Postnatal development of the secondary afferent fibers from the trigeminal principal sensory nucleus to the thalamusin the whisker-to-barrel pathway

Basic Sciences - Miscellaneous

Tuesday, 8 July /997

S145

The descending nigrofugalfibers ran dorsally inmesencephalicreticuthe Conclusion:Endothelialcells(HUV-EC-C) are sensitiveto ultrasoundwaves and show adifferentialresponse. At lowintensities,hemostasis is enhanced lar formation,which were separated into three groups. In the first group, the intensitieswhich also give rise to massive morphological fibers ranmedially, then terminated in the lateral portion of the central gray but inhibited at high (CG), the oculomotor nucleus (3N), the interstitial nucleus of MLF and the reddamageofendothelialcells. dorsally,thenterminatedin nucleus (RN). The fibers of the second group ran the intermediatelayer of the superior colliculus (SC). On the third group, the fibers randorsally, then terminated in the pedunculopontinenucleus (PPN). P-3-324I !Jevelopme.ntof a pharmac,?logic cocktailfor intraoperativeneuroprctecnon Dependingon the injection site of the SNR, obvious topographicdistributions were shown in the SC and PPN. Althoughthe descendingentopedunculofugal R. Andrews', K.Dehghani2. 1 Dept ofNeurosurgery,Suny Medctr. Syracuse, fibers also projected to the CG, SC and PPN, the major projectionfibers and NY, USA, 2 Dept ofNeurobiology,NorthwesternU, Evanston,IL, USA terminalswere observedin the SNR. We concludethat descendingnigrofuthe gal andentopedunculofugalfibers projectedto SC, CG, 3N, RN and PPN. The Introduction:Because the etiology of ischemic brain injury (such as intraoperative retraction)is multifactorial,optimalprophylaxisand treatment may directmonosynapticprojectionsfrom EP to SNR may be regarded as a part of likewise bemultifactorial.We studied the effects of nimodipine (NI), mannitol integratingmechanismin the basal ganglia. (MA), tromethamineor THAM (TH), ad the lazaroidU-74389G (UG) - singly and in variouscombinations- on local CBF and cortical brain pH as well as CSF pH and PC02 during ischemiaand reperfusionin a large animal model of P-3-322! Postnataldevelopmentof thesecondaryafferent focal ischemia under both normoventilation(NV) andhyperventilation(HV). fibersfrom thetrigeminalprincipalsensorynucleus Methods: Using ourpreviously-describedswine model ofintraoperative to thethalamusin the whisker-to-barrelpathway endotrachealanesthesia(isoflurane) brainretraction,35 animalsundergeneral Gen Kusaka" Souji Shinoda 1 , ToshioMasuzawa' , Makoto Yamakado2. underwentwide bilateral craniectomy.Subtemporal retraction at 50 mm Hg Neurology,Jichi MedicalSchool, Tochigi,Japan, , Departmentof Surgical pressurefor 30 min was followed by 30 min reperfusion.Drugs were giveni.v, 2 DepartmentofAnatomy,Jichi Medical School, Tochigi,Japan starting15 min prior to the first retraction:NI1 l1g1kglmin,MA 0.5 g/kg q t hr,TH 0.6 M 2.5 cc/kg q 30 min (4 doses),then0.5 cc/kg q 30 min thereafter,and/or UG The whisker-to-barrelpathway in the rat brain is characterizedby an extraordinary group of cellaggregates, namely barrels in lamina IV of the primary 3 glkg,repeated at hours2 and 6. Control animalsreceivedeither normal saline (NS)orpolyethyleneglycol(PEG,the vehiclefor NI). Corticalsurface brain pH in somatosensorycortex, barreloids in the dorsomedialsubnucleusof the venmicroelectrode, the ischemicregionwasmonitoredby a hydrogen ion selective trobasalnuclearcomplexin the thalamus(VBm)and barrelettesin thetrigeminal and CBF bylaser-Dopplerflowmetry.The fluorescent dye technique for CSF sensory nuclear complex. Because ofone-to-one a topographicalcorresponpH and PC02 measurementhas been previouslyreported. organized dence,cell aggregatessuchas barrels,barreloidsand barreleltesare Results: A decrease in blood pressure was seen with NI and NI + MA, in a distinct array which reflects the arrangementof facialvibrissae. In develbut not with NI+ MA + TH. CBF during ischemia was decreased with NI, UG, opment, those cellaggregates appear duringpostnataldays 0-4; first in the brain stem, second in the thalamus, and finally in the cerebral cortex. So, weand NI + TH, and increasedwith MA. The brain pH decrease during ischemia was minimal with TH (singly and in combinationwith NI or NI + MA), and examinedthe postnataldevelopmentof secondaryafferentconnectionfrom the also less with MA and UG. CBF during reperfusionin general was lower in PO to P3 in the mouse of trigeminalprincipal sensory nucleus to VBm during the experimentalgroups thancontrols,particularly during HV. Brain pH during ICR strain. reperlusionrecovered towardpreischemicbaseline with TH and NI + MA in PO or P3,the animalswerefixedby transcardial Materials and Methods: On comparisonwith PEG, with a similar trend in the other experimentalgroups. (pH7.4), and brains perfusion with 4%paraformaldehydein a buffer solution skull,and immersed in the same fixative For CSF, during NV and HV the pH was lower for NI, MA, TH - singly and in were removed immediately from the for a few days. Then small Oil crystal was inserted into the principal sensorycombination- than for NS. Allcomparisonssignificantat P< 0.01 or greater. nucleus on both sides or one side and stored in the fixative for another few Discussion:The combinationof NI + MA + TH offers theimprovementin CBF and brain pH during ischemiaseen with MA and TH, respectively,as well weeks.Horizontalsections,80 11m thick, were cut by aVibratomeand stained as the more rapid brain pH recovery during reperfusionseen with NI. Such withbisbenzymidefor cell nuclei. Terminal arborizationand cellcomposition combinationtherapies warrant further study in other models of transient focal werecharacterizedbyfluorescencemicroscopy. ischemia. Results: OnPO when no barreloids were recognizedyet in VBm, the secreached VBm and there terondary afferent fibers crossed at the brain stem, barreloidswererecognizable,they minateddiffusely.By contrast, on P3 when convergedat the centerof barreloidneuropilin whichglomerularterminalswere P-3-325I Steroid·inducedexpressionof annexinin brain made.This terminal specializationoccurred in the barreloidneuropilin harmony P.H. Voermans, K.G. Go, G.J. Ter Horst, M.H.J. Ruiters, E. Solito, L. Parente. withtopographicalcellaggregation.These results indicatethat the interactions Depts. of Neurosurgery,BiologicalPsychiatry,and BiomedicalTechnology prominentcellaggregates of fiber terminals and target neuronal cells provide Center, UniversityHospitalGroningen,Netherlands,Institut Cochin de study. with distinct connections.What kind ofinteractionsconcern is the next GentitiqueMoleculaire,Paris, France, Islituto diFarmacologiae Farmacognosia,Palermo, Italy

