Oxygen-induced modifications of benzodiazepine receptors and D2 dopamine receptors in the rat under hyperoxia.

Peripheral-type benzodiazepine Receptors (PBR) in the kidney and Central-type Benzodiazepine Receptors (CBR) in the cerebral cortex were not affected in rats exposed to chronic hyperoxia (85% O2, ATA, 6 days). Nevertheless, cortical CBR showed a significant decrease (29%) after hyperbaric hyperoxia (100% O2, 3.5 ATA, 2 h) in rats at a preconvulsive stage, with no concomitant alteration of kidney PBR. A similar down-regulation of striatal D2 dopamine receptors was noticed (27%)--after hyperbaric hyperoxia--without any modification of cortical PBR. On the contrary, an up regulation of liver PBR was obtained in the same conditions (20%). It is likely that receptors implicated in neurotransmission are particularly down regulated or altered under hyperbaric hyperoxia.