Vasopressin inhibits glutamate release via two distinct modes in the brainstem.

Timothy W. Bailey, Young Ho Jin, Mark W. Doyle, Stephen Smith, Michael Andresen

Research output: Contribution to journalArticle

82 Citations (Scopus)

Abstract

The hypothalamus coordinates autonomic responses in part through arginine vasopressin (AVP) released in medial nucleus tractus solitarius (NTS). However, the mechanisms and sites of AVP action within NTS pathways are uncertain. In brainstem slices, we activated solitary tract (ST) primary afferents to release glutamate and tested whether AVP modulated synaptic transmission to second-order neurons. NTS neurons were classified as second order by ST synaptic characteristics or the presence of anterograde tracers from peripheral baroreceptor afferents. Stimulus recruitment curves indicated ST-EPSCs on individual neurons were evoked by stimulation of single ST axons. Variance-mean (V-M) analysis of ST-EPSCs in individual neurons revealed uniformly high release probability (p approximately 0.9) from an average of 19 release sites (N) and a quantal size (q) of 34.0 +/- 4.7 pA. In 26 of 49 neurons, AVP inhibited afferent synaptic transmission. In most neurons, AVP reduced ST-EPSC amplitudes (n = 20) by decreasing p to 0.65, whereas q, N, and conduction times were unaffected. The V1a antagonist SR49059 alone decreased ST-EPSC V and increased M, suggesting tonic AVP actions, and blocked exogenous AVP action (n = 4). In other neurons with identical ST release properties, AVP induced synaptic failures and increased conduction time without altering the V-M relationship of successful ST-EPSCs (n = 6). Interestingly, frequency-depressed ST-EPSCs were not affected by AVP. AVP failed to alter holding or voltage-dependent potassium currents. Thus, AVP regulates NTS neurons by two distinct novel and state-dependent mechanisms: one, an analog, graded presynaptic inhibition of terminal glutamate release and the other, a binary, extraterminal block of conducted excitation.

Original languageEnglish (US)
Pages (from-to)6131-6142
Number of pages12
JournalThe Journal of neuroscience : the official journal of the Society for Neuroscience
Volume26
Issue number23
DOIs
StatePublished - Jun 7 2006

Fingerprint

Arginine Vasopressin
Vasopressins
Brain Stem
Glutamic Acid
Neurons
Solitary Nucleus
Synaptic Transmission
Pressoreceptors
Presynaptic Terminals
Hypothalamus
Axons
Analysis of Variance
Potassium

Cite this

Vasopressin inhibits glutamate release via two distinct modes in the brainstem. / Bailey, Timothy W.; Jin, Young Ho; Doyle, Mark W.; Smith, Stephen; Andresen, Michael.

In: The Journal of neuroscience : the official journal of the Society for Neuroscience, Vol. 26, No. 23, 07.06.2006, p. 6131-6142.

Research output: Contribution to journalArticle

@article{e9123250040149fdb127c52095e5640d,
title = "Vasopressin inhibits glutamate release via two distinct modes in the brainstem.",
abstract = "The hypothalamus coordinates autonomic responses in part through arginine vasopressin (AVP) released in medial nucleus tractus solitarius (NTS). However, the mechanisms and sites of AVP action within NTS pathways are uncertain. In brainstem slices, we activated solitary tract (ST) primary afferents to release glutamate and tested whether AVP modulated synaptic transmission to second-order neurons. NTS neurons were classified as second order by ST synaptic characteristics or the presence of anterograde tracers from peripheral baroreceptor afferents. Stimulus recruitment curves indicated ST-EPSCs on individual neurons were evoked by stimulation of single ST axons. Variance-mean (V-M) analysis of ST-EPSCs in individual neurons revealed uniformly high release probability (p approximately 0.9) from an average of 19 release sites (N) and a quantal size (q) of 34.0 +/- 4.7 pA. In 26 of 49 neurons, AVP inhibited afferent synaptic transmission. In most neurons, AVP reduced ST-EPSC amplitudes (n = 20) by decreasing p to 0.65, whereas q, N, and conduction times were unaffected. The V1a antagonist SR49059 alone decreased ST-EPSC V and increased M, suggesting tonic AVP actions, and blocked exogenous AVP action (n = 4). In other neurons with identical ST release properties, AVP induced synaptic failures and increased conduction time without altering the V-M relationship of successful ST-EPSCs (n = 6). Interestingly, frequency-depressed ST-EPSCs were not affected by AVP. AVP failed to alter holding or voltage-dependent potassium currents. Thus, AVP regulates NTS neurons by two distinct novel and state-dependent mechanisms: one, an analog, graded presynaptic inhibition of terminal glutamate release and the other, a binary, extraterminal block of conducted excitation.",
author = "Bailey, {Timothy W.} and Jin, {Young Ho} and Doyle, {Mark W.} and Stephen Smith and Michael Andresen",
year = "2006",
month = "6",
day = "7",
doi = "10.1523/JNEUROSCI.5176-05.2006",
language = "English (US)",
volume = "26",
pages = "6131--6142",
journal = "Journal of Neuroscience",
issn = "0270-6474",
publisher = "Society for Neuroscience",
number = "23",

}

TY - JOUR

T1 - Vasopressin inhibits glutamate release via two distinct modes in the brainstem.

