GNRH1 and posterior cortical atrophy: On the other hand, two classes of GnRH binding sites (one low affinity and one high affinity) were demonstrated in human PCa cells as well as in the Dunning R3327 rat model of PCa [97,98], while a single class of high affinity binding sites was observed in Dunning R3327 rats by Pinski and coworkers [99].