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Astrocytes in 17\beta-estradiol treated mixed hippocampal cultures show attenuated calcium response to neuronal activity

Rao, Shilpa P and Sikdar, SK (2006) Astrocytes in 17\beta-estradiol treated mixed hippocampal cultures show attenuated calcium response to neuronal activity. In: GLIA, 53 (8). pp. 817-826.

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Abstract

Glial cells in the brain are capable of responding to hormonal signals. The ovarian steroid hormone 17\beta-estradiol, in addition to its actions on neurons, can directly affect glial cells. Estrogen receptors have been described on both neurons and astrocytes, suggesting a complex interplay between these two in mediating the effects of the hormone. Astrocytes sense and respond to neuronal activity with a rise in intracellular calcium concentration ([Ca2+]i). Using simultaneous electrophysiology and calcium imaging techniques, we monitored neuronal activity evoked astrocyte $([Ca^{2+}]i)$ changes in mixed hippocampal cultures loaded with fluo-3 AM. Action potential firing in neurons, elicited by injecting depolarizing current pulses, was associated with $([Ca{^2^+}]i)$ elevations in astrocytes, which could be blocked by 200 M MCPG and also 1$\mu$ M TTX. We compared astrocytic $([Ca{^2^+}]i)$ transients in control and 24-hour estradiol treated cultures. The amplitude of the $([Ca{^2^+}]i)$ transient, the number of responsive astrocytes, and the $([Ca{^2^+}]i)$ wave velocity were all significantly reduced in estradiol treated cultures. $([Ca{^2^+}]i)$ rise in astrocytes in response to local application of the metabotropic glutamate receptor (mGluR) agonist t-ACPD was attenuated in estradiol treated cultures, suggesting functional changes in the astrocyte mGluR following 24-h treatment with estradiol. Since astrocytes can modulate synaptic transmission by release of glutamate, the attenuated $([Ca{^2^+}]i)$ response seen following estradiol treatment could have functional consequences on astrocyte-neuron signaling.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to John Wiley & Sons, Inc.
Keywords: Fluo-3 AM;Neuron-astrocyte signaling;Metabotropic glutamate receptors;Calcium wave
Department/Centre: Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited: 31 May 2006
Last Modified: 27 Aug 2008 12:06
URI: http://eprints.iisc.ernet.in/id/eprint/7192

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