European Journal zyxwvutsrq of Neuroscience, Vol. zyxwvutsrqp 7, pp. zyxwvuts 2508-2512, 1995 @ European Neuroscience Association SHORT COMMUNICATION Patch-clamp Analysis of Synaptic Transmission to Cerebellar Purkinje Cells of Prion Protein Knockout Mice Jochen W. Herms', Hans A. Kretzschmar', Stefan Titz2 and Bernhard U. Keller2 'Department of Neuropathology, Georg-August Universitat Gottingen, Robert-Koch-Strasse zyxw 40, zyxw 37075 Gottingen, Germany *Centre of Physiology and Pathophysiology,Georg-August Universitat Gottingen, Humboldtallee 23, 37073 Gottingen, Germany Keywords: Creutzfeldt-Jakob disease, cerebellum, inhibitory postsynaptic currents, excitatory postsynaptic currents, thin slice preparations Abstract The prion protein (PrP) plays a pivotal role in transmissible spongiform encephalopathies such as Creutzfeldt- Jakob disease in humans and scrapie and bovine spongiform encephalopathy in animals. Previous experiments have suggested that the normal cellular prion protein (PrPc) is involved in synaptic function in the hippocampus. Here, we utilized the controlled recording conditions of the patch-clamp technique to investigate the synaptic function of prion protein in cerebellar Purkinje cells. zyxwvut By performing whole-cell and outside-out patch-clamp experiments in thin slices, we investigated synaptic transmission in prion protein knockout mice (PrP-null) and control animals. In PrP-null mice, the kinetics of GABA- and glutamate receptor-mediated currents showed no significant deviation from those in control animals. In contrast to previous results in hippocampal neurons, our findings support the view that synaptic transmission is unimpaired in prion protein-deficient mice. Introduction The prion protein (PrP) is anchored to the neuronal membrane surface by glycosylphosphatidyl inositol, suggesting a role in cell signalling or adhesion (Borchelt et al., 1993). This highly conserved protein is involved in various transmissible and genetic neurodegenerative diseases such as Creutzfeldt-Jakob disease in humans and scrapie and bovine spongiform encephalopathy in animals (Prusiner, 1991). In these diseases the normal cellular protein, P r F , is converted to an altered form, zyxwvutsrqpo Prp, which shows greater protease resistance (Bolton et al., 1982), aggregates into extracellular fibrils and is part of the infectious agent which has been termed the prion (Prusiner, 1991). Although PrP has been found in all mammals examined, has a high turnover rate (Caughey et al., 1989) and is widely expressed in early embryogenesis (Manson et al., 1992) as well as postnatally (Lieberburg, 1987). mice homozygous for disrupted PrP genes appear developmentally and behaviourally normal (Biieler et al., 1992). These mice, however, have recently been shown to have altered synaptic transmission, giving rise to the hypothesis that PrP is necessary for normal synaptic function (Collinge et al., 1994). Intracellular single-electrode voltage-clamp measurements in hippocampal CAI neurons of PrP knockout mice (PrP-null) showed slower inhibitory postsynaptic currents (IPSCs) than control animals (Collinge et al., 1994). Depolarized reversal potentials of IPSCs suggested a postsynaptic function of PrP probably due to abnormal C1- gradients or selectivity of the GABA-gated ion channels (Collinge et al., 1994). Since the cerebellum is severely affected in most cases of human prion disease as well as in many experimental models of scrapie, we investigated the synaptic role of prion protein in cerebellar Purkinje cells. Patch-clamp experiments were performed in thin slice prepara- tions to compare synaptic properties of Purkinje cells in wild-type and prion protein knockout animals. By investigating excitatory and inhibitory synapses in both systems, we found that synaptic transmission in PrP-null and wild-type animals was determined by the same kinetic parameters. This argues against recent models (Collinge et al., 1994; Whittington et al., 1995) attributing pathological changes in prion disease to the lack of functionally intact prion protein and, as a result, to kinetically altered synaptic transmission in the diseased state. Materials and methods Patch-clamp experiments were performed on Purkinje cells in thin slices of the cerebellum following standard procedures (Hamill et al., 1981; Edwards et al., 1989). The two inbred lines (129/Sv and C57BL/6J) from which the PrP-null mice were derived (Biieler et al., 1992) as well as the FI cross between them were used as controls. The genotype of PrP-null mice was confirmed by Southern blot analysis of tail DNA. Sagittal slices of cerebellum (1 50 pm) were prepared from 9- to 16-day-old mice. Within this time interval, excitatory and inhibitory synapses displayed no systematic changes Correspondence ro: Prof. Dr zyxwvutsrq H. A. Kretzschmar, as above Received 22 May 1995, revised 7 July 1995, accepted 12 July 1995