The rostral hypothalamus: an area for the integration of autonomic and sensory responsiveness

1993 ◽  
Vol 70 (4) ◽  
pp. 1570-1577 ◽  
Author(s):  
B. M. Lumb ◽  
T. A. Lovick
Keyword(s):  
Anterior Hypothalamus ◽  
Reflex Activity ◽  
Type I ◽  
Type Ii ◽  
Response Type ◽  
Homocysteic Acid ◽  
Depressor Response ◽  
Arterial Blood ◽  
Rostral Hypothalamus ◽  
Stimulation Of

1. An investigation has been made of the effects of chemical stimulation of neurons in the rostral hypothalamus on cardiovascular and respiratory parameters and on a nociceptive viscerosomatic reflex (reflex activity recorded from a lumbar spinal nerve in response to electrical stimulation of visceral afferent fibers in the splanchnic nerve) in alphaxalone/alphadolone-anesthetised rats. 2. Neurons were stimulated by microinjection of DL-homocysteic acid (DLH) at ventromedial forebrain sites between 2 mm caudal and 3 mm rostral to bregma. Any changes were monitored in viscerosomatic reflex activity and in the rate and depth of respiration, arterial blood pressure, heart rate, and hindlimb muscle blood flow. 3. Viscero-somatic reflex activity was depressed to varying degrees after injection of DLH at 20/96 sites and this was always accompanied by some form of cardiovascular change. At 8 sites inhibition of the reflex was accompanied by a cardiovascular response that included an initial pressor response (type I response) and at the other 12 sites there was an initial depressor response (type II response). Injection of DLH at a further 30 sites evoked a depressor response and no change in viscerosomatic reflex activity and at the remaining 45 sites there was no detectable change in any of the variables measured. 4. The degree of inhibition evoked from type I sites (mean 90%) was significantly greater (P < 0.001) than that evoked from type II sites (mean 58%). Type I responses were only evoked from an extremely localized region in the rostral anterior hypothalamus that corresponds to the lateral area of the anterior hypothalamus.(ABSTRACT TRUNCATED AT 400 WORDS)

Responses of Medullary Dorsal Horn Neurons to Corneal Stimulation by CO2 Pulses in the Rat

1999 ◽  
Vol 82 (5) ◽  
pp. 2092-2107 ◽  
Author(s):  
Harumitsu Hirata ◽  
James W. Hu ◽  
David A. Bereiter
Keyword(s):  
Thalamic Nucleus ◽  
Receptive Fields ◽  
Male Rats ◽  
Cervical Cord ◽  
Type I ◽  
Type Ii ◽  
Upper Cervical ◽  
The Difference ◽  
Evoked Activity ◽  
Stimulation Of

Corneal-responsive neurons were recorded extracellularly in two regions of the spinal trigeminal nucleus, subnucleus interpolaris/caudalis (Vi/Vc) and subnucleus caudalis/upper cervical cord (Vc/C1) transition regions, from methohexital-anesthetized male rats. Thirty-nine Vi/Vc and 26 Vc/C1 neurons that responded to mechanical and electrical stimulation of the cornea were examined for convergent cutaneous receptive fields, responses to natural stimulation of the corneal surface by CO2 pulses (0, 30, 60, 80, and 95%), effects of morphine, and projections to the contralateral thalamus. Forty-six percent of mechanically sensitive Vi/Vc neurons and 58% of Vc/C1 neurons were excited by CO2 stimulation. The evoked activity of most cells occurred at 60% CO2 after a delay of 7–22 s. At the Vi/Vc transition three response patterns were seen. Type I cells ( n = 11) displayed an increase in activity with increasing CO2 concentration. Type II cells ( n = 7) displayed a biphasic response, an initial inhibition followed by excitation in which the magnitude of the excitatory phase was dependent on CO2 concentration. A third category of Vi/Vc cells (type III, n = 3) responded to CO2 pulses only after morphine administration (>1.0 mg/kg). At the Vc/C1 transition, all CO2-responsive cells ( n = 15) displayed an increase in firing rates with greater CO2 concentration, similar to the pattern of type I Vi/Vc cells. Comparisons of the effects of CO2 pulses on Vi/Vc type I units, Vi/Vc type II units, and Vc/C1 corneal units revealed no significant differences in threshold intensity, stimulus encoding, or latency to sustained firing. Morphine (0.5–3.5 mg/kg iv) enhanced the CO2-evoked activity of 50% of Vi/Vc neurons tested, whereas all Vc/C1 cells were inhibited in a dose-dependent, naloxone-reversible manner. Stimulation of the contralateral posterior thalamic nucleus antidromically activated 37% of Vc/C1 corneal units; however, no effective sites were found within the ventral posteromedial thalamic nucleus or nucleus submedius. None of the Vi/Vc corneal units tested were antidromically activated from sites within these thalamic regions. Corneal-responsive neurons in the Vi/Vc and Vc/C1 regions likely serve different functions in ocular nociception, a conclusion reflected more by the difference in sensitivity to analgesic drugs and efferent projection targets than by the CO2 stimulus intensity encoding functions. Collectively, the properties of Vc/C1 corneal neurons were consistent with a role in the sensory-discriminative aspects of ocular pain due to chemical irritation. The unique and heterogeneous properties of Vi/Vc corneal neurons suggested involvement in more specialized ocular functions such as reflex control of tear formation or eye blinks or recruitment of antinociceptive control pathways.

