Synaptic and morphologic properties in vitro of premotor rat nucleus tractus solitarius neurons labeled transneuronally from the stomach

2003 ◽  
Vol 464 (4) ◽  
pp. 525-539 ◽  
Author(s):  
Nicholas R. Glatzer ◽  
Christian P. Hasney ◽  
Muthu D. Bhaskaran ◽  
Bret N. Smith
Keyword(s):  
Nucleus Tractus Solitarius

Localization and retention in vitro of fluorescently labeled aortic baroreceptor terminals on neurons from the nucleus tractus solitarius

1992 ◽  
Vol 581 (2) ◽  
pp. 339-343 ◽  
Author(s):  
David Mendelowitz ◽  
Mingyong Yang ◽  
Michael C. Andresen ◽  
Diana L. Kunze
Keyword(s):  
Nucleus Tractus Solitarius

Reliability of Monosynaptic Sensory Transmission in Brain Stem Neurons In Vitro

2001 ◽  
Vol 85 (5) ◽  
pp. 2213-2223 ◽  
Author(s):  
Mark W. Doyle ◽  
Michael C. Andresen
Keyword(s):  
Brain Stem ◽  
Nucleus Tractus Solitarius ◽  
Temporal Integration ◽  
Second Order ◽  
Failure Rates ◽  
Critical Feature ◽  
Medial Nucleus ◽  
Nmda Glutamate Receptors ◽  
Spatio Temporal

The timing of events within the nervous system is a critical feature of signal processing and integration. In neurotransmission, the synaptic latency, the time between stimulus delivery and appearance of the synaptic event, is generally thought to be directly related to the complexity of that pathway. In horizontal brain stem slices, we examined synaptic latency and its shock-to-shock variability (synaptic jitter) in medial nucleus tractus solitarius (NTS) neurons in response to solitary tract (ST) electrical activation. Using a visualized patch recording approach, we activated ST 1–3 mm from the recorded neuron with short trains (50–200 Hz) and measured synaptic currents under voltage clamp. Latencies ranged from 1.5 to 8.6 ms, and jitter values (SD of intraneuronal latency) ranged from 26 to 764 μs ( n = 49). Surprisingly, frequency of synaptic failure was not correlated with either latency or jitter ( P > 0.147; n = 49). Despite conventional expectations, no clear divisions in latency were found from the earliest arriving excitatory postsynaptic currents (EPSCs) to late pharmacologically polysynaptic responses. Shortest latency EPSCs (<3 ms) were mediated by non– N-methyl-d-aspartate (non-NMDA) glutamate receptors. Longer latency responses were a mix of excitatory and inhibitory currents including non-NMDA EPSCs and GABAa receptor–mediated currents (IPSC). All synaptic responses exhibited prominent frequency-dependent depression. In a subset of neurons, we labeled sensory boutons by the anterograde fluorescent tracer, DiA, from aortic nerve baroreceptors and then recorded from anatomically identified second-order neurons. In identified second-order NTS neurons, ST activation evoked EPSCs with short to moderate latency (1.9–4.8 ms) but uniformly minimal jitter (31 to 61 μs) that were mediated by non-NMDA receptors but had failure rates as high as 39%. These monosynaptic EPSCs in identified second-order neurons were significantly different in latency and jitter than GABAergic IPSCs (latency, 2.95 ± 0.71 vs. 5.56 ± 0.74 ms, mean ± SE, P = 0.027; jitter, 42.3 ± 6.5 vs. 416.3 ± 94.4 μs, P = 0.013, n = 4, 6, respectively), but failure rates were similar (27.8 ± 9.0 vs. 9.7 ± 4.4%, P = 0.08, respectively). Such results suggest that jitter and not absolute latency or failure rate is the most reliable discriminator of mono- versus polysynaptic pathways. The results suggest that brain stem sensory pathways may differ in their principles of integration compared with cortical models and that this importantly impacts synaptic performance. The unique performance properties of the sensory-NTS pathway may reflect stronger axosomatic synaptic processing in brain stem compared with dendritically weighted models typical in cortical structures and thus may reflect very different strategies of spatio-temporal integration in this NTS region and for autonomic regulation.

Peripheral gastric leptin modulates brain stem neuronal activity in neonates

1999 ◽  
Vol 277 (3) ◽  
pp. G626-G630 ◽  
Author(s):  
Chun-Su Yuan ◽  
Anoja S. Attele ◽  
Ji An Wu ◽  
Liu Zhang ◽  
Zhi Q. Shi
Keyword(s):  
Brain Stem ◽  
Old Age ◽  
Neuronal Activity ◽  
Nucleus Tractus Solitarius ◽  
Control Level ◽  
Age Groups ◽  
Neonatal Rat ◽  
Activity Levels ◽  
Significant Difference

