MANGANESE TRANSPORT IN THE NEURAL CIRCUIT OF RAT CNS

To study manganese (Mn) transport in the neural circuit of rat CNS, br ain isotope distribution after Mn-54 injection into the brain was anal yzed by autoradiography, One day after (MnCl2)-Mn-54 injection into th e striatum, Mn-54 was highly distributed in the ipsilateral thalamus, hypothalamus, and substantia nigra, When (MnCl2)-Mn-54 was bilaterally injected into the striata after unilateral treatment with colchicine or vehicle into the medial forebrain bundle, Mn-54 was distributed in both sides of the substantia nigra of vehicle-treated rats, On the oth er hand, unilateral colchicine treatment caused a decrease of Mn-54 di stribution in the ipsilateral substantia nigra, suggesting that Mn is subjected to axonal transport in the striatonigra and/or nigrostriatal pathways, In the case of unilateral injection of (MnCl2)-Mn-54 into t he olfactory bulb, Mn-54 was distributed in the ipsilateral piriform, amygdaloid areas (the primary olfactory cortex), and entorhinal area ( the secondary olfactory cortex), These results suggest that Mn is subj ect to widespread axonal transport in the neural circuits, Moreover, M n may be taken up by the piriform neurons (the third olfactory neuron) after release from the secondary olfactory neuron terminals and trans ported to the entorhinal area. (C) 1998 Elsevier Science Inc.