Functional Organization of Central Cardiovascular Pathways

Dampney, R.A.L.

doi:10.1111/j.1440-1681.1981.tb00156.x

Cited by 66 publications

(24 citation statements)

References 98 publications

(109 reference statements)

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“…3 Whether these effects are mediated by the C1 cells in the RVL, however, remained to be established. In a recent series of experiments by combining electrical and chemical stimulation techniques along with careful correlation with the anatomy of neurons staining for PNMT, we 39 w have demonstrated an extremely tight correlation between the responses elicited from the Cl area and the distribution of neurons and their axonal processes, which contain the enzyme PNMT.…”

Section: Control Of Apmentioning

confidence: 99%

Brain stem catecholamine mechanisms in tonic and reflex control of blood pressure.

et al. 1984

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SUMMARY Neurons of the lower brain stem maintain resting levels of arterial pressure (AP), mediate reflex responses from cardiopulmonary receptors, and are an important site of the hypotensive actions of a 2 -adrenergic agonists. Details of the pathways and transmitters that mediate tonic and reflex control of AP are emerging. Afferent fibers of cardiopulmonary receptors in the ninth and tenth nerves terminate bilaterally in the nucleus of the tractus solitarius (NTS). Although some neurons contain substance P, the primary neurotransmitter appears to be the excitatory amino acid L-glutamate (L-glu). Neurons in rostral ventrolateral medulla, which most probably comprise the Cl group of epinephrine neurons, are also critical in AP control. Cl neurons project to innervate cholinergic preganglionic sympathetic neurons in the spinal cord. Stimulation of the Cl area electrically or with L-glu increases AP, while lesions or local injection of the inhibitory amino acid gamma-aminobutyric acid (GABA) lowers AP to levels comparable to spinal cord transection. Lesions of Cl neurons or their pathways abolish vasodepressor reflexes from baroreceptors and vagal afferents. In contrast, noradrenergic neurons of the caudal ventrolateral medulla, the Al group, project rostrally to innervate, in part, vasopressin neurons of the hypothalamus. Stimulation of Al neurons lowers AP, while lesions or GABA elevates it. We propose that Cl neurons comprise the so-called tonic vasomotor center of the brain stem and also mediate, via a projection from the NTS, the vasodepressor limb of baroreflexes. ; (2) are the site of termination of cardiopulmonary afferents, which includes those from high and low pressure baro-and other cardiopulmonary receptors 5 " 8 ; and (3) are the major targets of those centrally acting a-adrenergic agonists that act as antihypertensive agents, most notably, clonidine and a-methyldopa.9 " 12 Indeed that these agents, which act on receptors in the brain normally stimulated by catecholamines, produce cardiovascular actions by stimulation of baroreceptors," This paper reviews recent research from our laboratory directed toward clarifying the networks in the lower brain stem that are responsible for maintaining normal levels of AP and mediating barorefiex responses. Our findings suggest an important new role for catecholamine cell groups of the lower medulla in such control. We review these studies with the present knowledge of control of the circulation by the brain stem. Nucleus of the Tractus Solitariusand Arterial Pressure The nucleus of the tractus solitarius (NTS) is the major site of termination of afferents of the ninth and tenth cranial nerves. As such, the NTS is the major relay nucleus for information arising from baroreceptors and cardiopulmonary afferents.Interestingly, recognition that the NTS is critical for baroreceptor reflex function is relatively recent and has 1-7 by guest on May 12, 2018 http://hyper.ahajournals.org/ Downloaded from

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Section: Control Of Apmentioning

confidence: 99%

Brain stem catecholamine mechanisms in tonic and reflex control of blood pressure.

et al. 1984

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“…These nuclei, in turn, innervate the cardiovascular system via the autonomic nerves (Nosaka et al, 1978(Nosaka et al, ,1979Gillis and Quest, 1980;Dampney, 1981).…”

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confidence: 99%

Autoradiographic localization of ³H‐digoxin binding by neural cells in the medulla

1985

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The purpose of this investigation was to localize binding sites for the cardiac glycoside digoxin in the medulla of the rat in vivo. Adult male Sprague-Dawley rats were injected (IV) with 3H-digoxin and killed 30 minutes later. Autoradiographs of medullas showed evidence of 3H-digoxin binding to small- and medium-sized neural cells in the regions of the nucleus solitarius, dorsal motor nucleus of the vagus, area postrema, and in the zone between the area postrema and the underlying neuropil. However, the parasympathetic preganglionic neurons of the dorsal motor nucleus were not labeled. The 3H-digoxin-labeled cells in the medulla were located mainly in the commissural and medial portions of nucleus solitarius at the level of the area postrema. Animals injected with unlabeled digoxin followed by 3H-digoxin showed reduced binding of radioactivity. The small- and medium-sized neurons of the caudal portions of the nucleus solitarius are internuncial in position with respect to cardiovascular afferents of the glossopharyngeal and vagus nerves and sympathetic and parasympathetic cardiovascular efferent neurons of the medulla. The results of this study suggest that these 3H-digoxin-labeled cells, presumably neurons of nucleus solitarius, may possess high affinity binding sites for digoxin. Further, the area postrema, which lacks a blood-brain barrier, may provide a portal of entry for 3H-digoxin into regions of the medulla known to contain neurons that play a role in the regulation of cardiac rhythm.

