Odonatologica37(2): 119-130 June I,2008 Immunocytochemical localizationof some aminergicandpeptidergicneurosubstances inthe cephalicneurosecretory system of the dragonfly, Tramea virginia (Rambur) (Anisoptera: Libellulidae) N.V.Patankar and D.B.Tembhare* DepartmentofZoology,NagpurUniversityCampus,Amravati Road,Nagpur-440033,India ReceivedNovember6,2006 / RevisedandAcceptedOctober15, 2007 Animmunocytochemicalstudyshowedthepresenceof7neurosubstance-like ma- terials: FMRFamide,neuropeptide-Y(NPY),substance-P,serotonin,gastrin,chole- cystokinin(CCK)andvasoactiveintestinalpeptide(VIP)inthemedian,lateral,ventral andopticneurosecretory cellsgroups(MNC,LNC, VNCand ONC,respectively) in thebrain andin thecorporacardiaca (CC)oftheadult, T.virginia.Inthe MNCcell typeAshowed NPY- andserotonin- while Band C cell types showedNPY-, serot- onin-,substanceP-and CCK-likepositiveimmunoreaction. TheB cell typeinLNC showed FMRFamide-,NPY-and serotonin- and theC celltype showedonly NPY and serotonin-like positiveimmunoreaction. InVNC group,theBcell typeshowed substanceP-andgastrin-,whilethe Ccell typeshowedsubstanceP-andgastrin-and VIP-like positiveimmunoreaction. Band C cell typesofONCgroupshowed sub- stanceP-and serotonin-like positiveimmunoreaction. TheCCshowedonlyNPY-like positiveimmunoreactive intrinsicneurosecretorycells.Thefunctional significanceof these myotropic and vertebrate gastrointestinalhormone-like substancesin the ce- phalicneurosecretorysystemofT.Virginiaisdiscussed. INTRODUCTION Recently, anumberofworkers(KRAMER, 1984;RAABE, 1989;GADE, 1992; NIJHOUT, 1994;TEMBHARE,1995;GADEetal., 1997;NASSEL,1999,2000, 2002; PREDEL, 2001; SCHOOFS etal.,2001, NICHOLS, 2003; TAGHERT & VEENSTRA,2003)havereviewedtheaccumulatedinformationonlocalization. *Address forcorrespondence:Prof.D.B.Tembhare,44 VijayaNagar,South Ambazari Road, Nag- pur 440022, India; — [email protected] 120 N.V.Patankar&D.B.Tembhare isolation, characterizationandfunctionalsignificance ofseveralneurosubstances in theinsects. Apartfromseveral histomorphological, histochemical, ultrastructuralandex- perimental studiesexploring the structureand functionsofthe neuroendocrine system in variousodonates(ARVY & GABE, 1962;SCHALLER & MEUNI- ER, 1968;GILLOTT, 1969;THAKARE&TEMBHARE,1975a, 1975b;TEM- BHARE & THAKARE, 1976;TEMBHARE, 1980,2002) anda study on the immunocytochemical localizationof some vertebratepeptide hormones in the nervoussystem ofAeshnacyanea(ANDRIES etal., 1991),nothorough immu- nocytochemical studieshaveyetbeenmadeonthelocalizationofthe aminergic and peptidergic neuroactivesubstances in theneurosecretory cells(NSC) inthe brainofthe dragonflies. Thepresentstudywas, therefore, undertakentolocalize the presenceof someaminergic andpeptidergic neurohormone-likesubstances in theNSC inthebrain andinintrinsicneurosecretory cells(INC)andextrinsic neurosecretoryaxonsinthecorporacardiaca(CC)ofthedragonfly, Trameavir- ginia. MATERIAL AND METHODS HISTOLOGICALTECHNIQUES —Adultdragonflieswerecollected fromthe universitycam- pus, dissected immediatelyin Bouin’sfluid andfixed for 18-24hours. The materialwasdehydrated inethanol,cleared in xyleneandembedded in paraffinwaxat58-62°C. Thesectionswerecutat 4-5 pmthickness, fixed toMayer’salbumenized slidesandstained withBargman’sChrome alum,Hema- toxylinPhloxin (CHP)orEwen’sAldehydeFuchsin (AF). IMMUNOCYTOCHEMICAL TECHNIQUES —Forimmunocytochemicalstudies,the brain