Dr. Tindaro Renda（Professor of Rome University, Italy)
IMMUNOHISTOCHEMICAL LOCALIZATION OF cChAT AND pChAT IN THE NERVOUS SYSTEM OF INVERTEBRATES
Acetylcholine, the first neurotransmitter to be identified, is widely distributed in the animal kingdom. The most reliable method to visualize cholinergic neurons is immunohistochemistry for its synthesizing enzyme choline acetyltransferase (ChAT). In addition to the well-known enzyme (cChAT, common to both the central and peripheral nerves), the peripheral type of ChAT (pChAT) has recently been identified. Two polyclonal specific antibodies against cChAT and pChAT have been produced by the equipe of Prof. Hiro Kimura at their laboratory of MNRC in SUMS. Although cChAT is reportedly detectable consistently in the central, but not peripheral, nervous system, pChAT has been shown to be present preferentially in the peripheral nervous system of mammals. Since, however, the presence of pChAT in various vertebrates other than mammals has been hardly demonstrated, the current implication is that cChAT may be a phylogenetically more ancient form than pChAT that may be produced recently as a splicing variant of ChAT.
The present immunohistochemical study, carried out in our laboratory by using the two types of antibodies, reopens the debate because it shows that both enzymes can easily be demonstrated widely in the nervous system of various invertebrates. More importantly, cChAT and pChAT are often localized distinctively in different neuronal cells of the same ganglia. Among the invertebrate species we examined, I will present here some typical results in two mollusca, a gasteropode as the giant garden slug (Limax maximus, Linn.) and a cephalopode as the octopus (Octopus vulgaris, Cuvier).
Last Updated 2007/2/20