Neurobiology of Aging 29 (2008) 368–378 Impairment of muscarinic transmission in transgenic APPswe/PS1dE9 mice E. Machov´ a a , J. Jakub´ık a , P. Michal a , M. Oksman b , H. Iivonen c , H. Tanila c,d , V. Doleˇ zal a,∗ a Department of Neurochemistry, Institute of Physiology CAS, V´ıdeˇ nsk´ a 1083, 14220 Prague 4, Czech Republic b Department of Neuroscience and Neurology, University of Kuopio, Kuopio, Finland c Department of Neurobiology, A.I. Virtanen Institute, University of Kuopio, Kuopio, Finland d Department of Neurology, Kuopio University Hospital, Kuopio, Finland Received 28 June 2006; received in revised form 20 September 2006; accepted 30 October 2006 Available online 30 November 2006 Abstract We assessed the integrity of cholinergic neurotransmission in parietal cortex of young adult (7 months) and aged (17 months) transgenic APPswe/PS1dE9 female mice compared to littermate controls. Choline acetyltransferase and acetylcholinesterase activity declined age- dependently in both genotypes, whereas both age- and genotype-dependent decline was found in butyrylcholinesterase activity, vesicular acetylcholine transporter density, muscarinic receptors and carbachol stimulated binding of GTPS in membranes as a functional indicator of muscarinic receptor coupling to G-proteins. Notably, vesicular acetylcholine transporter levels and muscarinic receptor-G-protein coupling were impaired in transgenic mice already at the age of 7 months compared to wild type littermates. Thus, brain amyloid accumulation in this mouse model is accompanied by a serious deterioration of muscarinic transmission already before the mice manifest significant cognitive deficits. © 2006 Elsevier Inc. All rights reserved. Keywords: Cholinergic neurotransmission; Choline acetyltransferase; Vesicular acetylcholine transporter; Acetylcholinesterase; Butyrylcholinesterase; Mus- carinic receptors; G-protein coupling; Transgenic mouse 1. Introduction Original neurochemical findings in Alzheimer’s brains pointed out disturbances of cholinergic neurotransmission (Bowen et al., 1976; Davies and Maloney, 1976; Francis et al., 1985; Perry et al., 1977a,b; Sims et al., 1981) that were basis for the “cholinergic hypothesis” of Alzheimer’s disease (AD) (Bartus et al., 1982; Dolezal and Kasparova, 2003; Francis et al., 1999; Mesulam, 2004). Since then a large body of evidence has accumulated both supporting and questioning the hypothesis (Bartus, 2000). Cholinergic neurotransmis- sion plays an important role in learning and memory. These functions progressively deteriorate as the disease advances ∗ Corresponding author. Tel.: +420 296442287; fax: +420 296442488. E-mail address: dolezal@biomed.cas.cz (V. Doleˇ zal). and also decline in the course of natural aging. One of the important questions is whether disturbances of cholinergic mechanisms are present early in the pathogenesis of AD or are simply a reflection of a general neurodegeneration which afflicts many neurotransmitter systems in the terminal state of the disease. It has now been generally accepted that the primary event in the pathogenesis of AD is increased production and aggre- gation of noxious -amyloid fragments composed of 39–43 amino acids. Their overproduction in hereditary cases of the disease is due to known genetic defects (Selkoe, 2001) while the reason of increased production in sporadic cases is largely unknown. The active form of -amyloid consists of soluble oligomeric fragments (Haass and Steiner, 2001; Klein et al., 2001) that appear in the brain earlier than amyloid plaques and neurofibrillary tangles typical for pathological picture in 0197-4580/$ – see front matter © 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.neurobiolaging.2006.10.029