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Brain Research Bulletin Jan 2000The fundamental neuronal substrates of the arterial baroreceptor reflex have been elucidated by combining anatomical, neurophysiological, and pharmacological approaches.... (Review)
Review
The fundamental neuronal substrates of the arterial baroreceptor reflex have been elucidated by combining anatomical, neurophysiological, and pharmacological approaches. A serial pathway between neurons located in the nuclei of the solitary tract (NTS), the caudal ventrolateral medulla (CVL), and the rostral ventrolateral medulla (RVL) plays a critical role in inhibition of sympathetic outflow following stimulation of baroreceptor afferents. In this paper, we summarize our studies using tract-tracing and electron microscopic immunocytochemistry to define the potential functional sites for synaptic transmission within this circuitry. The results are discussed as they relate to the literature showing: (1) baroreceptor afferents excite second-order neurons in NTS through the release of glutamate; (2) these NTS neurons in turn send excitatory projections to neurons in the CVL; (3) GABAergic CVL neurons directly inhibit RVL sympathoexcitatory neurons; and (4) activation of this NTS-->CVL-->RVL pathway leads to disfacilitation of sympathetic preganglionic neurons by promoting withdrawal of their tonic excitatory drive, which largely arises from neurons in the RVL. Baroreceptor control may also be regulated over direct reticulospinal pathways exemplified by a newly recognized sympathoinhibitory region of the medulla, the gigantocellular depressor area. This important autonomic reflex may also be influenced by parallel, multiple, and redundant networks.
Topics: Animals; Baroreflex; Medulla Oblongata; Neural Inhibition; Neural Pathways; Neurons; Pressoreceptors; Rats; Sympathetic Nervous System
PubMed: 10709955
DOI: 10.1016/s0361-9230(99)00233-6 -
Respiratory Physiology & Neurobiology Oct 2010Much progress has been made in our understanding of central chemoreception since the seminal experiments of Fencl, Loeschcke, Mitchell and others, including... (Review)
Review
Much progress has been made in our understanding of central chemoreception since the seminal experiments of Fencl, Loeschcke, Mitchell and others, including identification of new brainstem regions and specific neuron types that may serve as central "sensors" of CO(2)/pH. In this review, we discuss key attributes, or minimal requirements a neuron/cell must possess to be defined as a central respiratory chemoreceptor, and summarize how well each of the various candidates fulfill these minimal criteria-especially the presence of intrinsic chemosensitivity. We then discuss some of the in vitro and in vivo evidence in support of the conclusion that medullary serotonin (5-HT) neurons are central chemoreceptors. We also provide an additional hypothesis that chemosensitive medullary 5-HT neurons are poised to integrate multiple synaptic inputs from various other sources thought to influence ventilation. Finally, we discuss open questions and future studies that may aid in continuing our advances in understanding central chemoreception.
Topics: Animals; Chemoreceptor Cells; Humans; Medulla Oblongata; Neurons; Respiratory Physiological Phenomena; Serotonin
PubMed: 20226279
DOI: 10.1016/j.resp.2010.03.006 -
Internal Medicine (Tokyo, Japan) Mar 2023Yolk sac tumor (YST) is a rare primary brain tumor that occurs almost exclusively in patients under 30 years old. Intracranial germ cell tumors are most frequently... (Review)
Review
Yolk sac tumor (YST) is a rare primary brain tumor that occurs almost exclusively in patients under 30 years old. Intracranial germ cell tumors are most frequently located in the pineal and suprasellar region. Medulla oblongata YSTs are particularly rare. Extragonadal YSTs may be difficult to diagnose because of their characteristics, such as the rarity and variety of growth patterns. Furthermore, they are known to have a very poor prognosis. We herein report a case of YST of the medulla oblongata in a 50-year-old woman. She was followed up for 18 months without any tumor recurrence.
Topics: Female; Humans; Middle Aged; Adult; Endodermal Sinus Tumor; Neoplasm Recurrence, Local; Neoplasms, Germ Cell and Embryonal; Medulla Oblongata; Skull
PubMed: 35989277
DOI: 10.2169/internalmedicine.9447-22 -
American Journal of Physiology.... Jun 2010A sedentary lifestyle is a major risk factor for cardiovascular disease, and rates of inactivity and cardiovascular disease are highly prevalent in our society.... (Review)
Review
A sedentary lifestyle is a major risk factor for cardiovascular disease, and rates of inactivity and cardiovascular disease are highly prevalent in our society. Cardiovascular disease is often associated with overactivity of the sympathetic nervous system, which has both direct and indirect effects on multiple organ systems. Although it has been known for some time that exercise positively affects the brain in terms of memory and cognition, only recently have changes in how the brain regulates the cardiovascular system been examined in terms of physical activity and inactivity. This brief review will discuss the evidence for physical activity-dependent neuroplasticity related to control of sympathetic outflow. It will focus particularly on recent studies from our laboratory and others that have examined changes that occur in the rostral ventrolateral medulla (RVLM), considered one of the primary brain regions involved in the regulation and generation of sympathetic nervous system activity.
