Changes of neurotensinlike immunoreactivity in the striatum of the cat after intrastriatal injection of kainic acid.

Abstract

In the course of our study on the effects of kainic acid (KA) on neuropeptidelike immunoreactivity in striatal neurons, it was found that neurotensinlike immunoreactivity (NT-LI) became visible immunohistochemically in cell bodies of some striatal neurons after injecting KA stereotaxically into the head of the caudate nucleus (Cd) of the cat. The adult cats injected with KA were allowed to survive for 1-56 days, and their brains were examined by the indirect immunoperoxidase method. In the intact Cd, NT-LI was observed in axonal elements that accumulated to form irregularly shaped patches and displayed a discrete island-and-matrix pattern. At the site of KA injection, where neuronal cell loss and gliosis were produced. NT-LI almost disappeared by the fourth day after KA injection. In parallel with these changes, many neuronal cell bodies with NT-LI became visible in striatal regions surrounding the site of KA injection. Most of these neuronal cell bodies that showed NT-LI were medium-sized and extended thick dendrites with spines; spiny processes were rarely seen on the cell bodies. On the other hand, when a lesion was placed in the head of the Cd by thermocoagulation, no NT-LI could be seen in cell bodies of striatal neurons. Thus it was presumed that NT-LI in cell bodies of medium-sized, spiny neurons of the cat striatum might be at a low level under normal conditions but enhanced in cell bodies of the neurons that survived the KA injections.