Electrophysiological study on the effects of leptin in rat dorsal motor nucleus of the vagus

2007 ◽  
Vol 292 (6) ◽  
pp. R2136-R2143 ◽  
Author(s):  
Tzu-Ling Li ◽  
Lih-Chu Chiou ◽  
You Shuei Lin ◽  
Jing-Ru Hsieh ◽  
Ling-Ling Hwang
Keyword(s):  
Potassium Conductance ◽  
Reversal Potential ◽  
Negative Slope ◽  
Motor Nucleus ◽  
Neonatal Rats ◽  
Patch Clamp Recording ◽  
Central Target ◽  
Preganglionic Neurons ◽  
Dorsal Motor Nucleus ◽  
Outward Currents

Immunoreactivity of leptin receptor (Ob-R) has been detected in rat dorsal motor nucleus of the vagus (DMNV). Here, we confirmed the presence of Ob-R immunoreactivity on retrograde-labeled parasympathetic preganglionic neurons in the DMNV of neonatal rats. The present study investigated the effects of leptin on DMNV neurons, including parasympathetic preganglionic neurons, by using whole cell patch-clamp recording technique in brain stem slices of neonatal rats. Leptin (30–300 nM) induced membrane depolarization and hyperpolarization, respectively, in 14 and 15 out of 80 DMNV neurons tested. Both leptin-induced inward and outward currents persisted in the presence of TTX, indicating that leptin affected DNMV neurons postsynaptically. The current-voltage (I–V) curve of leptin-induced inward currents is characterized by negative slope conductance and has an average reversal potential of −90 ± 3 mV. The reversal potential of the leptin-induced inward current was shifted to a more positive potential level in a high-potassium medium. These results indicate that a decrease in potassium conductance is likely the main ionic mechanism underlying the leptin-induced depolarization. On the other hand, the I–V curve of leptin-induced outward currents is characterized by positive slope conductance and has an average reversal potential of −88 ± 3 mV, suggesting that an increase in potassium conductance may underlie leptin-induced hyperpolarization. Most of the leptin-responsive DMNV neurons were identified as being parasympathetic preganglionic neurons. These results suggest that the DMNV is one of the central target sites of leptin, and leptin can regulate parasympathetic outflow from the DMNV by directly acting on the parasympathetic preganglionic neurons of the DMNV.

Galanin Inhibits Gut-Related Vagal Neurons in Rats

2004 ◽  
Vol 91 (5) ◽  
pp. 2330-2343 ◽  
Author(s):  
Zhenjun Tan ◽  
Ronald Fogel ◽  
Chunhui Jiang ◽  
Xueguo Zhang
Keyword(s):  
Potassium Channel ◽  
Reversal Potential ◽  
Outward Current ◽  
Motor Nucleus ◽  
Dorsal Vagal Complex ◽  
Solitary Tract ◽  
Membrane Hyperpolarization ◽  
Dorsal Motor Nucleus

Galanin plays an important role in the regulation of food intake, energy balance, and body weight. Many galanin-positive fibers as well as galanin-positive neurons were seen in the dorsal vagal complex, suggesting that galanin produces its effects by actions involving vagal neurons. In the present experiment, we used tract-tracing and neurophysiological techniques to evaluate the origin of the galaninergic fibers and the effect of galanin on neurons in the dorsal vagal complex. Our results reveal that the nucleus of the solitary tract is the major source of the galanin terminals in the dorsal vagal complex. In vivo experiments demonstrated that galanin inhibited the majority of gut-related neurons in the dorsal motor nucleus of the vagus. In vitro experiments demonstrated that galanin inhibited the majority of stomach-projecting neurons in the dorsal motor nucleus of the vagus by suppressing spontaneous activity and/or producing a fully reversible dose-dependent membrane hyperpolarization and outward current. The galanin-induced hyperpolarization and outward current persisted after synaptic input was blocked, suggesting that galanin acts directly on receptors of neurons in the dorsal motor nucleus of the vagus. The reversal potential induced by galanin was close to the potassium ion potentials of the Nernst equation and was prevented by the potassium channel blocker tetraethylammonium, indicating that the inhibitory effect of galanin was mediated by a potassium channel. These results indicate that the dorsal motor nucleus of the vagus is inhibited by galanin derived predominantly from neurons in the nucleus of the solitary tract projecting to the dorsal motor nucleus of the vagus nerve. Galanin is one of the neurotransmitters involved in the vago-vagal reflex.

Inhibitory effect of somatostatin on vagal motoneurons in the rat brain stem in vitro

1989 ◽  
Vol 256 (1) ◽  
pp. C155-C159 ◽  
Author(s):  
J. Nabekura ◽  
Y. Mizuno ◽  
Y. Oomura
Keyword(s):  
Brain Stem ◽  
Rat Brain ◽  
Reversal Potential ◽  
Input Resistance ◽  
Inhibitory Effect ◽  
Hill Coefficient ◽  
Resting Membrane Potential ◽  
Motor Nucleus ◽  
Dorsal Motor Nucleus

