Transport mechanisms governing serotonin clearance in vivo revealed by high-speed chronoamperometry

Lynette C Daws, Sylvia Montañez, W. Anthony Owens, Georgianna G Gould, Alan Frazer, Glenn M Toney, Greg A. Gerhardt

Research output: Contribution to journalArticle

58 Citations (Scopus)

Abstract

High-speed chronoamperometry was used to determine the kinetics of clearance of exogenously applied serotonin (5-HT) in the dorsal raphe nucleus (DRN), dentate gyrus, CA3 region of the hippocampus or corpus callosum of anesthetized rats. Maximal velocity (Vmax) for 5-HT clearance was greatest in the DRN > dentate gyrus > CA3 > corpus callosum. Apparent affinity (KT) of the serotonin transporter (5-HTT) was similar in DRN and CA3 but greater in dentate gyrus and corpus callosum. A 90% loss of norepinephrine transporters (NET) produced by 6-hydroxydopamine pretreatment, resulted in a two-fold reduction in Vmax and a 30% decrease in K T in the dentate gyrus, but no change in kinetic parameters in the CA3 region. Pretreatment with 5,7-dihydroxytryptamine that resulted in a 90% reduction in 5-HTT density, modestly reduced Vmax in dentate gyrus but not in CA3. The same treatment had no effect on KT in the dentate gyrus but increased KT two-fold in the CA3. Neurotoxin treatments had no effect on 5-HT clearance in the corpus callosum. In hippocampal regions of intact rats, local application of the selective serotonin reuptake inhibitor, fluvoxamine, inhibited 5-HT clearance most robustly when the extracellular concentration of 5-HT was less than the KT value. By contrast, the NET antagonist, desipramine, significantly inhibited 5-HT clearance when extracellular concentrations of 5-HT were greater than the KT value. These data indicate that hippocampal uptake of 5-HT may be mediated by two processes, one with high affinity but low capacity (i.e. the 5-HTT) and the other with low affinity but a high capacity (i.e. the NET). These data show for the first time in the whole animal that 5-HT clearance in brain is regionally distinct with regard to rate and affinity.

Original languageEnglish (US)
Pages (from-to)49-62
Number of pages14
JournalJournal of Neuroscience Methods
Volume143
Issue number1
DOIs
StatePublished - Apr 15 2005

Fingerprint

Serotonin
Dentate Gyrus
Corpus Callosum
Norepinephrine Plasma Membrane Transport Proteins
5,7-Dihydroxytryptamine
Fluvoxamine
Serotonin Plasma Membrane Transport Proteins
Desipramine
Oxidopamine
Neurotoxins
Serotonin Uptake Inhibitors
Hippocampus
Brain
Dorsal Raphe Nucleus

Keywords

  • Chronoamperometry
  • Dorsal raphe nucleus
  • Hippocampus
  • Norepinephrine transporter
  • Rat
  • Serotonin clearance rates
  • Serotonin transporter

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

Transport mechanisms governing serotonin clearance in vivo revealed by high-speed chronoamperometry. / Daws, Lynette C; Montañez, Sylvia; Owens, W. Anthony; Gould, Georgianna G; Frazer, Alan; Toney, Glenn M; Gerhardt, Greg A.

In: Journal of Neuroscience Methods, Vol. 143, No. 1, 15.04.2005, p. 49-62.

Research output: Contribution to journalArticle

Daws, Lynette C ; Montañez, Sylvia ; Owens, W. Anthony ; Gould, Georgianna G ; Frazer, Alan ; Toney, Glenn M ; Gerhardt, Greg A. / Transport mechanisms governing serotonin clearance in vivo revealed by high-speed chronoamperometry. In: Journal of Neuroscience Methods. 2005 ; Vol. 143, No. 1. pp. 49-62.
@article{5dbb174e3bc74d6099685f7564716c7a,
title = "Transport mechanisms governing serotonin clearance in vivo revealed by high-speed chronoamperometry",
abstract = "High-speed chronoamperometry was used to determine the kinetics of clearance of exogenously applied serotonin (5-HT) in the dorsal raphe nucleus (DRN), dentate gyrus, CA3 region of the hippocampus or corpus callosum of anesthetized rats. Maximal velocity (Vmax) for 5-HT clearance was greatest in the DRN > dentate gyrus > CA3 > corpus callosum. Apparent affinity (KT) of the serotonin transporter (5-HTT) was similar in DRN and CA3 but greater in dentate gyrus and corpus callosum. A 90{\%} loss of norepinephrine transporters (NET) produced by 6-hydroxydopamine pretreatment, resulted in a two-fold reduction in Vmax and a 30{\%} decrease in K T in the dentate gyrus, but no change in kinetic parameters in the CA3 region. Pretreatment with 5,7-dihydroxytryptamine that resulted in a 90{\%} reduction in 5-HTT density, modestly reduced Vmax in dentate gyrus but not in CA3. The same treatment had no effect on KT in the dentate gyrus but increased KT two-fold in the CA3. Neurotoxin treatments had no effect on 5-HT clearance in the corpus callosum. In hippocampal regions of intact rats, local application of the selective serotonin reuptake inhibitor, fluvoxamine, inhibited 5-HT clearance most robustly when the extracellular concentration of 5-HT was less than the KT value. By contrast, the NET antagonist, desipramine, significantly inhibited 5-HT clearance when extracellular concentrations of 5-HT were greater than the KT value. These data indicate that hippocampal uptake of 5-HT may be mediated by two processes, one with high affinity but low capacity (i.e. the 5-HTT) and the other with low affinity but a high capacity (i.e. the NET). These data show for the first time in the whole animal that 5-HT clearance in brain is regionally distinct with regard to rate and affinity.",
keywords = "Chronoamperometry, Dorsal raphe nucleus, Hippocampus, Norepinephrine transporter, Rat, Serotonin clearance rates, Serotonin transporter",
author = "Daws, {Lynette C} and Sylvia Monta{\~n}ez and Owens, {W. Anthony} and Gould, {Georgianna G} and Alan Frazer and Toney, {Glenn M} and Gerhardt, {Greg A.}",
year = "2005",
month = "4",
day = "15",
doi = "10.1016/j.jneumeth.2004.09.011",
language = "English (US)",
volume = "143",
pages = "49--62",
journal = "Journal of Neuroscience Methods",
issn = "0165-0270",
publisher = "Elsevier",
number = "1",

