Transgenic and antisense manipulations of impairments in cholinergic balance

Inhibitors of acetylcholinesterase (AChE) catalysis are increasingly used as insecticides as well as therapeutic and prophylactic agents. However, the long-term consequences of their use are not yet known. To investigate this topic, we used cultured neurons and transgenic mouse pedigrees that over-express natural variants of human AChE. Following exposure to an anti-AChE, alternative splicing of the pre-mRNA from the single ACHE gene produces the relatively rare AChE-R mRNA variant in mice and in cultured cerebellar neurons. This promotes a rapid (minutes) yet long-lasting (weeks) translocation of AChE-R mRNA into neurites that is associated with extreme neuronal hypersensitivity to both anti-AChEs and atropine (Meshorer et al. 2002, Science, 295, 508-512). In transgenic mice, over-expression of AChE-R causes stress-induced irregular bursts of increased locomotor activity and failure of short-term memory (Cohen et al. Mol. Psych., in press). Nanomolar concentrations of an antisense oligonucleotide selectively suppress AChE-R mRNA levels in both hyperproducing cultured neurons and mouse brain. Moreover, this treatment reverses the behavioral and cognitive deficits of the mice (effect apparent for > 24 h, vs. < 45 min for tacrine). The efficacy of our antisense experiments raises the possibility of eventually using such agents to achieve AChE variant-specific suppression, long-lasting effect, and, presumably, fewer side-effects than is offered by conventional anticholinesterase therapy.