Abstract
Degeneration of cholinergic neurons from the basal forebrain nuclei is suspected to be the cause of Alzheimer disease. We have developed dissociated cultures of cholinergic neurons from these nuclei (the nucleus basalis of Meynert, the medial septal nucleus, and the diagonal band nuclei). Brain slices of the forebrains were made by a vibratome, and the basal forebrain nuclei were dissected out, dissociated, and cultured. Choline acetyltransferase immunocytochemistry and acetylcholinesterase cytochemistry revealed large cholinergic cells (average diameter, 20-25 micron) in these cultures. About 75% of large neurons (20 micron or larger in diameter) were cholinergic. Electrophysiological experiments were performed on these large neurons. The neurons usually did not show spontaneous firing, but steady depolarizations produced trains of action potentials, which adapted quickly. The neurons responded with depolarization to the application of L-glutamic acid. Substance P produced depolarization (sometimes hyperpolarization), and during the depolarization membrane resistance was increased.