title: In vivo monitoring of serotonin in the striatum of freely moving rats with one minute temporal resolution by online microdialysis-capillary high-performance liquid chromatography at elevated temperature and pressure.
abstract: Online monitoring of serotonin in striatal dialysate from freely moving rats was carried out for more than 16 h at 1 min time resolution using microdialysis coupled online to a capillary HPLC system operating at about 500 bar and 50 °C. Several aspects of the system were optimized toward robust, in vivo online measurements. A two-loop, eight-port rotary injection valve demonstrated better consistency of continuous injections than the more commonly used two-loop, 10-port valve. A six-port loop injector for introducing stimulating solutions (stimulus injector) was placed in-line between the syringe pump and microdialysis probe. We minimized solute dispersion by using capillary tubing (75 μm inside diameter, 70 cm long) for the probe inlet and outlet. In vitro assessment of concentration dispersion during transport with a 30 s time resolution showed that the dispersion standard deviation for serotonin was well within the desired system temporal resolution. Each 30 or 60 s measurement reflects the integral of the true time response over the measurement time. We have accounted for this mathematically in determining the concentration dispersion during transport. The delay time between a concentration change at the probe and its detection is 7 min. The timing of injections from the stimulus injector and the cycle time for the HPLC monitoring of the flow stream were controlled. The electrochemical detector contained a 13 μm spacer to minimize detector dead volume. During in vivo experiments, retention time and separation efficiency were stable and reproducible. There was no statistically significant change over 5.5 h in the electrochemical detector sensitivity factor for serotonin. Dialysate serotonin concentrations change significantly in response to a 120 mM K(+) stimulus. Release of serotonin evoked by a 10 min, 120 mM K(+) stimulation, but not for other K(+) stimuli, exhibited a reproducible, oscillating profile of dialysate serotonin concentration versus time. Infusion of fluoxetine, a serotonin uptake inhibitor, increased dialysate serotonin concentrations and stimulated release magnitude. Transient serotonin increases were observed in response to the stress associated with unexpected handling. This system is simple, efficient, reliable, and suitable for the study of serotonin neurochemistry associated with emotion and behavior.
authors.affiliation: Department of Chemistry, University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.forename: Andrea
authors.initials: A
authors.lastname: Jaquins-Gerstl
authors.forename: Kathryn M
authors.initials: KM
authors.lastname: Nesbitt
authors.forename: Sarah C
authors.initials: SC
authors.lastname: Rutan
authors.forename: Adrian C
authors.initials: AC
authors.lastname: Michael
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Weber
mesh_terms: D000818:Animals; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D008297:Male; D017551:Microdialysis / Q000379:methods*; D009068:Movement; D017072:Neostriatum / Q000378:metabolism*; D009862:Online Systems; D011312:Pressure; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000378:metabolism*; D013696:Temperature
chemical_list: D012701:Serotonin
references.citation: Anal Chem. 2009 Nov 15;81(22):9462-71
references.pmid: 19827792
references.citation: Int J Food Sci Nutr. 1995 May;46(2):107-15
references.pmid: 7621082
references.citation: J Chromatogr A. 2009 Mar 20;1216(12):2394-403
references.pmid: 19203758
references.citation: Anal Chem. 2009 Jun 15;81(12):4623-43
references.pmid: 19425531
references.citation: ACS Chem Neurosci. 2013 May 15;4(5):715-20
references.pmid: 23597074
references.citation: J Chromatogr A. 2012 Aug 17;1251:54-62
references.pmid: 22771067
references.citation: Anal Chem. 2010 Dec 1;82(23):9611-6
references.pmid: 21062014
references.citation: Anal Chim Acta. 2009 Oct 19;653(1):1-22
references.pmid: 19800472
references.citation: J Am Chem Soc. 2012 Jun 27;134(25):10562-8
references.pmid: 22651886
references.citation: J Org Chem. 2010 Aug 20;75(16):5619-26
references.pmid: 20666502
references.citation: J Physiol. 1999 Jan 15;514 ( Pt 2):567-78
references.pmid: 9852336
references.citation: Pharmacogenomics J. 2002;2(4):217-35
references.pmid: 12196911
references.citation: Anal Chim Acta. 2009 Sep 28;651(1):1-14
references.pmid: 19733728
references.citation: J Neurochem. 1998 Mar;70(3):1077-87
references.pmid: 9489728
references.citation: Gastroenterology. 2007 Jun;132(7):2438-47
references.pmid: 17570217
references.citation: Chemphyschem. 2013 Jul 22;14(10):2288-94
references.pmid: 23794474
references.citation: Anal Chem. 2006 Mar 15;78(6):1755-60
references.pmid: 16536408
references.citation: Anal Chem. 2006 Oct 1;78(19):6717-25
references.pmid: 17007489
references.citation: Neuropharmacology. 2004 Feb;46(2):232-42
references.pmid: 14680761
references.citation: Electrophoresis. 2001 Oct;22(17):3668-76
references.pmid: 11699904
references.citation: J Memb Sci. 2010 Feb 15;348(1-2):131-149
references.pmid: 20161534
references.citation: Hum Psychopharmacol. 2000 Aug;15(6):397-415
references.pmid: 12404302
references.citation: Annu Rev Anal Chem (Palo Alto Calif). 2008;1:627-61
references.pmid: 20636092
references.citation: Anal Bioanal Chem. 2011 Jun;400(7):2013-23
references.pmid: 21465093
references.citation: J Pharm Biomed Anal. 1999 Mar;19(3-4):413-22
references.pmid: 10704106
references.citation: ACS Chem Neurosci. 2013 May 15;4(5):799-807
references.pmid: 23574576
references.citation: JPEN J Parenter Enteral Nutr. 2005 Mar-Apr;29(2):125-30
references.pmid: 15772391
references.citation: J Chromatogr B Analyt Technol Biomed Life Sci. 2007 May 1;850(1-2):303-9
references.pmid: 17166782
references.citation: ACS Chem Neurosci. 2013 May 15;4(5):790-8
references.pmid: 23614776
references.citation: J Chromatogr A. 2003 Feb 7;986(2):247-51
references.pmid: 12597631
references.citation: Annu Rev Pharmacol Toxicol. 2003;43:261-84
references.pmid: 12359863
references.citation: J Food Sci. 2011 Mar;76(2):H62-71
references.pmid: 21535769
references.citation: Anal Chem. 2004 Sep 1;76(17):5069-74
references.pmid: 15373444
references.citation: Nat Rev Neurosci. 2008 Feb;9(2):85-96
references.pmid: 18209729
references.citation: Electrophoresis. 2013 Mar;34(6):895-902
references.pmid: 23335091
references.citation: Anal Chem. 1994 May 1;66(9):1468-72
references.pmid: 8017633
references.citation: Anal Chem. 2011 Oct 15;83(20):7662-7
references.pmid: 21859125
references.citation: Anal Chem. 2007 Feb 1;79(3):947-54
references.pmid: 17263320
references.citation: Anal Chem. 1997 Nov 15;69(22):4560-5
references.pmid: 9375517