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132. Isolation rearing produces puberty-related deficits in sensorimotor gating in rats
40s
BIOLPSYCHL4TRY 1998;43:1S-133S
Thursday Abstracts
131. CLOZAPINE-INDUCED INTERNALIZATION OF THE 5-HT2A RECEPTOR ZN VITRO
133. MATERNAL DEPRIVATION REGULATES BRAIN 5-HT RECEPTORS IN THE INFANT RAT
S.A. Berry, D.L. Willins, L. Alsayegh & B.L. Roth
J.F. L6pez1, D.M. V6zquez1, S.J. Watsonl & S. Levine2
Departmentsof Biochemistryand Psychiatry,Case WesternReserve University,Cleveland,OH The importanceof the serotonin(5-HTM)receptorin the understanding of the biologicalbasis of major mentalillnessesis underscoredby the numberof medications,whichare5-HT2~receptorligands.Amongthese are the atypical antipsychotics(clozapitre,olanzapine,nsperidoneand quetiapine)and at least two antidepressants(trazadoneandnefazadone). Previouslywe have demonstratedthat 5-HT2Areceptoragonistsinduce the internalizationof this receptorvia the endosomepathway.Interestingly,5-HT2Areceptorantagonistsalso cause a rapid internalizationof the raeptor in vitro. In this study we have exploredmechanismsby which5-HT2~receptorantagonists,includingclozapine,inducereceptor internalizationin vitro. GF-62cells, a stablytransected fibmblastcell line whichover-expressesthe 5-HT2~receptor,were used. Cells were treatedwithclozapine(1 wM),quipazine(10 wM),MDL100,907(1 pm) or vehicle,then incubatedat 37 C for 30 minutes.Cells were thenfixed and labeledwith artantibodydirectedagainstthe 5-HTMreceptor.The receptor was visualizedusing a secondaryantibodyand viewed with confocallasermicroscopy.Imageanrdysissoftwarewasusedto quantify the percentageof a cell’s area whichfluoresced(a representationof the internalizedreceptor). In a typical experiment,approximately2% of receptor are internalizedin vehicle-treatedcells whereas 10-15%of receptoris internalizedin cellstreatedwithreceptorantagonists.We will present data, which addresses the importanceof phosphorylationin antagonist-induced internalization.Theeffectof variousphosphataseand kinaseinhibitorson antagonist-induced internalizationwillbe presented. Antagonist-induced internalizationof the 5-HT2~receptormayrepresent a mechanismthroughwhichatypicalantipsychoticseffect their actions.
132. ISOLATION REARING PRODUCES PUBERTY-RELATED DEFICITS IN SENSORIMOTOR GATING IN RATS
IMentalHealthResearchInstituteand Departmentof Psychiatry, Universityof Michigan,AnnArborMI 48109;2Departrnentof Psychology,Universityof Delaware,Newark,DE 19716 Animalsstudieshave shownthat the Serotorrin(5-I-IT)system can be modifiedby stress.For example,we and othershave demonstratedthat 5-HTIAreceptorsare dounregulatedin adultrat brainfollowingchronic stress. These changes appear to be mediated by increases in plasma corticostemne.Thismaybe differentin the developinganimal,whohas a limitedcorticosteroneresponseto acutechallengesbetweendays3 and 14 of life. Levineand co-workershave shownthat prolongedmaternal deprivation(24hr) resultsin increasedbasal and stress inducedcorticosterone levels. In this study we investigatedthe effect of maternal deprivationon 5-HT2A,5-HTIAand 5-HTtransportermRNAlevels in the developingbrain. In situ hybridizationwas used to quantifygene expressionin rat pupsages6, 9, and 12daysold. In eachage group,half were maternallydeprived(DEP)for 24 hr and half were kept with their mothers(nondeprived-NDEP).We foundan age effect in almostevery regionfor both5-HTIAand5-HT2AmRNAs.In addition,DEParrimafs were found to have: 1) elevated ACTH and corticosteronelevels, 2) significantlyelevated5-HTIA mRNAlevels in the CA1 hippocarrrpal regionand 3) significantlyelevated5-HT2AmRNAlevelsin cortex.No changeswere observedin 5-HTIAor 5-HTtransportermRNAlevelsin the DorsalRaphe.our resultsindicatethat post-synaptic5-HTreceptors in the developinghippocarrtpusand cortex are sensitive to maternal deprivation.The fact that matemafcare regulates5-HTreceptorexpression has implicationsfor our understandingof the neurobiologicalrisk factorsunderlyingDepression.(Supportedby a NARSADYoungInvestigatorAwardto DMV).