}

TY - JOUR

T1 - Transport mechanisms governing serotonin clearance in vivo revealed by high-speed chronoamperometry

AU - Daws, Lynette C

AU - Montañez, Sylvia

AU - Owens, W. Anthony

AU - Gould, Georgianna G

AU - Frazer, Alan

AU - Toney, Glenn M

AU - Gerhardt, Greg A.

PY - 2005/4/15

Y1 - 2005/4/15

N2 - High-speed chronoamperometry was used to determine the kinetics of clearance of exogenously applied serotonin (5-HT) in the dorsal raphe nucleus (DRN), dentate gyrus, CA3 region of the hippocampus or corpus callosum of anesthetized rats. Maximal velocity (Vmax) for 5-HT clearance was greatest in the DRN > dentate gyrus > CA3 > corpus callosum. Apparent affinity (KT) of the serotonin transporter (5-HTT) was similar in DRN and CA3 but greater in dentate gyrus and corpus callosum. A 90% loss of norepinephrine transporters (NET) produced by 6-hydroxydopamine pretreatment, resulted in a two-fold reduction in Vmax and a 30% decrease in K T in the dentate gyrus, but no change in kinetic parameters in the CA3 region. Pretreatment with 5,7-dihydroxytryptamine that resulted in a 90% reduction in 5-HTT density, modestly reduced Vmax in dentate gyrus but not in CA3. The same treatment had no effect on KT in the dentate gyrus but increased KT two-fold in the CA3. Neurotoxin treatments had no effect on 5-HT clearance in the corpus callosum. In hippocampal regions of intact rats, local application of the selective serotonin reuptake inhibitor, fluvoxamine, inhibited 5-HT clearance most robustly when the extracellular concentration of 5-HT was less than the KT value. By contrast, the NET antagonist, desipramine, significantly inhibited 5-HT clearance when extracellular concentrations of 5-HT were greater than the KT value. These data indicate that hippocampal uptake of 5-HT may be mediated by two processes, one with high affinity but low capacity (i.e. the 5-HTT) and the other with low affinity but a high capacity (i.e. the NET). These data show for the first time in the whole animal that 5-HT clearance in brain is regionally distinct with regard to rate and affinity.

AB - High-speed chronoamperometry was used to determine the kinetics of clearance of exogenously applied serotonin (5-HT) in the dorsal raphe nucleus (DRN), dentate gyrus, CA3 region of the hippocampus or corpus callosum of anesthetized rats. Maximal velocity (Vmax) for 5-HT clearance was greatest in the DRN > dentate gyrus > CA3 > corpus callosum. Apparent affinity (KT) of the serotonin transporter (5-HTT) was similar in DRN and CA3 but greater in dentate gyrus and corpus callosum. A 90% loss of norepinephrine transporters (NET) produced by 6-hydroxydopamine pretreatment, resulted in a two-fold reduction in Vmax and a 30% decrease in K T in the dentate gyrus, but no change in kinetic parameters in the CA3 region. Pretreatment with 5,7-dihydroxytryptamine that resulted in a 90% reduction in 5-HTT density, modestly reduced Vmax in dentate gyrus but not in CA3. The same treatment had no effect on KT in the dentate gyrus but increased KT two-fold in the CA3. Neurotoxin treatments had no effect on 5-HT clearance in the corpus callosum. In hippocampal regions of intact rats, local application of the selective serotonin reuptake inhibitor, fluvoxamine, inhibited 5-HT clearance most robustly when the extracellular concentration of 5-HT was less than the KT value. By contrast, the NET antagonist, desipramine, significantly inhibited 5-HT clearance when extracellular concentrations of 5-HT were greater than the KT value. These data indicate that hippocampal uptake of 5-HT may be mediated by two processes, one with high affinity but low capacity (i.e. the 5-HTT) and the other with low affinity but a high capacity (i.e. the NET). These data show for the first time in the whole animal that 5-HT clearance in brain is regionally distinct with regard to rate and affinity.

KW - Chronoamperometry

KW - Dorsal raphe nucleus

KW - Hippocampus

KW - Norepinephrine transporter

KW - Rat

KW - Serotonin clearance rates

KW - Serotonin transporter

UR - http://www.scopus.com/inward/record.url?scp=14844316658&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=14844316658&partnerID=8YFLogxK

U2 - 10.1016/j.jneumeth.2004.09.011

DO - 10.1016/j.jneumeth.2004.09.011

M3 - Article

C2 - 15763136

AN - SCOPUS:14844316658

VL - 143

SP - 49

EP - 62

JO - Journal of Neuroscience Methods

JF - Journal of Neuroscience Methods

SN - 0165-0270

IS - 1

ER -