wasfixedincoldBouin’sfluid,Zambonin or4%paraformaldehydefor24hours.Thereafter,overnight treatmentincoldsucrosesolution wasgivenforcryoprotectionofthetissue.Frozensectionsof 15pm thickness werecut onacryostat(Leica). The sectionswerefixed topoly-L-lysin coatedor gelatin subbed slides. Theslideswerepreserved inadeepfreezerand proceededforimmuno-staining. TheStreptavidin-biotin-peroxidase(Sigma)methodwasused. Thesections werewashed in PBS (pH-7.4)for 15min andtreated with 1%bovineserumalbumin (BSA)in PBScontaining0.3%Tri- tonX-100.ThepolyclonalantibodiesagainstFMRFamide(Incstar;Cat.No.20091,dilution-!;1000), neuropeptideY(NPY)(Sigma;CatNo.N-952B,dilution-1:800),serotonin (5-HT)(Zymed;Cat.No. 080077,dilution-L1000),substance-P(lCN;Cat.No.11820,dilution-1 TOGO),gastrin(Sigma;G-0785, dilution-l:800),cholecystokinin(CCK)(Sigma;Cat.No.C-2581,dilution-1:800)and vasoactivein- testinal peptide(VIP)(ICN; Cat.No. P-2026,dilution-1:800)werediluted inPBS in therespective concentrations containing0.3% TritonX-100and 1%BSA.Thesections werethen incubated for2 hrs at 25°Cwith eachantibodyseparately. Excessantibody wasrinsed in PBS and incubated with biotinylatedsecondaryantibodyfor40min,followedbyStreptavidin-peroxidaseconjugate(Sigma). 3-Amino-9-ethylCarbazole (AEC101)wasusedasachromogentovisualize thereddish brownre- actionproduct.Sectionswerewashedin distilledwatertostopthereaction and mountedin glycerol gelatin.Thespecificitiesandcrossreactivities oftheaboveantiseraweretestedbyliquid-phaseprea- bsorptionofthediluted antiserawiththerespectiveconcentrations separately,which inhibited posi- tive immunoreactions inthebrain sectionsofT. virginia. Immunocytochemistryin TrameaVirginia 121 RESULTS HISTOMORPHOLOGYOFTHE CEPHALICNEUROENDOCRINE SYSTEM Thecephalic neurosecretorysystemoftheadultT. virginia, consistsoftheneu- rosecretary cells(NSCs) inthe brain,anda pair ofcorpora cardiaca(CC). NEUROSECRETORYCELLSINTHEBRAIN - Therearefivepaired groupsofneu- rosecretory cellsinthebrain:themedial(MNC),mid-dorsal(MDNC)andlateral groupsintheprotocerebrum, a ventralgroup(VNC)inthetritocerebrumandan optic group(ONC)inthebasalregion oftheoptic lobes(Fig. 1)(TEMBHARE & ANDREW, 1995;PATANKAR,2004). Theaxons ofeach groupof MNC, MDNC, LNC and VNC form themedial(MNSP), mid-dorsal(MDNSP), lat- eral(LNSP)andventral(VNSP) neurosecretorypathways respectively. Theyrun dorso-ventrally and emergeas apair offine nerves, thenervi corporis cardiaci (NCC,) fromtheventero-posteriorregion ofthebrain.Thetwo NCCrunparal- leltoeachotheroneithersideof the aorta, dorsalto theoesophagus andenter theanteriorend oftheCC. Theaxons oftheONCs formthe optic neurosecre- tory pathways (ONSP), whichrun in an antero-posterior directiontowardsthe medullainternaandterminateinthe closevicinityofthe innerchiasma within the optic lobeswherethey appearto storeandreleasetheneurosecretory mate- rial. CORPORA CARDIACA — The CC is a paired, elongated, fusiformglistering white body lying just beneath the brain on themid-dorsalregion of the oesophagus, intimately associated with the dorsal aor- ta. Anteriorly thetwo lobesarefreefromone anotherbut fused to formasinglelobepos- teriorly. Apair oflat- eral nerves, the nervi Fig. I. Diagrammaticrepresentationofthecephalicneurosecretory cardiostomatogastrici system depictingthe distribution ofneurosecretory cell groups and connects the CC ven- their neurosecretory pathways in the brain of Tramea Virginia. trally to the hypocer- LNC: lateral neurosecretory cells; — LNSP: lateral neurosecretory ebral ganglion. Inter- pathways; - MDNC;mid-dorsal neurosecretory cells;- MNC:me- dialneurosecretory cells;— MNSP:medialneurosecretorypathways; nally, theCC consists - ONC:optic neurosecretory cells; - ONSP:optic neurosecretory of alarge number of pathways; - VNC: ventral neurosecretory cells; - VNSP: ventral extrinsic axonal end- neurosecretory pathways. 