134. DUAL EFFECT OF GLUCOCORTICOIDS ON 5-HTIA RECEPTOR SENSITIVITY
V.P. Bakshil, D.L. Braff2 & M.A. Geyerl’2 IDept.of Neuroscience, Universityof Californiaat SatrDiego,La JolltLCA 92093-08042Dept.of Psychiatry,Universityof Californiaat San Diego,La Jolla, CA 92093-0804 Prepulseirrhibition (PPI)is thephenomenoninwfrichpresentation ofa weak “atelyprior to an intensestartlingstimtdusdecrcawsthe Stimtdusirnmedl magnitudeof the startle response.PPI is so operationalmeasure of serrsorimotor gating,andisdeficientin schiropbreniapatiettts.Thisdeficitin PPI can be mcdelledin rats by developmentalmanipulationssuch as isolationrearing ~). Thepresentstudiessoughtto studythe ontogenyof PPIdeficitsin Et ratsto determinetheexistenceof a criticaldevelopmental periodforR-induceddisruptionof sensorimotorgating.Sepmategroupsof Sprague-Dawley (SD) rats upon wcaningwem placedinto isolated(JR, singlyhoused)orsocial(SR,housedin groupsof2-3)housingconditionsfor differentlengthsof time priorto testingin stmtlechambers.Six separate grOUpS ofratswerethusformal:IR-2weeks;SR-2WdCS;IR4 WCCkS; SR4 weeks;IR-6weeks;SR-6weeks.IRandSRratshadequalandlowlevelsof At 4 weeks(duringpuberty)or PPIat 2 WdG postWCdIlg (pre-puberty). 6 weeks(afterpuberty)postweaning,PPIin SRratswashigherthanit had beerrat2 weekspostweartirtg;PPIinIRratsretnairtedlowattheselaterdme points.Thus,JRproducesdeficitsin PPIthataremarrifestedeither duringor afterpubertyandappeartoarisefimthefailtrreof IRratstodevelopnormal PPI. Factorsassociatedwith the onsetof pubertymay thus be critically involvedin the &velopmentof normalsettsorimotorgatirtgin rata.
A. Dragomir, V.J. Djuri & M. Steiner Father SeanO’SullivrmResearchCentre,St. Joseph’sHospital, McMasterUniversity,Hamilton,Ontario,Canada,L8N4A6 Diffenmtlinesof evidencesuggestthatthe interactionbetweencotticostemids and the wrotonergicsystemis importantfor the pathophysiology of mooddisorders.Clinically,gluccworticoid imbalanceis frequentlyassociated with alteredmcod, while correctionof semtonergicdysfimctionin depressivesis paralleledby restorationof centralnervoussystemcontrol overseveralendocrineparametersincludingthe adrenalglands.Thisshxly investigatedthe effect of hydrocortisorre hemiauccinate(HCHS)on the 5-hydroxy-tryptamrne “ (5-I-IT)1A rweptor,whichhas beerrwidelyituplicatedin the etiologyof depression.AdultSpragtre-Dawiey malerats were injectedwith 25 mglkgHCHS or vehicle for one or seven days and challengedwith 0.5 mglkgof the 5-HT 1A specificagortis~8-hydmxydipmpil-amino-tetraline (8-OHDPAT)afterthe last steroidadministration. Changesin 5-HT 1Areceptorsensitivitywae assessedby meawing the hypothermic responseto 8-OHDPATinjection.AcuteHCHStreatmenthad a protectiveeffecton 8-OHDPAT-induced hypdermi% whereasgreater tempemturedropswererecoded withchronicHCHSexposure(Treatment x Timeinteraction:Fl,?l = 4.55;P=O.039).Ourdatasupportthenotionthat two differentmedranrstnsare rqxmsible for the opposingeffects of glucocorticoidson 5-HTIA receptorsensitivity.We suggestthat acute
BIOLPSYCHL4TRY 1998;43:1S-133S
Thursday Abstracts
131. CLOZAPINE-INDUCED INTERNALIZATION OF THE 5-HT2A RECEPTOR ZN VITRO
133. MATERNAL DEPRIVATION REGULATES BRAIN 5-HT RECEPTORS IN THE INFANT RAT
S.A. Berry, D.L. Willins, L. Alsayegh & B.L. Roth
J.F. L6pez1, D.M. V6zquez1, S.J. Watsonl & S. Levine2
