexes.

Role of endogenous angiotensin II on sympathetic reflexes in conscious rabbits

1997 ◽  
Vol 272 (6) ◽  
pp. R1816-R1825 ◽  
Author(s):  
R. D. Bendle ◽  
S. C. Malpas ◽  
G. A. Head
Keyword(s):  
Angiotensin Ii ◽  
Pressor Response ◽  
Ang Ii ◽  
At1 Antagonist ◽  
Before And After ◽  
Sympathetic Reflexes ◽  
Conscious Rabbits ◽  
Dose Dependent ◽  
Renal Sympathetic

In the present study we sought to determine the contribution of endogenous brain stem angiotensin to renal sympathetic reflexes in conscious rabbits. Initial studies determined the subtype of receptor involved in the pressor response to angiotensin II (ANG II) administration into the fourth ventricle (4V). The AT1 antagonist losartan (0.001-10 micrograms 4V) had no effect on blood pressure alone but caused a dose-dependent blockade of the pressor effect of ANG II, with complete blockade produced by 10 micrograms, an effect that lasted for at least 3 h. The AT2 antagonist PD-123319 (0.1-1,000 micrograms) and vehicle had no effect on the ANG II pressor response. The effect of losartan (10 micrograms) on the baroreceptor, chemoreceptor, and trigeminal reflexes was examined in eight rabbits that had been implanted with 4V catheters and an electrode for recording renal sympathetic nerve activity (RSNA) 1 wk earlier. Baroreflex assessments were made during normoxia and two conditions of hypoxia (10% O2 and 10% O2 + 3% CO2) before and after 10 micrograms losartan or vehicle, on separate experimental days. During normoxia and hypoxia+CO2 losartan increased resting RSNA, the range, and upper plateau of the RSNA-MAP baroreflex curves. By contrast the marked increase in RSNA due to activation of trigeminal afferents was not affected by losartan. In conclusion the effect of losartan to increase RSNA activity in conscious rabbits, particularly during hypoxia and baroreceptor unloading, suggests that endogenous ANG II via AT1 receptors normally inhibits renal sympathetic baroreceptor and chemoreceptor reflexes.

scholarly journals Nitric oxide in rostral ventrolateral medulla regulates cardiac-sympathetic reflexes: role of synthase isoforms

2009 ◽  
Vol 297 (4) ◽  
pp. H1478-H1486 ◽  
Author(s):  
Zhi-Ling Guo ◽  
Stephanie C. Tjen-A-Looi ◽  
Liang-Wu Fu ◽  
John C. Longhurst
Keyword(s):  
Blood Pressure ◽  
Methyl Ester ◽  
Arterial Blood Pressure ◽  
Ventrolateral Medulla ◽  
Nerve Activity ◽  
Renal Sympathetic Nerve Activity ◽  
Arterial Blood ◽  
Sympathetic Reflexes ◽  
Renal Sympathetic

Our previous studies have shown that nitric oxide (NO) synthase (NOS)-containing neurons in the rostral ventrolateral medulla (rVLM) are activated during cardiac sympathoexcitatory reflexes (Refs. 12 and 13 ). However, the precise function of NO in the rVLM in regulation of these reflexes has not been defined. Three isoforms of NOS, including neuronal NOS (nNOS), inducible NOS (iNOS), and endothelial NOS (eNOS), are located in the rVLM. We explored the role of NO, derived from different NOS isoforms in the rVLM, in processing cardiac-sympathetic reflexes using whole animal reflex and electrophysiological approaches. We found that, in anesthetized cats, increased mean arterial blood pressure and renal sympathetic nerve activity elicited by epicardial application of bradykinin (BK; 1–10 μg/ml, 50 μl) were significantly attenuated following unilateral rVLM microinjection of the nonselective NOS inhibitor, Nω-nitro-l-arginine methyl ester (50 nmol/50 nl), or a specific nNOS inhibitor, 7-nitroindazole (7-NI; 5–10 pmol/50 nl; both P < 0.05). In contrast, the responses of mean arterial blood pressure and renal sympathetic nerve activity to cardiac BK stimulation were unchanged by unilateral rVLM microinjection of Nω-nitro-d-arginine methyl ester (inactive isomer of Nω-nitro-l-arginine methyl ester, 50 nmol/50 nl), 3–6% methanol (7-NI vehicle), N6-(1-iminoethyl)-l-lysine (250 pmol/50 nl; iNOS inhibitor), or N5-(1-iminoethyl)-l-ornithine (250 nmol/50 nl; eNOS inhibitor). Furthermore, in separate cats, we noted that iontophoresis of 7-NI (0.1 mM) reduced the increased discharge of cardiovascular sympathoexcitatory rVLM neurons in response to cardiac stimulation with BK ( P < 0.05). These neurons were characterized by their responses to inputs from baroreceptors, and their cardiac rhythmicity was determined through frequency and time domain analyses, correlating their discharge to arterial blood pressure and cardiac sympathetic efferent nerve activity. These data suggest that NO, specifically nNOS, mediates sympathetic cardiac-cardiovascular responses through its action in the rVLM.

