Effects of in vivo estradiol and progesterone on tritiated flunitrazepam binding in rat spinal cord.
Tritiated flunitrazepam binding was measured in autoradiograms of lumbar spinal cord from control ovariectomized female rats and from ovariectomized females treated with either estradiol-silastic implants or one subcutaneous injection of 500 micrograms progesterone 4-5 h before being killed or both estradiol and progesterone. Four areas of spinal cord were analyzed: the substantia gelatinosa, the region leading to and around the central canal, the remainder of the dorsal horn and the ventral horn. Specific flunitrazepam binding was greatest in the substantia gelatinosa and in the region around the central canal and was weakest in the ventral horn. Estradiol had no effect on flunitrazepam binding in the spinal cord despite estradiol concentrating cells in the substantia gelatinosa and around the central canal. In vivo progesterone enhanced flunitrazepam binding in the substantia gelatinosa while 10(-8) M progesterone in vitro was without effect. One day after spinal transection flunitrazepam binding in endocrine controls and estradiol-treated animals was unchanged but a progesterone injection 4-5 h before being killed had no effect on binding in the substantia gelatinosa.
Schwartz-Giblin
S
S
Laboratory of Neurobiology and Behavior, Rockefeller University, New York, NY 10021.
Canonaco
M
M
McEwen
B S
BS
Pfaff
D W
DW
D000818:Animals; D001345:Autoradiography; D002712:Chlorides / Q000378:metabolism; D004958:Estradiol / Q000494:pharmacology*; D004971:Estrus; D005260:Female; D005445:Flunitrazepam / Q000378:metabolism*; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism; D010052:Ovariectomy; D011374:Progesterone / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011963:Receptors, GABA-A / Q000378:metabolism; D013116:Spinal Cord / Q000187:drug effects / Q000378:metabolism*
D002712:Chlorides; D007473:Ion Channels; D011963:Receptors, GABA-A; D011374:Progesterone; D004958:Estradiol; D005445:Flunitrazepam