122 N.V.Patankar&D.B.Tembhare ingsoftheNSCs ofthebrain, someintrinsicneurosecretorycells(INC)dispersed randomly (Fig. 2)andafewordinaryneurons. IMMUNOCYTOCHEMISTRY TheNSCswereclassifiedintoA, BandCcellsbasedontheirstainingaffinities withthechrome-alumhematoxylin phloxine (CHP)and aldehyde fuschin (AF) stains(Tab. I). FMRF-AMIDE POSITIVENEUROSECRETORYCELLS - Threetypes of B cell in the LNC, onetypeof Band one typeofC cellin the VNCandtwo typesofB andthreetypesofCcellintheONC,alongwiththeiraxonsinthebrain,showed strongimmunoreactivity withthe FMRFamideantisera(Figs 3-5). THE NEUROPEPTIDEYPOSITIVENEUROSECRETORYCELLS - InthebraintheCell bodiesofoneA,eight BandfourCcelltypes intheMNCandsix B and four C cell types in the LNC showed strong reaction with the neuropeptide-Y antibody (Figs 3, 6, 7). TheINCintheCC also exhibitedpromi- nent neuropeptide-Y positive immunoreac- tion(Fig. 8). THE SUBSTANCE-P POSITIVE NEUROSE- CRETORY CELLS - Ten Aand two C cell typesintheMNCand all B andC cell types intheVNCandONC, along with theirneu- rosecretory pathways, showedintenseimmu- noreaction with the substance-P antisera Fig.2.Sectionthroughthecorporacardiaca ofTrameavirginiashow- (Figs 9-11). ingtheintrinsicneurosecretory cells. — AO;aorta; — CCC: corpora cardiaci connectives;—CB-INC:chromophobicintrinsicneurosecre- THESEROTONINPOS- torycells; —CL-INC:chromophillicintrinsicneurosectretory cells;— ITIVE NEUROSECRE- NSM-neurosecretorymaterial. — [Scalebar: 1000pm] TORY CELLS - The Immunocytochemistryin Tramea Virginia 123 TableI Cytomorphologicalcharacteristics ofthecerebralneurosecretorycellsin TrameaVirginia s# CytomophologicalCharacteristics NeurosecretoryCell Type A-cell B-cell C-cell 1.0 STAININGAFFINITIES 1.1 Chrome-alum haematoxylinphloxine Blue black Red Blueblack inclusion. (CHP) red cytoplasm 1.2 Aldehydefuchsin(AF) Dark purple Greenish Purpleinclusion,brown cytoplasm 2.0 SHAPE Pyriform Spherical Oval 3.0 SIZE 3.1 Cell diameter(pra) 1063±027 960± 080 18621056 3.2 Nuclear diameter(pm) 572±032 540± 027 920±036 4.0 DISTRIBUTION 4.1 Medial group 40-45 25-30 8-10 4.2 Mid-dorsal group - 10- 15 10- 12 4.3 Lateral group - 15-18 4- 6 4.4 Ventral group - 15-18 10-12 4.5 Opticgroup - 8- 12 10-12 serotonin-positive immunoreactivity was observeddistinctlyinoneA,two Band two CcelltypesintheMNC,fourB celltypesinthe LNCandsix B celltypesin theONC andtheiraxons inthebrain (Figs 12-14). THEGASTRINPOSITIVE NEUROSECRETORY CELLS - One B and one C cell typeinthe MNC,threeBandC celltypesintheLNC andfiveBandoneC cell typesin the VNC showedthe immunoreactionwiththe gastrin antibody (Figs 15-17). THECCK POSITIVENEUROSECRETORY CELLS - Two B and C cell types of MNCandthreeCandall B celltypeintheVNC displayed astrongimmunore- actionwith theCCK antibody(Figs 18-19). THEVIPPOSITIVENEUROSECRETORY CELLS - Six Band fourCcell typesin theVNC andallB celltypesintheONC showedtheimmunoreactionwithVIP antibody (Figs 20-21). DISCUSSION