I

I

I

I P-3-323I

Introduction:Steroidadministrationhas been shown to induce in various tissues theexpressionof annexins (Anx) (orlipocortins).These are a class of proteins, capable of inhibiting phospholipaseA2, an enzyme which releases Uwe Karsch' , Wolfram Henn2, Ulrich Theo Seyfert 3, WolfingoSteudel' , arachidonicacid (AA) frommembrane phospholipids,while AA is known as Johannes Reif1. ' Dept.Neurosurgery,2Dept. HumanGenetics, 3 Dept. the precursorof theeicosanoids,many of which are involved as mediators of Hemostaseology,SaarlandUniversity,Homburg/Saar,Germany inflammation.In the brain,AA has been shown to be released after ischemia Introduction:The experimentalstudy was designed to clarify whether the ap- and otherinjuries,and to induce brain edema. Therefore, Anx may well be the mediatorof steroid action on brain edema. In an earlier study, we have shown plicationof ultrasounddissectionat the outer surface of blood vesselsactivates that in control brain, Anx occur only sporadically,whereas steroid treatment hemostaticmechanismsat theendothelium. in various brain structures. inducedwidespreadAnx-immunoreactivily Methods: We developed an in vitro model system for measurementof the Methods: Control rats, rats pretreated with methylprednisolone(MP) (2 hemostaseologicaleffects ofultrasoundon monolayerendothelialcell cultures mg/kg), or with the21-aminosteroidU74389F (AMU) (10 mglkg), 24 and2 hrs (ATCCHUV-EC-C) avoiding superficial sound effects like cavitationand heat. before, were perfused with paraformaldehydeunder anesthesia. Sections of We used a closed cooling circuit separating the ultrasounddevice from a cell 2 the brain were assessed for Annexin-1 (Anx-1) byimmunohistochemistry usmembrane.Ultrasound(10 and 100 W/cmat about culturechamber by a latex ing a polyclonalantibody,and forAnx-1 mRNA by in situhybridization(ISH) 23 kHz) was applied for 2 minutes to the endothelialcells. Wemeasured the with a digoxigenin-conjugated cRNA. The probe had been prepared by amconcentrationof 14 hemostaticsubstancesin the culturemediumfor correlation plifyingAnx-1 cDNA withsimultaneousincorporationof a T7-RNA-polymerase with cellmorphologyand trypan blueexclusion. promoter using the polymerasechainreaction.Then digoxigenin-11-UTPwas Results: The parameters TXB 2, PGF1a , PAl Ag, TM, and TSP were found incorporatedinto thetranscribedcRNA withT7-RNA-polymerase.The digoxto be influencedby high powerultrasound.The cytologicaleffects rangedfrom igenin served as a label forimmunodetectionwith anti-digoxigeninalkaline disintegrationof single vital cells to intracellular cavitationand membrane dephosphataseconjugatedantibodywhile Nitro Blue Tetrazoliumsalt was used to fects.Ultrasoundliberatedcoagulationfactorsfromendothelialcellswithout vital visualizethephosphatasereaction. membrane disruption. Low intensities around W/cm 10 2 enhanced temperaResults and Comments: The various brain areas of the control animals ture-independenthemostasisby significantemissionof TXB 2 and PAlAg2 (p < showedanappreciableamountofAnx-1 at mRNAor protein level. The animals 0.05: n =10). High intensities of about 100 W/cm2 were associatedwith local pretreated with MP or AMU showed in many areas a more intense Anx-1 heating ad lowered theconcentrationof TXB2 and PAl Ag whilesignificantly controls.In thepretreatedanimalsAnx-1 immunostaining liberating PGFt a (p < 0.05; n = 6); effects which in vivo should enhance blood mRNAsignalthan the was unchanged in cortex, basal ganglia, amygdala and septum, but more flow.

Hemostaseologiceffectsof high powerultrasound on endothelialcells in vitro.An experimental study