Increase in immunohistochemical staining of GABAergic axons in the superior colliculus and thalamus of the rat following damage of the ipsilateral striatum and frontal cortex.

The superior colliculus and ventromedial nucleus of the thalamus have been examined in rats following damage of the frontal cortex and underlying striatum with immunohistochemical staining using an antiserum directed against gamma-aminobutyric acid (GABA). Following such lesions, at a time when the cell bodies of the neurones in the ipsilateral pars reticulata of the substantia nigra are known to be significantly enlarged, there is substantially more immunostaining of GABAergic fibres in both sites when compared with the contralateral side and with normal littermate control animals. The increase in immunoreactivity may indicate sprouting of the axons of the enlarging pars reticulata neurones or an increase in immunoreaction of existing fibres.