2003 Volume 36 Issue 4 Pages 399-407
We determined the distribution pattern of cholinergic neurons in laboratory shrews (Suncus murinus) based on comparative morphology by an immunohistochemical method using an anticholine acetyltransferase (ChAT) antibody. ChAT-positive neurons were observed in the striatum, magnocellular nucleus and basal nucleus, pontine tegmentum and cranial nerve motor nuclei (IV, V, VII, X and XII). Specific findings were as follows: many ChAT-positive neurons were observed in the locus ceruleus (LC) and raphe dorsalis (RD), and the colocalization of ChAT-positive neurons and tyrosine hydroxylase in the LC and that of ChAT-positive neurons and serotonin in the RD were clarified. On the other hand, in the rat brain, ChAT-positive neurons were present in the central amygdaloid nucleus; however, this was not observed in the brains of laboratory shrews. Laboratory shrews are among the most primitive mammalian species and have a different distribution pattern of aminergic neurons, other than cholinergic neurons, from that in rats. A unique distribution pattern of ChAT-positive neurons in the laboratory shrew brain was thus noted.
