Effect of heat stress on serotonin-2A receptor-mediated intracellular calcium mobilization in rat C6 glioma cells.
This study was conducted to investigate an effect of heat stress at 44 degrees C for 30 min on intracellular Ca2+ signaling system and on heat shock protein (HSP)-70 expression. 5-HT-induced Ca2+ mobilization was reduced 1, 3 and 6 hrs after heat stress, and recovered to the control level 12 and 24 hrs after heat stress. One hr after heat stress, Ca2+ rise was significantly decreased when the cells were stimulated by any concentration of 5-HT. Thrombin-induced Ca2+ increase was also markedly reduced 1 hr after heat stress. HSP-70 level was increased 6 and 9 hr after heat stress. In HSP synthesis inhibitor quercetin-treated cells, HSP-70 expression was not enhanced after heat stress, and Ca2+ rise in response to 5-HT did not return to the control level. However, the Ca2+ rise induced by 5-HT was not restored to the control level after stress in Ac-Asp-Glu-Val-Asp-H (DEVD)-exposed cells while DEVD had little effect on heat stress-induced synthesis of HSP-70. Dexamethasone did not alter the change in HSP-70 expression or Ca2+ response after heat stress. These results indicate that heat stress attenuated 5-HT-induced Ca2+ mobilization and that HSP-70 expression played an important role in recovery from Ca2+ impairment, possibly via protease activity in C6 cells.
Kagaya
A
A
Department of Psychiatry and Neurosciences, Hiroshima University School of Medicine, Japan. kagaya@ue.ipc.hiroshima-u.ac.jp
Okada
A
A
Jitsuiki
H
H
Tawara
Y
Y
Inagaki
M
M
Takebayashi
M
M
Saeki
T
T
Nishida
A
A
Nakata
Y
Y
Yamawaki
S
S
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology; D005910:Glioma; D005938:Glucocorticoids / Q000494:pharmacology; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D018869:Heat-Shock Response / Q000187:drug effects / Q000502:physiology*; D006358:Hot Temperature; D009842:Oligopeptides / Q000494:pharmacology; D011794:Quercetin / Q000494:pharmacology; D051381:Rats; D044402:Receptor, Serotonin, 5-HT2A; D011985:Receptors, Serotonin / Q000378:metabolism*; D012701:Serotonin / Q000378:metabolism; D014407:Tumor Cells, Cultured
D015853:Cysteine Proteinase Inhibitors; D005938:Glucocorticoids; D018840:HSP70 Heat-Shock Proteins; D009842:Oligopeptides; D044402:Receptor, Serotonin, 5-HT2A; D011985:Receptors, Serotonin; C108637:aspartyl-glutamyl-valyl-aspartal; D012701:Serotonin; D003907:Dexamethasone; D011794:Quercetin; D002118:Calcium