Thehistomorphological organization ofthe cephalic neuroendocrinesystem in the adultdragonfly, Tramea virginia was described by TEMBHARE & AN- DREW(1994) and PATANKAR(2004)and isbasically similartothatinAeshna cyanea (CHARLET, 1972a, 1972b;TEMBHARE,1980)and Orthetrumchrysis 124 N.V.Patankar& D.B.Tembhare Immunocytochemistryin Tramea Virginia 125 (TEMBHARE &THAKARE, 1976).Thepresent study haslocalizedthe pres- enceofFMRFamide-, NPY-,serotonin-, substanceP-,gastrin-, CCK-andVIP- likesubstances intheNSCsof differentgroupsinthe brainandCC oftheadult T. virginia. TheFMRFamide-likepositive immunoreactionhas been noticedintheNSC inthebrainofseveralinsectspecies. Inthelocust, SchistocercagregariaMYERS & EVANS(1985)tested BPPantiseranot specific fortheCterminalhexapeptide, along with liquid preabsorption experiments with BPPand FMRFamide, and suggested thattheendogenous peptide antigen containedinthestainedneurones maybelong to the pancreatic polypeptide family or to the FMRFamidefamily. WHITEetal.(1986) characterizedneuropeptide-FMRFamide-like immunoreac- tivityinthefruit fly;Drosophila melanogasterandsuggested itssignificance during development. EICHMULLERetal. (1991)analysed thebrainandsuboesopha- geal ganglion ofthehoneybee ApismelliferaL. immunocytochemically andob- servedFMRFamide-likeimmunoreactivity inthecellsprojectingto theCCfrom themedian, lateralandsuboesophageal ganglion, suggestngtheirneurosecretory nature. Definitiveevidencefor thepresenceofFMRFamideininsects was pro- videdbyKINGAN etal.(1990)whoextractedandpurified thispeptide fromthe centralnervous system ofthehawkmoth, Manducasexta. HEWES etal. (1998) analyzed the effectof eightFMRFamide-relatedpeptides expressed by neuro- secretory cells onnerve-stimulatedcontraction(twitch tensions) of Drosophila larval body wall muscles encoded by Drosophila FMRFamidegene. They sug- gested thatFMRFamidefunctionsas aneurohormonetomodulatethestrength ofcontraction atthelarvalneuromuscularjunction inwhichthe functionalrole of the seven peptides appearto be functionally redundant. ROBB & EVANS (1990) studied the quantitativedistributionof FMRFamide-likepeptides inthe nervous system and in theirputative target sites in the locustSchistocerca gre- gariaand suggested thatFMRFamide-likepeptides in thelocustfunctionboth as circulatingneurohormonesandas locallyreleasedneuromodulatorsorneuro- transmitters. RANKIN&SEYMOUR(2001), immunocytochemically observed amaterialsimilartothatofFMRFamideintheneurosecretorysystem oftheear- wig,Eubeorelliaannulipes andsuggested itsfunctionalsignificance. Recently, NI- CHOLS(2003),reviewedstructures,precursors, organizations, distributionsand Figs3-21. Immunocytochemistryoftheneurosecretorycellsinthebrain andcorporacardiaca (CC) ofTramea virginia:(3-5)brainNSCstainedwithFMRFamideantibody:(3)B-LNC andLNSP (ar- row),(4)C-VNC,(5)B andC-ONCandONSP(arrow); - (6-8)NSCstained withNPYantibody: (6)BandC-MNC, inthebrain,(7)C-LNC,inthebrain,(8)ExtrinsicaxonalfibersinCC(arrow); — (9-11)NSCinthebrainstainedwith SubstancePantibody:(9)BandC-MNC,(10)BandC-VNC, (11)Band C-ONC; — (12-14)NSCinthe brainstainedwith Serotoninantibody:(12)A,BandC- MNC, (13)B-LNC,(14)B-ONC; — (15-17)NSCin thebrainstainedwith Gastrinantibody:(15) BandC- MNC, (16)C-LNC, (17)B and C-VNC; - (18-19)NSCinthe brainstainedwith CCK antibody:(18)A,BandC-MNC,(19)B andC-VNC; —(20-21)NSCinthebrainstainedwithVIP antibody:(20)B andC- VNC, (21)B