AU - Bailey, Timothy W.

AU - Jin, Young Ho

AU - Doyle, Mark W.

AU - Smith, Stephen

AU - Andresen, Michael

PY - 2006/6/7

Y1 - 2006/6/7

N2 - The hypothalamus coordinates autonomic responses in part through arginine vasopressin (AVP) released in medial nucleus tractus solitarius (NTS). However, the mechanisms and sites of AVP action within NTS pathways are uncertain. In brainstem slices, we activated solitary tract (ST) primary afferents to release glutamate and tested whether AVP modulated synaptic transmission to second-order neurons. NTS neurons were classified as second order by ST synaptic characteristics or the presence of anterograde tracers from peripheral baroreceptor afferents. Stimulus recruitment curves indicated ST-EPSCs on individual neurons were evoked by stimulation of single ST axons. Variance-mean (V-M) analysis of ST-EPSCs in individual neurons revealed uniformly high release probability (p approximately 0.9) from an average of 19 release sites (N) and a quantal size (q) of 34.0 +/- 4.7 pA. In 26 of 49 neurons, AVP inhibited afferent synaptic transmission. In most neurons, AVP reduced ST-EPSC amplitudes (n = 20) by decreasing p to 0.65, whereas q, N, and conduction times were unaffected. The V1a antagonist SR49059 alone decreased ST-EPSC V and increased M, suggesting tonic AVP actions, and blocked exogenous AVP action (n = 4). In other neurons with identical ST release properties, AVP induced synaptic failures and increased conduction time without altering the V-M relationship of successful ST-EPSCs (n = 6). Interestingly, frequency-depressed ST-EPSCs were not affected by AVP. AVP failed to alter holding or voltage-dependent potassium currents. Thus, AVP regulates NTS neurons by two distinct novel and state-dependent mechanisms: one, an analog, graded presynaptic inhibition of terminal glutamate release and the other, a binary, extraterminal block of conducted excitation.

AB - The hypothalamus coordinates autonomic responses in part through arginine vasopressin (AVP) released in medial nucleus tractus solitarius (NTS). However, the mechanisms and sites of AVP action within NTS pathways are uncertain. In brainstem slices, we activated solitary tract (ST) primary afferents to release glutamate and tested whether AVP modulated synaptic transmission to second-order neurons. NTS neurons were classified as second order by ST synaptic characteristics or the presence of anterograde tracers from peripheral baroreceptor afferents. Stimulus recruitment curves indicated ST-EPSCs on individual neurons were evoked by stimulation of single ST axons. Variance-mean (V-M) analysis of ST-EPSCs in individual neurons revealed uniformly high release probability (p approximately 0.9) from an average of 19 release sites (N) and a quantal size (q) of 34.0 +/- 4.7 pA. In 26 of 49 neurons, AVP inhibited afferent synaptic transmission. In most neurons, AVP reduced ST-EPSC amplitudes (n = 20) by decreasing p to 0.65, whereas q, N, and conduction times were unaffected. The V1a antagonist SR49059 alone decreased ST-EPSC V and increased M, suggesting tonic AVP actions, and blocked exogenous AVP action (n = 4). In other neurons with identical ST release properties, AVP induced synaptic failures and increased conduction time without altering the V-M relationship of successful ST-EPSCs (n = 6). Interestingly, frequency-depressed ST-EPSCs were not affected by AVP. AVP failed to alter holding or voltage-dependent potassium currents. Thus, AVP regulates NTS neurons by two distinct novel and state-dependent mechanisms: one, an analog, graded presynaptic inhibition of terminal glutamate release and the other, a binary, extraterminal block of conducted excitation.

UR - http://www.scopus.com/inward/record.url?scp=33745626206&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33745626206&partnerID=8YFLogxK

U2 - 10.1523/JNEUROSCI.5176-05.2006

DO - 10.1523/JNEUROSCI.5176-05.2006

M3 - Article

C2 - 16763021

AN - SCOPUS:33745626206

VL - 26

SP - 6131

EP - 6142

JO - Journal of Neuroscience

JF - Journal of Neuroscience

SN - 0270-6474

IS - 23

ER -