Distribution of acetylcholinesterase in the limbic system of the brain of the rabbit.

The aim of the study is to present a detailed and thorough description of the acetylcholinesterase enzyme (AChE) content of the limbic structures of the rabbit, now commonly used in our laboratory for investigating the electrographic-behavioral correlations of the cholinergic limbic system. We use 'chemitrodes' for intracerebral mi croinjections of cholinomimetic drugs; a detailed histochemical study (using Koelle's method) of the distributions of AChE enzyme in the limbic system of the rabbit was deemed necessary. Such areas as the septum and the amygdala are particularly poorly described in the rabbit and an attempt was made to clarify the confusion that still exists in the literature on the comparative anatomy and exact localization of these structures. On the whole, it could be inferred from this study that AChE-bearing neurons are generally better developed in phylogenetically older parts of the brain. Practically all the relays in Papez's 'cortical circuits of emotion' have a fairly AChE activity. As noted by us in other phyogenetically lower macrosmatic mammals, the reaction of AChE in the rabbit brain is more intense than in primates.