Efferent Synaptic Transmission at the Vestibular Type II Hair Cell Synapse

2020 ◽  
Author(s):  
Zhou Yu ◽  
J. Michael McIntosh ◽  
Soroush Sadeghi ◽  
Elisabeth Glowatzki
Keyword(s):  
Hair Cells ◽  
Nerve Fibers ◽  
Repetitive Stimulation ◽  
Vestibular Nerve ◽  
Type I ◽  
Type Ii ◽  
Optogenetic Stimulation ◽  
Vestibular Afferents ◽  
Stimulation Of

ABSTRACTIn the vestibular peripheral organs, type I and type II hair cells (HCs) transmit incoming signals via glutamatergic quantal transmission onto afferent nerve fibers. Additionally, type I HCs transmit via ‘non-quantal’ transmission to calyx afferent fibers, by accumulation of glutamate and potassium in the synaptic cleft. Vestibular efferent inputs originating in the brainstem contact type II HCs and vestibular afferents. Here, we aimed at characterizing the synaptic efferent inputs to type II HCs using electrical and optogenetic stimulation of efferent fibers combined with in vitro whole-cell patch clamp recording from type II HCs in the rodent vestibular crista. Properties of efferent synaptic currents in type II HCs were similar to those found in cochlear hair cells and mediated by activation of α9/α10 nicotinic acetylcholine receptors (AChRs) and SK potassium channels. While efferents showed a low probability of release at low frequencies of stimulation, repetitive stimulation resulted in facilitation and increased probability of release. Notably, the membrane potential of type II HCs measured during optogenetic stimulation of efferents showed a strong hyperpolarization even in response to single pulses and was further enhanced by repetitive stimulation. Such efferent-mediated inhibition of type II HCs can provide a mechanism to adjust the contribution of signals from type I and type II HCs to vestibular nerve fibers. As a result, the relative input of type I hair cells to vestibular afferents will be strengthened, emphasizing the phasic properties of the incoming signal that are transmitted via fast non-quantal transmission.New and NoteworthyType II vestibular hair cells (HCs) receive inputs from efferent fibers originating in the brainstem. We used in vitro optogenetic and electrical stimulation of efferent fibers to study their synaptic inputs to type II HCs. Efferent inputs inhibited type II HCs, similar to cochlear efferent effects. We propose that efferent inputs adjust the contribution of signals from type I and type II HCs that report different components of the incoming signal to vestibular nerve fibers.

scholarly journals Mechanical stretch activates piezo1 in caveolae of alveolar type I cells to trigger ATP release and paracrine stimulation of surfactant secretion from alveolar type II cells

2020 ◽  
Vol 34 (9) ◽  
pp. 12785-12804 ◽  
Author(s):  
Kathrin Diem ◽  
Michael Fauler ◽  
Giorgio Fois ◽  
Andreas Hellmann ◽  
Natalie Winokurow ◽  
...  
Keyword(s):  
Atp Release ◽  
Mechanical Stretch ◽  
Alveolar Type ◽  
Type I ◽  
Type Ii Cells ◽  
Type Ii ◽  
Alveolar Type Ii Cells ◽  
Surfactant Secretion ◽  
I Cells ◽  
Stimulation Of

scholarly journals Functional Exhaustion of Type I and II Interferons Production in Severe COVID-19 Patients