Role of central catecholaminergic pathways in the actions of endogenous ANG II on sympathetic reflexes

1998 ◽  
Vol 275 (4) ◽  
pp. R1174-R1184 ◽  
Author(s):  
Elisabeth A. Gaudet ◽  
Shirley J. Godwin ◽  
Geoffrey A. Head
Keyword(s):  
Enzyme Inhibitor ◽  
Renin Angiotensin System ◽  
Ringer Solution ◽  
Ang Ii ◽  
Central Administration ◽  
Before And After ◽  
Sympathetic Reflexes ◽  
6 Hydroxydopamine ◽  
Renal Sympathetic

In the present study, we examined the effect of blockade of the brain stem renin-angiotensin system on renal sympathetic baroreflexes and chemoreflexes in conscious rabbits and examined the role of central catecholaminergic pathways in these responses. Eleven rabbits underwent preliminary surgical instrumentation and pretreatment with central 6-hydroxydopamine (6-OHDA, 500 μg/kg) or ascorbic acid 6 wk before the commencement of the experiments. Baroreflex curves were determined under conditions of normoxia and hypoxia (10% O2+ 3% CO2) before and after central administration of either Ringer solution, the ANG II receptor antagonist losartan (10 μg), or the angiotensin-converting enzyme inhibitor enalaprilat (500 ng) on separate days. Losartan increased the upper plateau and the range of the mean arterial pressure (MAP)-renal sympathetic nerve activity (RSNA) curve (79 and 78%, respectively) in intact rabbits, whereas this effect was not observed in 6-OHDA-pretreated rabbits. Hypoxia elicited an increase in resting RSNA (111% in intact rabbits and 74% in 6-OHDA-injected rabbits) and elevated the upper plateau of the RSNA-MAP curve in both groups (89% in intact rabbits and 114% in 6-OHDA-injected rabbits). During hypoxia, losartan and enalaprilat increased the RSNA upper plateau in intact rabbits but had no effect in 6-OHDA-pretreated rabbits. No effects on the MAP-heart rate baroreflex curves were observed. Thus the effect of losartan to increase RSNA, particularly during hypoxia and baroreceptor unloading, being abolished by central noradrenergic depletion suggests that the endogenous ANG II which normally causes an inhibition of renal sympathetic motoneurons is dependent on the integrity of central catecholaminergic pathways.

Role of spinal NMDA and AMPA receptors in episodic hypertension in conscious spinal rats

1997 ◽  
Vol 273 (3) ◽  
pp. H1266-H1274 ◽  
Author(s):  
D. N. Maiorov ◽  
N. R. Krenz ◽  
A. V. Krassioukov ◽  
L. C. Weaver
Keyword(s):  
Receptor Antagonist ◽  
Ampa Receptors ◽  
Nmda Receptor Antagonist ◽  
Glutamatergic Transmission ◽  
Testing Effects ◽  
Pressor Responses ◽  
Cord Injury ◽  
Colon Distension ◽  
Sympathetic Reflexes

