ULTRASTRUCTURAL CHARACTERISTICS OF SUBSTANCE P-LIKE IMMUNOREACTIVE TERMINALS IN THE MARGINAL DIVISION OF THE STRIATUM OF THE RAT / 解剖学报

ABSTRACT

Using the immunohistochemical method combined with tract tracing techniques, a new subdivision, the marginal division, was found in the striatum of the rat. In this subdivision, substance P, enkephaline and dynorphin B terminals were densely localized. The present study investigated the synaptic organization of the substance P-like immunoreactive nerve terminals in the marginal division. Four major types of substance P immunoreactive synapses were identified. Axodendritic and axospinous synapses were the most common ones. Compound synapses with more than two synaptic components were also observed. One axo-axonic synapse was present. Both symmetric and asymmetric substance P-like immunoreactive synapses were seen in the marginal division. The existence of asymmetric synapses, small postsynaptic dendrites and axo-axonic synapses, distinguished the substance P-like immunoreactive nerve terminals in the marginal division from those in the other part of the striatum. The characteristics and complexity of the synaptic organization suggested that the substance P-like immunoreactive nerve terminals in the marginal division probably orginate from a different source and have a different function, as compared to those in the rest part of striatum.