Ca2+ uptake by rat brain region synaptosomes following in vivo administration of ovarian steroids.
Effects of progesterone (P) and estradiol-17 beta benzoate (EB), applied s.c. into sexually mature, long-term ovariectomized (OVX) rats, on subsequent depolarization-induced uptake of Ca2+ were studied in synaptosomes isolated from the brain stem, mesencephalic reticular formation (MRF), nucleus caudatus putamen (NCP) and the hippocampus. In intact animals, synaptosomal Ca2+ uptake differed from region to region: it was lowest in the brain stem and highest in the hippocampus. In comparison to intact animals, ovariectomy resulted in a marked increase of the uptake regardless the structure investigated, suggesting an inhibitory action of ovaries on the uptake of Ca2+ in a considerable portion of rat brain. Single injection of 2 mg P, given to OVX rats 24 h prior to decapitation, evoked a marked decrease in Ca2+ uptake by synaptosomes of the brain stem and MRF and particularly by those of NCP and the hippocampus. Single injection of 5 micrograms EB into OVX animals 72 h prior to the experiment was as effective as P in inhibiting Ca2+ uptake by synaptosomes of the brain stem and MRF, but less effective than P in case of NCP and the hippocampus. This suggests involvement of P and EB in the modulation of synaptic transmission by affecting neuronal Ca2+ uptake.
Nikezić
G
G
Institute for Molecular Biology and Endocrinology, Boris Kidric Institute for Nuclear Sciences, Belgrade, Yugoslavia.
Horvat
A
A
Milenković
L
L
Martinović
J V
JV
D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000493:pharmacokinetics*; D002421:Caudate Nucleus / Q000187:drug effects / Q000378:metabolism; D004958:Estradiol / Q000031:analogs & derivatives / Q000494:pharmacology; D005260:Female; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D008636:Mesencephalon / Q000187:drug effects / Q000378:metabolism; D010052:Ovariectomy; D011374:Progesterone / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D009435:Synaptic Transmission / Q000187:drug effects; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism*; D013997:Time Factors
D011374:Progesterone; D004958:Estradiol; C010452:estradiol-17 beta-benzoate; D002118:Calcium