CHARACTERIZATION OF BENZODIAZEPINE RECEPTOR CHANGES IN SUBSTANTIA NIGRA, GLOBUS PALLIDUS AND ENTOPEDUNCULAR NUCLEUS AFTER STRIATAL LESIONS

  • 1 January 1984
    • journal article
    • research article
    • Vol. 230  (3) , 768-775
Abstract
This study explored the character and time course of benzodiazepine (BDZ) receptor changes in substantia nigra pars reticulata, globus pallidus and entopeduncular nucleus after striatal kainate lesions in the rat. Receptor levels at the lesion site and striatal projection areas were measured at 1 wk, 1 mo. and 2-3 mo. after the lesion. One wk after the lesion, no receptor changes in substantia nigra pars reticulata, globus pallidus or entopeduncular nucleus were detected. There were small but insignificant increases in BDZ binding in striatal projection sites 1 mo. after the lesion. At the 2- to 3-mo. time point, BDZ binding increased in substantia nigra pars reticulata (44%, P < 0.01), globus pallidus (43%, P < 0.02) and entopeduncular nucleus (54%, P < 0.05). At all time points, the binding affinities of BDZ receptors were unchanged in the denervated and corresponding intact structures. Likewise, BDZ binding was enhanced to a similar extent by GABA on both sides of the brain. CL 218,872, a triazolopyridazine and ethyl .beta.-carboline-3-carboxylate were used to delineate BDZ receptor subtypes involved in the receptor increase. Deafferented areas were less sensitive to triazolopyridazine and ethyl .beta.-carboline-3-carboxylate when compared to the corresponding intact areas. A proliferation of the triazolopyridazine-insensitive BDZ receptor subtype (BDZ2 receptors) has taken place.