Furthermore, no differences in [125I]-bungarotoxin binding were found in the frontal cortex of AD patients [103] and negative reduction of the7 nAChR protein levels [104]

Furthermore, no differences in [125I]-bungarotoxin binding were found in the frontal cortex of AD patients [103] and negative reduction of the7 nAChR protein levels [104]. == 3.4. In this paper, we discuss the current topics onin vivoimaging of two subtypes of nAChRs in the brain of patients Fusidate Sodium with AD. == 1. Introduction == Alzheimer’s disease (AD) is the most common neurodegenerative disorder in the elderly and has become a major worldwide health problem. Several reports indicated that it is affecting almost 1 in 10 individuals over the age of 65 [1], and as life expectancy increases, over 37 million people suffer with AD, and it is projected to quadruple by 2050 [2]. AD accounts for over 50% of senile dementia and the majority of presenile dementia cases and is characterized by progressive deterioration of higher cognitive functions including the loss of memory [3,4]. van Duijn and Hofman [5] reported the inverse relationship between smoking history and early onset AD, suggesting that smoking may protect against AD [6]. Furthermore, Rusted and Trawley [7] reported acute improvements in prospective memory following nicotine administration. Although Swan and Lessov-Schlaggar [8] discuss the effects of tobacco smoke and nicotine on cognition in their review, smoking is associated with increased risk for unfavorable preclinical and cognitive outcomes in younger people as well as in older adults. More recently, a meta-analysis including longitudinal studies published between 1995 and 2007 reported that current smokers relative to never-smokers were at increased risk of AD, vascular dementia, any dementia, and cognitive decline, in over the age of 65 [9]. Several lines of evidence demonstrated that smoking almost doubled the risk of AD and that smoking cessation might contribute to a reduction of risk factors for AD and cardiovascular disease [10,11]. Noteworthy, the later is also known as a risk factor for AD. These results suggest that smoking cessation may play an important role in not only primary but also secondary prevention of AD. In contrast, although the discussion about neuroprotection by smoking has been continued, it is possible that nicotinic acetylcholine receptors (nAChRs) in the brain might play a role in the pathophysiology of AD. The nAChRs are one of the main classes of AChRs, which have a pentameric structure composed of five membrane spanning subunits, of which nine different types have thus far been identified and cloned. To date, twelve neuronal nAChR subunits have been described [12]; nine (210) code for subunits [12] based on the presence of adjacent cysteine residues in the predicted protein sequences, in a region homologous to the putative agonist-binding site of the muscle, a subunit (1) and three referred to as non-or-subunits (24). Among the several nAChR subtypes in the human central nervous system (CNS), the heteromeric42 and homomeric7 subtypes (Physique 1) are predominant in the brain [13,14]. It has been reported that other subtypes (e.g.,3,6) exist in the brain [15,16] and that6 subtype might be mainly involved in the pathophysiology of Parkinson’s disease [16]. Furthermore, studies using postmortem human brain samples have exhibited alterations in the levels of4 Fusidate Sodium and7 nAChR in the brains of patients with AD [15,1719]. Despite its lower number, loss of3 subtype consistent with4 and7 nAChR subtypes was also observed in the brains of patients with AD [15]. Taken together, it is likely that these two subtypes (42 and7) of nAChR might play a role in the pathogenesis of AD. Therefore, it is of great interest to examine whether these two subtypes of nAChR are altered in the living brain of patients with AD using brain Fusidate Sodium imaging techniques. == Physique 1. == Structures of42 nAChR (a) and7 nAChR (b). In this paper, we discuss the recent findings on imaging of these two nAChRs (42 and7) in the brain with AD using positron emission tomography (PET) and single-photon emission computed tomography (SPECT). == 2.42 nAChRs Subtype == == 2.1. Relationship between Amyloid-and42 nAChR == Amyloidprotein (A) is usually a major constituent of senile plaques and one of the candidates for the cause of the neurodegeneration found in AD. It has been shown that this accumulation of Aprecedes other pathological changes and causes neurodegeneration or neuronal deathin vitro and in vivo[20,21]. The loss of memory seen in AD is thought to be associated with A-induced impairment of synaptic plasticity such as long-term potentiation (LTP) in the hippocampus. There are Mouse monoclonal to NKX3A lines of evidence suggesting.