Effects of self-administered phencyclidine on regional uptake of 2-deoxy-D-[1-14C]glucose in brain

Phencyclidine profoundly alters cerebral metabolism in the rat. This study explored whether cerebral metabolic effects of phencyclidine differed when the drug was self-administered by trained rats, compared with when it was given acutely to naive rats. The regional cerebral uptake of 2-deoxy-D-[1-(D14C] glucose (DG) was examined following two injections of phencyclidine (0.5 mg/kg/injection, i.v.) or saline in freely-moving, drug-experienced rats. Naive controls received phencyclidine or saline according to an identical dose regimen. In self-administering and naive rats, phencyclidine produced many of the same effects on uptake of DG, including the following: decreases in the habenula, inferior colliculus, sensory cortical areas and corresponding thalamic relay nuclei; and increases in limbic areas (entorhinal and retrosplenial cortices, subicular areas). Some regions (auditory and motor cortices, medial geniculate body, globus pallidus) showed different effects in self-administering and naive rats. Another study, in which rats were not self-administering phencyclidine, but had histories of treatment with drugs similar to those of the self-administering rats, indicated that chronic exposure to drug accounted for some of the differences. Furthermore, differences between the effects of phencyclidine in self-administering, versus non-self-administering rats with similar histories suggested that activity in some regions of the brain may relate to training in drug self-administration and/or behavior.