Mesopontine cholinergic and non-cholinergic neurons in schizophrenia

Mesopontine cholinergic neurons influence midbrain dopaminergic neurons, an d thalamic and cerebellar structures which have been implicated in the neur oanatomy of schizophrenia. It has been reported that there are approximatel y twice as many mesopontine cholinergic neurons in schizophrenics than in n ormals, using nicotinomide adenosine dinucleotide phosphate-diaphorase hist ochemistry to identify the cholinergic neurons. The present study sought to replicate this finding by analysing mesopontine cholinergic neurons using an antibody against choline acetyltransferase. The mesopontine cholinergic neurons are located in the pars compacta and pars dissipata of the peduncul opontine nucleus, and in the laterodorsal tegmental nucleus. Quantitative c omputer imaging techniques were used to map the distribution of mesopontine cholinergic neurons. In addition, all medium-sized and large neurons in a region of interest containing the middle portion of the pedunculopontine nu cleus pars compacta were counted in Nissl-stained sections. There was no di fference between schizophrenic and normal brains in terms of: (i) the rostr al-caudal length of the cholinergic cell complex, similar to 10 mm; (ii) th e estimated total number of cholinergic neurons in the combined pedunculopo ntine nucleus and laterodorsal tegmental nucleus, similar to 20,000 cells u nilaterally; and (iii) the combined number of cholinergic and non-cholinerg ic Nissl-stained neurons in the middle portion of the pedunculopontine nucl eus. The present data do not support the previous observation of increased numbers of mesopontine cholinergic neurons in schizophrenia. (C) 1999 IBRO. Published by Elsevier Science Ltd.