beta 25-35 alters calcium homeostasis and induces neurotoxicity in cerebellar granule cells.
We studied the neurotoxic effects of beta 25-35 amyloid fragment (beta 25-35) on cerebellar granule cells and the intracellular mechanisms involved. Treatment for 3 days with peptide greatly reduced the survival of 1 day in vitro (DIV) cultures kept in 5 mM KCI but slightly modified the survival of 25 mM KCI-cultured cerebellar granule cells. We also studied the effect of glutamate on survival of undifferentiated cerebellar granules. We report no neurotoxic effect of glutamate on 3-DIV-treated cultures; whereas in beta 25-35-pretreated cells, a significant glutamate toxicity was observed. Treatment of 6-DIV cells with beta 25-35, performed with 25 mM KCI, induced a late but significant neurotoxic effect after 5 days of exposure, and death occurred within 8 days. Differentiated cerebellar granule cells were also sensitive to glutamate-related neurotoxicity, and this effect was enhanced by beta 25-35 pretreatment. To study the molecular mechanisms underlying the neurotoxic effects of beta 25-35, changes in calcium homeostasis after glutamate stimulation were evaluated in control and beta 25-35-treated cells. beta 25-35 did not affect basal [Ca2+]i but modified glutamate-induced [Ca2+]i increase, causing a sustained plateau phase that persisted even after the removal of the agonist. These results show that beta 25-35 induces neurotoxicity in cerebellar granule cells and that this effect is related to modifications in the control of calcium homeostasis.
Scorziello
A
A
Dipartimento di Oncologia Clinica e Sperimentale, Università degli Studi di Genova, Italia.
Meucci
O
O
Florio
T
T
Fattore
M
M
Forloni
G
G
Salmona
M
M
Schettini
G
G
D016229:Amyloid beta-Peptides / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology / Q000502:physiology*; D004357:Drug Synergism; D018698:Glutamic Acid / Q000494:pharmacology; D006706:Homeostasis / Q000187:drug effects*; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D009498:Neurotoxins / Q000494:pharmacology*; D010446:Peptide Fragments / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar
D016229:Amyloid beta-Peptides; D009498:Neurotoxins; D010446:Peptide Fragments; C074636:amyloid beta-protein (25-35); D018698:Glutamic Acid; D002118:Calcium