2021 ◽  
Vol 7 ◽  
Author(s):  
Caroline Ruetsch ◽  
Vesna Brglez ◽  
Marion Crémoni ◽  
Kévin Zorzi ◽  
Céline Fernandez ◽  
...  
Keyword(s):  
Inflammatory Cytokines ◽  
Immune Cells ◽  
Type I ◽  
Type Ii ◽  
Systemic Complications ◽  
Adaptive Immune ◽  
Functional Exhaustion ◽  
Cytokine Levels ◽  
Stimulation Of

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has emerged in Wuhan in December 2019 and has since spread across the world. Even though the majority of patients remain completely asymptomatic, some develop severe systemic complications. In this prospective study we compared the immunological profile of 101 COVID-19 patients with either mild, moderate or severe form of the disease according to the WHO classification, as well as of 50 healthy subjects, in order to identify functional immune factors independently associated with severe forms of COVID-19. Plasma cytokine levels, and cytokine levels upon in vitro non-specific stimulation of innate and adaptive immune cells, were measured at several time points during the course of the disease. As described previously, inflammatory cytokines IL1β, IL6, IL8, and TNFα associated with cytokine storm were significantly increased in the plasma of moderate and severe COVID-19 patients (p &lt; 0.0001 for all cytokines). During follow-up, plasma IL6 levels decreased between the moment of admission to the hospital and at the last observation carried forward for patients with favorable outcome (p = 0.02148). After in vitro stimulation of immune cells from COVID-19 patients, reduced levels of both type I and type II interferons (IFNs) upon in vitro stimulation were correlated with increased disease severity [type I IFN (IFNα): p &gt; 0.0001 mild vs. moderate and severe; type II IFN (IFNγ): p = 0.0002 mild vs. moderate and p &lt; 0.0001 mild vs. severe] suggesting a functional exhaustion of IFNs production. Stimulated IFNα levels lower than 2.1 pg/ml and IFNγ levels lower than 15 IU/mL at admission to the hospital were associated with more complications during hospitalization (p = 0.0098 and p =0.0002, respectively). A low IFNγ level was also confirmed by multivariable analysis [p = 0.0349 OR = 0.98 (0.962; 0.999)] as an independent factor of complications. In vitro treatment with type IFNα restored type IFNγ secretion in COVID-19 patients while the secretion of pro-inflammatory cytokines IL6 and IL1β remained stable or decreased, respectively. These results (a) demonstrate a functional exhaustion of both innate and adaptive immune response in severe forms of COVID-19; (b) identify IFNα and IFNγ as new potential biomarkers of severity; and (c) highlight the importance of targeting IFNs when considering COVID-19 treatment in order to re-establish a normal balance between inflammatory and Th1 effector cytokines.

scholarly journals Congenital methemoglobinemia misdiagnosed as polycythemia vera: Case report and review of literature

2018 ◽  
Vol 10 (1) ◽  
Author(s):  
Dina Sameh Soliman ◽  
Mohamed Yassin
Keyword(s):  
English Literature ◽  
Cytochrome B5 ◽  
Arterial Oxygen Tension ◽  
Arterial Oxygen ◽  
Type I ◽  
Type Ii ◽  
Male Predominance ◽  
Cytochrome B5 Reductase ◽  
Methemoglobin Level ◽  
Arterial Blood

