ABSTRACT

The muscarinic receptors (mAChRs) belong to the Gprotein coupled family, and five different subtypes (M1-M5) have been cloned and sequenced in human brain tissue.43 The subtypes M1, M3, and M5 are coupled to G-proteins that stimulate phospholipase cyclase C, whereas M2 and M4 are coupled to Gproteins that inhibit adenyl cyclase.43 A high density of M1 receptors is found in the cortex, hippocampus, and

Table 14.3 PET studies in monkey and man with different nicotinic receptor tracers

Tracer Species References

[11C]nicotine Monkey 35 Monkey 36 Monkey 37 Human controls 34, 38 Alzheimer patients 12-16, 34, 38

[11C]MPA Monkey 37 [11C]ABT-418 Monkey 37 [76Br]Br-A-85380 Human controls 24 2-[18F]F-A-85380 Monkey 27

Human controls 18 6-[18F]F-85380 Human controls 17 [18F]Nifrolidine Monkey 31 5-[11C]methyl-A-85360 Monkey 39 [11C]Me-p-PVC Monkey 21 [18F]-35 Monkey 40

thalamus, as was also found for 2-[18F]F-A-85380 (Table 14.3).