Departmentsof Biochemistryand Psychiatry,Case WesternReserve University,Cleveland,OH The importanceof the serotonin(5-HTM)receptorin the understanding of the biologicalbasis of major mentalillnessesis underscoredby the numberof medications,whichare5-HT2~receptorligands.Amongthese are the atypical antipsychotics(clozapitre,olanzapine,nsperidoneand quetiapine)and at least two antidepressants(trazadoneandnefazadone). Previouslywe have demonstratedthat 5-HT2Areceptoragonistsinduce the internalizationof this receptorvia the endosomepathway.Interestingly,5-HT2Areceptorantagonistsalso cause a rapid internalizationof the raeptor in vitro. In this study we have exploredmechanismsby which5-HT2~receptorantagonists,includingclozapine,inducereceptor internalizationin vitro. GF-62cells, a stablytransected fibmblastcell line whichover-expressesthe 5-HT2~receptor,were used. Cells were treatedwithclozapine(1 wM),quipazine(10 wM),MDL100,907(1 pm) or vehicle,then incubatedat 37 C for 30 minutes.Cells were thenfixed and labeledwith artantibodydirectedagainstthe 5-HTMreceptor.The receptor was visualizedusing a secondaryantibodyand viewed with confocallasermicroscopy.Imageanrdysissoftwarewasusedto quantify the percentageof a cell’s area whichfluoresced(a representationof the internalizedreceptor). In a typical experiment,approximately2% of receptor are internalizedin vehicle-treatedcells whereas 10-15%of receptoris internalizedin cellstreatedwithreceptorantagonists.We will present data, which addresses the importanceof phosphorylationin antagonist-induced internalization.Theeffectof variousphosphataseand kinaseinhibitorson antagonist-induced internalizationwillbe presented. Antagonist-induced internalizationof the 5-HT2~receptormayrepresent a mechanismthroughwhichatypicalantipsychoticseffect their actions.
132. ISOLATION REARING PRODUCES PUBERTY-RELATED DEFICITS IN SENSORIMOTOR GATING IN RATS
IMentalHealthResearchInstituteand Departmentof Psychiatry, Universityof Michigan,AnnArborMI 48109;2Departrnentof Psychology,Universityof Delaware,Newark,DE 19716 Animalsstudieshave shownthat the Serotorrin(5-I-IT)system can be modifiedby stress.For example,we and othershave demonstratedthat 5-HTIAreceptorsare dounregulatedin adultrat brainfollowingchronic stress. These changes appear to be mediated by increases in plasma corticostemne.Thismaybe differentin the developinganimal,whohas a limitedcorticosteroneresponseto acutechallengesbetweendays3 and 14 of life. Levineand co-workershave shownthat prolongedmaternal deprivation(24hr) resultsin increasedbasal and stress inducedcorticosterone levels. In this study we investigatedthe effect of maternal deprivationon 5-HT2A,5-HTIAand 5-HTtransportermRNAlevels in the developingbrain. In situ hybridizationwas used to quantifygene expressionin rat pupsages6, 9, and 12daysold. In eachage group,half were maternallydeprived(DEP)for 24 hr and half were kept with their mothers(nondeprived-NDEP).We foundan age effect in almostevery regionfor both5-HTIAand5-HT2AmRNAs.In addition,DEParrimafs were found to have: 1) elevated ACTH and corticosteronelevels, 2) significantlyelevated5-HTIA mRNAlevels in the CA1 hippocarrrpal regionand 3) significantlyelevated5-HT2AmRNAlevelsin cortex.No changeswere observedin 5-HTIAor 5-HTtransportermRNAlevelsin the DorsalRaphe.our resultsindicatethat post-synaptic5-HTreceptors in the developinghippocarrtpusand cortex are sensitive to maternal deprivation.The fact that matemafcare regulates5-HTreceptorexpression has implicationsfor our understandingof the neurobiologicalrisk factorsunderlyingDepression.(Supportedby a NARSADYoungInvestigatorAwardto DMV).