andC-ONC. —[Scalebars: 1800;im] 126 N.V.Patankar&D.B.Tembhare activitiesofFMRFamiderelatedpeptides(FaRPs) encodedby themelanogaster FMRFamide(dFMRFamide), myosuppressin (Dms) andsulfakinin(Dsk)genes andpredictedtheirsignalingpathways andbiologicalfunctions. DUTTLINGER etal. (2003) observedthestructureof the FMRFamidereceptorandthe activ- ity ofthecardioexcitatory neuropeptide ina mosquito. Theyconcludedthat its structureandactivity are conservedinthemosquito,whichmayhelp toincrease the frequency of spontaneouscontractionsofthe larval heart, thus increasing heartrate. REMY etal. (1988)demonstratedaneuropeptide relatedto mammalianneu- ropeptide Y(NPY) inLocusta migratoriainvarious neurosecretorycells which also display anFMRFamide-likeimmunoreactivity inthecephalic andthoracic nervous systems. They inferredthat inlocustNSC thesetwoantiserarecognize twodistinctantigenic sitesbelonging eitherto alargepolypeptide, orto twodis- tinctneuropeptides. SETTEMBRINIetal. (2003)observed NPY andNPY-Y1 receptor-like immuno-reactivity initsreceptorsandcolocalizationwithcCK-LI, inthecentralnervoussystem ofTriatomainfestans andanalysed its distribution patterns,suggesting thatpeptideandreceptoraremainly involvedintheprocess- ing ofinformationcoming fromsensory receptors SCHURMANN & KLEMM (1984), observed serotonin immunoreactive neurons in the brain of the honeybee and concluded that the serotonin- and catecholamine-containing neuronsoftenoccur togetherinthe samebrainareas. KLEMM etal.(1986) observedneuronsreactive toantibodiesagainst serotonin inthestomato-gastric nervous system andin thealimentary canaloflocustand crickets and suggested thatserotonin actsas a neurotransmitterand/or neuro- modulatoronintestinaland somesomaticmusclesandglandularcells, andalso actsas a neurohormonereleased fromthe neurohaemalsites intothe body flu- id. GRANGER etal.(1989) observed serotonin-immunoreactiveneuronsinthe brain ofManducasexta during larval development and larval-pupal metamor- phosis andsuggested thepossible relationship ofserotonintocerebralneuroen- docrinefunctionsduringthepostembryonic development.AccordingtoNASSEL (1995), in Drosophilamelanogasterthese peptides, liketheirmammaliancounter parts, actasneuromodulators(neurohormones) through asecond-messenger and facilitaterelease of hormones, such as prothoracicotropic (PTTH), allatotropic (ATH), allatostatic(ASH)andeclosion hormone(EH), PREDELetal. (2001a, 2001b) discussedthe structure, distribution, pharmacological activitiesand mi- metic analogs of the myoinhibitory and myostimulatory neuropeptidesin the American cockroach, Periplaneta americana.Thedistributionof cholinacetyl- transferase(CHAT); GABA, histamineandoctapamine andserotoninhavebeen reported inthelarvalchemosensory system ofDrosophilamelanogaster(FRAN- CIOSE etal., 2002) suggesting theirroleas neurotransmitters.NASSEL(2002) suggested thattheneuropeptides in thenervous system of Drosophila andother insects actas a neuromodulatorandneurohormones.LANGE (2004) observed ImmunocytochemistryinTramea Virginia 127 thatserotoninincreasesthe frequency and amplitude ofspontaneouscontrac- tionsandleadsto anincreaseinthebasaltonus oflocustoviducts suggesting the neurohormonalrole forserotoninin thecontroloflocustoviducts. MARTINI etal.