ASSESSMENT OF STRIATAL GRAFT VIABILITY IN THE RAT IN-VIVO USING A SMALL-DIAMETER PET SCANNER

A small diameter positron emission tomography (PET) scanner has been u sed to monitor [C-11]raclopride (D-2 receptor) binding in vivo in eith er intact striatum, denervated striatum following an excitotoxic lesio n with ibotenic acid, or lesioned and grafted striatum following impla ntation of cortical or striatal tissue grafts in rats. Binding of [C-1 1]raclopride was localized in the intact striatum within 20 min of inj ection of the radioligand, and was much reduced within the lesioned st riatum. Cortical grafts exhibited a similar low level of binding to th e lesioned striatum, whereas striatal grafts showed specific binding a t an intermediate level. The [C-11]raclopride binding signal in vivo c orrelated well with the extent of surviving or grafted striatal tissue observed post morten by Nissl staining and acetylcholinesterase histo chemistry. Thus, the distribution of dopamine receptors as seen in the PET scanner are consistent with post mortem anatomical observations o f striatal, lesion and graft sizes, and suggest that PET can provide a useful tool for monitoring the viability of implanted striatal graft tissues in vivo.