Emerging role for drug transporters at the blood-testis barrier.

Drug transporters are integral membrane proteins that transport a broad range of substrates into and out of cells, usually against a concentration gradient. Studies have shown that efflux pumps such as P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) localize at the blood-testis barrier (BTB), where they protect the testis from drugs and xenobiotics that are detrimental to spermatogenesis. At the same time, efflux pumps might also preclude entry of non-hormonal contraceptives to the testis. In more recent studies, P-gp function was correlated with BTB integrity. In this review, we discuss findings that have made a significant impact on our understanding of efflux pumps in the testis. Modulation of efflux pump function via specific inhibitors could help to deliver contraceptives to the testis in the future.