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“…Medulla oblongata and Pons are crucial for tonic and reflex regulation of arterial pressure via the spinal sympathetic outflow (Alexander 1946, Dampney 1981. The neurons in the nucleus tractus solitarius are where afferent signals from baro-receptors terminate (Reis, Granata et al 1984).…”

Section: 5: Hypothalamic Control Of Autonomic Nervous System (Ans)mentioning

confidence: 99%

“…The neurons in the nucleus tractus solitarius are where afferent signals from baro-receptors terminate (Reis, Granata et al 1984). Those neurons maintain tonic background drive to sympathetic preganglionic neurons directly (Dampney 1981, Reis, Granata et al 1984 and are the target organs for the centrally acting anti-hypertensive agents such as Clonidine (Haeusler 1973). A1 fibers from the Nucleus Tractus Solitarius project cephalically to the paraventricular and supraoptic nuclei of hypothalamus for integration of sensory signals (Blessing, Goodchild et al 1981, Blessing, Jaeger et al 1982.…”

Section: 5: Hypothalamic Control Of Autonomic Nervous System (Ans)mentioning

confidence: 99%

Energy Homeostasis in children with Prader- Willi syndrome

Nyunt¹

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IntroductionPrader-Willi syndrome (PWS) is a genetic condition commonly associated with hyperphagia and obesity. PWS is thought to have hypothalamic dysfunction which is the head ganglion of autonomic nervous system (ANS). In current literature, ANS is believed to be defective in PWS. ANS may also have a role in controlling orexigenic hormone ghrelin and energy expenditure. One study reported higher resting energy expenditure adjusted for lean body mass in growth hormone naive PWS group but another study found lower activity associated energy expenditure compared to controls. Other studies found adjusted basal and sleeping metabolic rates were not different to the controls. Complete profile of energy expenditure in PWS remains unclear.We hypothesize that there is defective ANS in PWS, as a result of hypothalamus dysfunction, and it leads to high orexigenic hormone, acyl ghrelin, and low energy expenditure that in turn cause obesity. MethodsWe compared the ANS functions, acyl ghrelin status and energy expenditure in children with PWS and controls.We recruited 16 genetically-confirmed children with PWS and 16 controls. Exclusion criteria were diabetes mellitus, psycho-trophic medications, and other hypothalamic pathologies.We performed a mixed meal challenge to assess ANS function and acyl ghrelin status of PWS and control groups. We used Bodystat 1500 ® to measure body composition.Orthostatic hypotension, due to gravity, stimulates baroreceptors and activates sympathetic nervous system to counter regulate postural drop in blood pressure by increasing pulse rate, stroke volume and vasoconstriction. We used orthostatic change in pulse rate (PR), blood pressure (BP), and mean arterial pressure (MAP) expressed as per cent change of PR (%ΔPR), BP (%ΔBP), and MAP (%ΔMAP) from lying to standing to access sympathetic nervous function. ANS was further stimulated by a mixed meal and we examined %ΔPR, %ΔBP, and %ΔMAP at 15 and 30 seconds after standing from recumbent position; at fasting, and post-prandial periods. We also measured plasma gastrin, catecholamines (Pcat) and urinary catecholamines (Ucat) at fasting and postprandial periods to complement autonomic cardiovascular data. Using Actiheart®, we compared weight and fat free mass adjusted total, resting, activity-associated and nonexercise associated thermogenesis between two groups. 3 ResultsPWS group was younger, shorter, and had reduced lean mass than the controls. Postprandial %ΔPR at both 15 and 30 seconds were significantly lower in PWS group than controls. The difference in %Δ systolic BP and diastolic BP did not reach statistical significance but %ΔMAP at 60 min and 120 min after meal was significantly lower in PWS.Postprandial plasma gastrin and Ucat were higher in PWS group than controls but Pcat were not different in two groups. Fasting plasma acyl ghrelin (AG) was significantly higher in PWS but it decreased to similar level of controls at 60 and 120 minutes after a meal.The rate of fall of plasma acyl ghrelin was faster in the PWS group than the ...

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Functional Organization of Central Cardiovascular Pathways

Cited by 66 publications

References 98 publications

Brain stem catecholamine mechanisms in tonic and reflex control of blood pressure.

Brain stem catecholamine mechanisms in tonic and reflex control of blood pressure.

Autoradiographic localization of ³H‐digoxin binding by neural cells in the medulla

Energy Homeostasis in children with Prader- Willi syndrome

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Functional Organization of Central Cardiovascular Pathways

Cited by 66 publications

References 98 publications

Brain stem catecholamine mechanisms in tonic and reflex control of blood pressure.

Brain stem catecholamine mechanisms in tonic and reflex control of blood pressure.

Autoradiographic localization of 3H‐digoxin binding by neural cells in the medulla

Energy Homeostasis in children with Prader- Willi syndrome

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Autoradiographic localization of ³H‐digoxin binding by neural cells in the medulla