P-glycoprotein and caveolin-1alpha in endothelium and astrocytes of primate brain.

P-glycoprotein (P-gp) and caveolin-1alpha are both involved in membrane transport, and studies in rodent brain show that these proteins are specifically localized at the microvascular endothelium, which forms the blood-brain barrier (BBB). In humans, P-gp is also expressed in astrocytes, especially in pathological tissue. The present study examines the cellular expression of P-gp and caveolin-1alpha in fresh-frozen brain from healthy rhesus monkey using confocal microscopy and polyclonal antibodies against either P-gp or caveolin-1alpha co-labeled for astrocytes or microvascular endothelium. P-gp and caveolin-1alpha are expressed in both astrocytes and endothelium of healthy primate brain. These findings suggest that P-gp and caveolin-1alpha share a broad spectrum of cellular expression and may play a role in drug transport within the brain in addition to the BBB.