Topics: Animals; Medulla Oblongata; Neuronal Plasticity; Rats; Sedentary Behavior; Sympathetic Nervous System
PubMed: 20357021
DOI: 10.1152/ajpregu.00101.2010 -
Progress in Neurobiology 1989
Review
Topics: Animals; Cardiovascular Physiological Phenomena; Chemoreceptor Cells; Medulla Oblongata; Respiration; Vomiting
PubMed: 2660187
DOI: 10.1016/0301-0082(89)90028-2 -
The Neuroradiology Journal Apr 2022Giant aneurysms of the intracranial vertebral artery are very rare cerebrovascular lesions. Due to the rarity of these aneurysms, we know little about them.
BACKGROUND
Giant aneurysms of the intracranial vertebral artery are very rare cerebrovascular lesions. Due to the rarity of these aneurysms, we know little about them.
METHODS
We performed a systematic review of the English literature by searching the PubMed database. The inclusion criteria were as follows: (a) the full text was available and (b) complete clinical data were available.
RESULTS
A total of 45 articles were identified, containing 53 patients (53 aneurysms). The patients were aged from 5 to 77 years (48.8 ± 20.8 years). Four patients receiving conservative treatment died. The remaining 49 patients were divided into the aneurysm removal group ( = 17) and the aneurysm reserve group ( = 32). The outcomes of the 49 treated cases could be obtained in 45 cases, 31 of which (68.9%, 31/45) had a Glasgow outcome scale score of 4-5.
CONCLUSIONS
It is still difficult to treat intracranial giant vertebral artery aneurysms, regardless of the treatment selected. Because of the malignant natural history, aggressive treatment is still advocated.
Topics: Adolescent; Adult; Aged; Child; Child, Preschool; Embolization, Therapeutic; Humans; Intracranial Aneurysm; Medulla Oblongata; Middle Aged; Spine; Treatment Outcome; Vertebral Artery; Young Adult
PubMed: 34477003
DOI: 10.1177/19714009211042881 -
PloS One 2021Baroreflex dysfunction is partly implicated in hypertension and one responsible region is the dorsal medulla oblongata including the nucleus tractus solitarius (NTS)....
Baroreflex dysfunction is partly implicated in hypertension and one responsible region is the dorsal medulla oblongata including the nucleus tractus solitarius (NTS). NTS neurons receive and project glutamatergic inputs to subsequently regulate blood pressure, while G-protein-coupled metabotropic glutamate receptors (mGluRs) play a modulatory role for glutamatergic transmission in baroreflex pathways. Stimulating group II mGluR subtype 2 and 3 (mGluR2/3) in the brainstem can decrease blood pressure and sympathetic nervous activity. Here, we hypothesized that the chronic stimulation of mGluR2/3 in the dorsal medulla oblongata can alleviate hypertensive development via the modulation of autonomic nervous activity in young, spontaneously hypertensive rats (SHRs). Compared with that in the sham control group, chronic LY379268 application (mGluR2/3 agonist; 0.40 μg/day) to the dorsal medulla oblongata for 6 weeks reduced the progression of hypertension in 6-week-old SHRs as indicated by the 40 mmHg reduction in systolic blood pressure and promoted their parasympathetic nervous activity as evidenced by the heart rate variability. No differences in blood catecholamine levels or any echocardiographic indices were found between the two groups. The improvement of reflex bradycardia, a baroreflex function, appeared after chronic LY379268 application. The mRNA expression level of mGluR2, but not mGluR3, in the dorsal medulla oblongata was substantially reduced in SHRs compared to that of the control strain. In conclusion, mGluR2/3 signaling might be responsible for hypertension development in SHRs, and modulating mGluR2/3 expression/stimulation in the dorsal brainstem could be a novel therapeutic strategy for hypertension via increasing the parasympathetic activity.
Topics: Amino Acids; Animals; Antihypertensive Agents; Blood Pressure; Bridged Bicyclo Compounds, Heterocyclic; Hypertension; Male; Medulla Oblongata; Rats, Inbred SHR; Receptors, Metabotropic Glutamate; Rats
PubMed: 34010316
DOI: 10.1371/journal.pone.0251495 -
Journal of Neurophysiology Jun 2022Pulmonary vagal nociceptors defend the airways. Cardiopulmonary vagal nociceptors synapse in the nucleus tractus solitarius (NTS). Evidence has demonstrated the...