Afferent sensory fibers are the primary neuroanatomic link between nutrient-related events in the gastrointestinal tract and the central neural substrates that modulate ingestion. In this study, we evaluated the peripheral gastric effects of leptin (OB protein) on brain stem neuronal activities using an in vitro neonatal rat preparation. We also tested gastric leptin effects as a function of age in neonates. For ∼33% of the nucleus tractus solitarius units observed, gastric leptin (10 nM) produced a significant activation of 188.2 ± 8.6% (mean ± SE) compared with the control level of 100% ( P < 0.01). Concentration-dependent leptin effects have also been shown. The remaining neurons (67%) had no significant response to gastric leptin application. Next, we evaluated the peripheral gastric effects of leptin (10 nM) on brain stem unitary activity in three different age groups (1–2 days old, 3–5 days old, and 7–8 days old) of neonatal rats. In the 1- to 2-day-old and the 3- to 5-day-old groups, we observed that response ratios and activity levels were similar. However, there was a significant difference between the 7- to 8-day-old group and the two younger age groups in both the response ratios and the activation levels. The percentage of activation responses increased from ∼26% in the 1- to 2-day-old and the 4- to 5-day-old age groups to 70% in the 7- to 8-day-old group ( P < 0.05). The level of activation increased from 168.3 ± 2.7% (compared with the control level) in the 1- to 2-day-old and the 4- to 5-day-old age groups to 231.4 ± 11.9% in the 7- to 8-day-old group ( P < 0.01). Our data demonstrate that peripheral gastric leptin modulates brain stem neuronal activity and suggest that gastric leptin has a significantly stronger effect in the 7- to 8-day-old animals than in the younger neonates.

In vitro characterization of neurons in the ventral part of the nucleus tractus solitarius. I. Identification of neuronal types and repetitive firing properties

1987 ◽  
Vol 58 (1) ◽  
pp. 195-214 ◽  
Author(s):  
M. S. Dekin ◽  
P. A. Getting ◽  
S. M. Johnson
Keyword(s):  
High Frequency ◽  
Nucleus Tractus Solitarius ◽  
State Level ◽  
Repetitive Firing ◽  
Type I ◽  
Type Ii ◽  
Steady State Level ◽  
Shaped Cell ◽  
Firing Properties

1. An in vitro brain stem slice preparation from adult guinea pigs was used to determine the properties of neurons located in the ventral part of the nucleus tractus solitarius (NTS), an area associated with the dorsal respiratory group. Based upon their morphology and their repetitive firing properties, three classes of ventral NTS neurons, termed types I, II, and III, were observed. 2. Type I neurons were multipolar with pyramidal-shaped cell bodies. These neurons responded to prolonged depolarizations from a resting level of -50 mV with a discrete, high-frequency burst of spikes, which rapidly adapted to a low steady-state level. When depolarized from levels more negative than -65 mV, the initial burst was diminished. 3. Type II neurons were multipolar with fusiform-shaped cell bodies. Type II neurons responded to depolarizations from -50 mV with an initial high spike frequency, which gradually adapted to a steady-state level. When depolarized from levels more negative than -60 mV, these neurons displayed a delay between the onset of the stimulus and the first spike. This delay has been termed “delayed excitation.” The expression of delayed excitation was modulated by both the size and duration of hyperpolarizing prepulses that preceded depolarization. 4. Type III neurons were multipolar with spherical shaped-cell bodies. In response to depolarizations from -50 mV, these neurons displayed high-frequency firing with little adaptation. The repetitive firing properties of type III neurons were not modulated by hyperpolarization. 5. Bulbospinal neurons in the ventral NTS were identified using retrograde transport of rhodamine-labeled latex beads injected into the region of the phrenic motor nucleus at spinal cord levels C4 through C6. Only type I and type II neurons were labeled in the ventral NTS (0.2-1.0 mm rostral to the obex). Both contralateral and ipsilateral projections were observed. Contralaterally, type I and II neurons were evenly distributed. Ipsilaterally, however, type II neurons accounted for two-thirds of the labeled neurons. 6. Type I and II neurons had similar input resistances and time constants: 97.0 +/- 17.6 M omega and 14.4 +/- 2.2 ms (n = 5) for type I and 107.0 +/- 11.2 M omega and 13.7 +/- 1.6 ms for type II (n = 5).(ABSTRACT TRUNCATED AT 400 WORDS)

Synaptic responses of neurons of the nucleus tractus solitarius in vitro

1985 ◽  
Vol 325 (1-2) ◽  
pp. 49-56 ◽  
Author(s):  
J. Champagnat ◽  
G.R. Siggins ◽  
L.Y. Koda ◽  
M. Denavit-Saubié
Keyword(s):  
Nucleus Tractus Solitarius ◽  
Synaptic Responses

scholarly journals In Vitro Research of the Alteration of Neurons in Vagal Core in Medulla Oblongata at Asphyxic Deaths