Effects of somatostatin-14 (SRIF) on membrane electrical properties were studied in rat brain stem slice preparations maintained in vitro. SRIF hyperpolarized the resting membrane potential and decreased the input resistance of more than two-thirds of the 85 vagal motoneurons tested in the dorsal motor nucleus of the vagus. These effects persisted under synaptic blockade caused by perfusion with a solution containing tetrodotoxin or a Ca2+-free/high-Mg2+ solution and were dependent on the extracellular SRIF concentration (5 X 10(-8) to 1 X 10(-8) M). The Hill coefficient was estimated to be 2. The reversal potential of SRIF-induced hyperpolarization was affected by changing external K+ concentration. The results suggest that, in addition to its well-known peripheral action, SRIF may inhibit secretomotor functions of visceral organs by reducing vagal output in the central nervous system.

scholarly journals Spatial organization of neurons in the dorsal motor nucleus of the vagus synapsing with intragastric cholinergic and nitric oxide/VIP neurons in the rat

2008 ◽  
Vol 294 (5) ◽  
pp. G1201-G1209 ◽  
Author(s):  
Shi-Yi Zhou ◽  
Yuan-Xu Lu ◽  
HongRen Yao ◽  
Chung Owyang
Keyword(s):  
Nitric Oxide ◽  
Spatial Organization ◽  
Cholinergic Neurons ◽  
Motor Nucleus ◽  
Neural Pathways ◽  
Myenteric Neurons ◽  
Preganglionic Neurons ◽  
Gastric Contraction ◽  
Dorsal Motor Nucleus ◽  
Contraction And Relaxation

The dorsal motor nucleus of the vagus (DMV) contains preganglionic neurons that control gastric motility and secretion. Stimulation of different parts of the DMV results in a decrease or an increase in gastric motor activities, suggesting a spatial organization of vagal preganglionic neurons in the DMV. Little is known about how these preganglionic neurons in the DMV synapse with different groups of intragastric motor neurons to mediate contraction or relaxation of the stomach. We used pharmacological and immunohistochemical methods to characterize intragastric neural pathways involved in mediating gastric contraction and relaxation in rats. Microinjections of l-glutamate (l-Glu) into the rostral or caudal DMV produced gastric contraction and relaxation, respectively, in a dose-related manner. Intravenous infusion of hexamethonium blocked these actions, suggesting mediation via preganglionic cholinergic pathways. Atropine inhibited gastric contraction by 85.5 ± 4.5%. Gastric relaxation was reduced by intravenous administration of NG-nitro-l-arginine methyl ester (l-NAME; 52.5 ± 11.9%) or VIP antagonist (56.3 ± 14.9%). Combined administration of l-NAME and VIP antagonist inhibited gastric relaxation evoked by l-Glu (87.8 ± 4.3%). Immunohistochemical studies demonstrated choline acetyltransferase immunoreactivity in response to l-Glu microinjection into the rostral DMV in 88% of c-Fos-positive intragastric myenteric neurons. Microinjection of l-Glu into the caudal DMV evoked expression of nitric oxide (NO) synthase and VIP immunoreactivity in 81 and 39%, respectively, of all c-Fos-positive intragastric myenteric neurons. These data indicate spatial organization of the DMV. Depending on the location, microinjection of l-Glu into the DMV may stimulate intragastric myenteric cholinergic neurons or NO/VIP neurons to mediate gastric contraction and relaxation.

scholarly journals Glutamatergic Neurotransmission between the C1 Neurons and the Parasympathetic Preganglionic Neurons of the Dorsal Motor Nucleus of the Vagus

2013 ◽  
Vol 33 (4) ◽  
pp. 1486-1497 ◽  
Author(s):  
S. D. DePuy ◽  
R. L. Stornetta ◽  
G. Bochorishvili ◽  
K. Deisseroth ◽  
I. Witten ◽  
...  
Keyword(s):  
Motor Nucleus ◽  
Glutamatergic Neurotransmission ◽  
Preganglionic Neurons ◽  
Dorsal Motor Nucleus

Central Control of the Cardiovascular and Respiratory Systems and Their Interactions in Vertebrates

1999 ◽  
Vol 79 (3) ◽  
pp. 855-916 ◽  
Author(s):  
Edwin W. Taylor ◽  
David Jordan ◽  
John H. Coote
Keyword(s):  
Respiratory Rhythm ◽  
Nucleus Ambiguus ◽  
Motor Nucleus ◽  
Cardiorespiratory System ◽  
Preganglionic Neurons ◽  
Larval Amphibians ◽  
Dorsal Motor Nucleus ◽  
Changing Roles ◽  
Productive Research ◽  
And Control

This review explores the fundamental neuranatomical and functional bases for integration of the respiratory and cardiovascular systems in vertebrates and traces their evolution through the vertebrate groups, from primarily water-breathing fish and larval amphibians to facultative air-breathers such as lungfish and some adult amphibians and finally obligate air-breathers among the reptiles, birds, and mammals. A comparative account of respiratory rhythm generation leads to consideration of the changing roles in cardiorespiratory integration for central and peripheral chemoreceptors and mechanoreceptors and their central projections. We review evidence of a developing role in the control of cardiorespiratory interactions for the partial relocation from the dorsal motor nucleus of the vagus into the nucleus ambiguus of vagal preganglionic neurons, and in particular those innervating the heart, and for the existence of a functional topography of specific groups of sympathetic preganglionic neurons in the spinal cord. Finally, we consider the mechanisms generating temporal modulation of heart rate, vasomotor tone, and control of the airways in mammals; cardiorespiratory synchrony in fish; and integration of the cardiorespiratory system during intermittent breathing in amphibians, reptiles, and diving birds. Concluding comments suggest areas for further productive research.

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