Methemoglobinemia is a rare overlooked differential diagnosis in patients presented with cyanosis and dyspnea unrelated to cardiopulmonary causes. Our patient is 29 year old Indian non-smoker male, his story started 6 months prior to presentation to our center when he had generalized fatigue and discoloration of hands. He presented with persistent polycythemia with elevated hemoglobin level. The patient was misdiagnosed in another center as polycythemia and treated with Imatinib. The diagnosis of PV was revisited and ruled out in view of negative JAK2, normal erythropoietin level and absence of features of panmyelosis. Clinical cyanosis and lowoxygen saturation in the presence of normal arterial oxygen tension was highly suggestive of methemoglobinemia. Arterial blood gas revealed a methemoglobin level of 38% (normal: 0-1.5%). Cytochrome B5 reductase (Methemoglobin reductase B) was deficient at level of <2.6 U/g Hb) (normal: 6.6-13.3), consistent with methemoglobin reductase (cytochrome b5) deficiency and hence the diagnosis of congenital methemoglobinemia was established. The role of Imatinib in provoking methemoglobinemia is questionable and association between Imatinib and methemoglobinemia never described before. In our case, there were no other offending drugs in aggravating the patients’ symptoms and cyanosis. The patient started on Vitamin C 500 mg once daily for which he responded well with less cyanosis and significant reduction of methemoglobin level. Congenital methemoglobinemia is a rare underreported hemoglobin disease and often clinically missed. Upon extensive review of English literature for cases of congenital methemoglobinemia due to deficiency of cytochrome b5 reductase, we found 23 cases diagnosed as type I (including the case reported here). 17 cases (~74%) of type I and 6 cases (27%) of type II. There is male predominance 73% versus 26% in females. Almost half of reported cases 12 cases (52%) are Indian, 2 Japanese, 3 English, 2 Arabic, one case Spanish and one case Italian. For type I, the median calculated age is 31 years with cyanosis and shortness of breath being the most common sign and symptoms. For type II: Six cases were reported in English literature, all in pediatric age group with median calculated age at presentation is 6 years with neurologic manifestations and mental retardation are the most common type II associated symptoms. Due to lack of systematic epidemiological studies, congenital methemoglobinemia is under diagnosed as it is under investigated and usually overlooked especially when presenting in adulthood and in absence of obvious acquired agents.

scholarly journals Differential routes of Ca2+ influx in Swiss 3T3 fibroblasts in response to receptor stimulation

1998 ◽  
Vol 329 (1) ◽  
pp. 107-114 ◽  
Author(s):  
Tomoya MIYAKAWA ◽  
Masatoyo KOJIMA ◽  
Michio UI
Keyword(s):  
Phospholipase A2 ◽  
Pertussis Toxin ◽  
Growth Factor Receptor ◽  
Type I ◽  
Type Ii ◽  
Type Iii ◽  
3T3 Fibroblasts ◽  
Swiss 3T3 ◽  
Swiss 3T3 Fibroblasts ◽  
Stimulation Of

Ca2+ influx into cells in response to stimulation of various receptors was studied with Swiss 3T3 fibroblasts. The mechanisms involved were found to be so diverse that they were classified into four groups, Type I to IV. Type-I influx occurred, via pertussis toxin-susceptible G-proteins, immediately after internal Ca2+ mobilization by bradykinin, thrombin, endothelin, vasopressin or angiotensin II. Type-II influx induced by bombesin differed from Type I in its insusceptibility to pertussis toxin treatment. Ca2+ influx induced by prostaglandin E1, referred to as Type-III influx, was unique in that phospholipase C was apparently not activated without extracellular Ca2+, strongly suggesting that the Ca2+ influx preceded and was responsible for InsP3 generation and internal Ca2+ mobilization. More Ca2+ entered the cells more slowly via the Type-IV route opened by platelet-derived and other growth factors. These types of Ca2+ influx could be differentiated by their different susceptibilities to protein kinase C maximally activated by 1 h of exposure of cells to PMA, which inhibited phospholipase Cβ coupled to receptors involved in Type-I and -II influx but did not inhibit growth-factor-receptor-coupled phospholipase Cγ. Type-I and -II Ca2+ influxes, together with store-operated influx induced by thapsigargin, were not directly inhibited by exposure of cells to PMA, but Type-III and -IV influxes were completely inhibited. In addition, stimulation of receptors involved in Type-I and -IV Ca2+ influx, but not Type-II and -III influx, led to phospholipase A2 activation in the presence of extracelluar Ca2+. Inhibition of Type-I and -IV Ca2+ influxes by their respective inhibitors, diltiazem and nifedipine, resulted in abolition of phospholipase A2 activation induced by the respective receptor agonists, in agreement with the notion that Ca2+ influx via these routes is responsible for receptor-mediated phospholipase A2 activation.

