PERIPHERAL-TYPE BENZODIAZEPINE RECEPTORS ON HUMAN BLOOD MONONUCLEAR-CELLS ARE NOT REGULATED BY OVARIAN-STEROIDS

Peripheral-type benzodiazepine receptors (pBZr) have been shown to be sensitive to hormonal perturbations, including changes in ovarian ster oids. This study examines whether estradiol and progesterone modulate pBZr binding in membranes of human blood mononuclear cells, as measure d by binding of both H-3-PK 11195 and H-3-Ro 5-4864. Our findings were negative. There was no steroidal modulation of pBZr binding to these membrane preparations in vivo in normal women studied at different sex -steroid phases of the menstrual cycle, or during 8-30 weeks of pregna ncy. There was also no effect of hormones on the binding sites in cult ures of mononuclear cells treated with estradiol or progesterone (up t o 10(-5) M) over a period between 2 and 72 h. Further, we performed in vitro competition experiments, which showed that both steroids are no t active at the pBZr. Our data suggest that pBZr located in human bloo d mononuclear cells are insensitive to the physiological variations of circulating female hormones.