Corticosterone acutely prolonged N-methyl-d-aspartate receptor-mediated Ca2+ elevation in cultured rat hippocampal neurons.
This work reports the first demonstration that corticosterone (CORT) has a rapid and transient effect on NMDA receptor-mediated Ca2+ signaling in cultured rat hippocampal neurons. Using single cell Ca2+ imaging, CORT and agonists of glucocorticoid receptors were observed to modulate the NMDA receptor-mediated Ca2+ signals in a completely different fashion from pregnenolone sulfate. In the absence of steroids, 100 micro m NMDA induced a transient Ca2+ signal that lasted for 30-70 s in 86.1% of the neurons prepared from postnatal rats (3-5 days old). After pre-treatment with 0.1-100 micro m CORT for 10-20 min, NMDA induced extremely prolonged Ca2+ elevation. This prolonged Ca2+ elevation was terminated by the application of MK-801 and followed by washing out of CORT. The proportion of CORT-modulated neurons within the NMDA-responsive cells increased from 25.1 to 95.5% when the concentration of CORT was raised from 0.1 to 50 micro m. Substitution of BSA-conjugated CORT produced essentially the same results. When hippocampal neurons were preincubated with 10 micro m cortisol and 1 micro m dexamethasone for 20 min, a very prolonged Ca2+ elevation was also observed upon NMDA stimulation. The CORT-prolonged Ca2+ elevation caused a long-lasting depolarization of the mitochondrial membrane, as observed with rhodamine 123. In contrast, incubation with 100 micro m pregnenolone sulfate did not considerably alter the time duration of NMDA-induced transient Ca2+ elevation, but caused a significant increase in the peak amplitude of Ca2+ elevation in hippocampal neurons. These results imply that high levels of CORT induce a rapid and non-genomic prolongation of NMDA receptor-mediated Ca2+ elevation, probably via putative membrane surface receptors for CORT in the hippocampal neurons.
Takahashi
Taiki
T
Department of Biophysics and Life Sciences, Graduate School of Arts and Sciences, University of Tokyo at Komaba, Meguro, Tokyo, Japan.
Kimoto
Tetsuya
T
Tanabe
Nobuaki
N
Hattori
Taka-aki
TA
Yasumatsu
Nobuaki
N
Kawato
Suguru
S
D000732:Androstanols / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects; D002478:Cells, Cultured; D003345:Corticosterone / Q000494:pharmacology*; D016291:Dizocilpine Maleate / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005456:Fluorescent Dyes; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D006727:Hormone Antagonists / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D015735:Mifepristone / Q000494:pharmacology; D008928:Mitochondria / Q000187:drug effects / Q000502:physiology; D016202:N-Methylaspartate / Q000494:pharmacology; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D011284:Pregnenolone / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D011965:Receptors, Glucocorticoid / Q000819:agonists / Q000037:antagonists & inhibitors; D016194:Receptors, N-Methyl-D-Aspartate / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*
D000732:Androstanols; D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D005456:Fluorescent Dyes; D006727:Hormone Antagonists; D011965:Receptors, Glucocorticoid; D016194:Receptors, N-Methyl-D-Aspartate; C018370:pregnenolone sulfate; D015735:Mifepristone; D016202:N-Methylaspartate; D016291:Dizocilpine Maleate; D011284:Pregnenolone; C049154:11,17-dihydroxy-6-methyl-17-(1-propynyl)androsta-1,4,6-triene-3-one; D002118:Calcium; D003345:Corticosterone