The alpha 7-nACh nicotinic receptor and its role in memory and selected diseases of the central nervous system

alpha 7-nACh is one of the major nicotinic cholinergic receptor subtypes found in the brain. It is broadly expressed in the hippocampal and cortical neurons, the regions which play a key role in memory formation. Although alpha 7-nACh receptors may serve as postsynaptic receptors mediating classical neurotransmission, they usually function as presynaptic modulators responsible for the release of other neurotransmitters, such as glutamate, gamma-aminobutyric acid, dopamine, and norepinephrine. They can, therefore, affect a wide array of neurobiological functions. In recent years, research has found that a large number of agonists and positive allosteric modulators of alpha 7-nAChR induce beneficial effects on learning and memory. Consistently, mice deficient in chrna7 (the gene encoding alpha 7-nAChR protein), are characterized by memory deficits. In addition, decreased expression and function of alpha 7-nAChR is associated with many neurological diseases including schizophrenia, bipolar disorder, learning disability, attention deficit hyperactivity disorder, Alzheimer disease, autism, and epilepsy. In the recent years many animal experiments and clinical trials using alpha 7-nAChR ligands were conducted. The results of these studies strongly indicate that agonists and positive allosteric modulators of alpha 7-nAChR are promising therapeutic agents for diseases associated with cognitive deficits.