Organization of inhibition in the rat olfactory bulb external plexiform layer

1993 ◽  
Vol 70 (1) ◽  
pp. 263-274 ◽  
Author(s):  
P. I. Ezeh ◽  
D. P. Wellis ◽  
J. W. Scott
Keyword(s):  
Olfactory Bulb ◽  
Plexiform Layer ◽  
Type I ◽  
Mitral Cells ◽  
Type Ii ◽  
Cell Responses ◽  
Basal Dendrites ◽  
Antidromic Stimulation ◽  
Tufted Cells ◽  
Stimulation Of

1. Intracellular recordings were made from the output neurons (mitral and tufted cells) of the rat olfactory bulb during electrical orthodromic stimulation of the olfactory nerve layer (ONL) and antidromic stimulation of the lateral olfactory tract and posterior piriform cortex (pPC) to test for physiological differences among the neuron types. Many of these neurons were identified by intracellular injections of biocytin, and others were identified by their pattern of antidromic activation. 2. Both marked and unmarked mitral cells showed large inhibitory postsynaptic potentials (IPSPs) in response to antidromic stimulation of the pPC, whereas tufted cells exhibited small IPSPs in response to pPC stimulation. Tufted cells, however, showed large IPSPs in response to ONL stimulation. In many cases, these tufted cell responses to ONL stimulation were larger than the mitral cell responses. The marked superficial tufted cells, those with basal dendrites in the superficial sublayer of the external plexiform layer (EPL), had the smallest IPSPs in response to pPC stimulation. These data support anatomic observations suggesting that the granule cell populations responsible for the IPSPs may be different for mitral and for superficial tufted cells. 3. The different types of output cells also showed differences in their responses to orthodromic stimulation. Type I mitral cells, which have basal dendrites confined to the deep sublayer of the EPL, were significantly less excitable by ONL stimulation than were the type II mitral cells, which have basal dendrites distributed within the intermediate sublayer of the EPL. Half of the type I mitral cells could not be excited at all by ONL stimulation. Superficial tufted cells showed even greater orthodromic excitability than type II mitral cells, usually responding to ONL stimulation with two or more spikes. 4. The ionic basis of the IPSPs in the superficial tufted cells appeared similar to those described for mitral cells. These IPSPs could be reversed by chloride injection and were associated with increased membrane conductance. 5. For both mitral and tufted cells, the number of ONL electrodes evoking IPSPs was greater than the number evoking spikes. These data suggest a kind of center-surround organization of inputs to these cells from the ONL, although this does not yet imply that the sensory receptive field of these output cells has a center-surround organization. 6. In conclusion, the properties of rat olfactory bulb output cells correlate with the sublayers of the EPL in which their basal dendrites lie.(ABSTRACT TRUNCATED AT 400 WORDS)

Two Distinct Types of Corticothalamic EPSPs and Their Contribution to Short-Term Synaptic Plasticity

2003 ◽  
Vol 90 (5) ◽  
pp. 3429-3440 ◽  
Author(s):  
Jianli Li ◽  
William Guido ◽  
Martha E. Bickford
Keyword(s):  
Synaptic Plasticity ◽  
Rise Time ◽  
Type I ◽  
Type Ii ◽  
Short Term ◽  
Frequency Dependent ◽  
Nmda Glutamate Receptors ◽  
Lateral Posterior ◽  
Layer V ◽  
Stimulation Of

The lateral posterior nucleus (LPN) is innervated by two different morphological types of cortical terminals that originate from cortical layers V and VI. Here we describe two distinct types of excitatory postsynaptic potentials (EPSPs) that were recorded in the LPN after stimulation of corticothalamic fibers. These types of EPSPs differed in amplitude, latency, rise time, and response to increasing levels of stimulus intensity. The most frequently encountered EPSP, type I, displayed a longer latency and slower rise time than the less frequently encountered type II EPSP. Type I EPSPs also showed a graded increase in amplitude with increasing levels of stimulation, whereas type II EPSPs showed an all-or-none response. In response to repetitive stimulation (0.5-20 Hz), type I EPSPs displayed frequency-dependent facilitation, whereas type II EPSPs displayed frequency-dependent depression. Further details of these distinct forms of short-term synaptic plasticity were explored using paired-pulse stimuli. Pharmacology experiments revealed that both N-methyl-d-aspartate (NMDA) and non-NMDA glutamate receptors are involved in corticothalamic synaptic transmission in the LPN and contribute to both synaptic facilitation and depression. Taken together with the results of our previous anatomical studies, these results suggest that type I EPSPs arise from stimulation of layer VI afferents, whereas type II EPSPs arise from stimulation of layer V inputs. Moreover, type I and II EPSPs in the LPN may be functionally similar to corticogeniculate and retinogeniculate EPSPs, respectively.

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