title: Long-term effect of neonatal inhibition of APP gamma-secretase on hippocampal development in the Ts65Dn mouse model of Down syndrome.
abstract: Neurogenesis impairment is considered a major determinant of the intellectual disability that characterizes Down syndrome (DS), a genetic condition caused by triplication of chromosome 21. Previous evidence obtained in the Ts65Dn mouse model of DS showed that the triplicated gene APP (amyloid precursor protein) is critically involved in neurogenesis alterations. In particular, excessive levels of AICD (amyloid precursor protein intracellular domain) resulting from APP cleavage by gamma-secretase increase the transcription of Ptch1, a Sonic Hedgehog (Shh) receptor that keeps the mitogenic Shh pathway repressed. Previous evidence showed that neonatal treatment with ELND006, an inhibitor of gamma-secretase, reinstates the Shh pathway and fully restores neurogenesis in Ts65Dn pups. In the framework of potential therapies for DS, it is extremely important to establish whether the positive effects of early intervention are retained after treatment cessation. Therefore, the goal of the current study was to establish whether early treatment with ELND006 leaves an enduring trace in the brain of Ts65Dn mice. Ts65Dn and euploid pups were treated with ELND006 in the postnatal period P3-P15 and the outcome of treatment was examined at ~one month after treatment cessation. We found that in treated Ts65Dn mice the pool of proliferating cells in the hippocampal dentate gyrus (DG) and total number of granule neurons were still restored as was the number of pre- and postsynaptic terminals in the stratum lucidum of CA3, the site of termination of the mossy fibers from the DG. Accordingly, patch-clamp recording from field CA3 showed functional normalization of the input to CA3. Unlike in field CA3, the number of pre- and postsynaptic terminals in the DG of treated Ts65Dn mice was no longer fully restored. The finding that many of the positive effects of neonatal treatment were retained after treatment cessation provides proof of principle demonstration of the efficacy of early inhibition of gamma-secretase for the improvement of brain development in DS.
authors.affiliation: Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy.
authors.forename: Fiorenza
authors.initials: F
authors.lastname: Stagni
authors.affiliation: Department of Biology and Biotechnology "L. Spallanzani", University of Pavia, Pavia, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Raspanti
authors.affiliation: Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Giacomini
authors.affiliation: Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy.
authors.forename: Sandra
authors.initials: S
authors.lastname: Guidi
authors.affiliation: Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Emili
authors.affiliation: Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy.
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Ciani
authors.affiliation: Department of Veterinary Medical Sciences,University of Bologna, Bologna, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Giuliani
authors.affiliation: Health Sciences and Technologies - Interdepartmental Center for Industrial Research (HST-ICIR), University of Bologna, Bologna, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Bighinati
authors.affiliation: Health Sciences and Technologies - Interdepartmental Center for Industrial Research (HST-ICIR), University of Bologna, Bologna, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Calzà
authors.affiliation: Department of Biology and Biotechnology "L. Spallanzani", University of Pavia, Pavia, Italy.
authors.forename: Jacopo
authors.initials: J
authors.lastname: Magistretti
authors.affiliation: Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy. Electronic address: renata.bartesaghi@unibo.it.
authors.forename: Renata
authors.initials: R
authors.lastname: Bartesaghi
mesh_terms: D053829:Amyloid Precursor Protein Secretases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D004195:Disease Models, Animal; D004314:Down Syndrome / Q000188:drug therapy* / Q000201:enzymology* / Q000473:pathology; D005260:Female; D006624:Hippocampus / Q000187:drug effects / Q000201:enzymology* / Q000254:growth & development; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D011720:Pyrazoles / Q000494:pharmacology / Q000627:therapeutic use*; D011804:Quinolines / Q000494:pharmacology / Q000627:therapeutic use*; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D011720:Pyrazoles; D011804:Quinolines; C573127:(R)-4-cyclopropyl-7,8-difluoro-5-(4-(trifluoromethyl)phenylsulfonyl)-4,5-dihydro-1H-pyrazolo(4,3-c)quinoline; D053829:Amyloid Precursor Protein Secretases
keywords: APP; Down syndrome; Gamma-secretase; Hippocampal development; Neonatal pharmacotherapy