Pulmonary vagal nociceptors defend the airways. Cardiopulmonary vagal nociceptors synapse in the nucleus tractus solitarius (NTS). Evidence has demonstrated the convergence of cardiopulmonary nociceptors with afferents from carotid chemoreceptors. Whether sensory convergence occurs in motor nuclei and how sensory convergence affects reflexive efferent motor output directed toward the airways are critical knowledge gaps. Here, we show that distinct tracer injection into the pulmonary nociceptors and carotid chemoreceptors leads to co-labeled neurons in the nucleus tractus solitarius and nucleus ambiguus. Precise simultaneous stimulation delivered to pulmonary nociceptors and carotid chemoreceptors doubled efferent vagal output, enhanced phrenic pause, and subsequently augmented phrenic motor activity. These results suggest that multiple afferents are involved in protecting the airways and concurrent stimulation enhances airway defensive reflex output. Sensory afferents have been shown to converge onto nucleus tractus solitarius primary neurons. Here, we show sensory convergence of two distinct sets of sensory afferents in motor nuclei of the nucleus ambiguus, which results in augmentation of airway defense motor output.
Topics: Chemoreceptor Cells; Medulla Oblongata; Neurons; Nociceptors; Solitary Nucleus; Vagus Nerve
PubMed: 35443145
DOI: 10.1152/jn.00125.2022 -
The Japanese Journal of Physiology Dec 1999Nitric oxide (NO) is involved in numerous physiological functions. Besides its role as an endothelium-dependent relaxing factor (EDRF), NO inhibits platelet aggregation,... (Review)
Review
Nitric oxide (NO) is involved in numerous physiological functions. Besides its role as an endothelium-dependent relaxing factor (EDRF), NO inhibits platelet aggregation, contributes to cytotoxicity against bacteria, is active in synaptic transmission within the brain, etc. NO synthase (NOS) is distributed in brain regions related to the regulation of cardiovascular functions. NO has been inferred not only to act directly on vascular vessels, but also to regulate circulation within the brain. In this review paper, we mainly consider the functions of NO in the cardiovascular center of the medulla oblongata. That is, we describe the anatomical distribution of NOS in the brain, effects of intravenous and intracerebroventricular administration of NOS inhibitors on the circulation, effects of microinjection of NO donors and NOS inhibitors into the nucleus tractus solitarius (NTS) and ventrolateral medulla (VLM), the results of electrophysiological studies on these areas, and finally, the data obtained by new molecular biological techniques.
Topics: Animals; Cardiovascular Physiological Phenomena; Humans; Medulla Oblongata; Nitric Oxide
PubMed: 10603432
DOI: 10.2170/jjphysiol.49.467 -
The Japanese Journal of Physiology Oct 1997The respiratory network in the ventrolateral medulla of the brainstem-spinal cord preparation from newborn rat involves pre-inspiratory (Pre-I) neurons, three types of... (Comparative Study)
Comparative Study Review
The respiratory network in the ventrolateral medulla of the brainstem-spinal cord preparation from newborn rat involves pre-inspiratory (Pre-I) neurons, three types of inspiratory (Insp I, II, III) neurons and two types of expiratory (Exp-i, Exp-p-i) neurons as major subtypes, which were classified according to patterns of postsynaptic potentials. The neuronal respiratory-related membrane potential fluctuations of these cells indicate at least four distinguishable phases of the in vitro respiratory cycle: pre-inspiratory, inspiratory, post-inspiratory (E1), and late-expiratory (E2). A current hypothesis for the central pattern generator of respiration proposed by our group is that Pre-I neurons in the rostral ventrolateral medulla, with intrinsic burster properties, produce the primary respiration rhythm. This rhythm triggers an inspiratory pattern generator composed of Insp neurons in the rostral and caudal ventrolateral medulla. Respiratory neurons possess several types of ionic channels which are involved in the generation of rhythm and burst pattern. Particularly, P-type Ca2+ channels and TTX-sensitive persistent Na+ channels are postulated to contribute to the intrinsic burst generation of Pre-I neurons. N-type Ca2+ channels may be involved in the maintenance and termination of inspiratory burst activity via the activation of Ca2(+)-dependent K+ channels. Respiratory neuron networks in this preparation were compared with those of different in vitro preparations, like rhythmic slices or perfused brainstems and of adult mammals in vivo. Many types of synaptic connections among respiratory neurons in adult mammals were also found in the (rostral) ventrolateral medulla of a brainstem-spinal cord preparation from newborn rat. The characteristics of the inspiratory burst pattern and inspiratory off switch mechanisms in newborn rat preparations might be explained by insufficient inhibitory (or excitatory) synaptic inputs to the inspiratory pattern generator due to an immature neuron network and/or deafferentiation.
Topics: Animals; Animals, Newborn; Electrophysiology; In Vitro Techniques; Ion Channels; Mammals; Medulla Oblongata; Membrane Potentials; Mice; Nerve Net; Neurons; Periodicity; Rats; Respiratory Mechanics; Rodentia; Synapses
PubMed: 9504127
DOI: 10.2170/jjphysiol.47.385