Glial calcium

Abstract

This review summarizes current knowledge relating intracellular calcium and glial function. During steady state, glia maintain a low cytosolic calcium level by pumping calcium into intracellular stores and by extruding calcium across the plasma membrane. Glial Ca2+ increases in response to a variety of physiological stimuli. Some stimuli open membrane calcium channels, others release calcium from intracellular stores, and some do both. The temporal and spatial complexity of glial cytosolic calcium changes suggest that these responses may form the basis of an intracellular or intercellular signaling system. Cytosolic calcium rises effect changes in glial structure and function through protein kinases, phospholipases, and direct interaction with lipid and protein constituents. Ultimately, calcium signaling influence glial gene expression, development, metabolism, and regulation of the extracellular milieu. Disturbances in glial calcium homeostasis may have a role in certain pathological conditions. The discovery of complex calcium-based glial signaling systems, capable of sensing and influencing neural activity, suggest a more integrated neuro-glial model of information processing in the central nervous system.

Astroglial calcium signalling in Alzheimer's disease

“…In this review we shall focus on astrocytes, the homeostatic cells of CNS which significantly contribute to the AD pathology. waves [29][30][31][32]. Astroglial calcium signals have been subsequently characterised in in vitro and in vivo settings (see [33][34][35] for details and critical discussion).…”

In vitro ischemia promotes calcium influx and intracellular calcium release in hippocampal astrocytes

“…Voltage-gated Ca2+ influx and internal release were measured in acutely isolated astrocytes during in vitro ischemia to examine these processes in the absence of surrounding neurons. Hypoxia-hypoglycemia (7.5-34.0 min) induced only modest, slow increases in the basal [Ca2'li of Fura-2-loaded isolated astrocytes (average 12% increase in Fura-ratio R,,,,, after 10 min) that were blocked by Ca2+ influx was still functional under ischemia, however, as 50 mM [K+] (Finkbeiner, 1993), and the induction of [Ca2+], signals by neurotransmitters and other messengers in the extracellular microenvironment could mediate a functional coupling of astrocyte physiology to neuronal activity. Direct evidence for [Ca2+],-dependent neuron-to-glial communication, however, requires examination of astrocytic [Ca2+li responses during well defined physiological or pathological processes in intact tissue.…”

ATPasa de calcio en el sistema nervioso

“…Uno de los iones importantes en este ambiente iónico es el calcio (13), el cual se encuentra normalmente en mayor concentración en el medio extracelular. Cuando la célula es estimulada eléctricamente (impulso nervioso) o químicamente (por medio de hormonas o neurotransmisores), el calcio ingresa a la célula, a favor de su gradiente de concentración, especificamente, generando cambios en la conformación de la proteína receptora, traduciendo el mensaje y generando respuesta, que puede ser, como en el caso de la calmodulina, el ensamblaje y desensamblaje de tubulina o la síntesis de proteínas (5,14).…”