The neurotransmitters mediating the spinal sympathetic reflexes that initiate episodic hypertension after spinal cord injury are unknown. We examined the role of glutamatergic transmission in these reflexes by testing effects of the N-methyl-D-aspartate (NMDA)-receptor antagonist 2-amino-5-phosphonopentanoic acid (AP-5) and of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-receptor antagonist 2,3-dihydroxy-6-nitro-7-sulfamoylbenzoquinone (NBQX) on the reflex hypertension caused by colon distension. Antagonists were administered intrathecally in conscious rats 1-2 days (acute, n = 10) or 15-16 days (chronic, n = 14) after cord transection at the fifth thoracic segment under barbiturate anesthesia. AP-5 blocked pressor responses to intrathecal NMDA but had no effect on responses to AMPA; similarly, NBQX blocked responses to AMPA but had no effect on responses to NMDA. Before antagonist injection, colon distension increased mean arterial pressure by 24 +/- 1 mmHg (from 100 +/- 3 mmHg) and by 37 +/- 2 mmHg (from 116 +/- 3 mmHg) in the acute and chronic groups, respectively. Pretreatment with AP-5 attenuated the pressor responses by 36 and 37% in these respective groups; pretreatment with NBQX attenuated them by 34 and 31%. These data suggest that both NMDA and AMPA receptors contribute to spinal viscerosympathetic transmission and initiation of episodic hypertension in conscious spinal rats.

Role of dactinomycin in the improved survival of children with Wilms' tumor

JAMA ◽  
1966 ◽  
Vol 195 (12) ◽  
pp. 1005-1009 ◽  
Author(s):  
D. J. Fernbach
Keyword(s):  
Wilms Tumor

Role of the allergist in diagnosis and management of patients with uveitis

JAMA ◽  
1966 ◽  
Vol 195 (3) ◽  
pp. 167-172 ◽  
Author(s):  
T. E. Van Metre
Keyword(s):  
Diagnosis And Management

The power of norms to sway fused group members

2018 ◽  
Vol 41 ◽  
Author(s):  
Winnifred R. Louis ◽  
Craig McGarty ◽  
Emma F. Thomas ◽  
Catherine E. Amiot ◽  
Fathali M. Moghaddam
Keyword(s):  
Evolutionary Anthropology ◽  
Normative Systems ◽  
Violent Extremism ◽  
Identity Fusion ◽  
Group Members

AbstractWhitehouse adapts insights from evolutionary anthropology to interpret extreme self-sacrifice through the concept of identity fusion. The model neglects the role of normative systems in shaping behaviors, especially in relation to violent extremism. In peaceful groups, increasing fusion will actually decrease extremism. Groups collectively appraise threats and opportunities, actively debate action options, and rarely choose violence toward self or others.

Elaborating the role of reflection and individual differences in the study of folk-economic beliefs

2018 ◽  
Vol 41 ◽  
Author(s):  
Kevin Arceneaux
Keyword(s):  
Decision Making ◽  
Individual Differences ◽  
Cognitive Processes ◽  
Evolutionary History ◽  
Behavioral Responses ◽  
History Of ◽  
Economic Beliefs

AbstractIntuitions guide decision-making, and looking to the evolutionary history of humans illuminates why some behavioral responses are more intuitive than others. Yet a place remains for cognitive processes to second-guess intuitive responses – that is, to be reflective – and individual differences abound in automatic, intuitive processing as well.

The role of affect in feelings of obligation

2020 ◽  
Vol 43 ◽  
Author(s):  
Stefen Beeler-Duden ◽  
Meltem Yucel ◽  
Amrisha Vaish
Keyword(s):  
Positive Emotions ◽  
The Creation ◽  
Sense Of Obligation

Abstract Tomasello offers a compelling account of the emergence of humans’ sense of obligation. We suggest that more needs to be said about the role of affect in the creation of obligations. We also argue that positive emotions such as gratitude evolved to encourage individuals to fulfill cooperative obligations without the negative quality that Tomasello proposes is inherent in obligations.

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