2010 ◽  
Vol 10 (3) ◽  
pp. 251-259
Author(s):  
Naim Haliti ◽  
Hilmi Islami ◽  
Nevzat Elezi ◽  
Ragip Shabani ◽  
Bedri Abdullahu ◽  
...  
Keyword(s):  
Vagus Nerve ◽  
Medulla Oblongata ◽  
Nucleus Tractus Solitarius ◽  
Morphological Changes ◽  
Testing System ◽  
Autopsy Material ◽  
Universal Testing ◽  
Cytoplasmic Vacuolization ◽  
Death Cases

The aim of this study was to research the morphological changes of neurons in the vagus nerve nuclei in medulla oblongata in asphyxia related death cases. Morphological changes that were investigated were mainly in the dorsal motor respiratory center (DMRC), nucleus tractus solitarius (nTS) and nucleus ambigus (nA) in the medulla oblongata. In our research, the autopsy material from asphyxia related death cases was used from various etiologies: monoxide carbon (CO), liquid drowning, strangulation, electricity, clinical-pathological death, firing weapon, explosive weapon, sharp and blunt objects and death cases due to accident. The material selected for research was taken from medulla oblongata and lungs from all lobes. The material from the medulla oblongata and lungs was fixed in a 10% solution of buffered formalin. Special histochemical methods for central nervous system (CNS) were employed like: Cresyl echt violet, toluidin blue, Sevier-Munger modification and Grimelius. For stereometrical analysis of the quantitative density of the neurons the universal testing system Weibel M42 was used. The acquired results show that in sudden asphyxia related death cases, there are alterations in the nuclei of vagal nerve in form of: central chromatolysis, axonal retraction, axonal fragmentation, intranuclear vacuolization, cytoplasmic vacuolization, edema, condensation and dispersion of substance of Nissl, proliferation of oligodendrocytes, astrocytes and microglia. The altered population of vagus nerve neurons does not show an important statistica! significarne compared to the overall quantity of the neurons in the nuclei of the vagus nerve (p<0,05).

scholarly journals Progesterone reverses the neuronal responses to hypoxia in rat nucleus tractus solitarius in vitro

2002 ◽  
Vol 544 (2) ◽  
pp. 511-520 ◽  
Author(s):  
Olivier Pascual ◽  
Marie‐Pierre Morin‐Surun ◽  
Barbara Barna ◽  
Monique Denavit‐Saubié ◽  
Jean‐Marc Pequignot ◽  
...  
Keyword(s):  
Nucleus Tractus Solitarius ◽  
Neuronal Responses

scholarly journals Hindbrain GLP-1 receptor-mediated suppression of food intake requires a PI3K-dependent decrease in phosphorylation of membrane-bound Akt

2013 ◽  
Vol 305 (6) ◽  
pp. E751-E759 ◽  
Author(s):  
Laura E. Rupprecht ◽  
Elizabeth G. Mietlicki-Baase ◽  
Derek J. Zimmer ◽  
Lauren E. McGrath ◽  
Diana R. Olivos ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Food Intake ◽  
Intracellular Signaling ◽  
Nucleus Tractus Solitarius ◽  
Ex Vivo ◽  
Mapk Signaling ◽  
Current Data ◽  
Akt Phosphorylation ◽  
Membrane Bound

Glucagon-like peptide-1 (GLP-1) receptors (GLP-1R) expressed in the nucleus tractus solitarius (NTS) are physiologically required for the control of feeding. Recently, NTS GLP-1R-mediated suppression of feeding was shown to occur via a rapid PKA-induced suppression of AMPK and activation of MAPK signaling. Unknown are the additional intracellular signaling pathways that account for the long-term hypophagic effects of GLP-1R activation. Because cAMP/PKA activity can promote PI3K/PIP3-dependent translocation of Akt to the plasma membrane, we hypothesize that hindbrain GLP-1R-mediated control of feeding involves a PI3K-Akt-dependent pathway. Importantly, the novel evidence presented here challenges the dogmatic view that PI3K phosphorylation results in an obligatory activation of Akt and instead supports a growing body of literature showing that activation of cAMP/PKA can inhibit Akt phosphorylation at the plasma membrane. Behavioral data show that inhibition of hindbrain PI3K activity by a fourth icv administration of LY-294002 (3.07 μg) attenuated the food intake- and body weight-suppressive effects of a fourth icv administration of the GLP-1R agonist exendin-4 (0.3 μg) in rats. Hindbrain administration of triciribine (10 μg), an inhibitor of PIP3-dependent translocation of Akt to the cell membrane, also attenuated the intake-suppressive effects of a fourth icv injection of exendin-4. Immunoblot analyses of ex vivo NTS tissue lysates and in vitro GLP-1R-expressing neurons (GT1–7) support the behavioral findings and show that GLP-1R activation decreases phosphorylation of Akt in a time-dependent fashion. Current data reveal the requirement of PI3K activation, PIP3-dependent translocation of Akt to the plasma membrane, and suppression in phosphorylation of membrane-bound Akt to mediate the food intake-suppressive effects of hindbrain GLP-1R activation.

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