The extended striatum is a large, dopamine-innervated forebrain structure comprising the caudate-putamen, nucleus accumbens and olfactory tubercle (OT). The OT remains largely unexplored, despite its potentially important role in behaviour and dopamine (DA)-mediated reward. One method of studying function is examining "supersensitive" behavioural responses to DA agonists in animals after striatal DA loss. We examined whether D1 or D2 receptor supersensitivity occurs in the OT and neighbouring islands of Calleja (ICj), after unilateral 6-hydroxydopamine lesions of the medial forebrain bundle and medial OT (mOT). We also asked if the resulting DA receptor supersensitivity is anatomically heterogeneous. Our results showed D1-like receptor supersensitivity occurring in the OT with several DA agonists, and heterogeneously across the extended striatum. There is evidence of D2-like receptor supersensitivity in the ICj. Our focal mOT lesion failed to show DA receptor supersensitivity. Finally, there is little evidence for D2 supersensitivity as measured by [ 35S]GTPgammaS binding.

No description available.