134. DUAL EFFECT OF GLUCOCORTICOIDS ON 5-HTIA RECEPTOR SENSITIVITY
V.P. Bakshil, D.L. Braff2 & M.A. Geyerl’2 IDept.of Neuroscience, Universityof Californiaat SatrDiego,La JolltLCA 92093-08042Dept.of Psychiatry,Universityof Californiaat San Diego,La Jolla, CA 92093-0804 Prepulseirrhibition (PPI)is thephenomenoninwfrichpresentation ofa weak “atelyprior to an intensestartlingstimtdusdecrcawsthe Stimtdusirnmedl magnitudeof the startle response.PPI is so operationalmeasure of serrsorimotor gating,andisdeficientin schiropbreniapatiettts.Thisdeficitin PPI can be mcdelledin rats by developmentalmanipulationssuch as isolationrearing ~). Thepresentstudiessoughtto studythe ontogenyof PPIdeficitsin Et ratsto determinetheexistenceof a criticaldevelopmental periodforR-induceddisruptionof sensorimotorgating.Sepmategroupsof Sprague-Dawley (SD) rats upon wcaningwem placedinto isolated(JR, singlyhoused)orsocial(SR,housedin groupsof2-3)housingconditionsfor differentlengthsof time priorto testingin stmtlechambers.Six separate grOUpS ofratswerethusformal:IR-2weeks;SR-2WdCS;IR4 WCCkS; SR4 weeks;IR-6weeks;SR-6weeks.IRandSRratshadequalandlowlevelsof At 4 weeks(duringpuberty)or PPIat 2 WdG postWCdIlg (pre-puberty). 6 weeks(afterpuberty)postweaning,PPIin SRratswashigherthanit had beerrat2 weekspostweartirtg;PPIinIRratsretnairtedlowattheselaterdme points.Thus,JRproducesdeficitsin PPIthataremarrifestedeither duringor afterpubertyandappeartoarisefimthefailtrreof IRratstodevelopnormal PPI. Factorsassociatedwith the onsetof pubertymay thus be critically involvedin the &velopmentof normalsettsorimotorgatirtgin rata.
A. Dragomir, V.J. Djuri & M. Steiner Father SeanO’SullivrmResearchCentre,St. Joseph’sHospital, McMasterUniversity,Hamilton,Ontario,Canada,L8N4A6 Diffenmtlinesof evidencesuggestthatthe interactionbetweencotticostemids and the wrotonergicsystemis importantfor the pathophysiology of mooddisorders.Clinically,gluccworticoid imbalanceis frequentlyassociated with alteredmcod, while correctionof semtonergicdysfimctionin depressivesis paralleledby restorationof centralnervoussystemcontrol overseveralendocrineparametersincludingthe adrenalglands.Thisshxly investigatedthe effect of hydrocortisorre hemiauccinate(HCHS)on the 5-hydroxy-tryptamrne “ (5-I-IT)1A rweptor,whichhas beerrwidelyituplicatedin the etiologyof depression.AdultSpragtre-Dawiey malerats were injectedwith 25 mglkgHCHS or vehicle for one or seven days and challengedwith 0.5 mglkgof the 5-HT 1A specificagortis~8-hydmxydipmpil-amino-tetraline (8-OHDPAT)afterthe last steroidadministration. Changesin 5-HT 1Areceptorsensitivitywae assessedby meawing the hypothermic responseto 8-OHDPATinjection.AcuteHCHStreatmenthad a protectiveeffecton 8-OHDPAT-induced hypdermi% whereasgreater tempemturedropswererecoded withchronicHCHSexposure(Treatment x Timeinteraction:Fl,?l = 4.55;P=O.039).Ourdatasupportthenotionthat two differentmedranrstnsare rqxmsible for the opposingeffects of glucocorticoidson 5-HTIA receptorsensitivity.We suggestthat acute