Autoradiographic evidence for increased dopamine uptake sites in striatum of hypoxic mice

Ligand binding to dopamine uptake sites, D1 and D2 dopamine receptors was measured autoradiographically in brain sections of mice exposed to intermittent hypobaric hypoxia (450 Torr; 4,300 m) for 14 days and compared to sea level controls. Desipramine-insensitive [3H]mazindol, [3H]SCH23390 and [3H]YM-09151-2 were used respectively for the labeling of the three binding sites. After 14 days, the striatum of hypoxic mice showed a significant 21% increase in dopamine uptake sites, one of the loci of action of cocaine. A similar (28%) but non-significant increase was found in the ventral tegmental area. No changes were seen in the activities of D1 or D2 receptors in several areas examined including the substantia nigra and the striatum.