No abstract

The presence of interconnections between cholinergic and parvalbumin (PARV)-containing gamma aminobutyric acid (GABA)ergic septohippocampal projection neurons is still a matter of debate. To search for contacts of cholinergic collateral axon terminals in the septal-diagonal band region the immunotoxin 192IgG-saporin was applied, which was proved to selectively destroy cholinergic basal forebrain neurons. Seven and 10 days after administration of the immunotoxin, choline acetyltransferase immunoreactivity had disappeared, and numerous neuronal somata and dendrites as well as axonal terminals revealed characteristics of electron-lucent degeneration. Electron-dense degeneration was never observed in dendrites and synaptic boutons. Degenerating terminals were found in contact with PARV-immunopositive and PARV-negative neurons. Because only cholinergic cells were degenerating, the terminals should be collaterals from cholinergic neurons. In addition to such contacts, PARV-immunoreactive boutons were seen in contact with PARV-positive and PARV-negative cells, but were not identified at degenerating postsynaptic profiles. As suggested in other studies, cholinergic boutons contacting GABAergic PARV-containing septal projection cells may influence hippocampal theta activity. Furthermore, multiple synaptic connections of both neuronal populations forming the septohippocampal pathway may contribute to their high rate of survival after fimbria-fornix transection.

No abstract

Choline acetyltransferase (ChAT) was partially purified from human placenta and brain. In order to raise monoclonal antibodies, Balb/c mice were immunized with a preparation from placenta or with a mixture of eight synthetic peptides that were deduced from the primary structures of porcine and human ChAT. Polyclonal antibodies were raised in rabbits against five synthetic peptides deduced from the amino acid sequence of human ChAT. The monoclonal and polyclonal antibodies were characterized by their ability to recognize ChAT in various immunoassays: immunoblot, enzyme-linked immunosorbent assay (ELISA), two-side ELISA and immunohistochemistry. With one exception all monoclonal antibodies recognized ChAT on immunoblots, some were particularly sensitive; one bound active ChAT in ELISA when used as capture reagent; most antibodies recognized immobilized ChAT in ELISA. Two monoclonal antibodies out of nine gave particularly excellent results in staining cholinergic neurons and fibers on sections from rat and primate brain. With the help of nine synthetic peptides it was possible to evaluate two major binding sites for the monoclonal antibodies on the ChAT molecule, comprising amino acids 167-189 and 57-76, respectively.

No abstract