(2004), observed thepossibleregulation by serotonin(5-HT) to detect the presenceofanaquoporin-like waterchannelinthemalphigian tubules(MT)of thehematophagous insectRhodniusprolixus, andsuggested thattheup-regulated expression ofMTMIPmRNA aftera bloodmealis probably due to theaction of5-HT via. acyclic AMPdependent pathway. SEVERINI etal. (2002) stated thattachykinins havebeen recognized to have a varietyofeffects inphysiological andpathological conditions, andthereisevi- dencesuggesting intrinsicneuroprotective and neurodegenerative properties of theseneuropeptides. Thisreviewprovides an update onthecurrent bodyofknow- ledgeregarding theoccurrence anddistributionoftachykinin intheanimalking- domandthephysiological andpharmacological actionsoftachykinins, outlining theimportance ofthislarge peptide family. LUNDQUIST & NASSEL, (1990) demonstratedneurons displaying substanceP-(SPLI), FMRFamide-(FLI), and cholecystokinin-like (CCKLI) immunoreactivity inthethoraco-abdominalgan- gliaofthe dipterans Drosophila melanogasterand Calliphora vomitoria. Gastrin/CCK-likeimmunoreactivity havebeenobservedintheNSCandCCof variousinsects. DUVE& THORPE (1984) studied itsdistribution in theretro- cerebralcomplex ofCalliphora vomitoriaandobservedthatCC containsCOOH- -terminalspecific gastrin/CCK-like materialwithintheintrinsic cells andinthe neuropile, suggesting its co-existencein thecellsofCC. HANSEN et al.(1987) observed COOH-terminalspecific gastrin/CCK-likematerialinCC-CAcomplex, suggesting theappearanceoftheseantibodiesearlyinevolutionwithinneuralel- ements andbeingconserved during phylogeny. ANDRIES etal. (1991) studied antiseragastrin/CCK, VIPimmunohistochemically inthebrain,suboesophageal ganglion and corpora cardiaca of Aeshna cyanea and found multiple peptide immunoreactivities.TAMARELLE& VANHEMS,(1997) characterizedanew neurosecretory cell-type inthe locust Schistocerca gregaria pars intercerebralis, immunolabelledwith an antiserumagainst a vertebratepeptide related to gas- trin-cholecystokinin (CCK-8 (s)), both in situand in primary cell cultures. On thebasisoftheir number, sizeandlocalizationthey suggested thepossibility of CCK-likeneurosecretorycellscorresponding to aneurosecretorycelltypewhich has not to datebeen identified at the fine structural level. HEWES& TAGH- ERT(2001) scanned therecently completed Drosophila genomesequence forG protein-coupled receptorssensitive to bioactivepeptides (peptide GPCRs) and also scannedfor genesencoding potential ligands. They described 22bioactive peptideprecursorsandfoundthatatleast32Drosophila peptidereceptorsappear to haveevolved fromcommonancestors of 15monophyletic vertebrateGPCR subgroups (e.g.,theancestralgastrin/cholecystokinin receptor),shedding lighton theevolutionary history ofpeptideGPCRs andproviding a template forphysi- 128 N.V.Patankar&D.B.Tembhare ological andgenetic analyses ofpeptide signalinginDrosophila. Thepresentpaperprovides informationbasedonimmunocytochemical stud- iesregarding thepresenceof some vertebratehormone-, neurotransmitter-and neuromodulator-likesubstances inthecerebralneurosecretorysystem whichmay representco-localizationwiththe intrinsicinsect neuropeptides andmay exerta vitalrolein thelifeofan insect. ACKNOWLEDGEMENTS We aregratefultoProf.N.K.SUBHEDAR forprovidingtrainingin immunocytochemicaltech- niquesand permittingtowork inhis laboratory.The“UniversityResearch Fellowship”awardedto NVPbytheNagpurUniversityisalsoacknowledged. REFERENCES ANDR1ES, J.C.,G. 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