Reorganization of CA3 area of the mouse hippocampus after pilocarpine induced temporal lobe epilepsy with special reference to the CA3-septum pathway

We showed that when CA3 pyramidal neurons in the caudal 80% of the dorsal hippocampus had almost disappeared completely, the efferent pathway of CA3 was rarely detectable. We used the mouse pilocarpine model of temporal lobe epilepsy (TLE), and injected iontophoretically the anterograde tracer phaseolus vulgaris leucoagglutinin (PHA-L) into gliotic CA3, medial septum and the nucleus of diagonal band of Broca, median raphe, and lateral supramammillary nuclei, or the retrograde tracer cholera toxin B subunit (CTB) into gliotic CA3 area of hippocampus. In the afferent pathway, the number of neurons projecting to CA3 from medial septum and the nucleus of diagonal band of Broca, median raphe, and lateral supramammillary nuclei increased significantly. In the hippocampus, where CA3 pyramidal neurons were partially lost, calbindin, calretinin, parvalbumin immunopositive back-projection neurons from CA1-CA3 area were observed. Sprouting of Schaffer collaterals with increased number of large boutons in both sides of CA1 area, particularly in the stratum pyramidale, was found. When CA3 pyramidal neurons in caudal 80% of the dorsal hippocampus have almost disappeared completely, surviving CA3 neurons in the rostral 20% of the dorsal hippocampus may play an important role in transmitting hyperactivity of granule cells to surviving CA1 neurons or to dorsal part of the lateral septum. We concluded that reorganization of CA3 area with its downstream or upstream nuclei may be involved in the occurrence of epilepsy.

Differential effects of intranasal vaccination with recombinant NcPDI in different mouse models of Neospora caninum infection

In this study, mice were vaccinated intranasally with recombinant N. caninum protein disulphide isomerase (NcPDI) emulsified in cholera toxin (CT) or cholera toxin subunit B (CTB) from Vibrio cholerae. The effects of vaccination were assessed in the murine nonpregnant model and the foetal infection model, respectively. In the nonpregnant mice, previous results were confirmed, in that intranasal vaccination with recNcPDI in CT was highly protective, and low cerebral parasite loads were noted upon real-time PCR analysis. Protection was accompanied by an IgG1-biased anti-NcPDI response upon infection and significantly increased expression of Th2 (IL-4/IL-10) and IL-17 transcripts in spleen compared with corresponding values in mice treated with CT only. However, vaccination with recNcPDI in CT did not induce significant protection in dams and their offspring. In the dams, increased splenic Th1 (IFN-γ/IL-12) and Th17 mRNA expressions was detected. No protection was noted in the groups vaccinated with recNcPDI emulsified in CTB. Thus, vaccination with recNcPDI in CT in nonpregnant mice followed by challenge infection induced a protective Th2-biased immune response, while in the pregnant mouse model, the same vaccine formulation resulted in a Th1-biased inflammatory response and failed to protect dams and their progeny.