Glutamate modulates intracellular Ca2+ stores in brain stem auditory neurons

Abstract

1. Fura-2 imaging was used to measure the effects of glutamate on caffeine-sensitive Ca2+ stores in neurons of the avian cochlear nucleus, n. magnocellularis (NM). 2. On average, 100-mM caffeine stimulated a 250-nM increase in intracellular calcium ion concentration {[Ca2+]i} in Ca(2+)-free media; 1-mM glutamate significantly attenuated caffeine-stimulated Ca2+ responses. 3. The metabotropic glutamate receptor agonist, ACPD, also inhibited the caffeine-stimulated rise in [Ca2+]i. 4. Glutamate has an important role in regulating Ca2+ stores in NM neurons. Glutamate-deprivation (viz. cochlear removal) results in a rise in [Ca2+]i that may, in part, be the result of release from Ca2+ stores. We hypothesize that Ca(2+)-induced Ca2+ release stores (CICRs) may be involved in deprivation-induced cell death.