Horváth, Szatmár

English

Horváth Szatmár

University of Szeged

Volume 47(1-4):63, 2003Acta Biologica Szegediensishttp://www.sci.u-szeged.hu/ABSDISSERTATION SUMMARYDepartment of Comparative Physiology, Faculty of Sciences, University of Szeged, Szeged, HungaryUse of pseudorabies virus to delineate plastic neuronalcircuits in the brain: opportunities and limitations, andpossible backgroundSzatmár HorváthSupervisor: József ToldiE-mail: szatmar@bio.u-szeged.hu63It has earlier been demonstrated that strain Bartha (PRV-Ba),an attenuated pseudorabies virus (PRV) live vaccine virus, issuitable as a retrograde tracing tool for revealing neuralcircuitries. Although fewer studies have employed intrace-rebral injections of the virus, available evidence suggests thatthis experimental approach is also an effective means ofdefining multisynaptic circuits. We tested whether thismethod based on the use of this virus is sensitive enough todetect fine plastic changes induced in the central nervoussystem (CNS).A number of publications have demonstrated that oestro-gen induces plastic alterations in the synaptic connections inthe CNS. We examined that neuronal infectivity and thespreading of PRV through the synapses in the CNS areinfluenced by the oestrogen levels. The arcuate nucleus andthe subfornical organ were chosen as models for analysis; theneurons in both structures possess oestrogen receptors andare mutually connected. Our results demonstrate that trans-neuronal PRV labelling depends on the effects of oestrogenon certain CNS structures and connections (Horváth et al.2002).In adult mammals, the somatotopic representation map ofthe muscle system in the motor cortex is not stable, but maybe modified within hours to days after peripheral facial nerveinjury. In particular, we have previously demonstrated anfacial nerve injury (N7x)-induced early disinhibition of thecommissural connections between the primary motor cortices(MIs) by intracortical microstimulation of the facial musclerepresentation field. In our second experiment, unilateral N7xwas found to influence the transcallosal spread of PRV-Bafrom the affected (left) primary motor cortex (MI) to thecontralateral MI of rats (Horváth et al.).To explain these results, it should be taken into accountthat the entry of alpha herpes viruses into the cells usuallyrequires multiple interactions between the viral envelope andthe cell surface proteins. At least two groups (HSPGs andnectins) of these cell surface glycoproteins are known to playroles in these processes (Mettenleiter 2000). It should alsobe taken into account that HSPGs and nectins participate inthe development and plasticity in adulthood of tissues ofneuroepithelial origin (Mizoguhi et al. 2002; Rauvala andPeng 1997). We have shown here that oestrogen level andN7x does not affect the entry of PRV, but increases theefficiency of its cell-to-cell spread. Thus, the infection patterndoes not appear to be related to cellular components (HSPGs)involved in the attachment of the virus, but rather to cellularcomponents located at the synaptic region of the membraneof post-synaptic neurons.Nectin-1 and nectin-2, components of a novel cell-celladhesion system, and localized within the cadherin-cateninsystem at cell-cell adhesive junctions, have been shown toplay important parts in synapse formation (Mizoguhi et al.2002). In ep-ithelial cells, dissociation of the cell junctionsreleases nectin-1 to serve more efficiently as an entryreceptor. Sakisaka and coworkers (2001) have reported thatthe interaction of nectin-1a with afadin does not affect theentry of HSV-1, but increases the efficiency of the cell-cellspread of that virus. The mechanism by which oestrogenlevel and N7x increases the efficiency of cell-cell spread ofPRV in the cortical network in vivo remains to be elucidated,but one possible explanation will be discussed.ReferencesHorvath S, Kis Z, Boldogkoi Z, Nogradi A, Toldi J (2002) Oestrogen-dependent tracing in the rat CNS after pseudorabies virus infection. EurJ Neurosci 15:937-43.Horvath S, Pankotai E, Kis Z, Farkas T, Boldogkoi Z, Boda K, Toldi JTranscallosal tracing with pseudorabies virus is influenced by aperipheral nerve injury. (submitted).Mettenleiter T C (2000) Aujeszky’s disease (pseudorabies) virus: the virusand molecular pathogenesis—state of the art. Vet Res 31:99-115.Mizoguchi A, Nakanishi H, Kimura K, Matsubara K, Ozaki-Kuroda K,Katata T, Honda T, Kiyohara Y, Heo K, Higashi M, Tsutsumi T, SonodaS, Ide C, Takai Y (2002) Nectin: an adhesion molecule involved information of synapses. J Cell Biol 156:555-565.Rauvala H, Peng HB (1997) HB-GAM (heparin-binding growth-associatedmolecule) and heparin-type glycans in the development and plasticityof neuron-target contacts. Prog Neurobiol 52:127-144.Sakisaka T, Taniguchi T, Nakanishi H, Takahashi K, Miyahara M, Ikeda W,Yokoyama S, Peng YF, Yamanishi K, Takai Y (2001) Requirement ofinteraction of nectin-1alpha/HveC with afadin for efficient cell-cellspread of herpes simplex virus type 1. J Virol 75:4734-43.

Use of Pseudorabies virus to delineate plastic neuronal circuits in the brain: opportunities and limitations, and possible background

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Use of Pseudorabies virus to delineate plastic neuronal circuits in the brain: opportunities and limitations, and possible background

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