Evidence for the neuronal origin of brain capillary acetylcholinesterase activity.

Acute administration of monosodium-L-glutamate (MSG) to rats induces the degeneration of acetylcholinesterase (AChE)-positive neurons of the area postrema (AP). Chronic treatment with MSG results in the disappearance of AChE activity of area subpostrema (ASP) capillaries. It is concluded that processes of AChE-positive AP neurons terminate within the ASP and may contribute to the AChE activity of ASP capillaries.