1999), which are normally innervated by septal cholinergic axons (Frotscher and Leranth 1985). Taken together, these studies suggest that L1 could be involved in the proper development of septal cholinergic neurons and that an abnormal maturation of these

neurons may contribute to the known defective development of hippocampal neurons in L1-deficient mice. We report that L1 is critical for the timely maturation of septal cholinergic neurons and ChAT expression and activity in vivo. We also provide direct evidence that Inhibitors,research,lifescience,medical L1 stimulates ChAT activity in vitro. The absence of L1 in transgenic mice did not influence the number or size of total neurons in the septum and CPu, or the cholinergic development of striatal neurons. The role of L1 in the regulation of ChAT may be of significance in cognitive impairments observed in L1-deficient cases and in the design of strategies aiming to treat mental retardation Inhibitors,research,lifescience,medical and disorders with cholinergic deficits, such as Alzheimer’s disease. Materials and Methods Animals and tissue Inhibitors,research,lifescience,medical preparation All experimental procedures were approved by the Animal Care Committee of Sunnybrook Research Institute and conformed to the guidelines set by the Canadian Council on Animal Care and the Animals for Research Act of Ontario. L1-deficient mice L1 expression in mutant mice was

abolished by the insertion of a selleck screening library tetracycline-controlled transactivator in the second exon of the L1 gene Inhibitors,research,lifescience,medical (L1/tTA knock-in) (Rolf et al. 2001; Dihné et al. 2003; Ohyama et al. 2004; Saghatelyan et al. 2004; Bernreuther et al. 2006). L1-deficient males (L1−/y), heterozygous females (L1+/−), and wild-type littermates were generated by crossing heterozygous female mice (L1+/−) on a C57BL/6J/129SvJ genetic background with wild-type 129X1/SvJ male mice (JAX mice, ME). Genotyping was performed by polymerase

chain reaction (PCR). Briefly, genomic tail DNA was isolated and the L1 mutant allele was detected by a 454 base pair DNA fragment Inhibitors,research,lifescience,medical generated by PCR using a 5′ primer that anneals to the tTA sequence (5′-TAC ATG CCA ATA CAA TGT AGG CTG C) and a 3′ primer in the L1 sequence (5′-GGA ATT TGG AGT TCC AAA CAA GGT GAT C). The wild-type L1 allele was detected by a 351 base pair PCR product not generated using the primers 5′ (5′-AGA GGC CAC ACG TAC CGC AGC ATC) and 3′ (5′-GGA ATT TGG AGT TCC AAA CAA GGT GAT C) in the L1 sequence. PCR results were confirmed by immunoblot and immunocytochemistry analyses in brain tissue, assuring that L1 is abolished in L1-deficient mice. L1-deficient mice and their wild-type littermates were used at the following postnatal ages: 1 day and 1, 2, 4, and 8 weeks. As reported by other groups, L1-deficient mice were significantly smaller than their wild-type littermates, and had significantly lower body weight at 1 day and at 1, 2, and 4 weeks (but not at 8 weeks) postnatally (Fig. 1).