Astrocytes in 17β-estradiol treated mixed hippocampal cultures show attenuated calcium response to neuronal activity
✍ Scribed by Shilpa P. Rao; S.K. Sikdar
- Publisher
- John Wiley and Sons
- Year
- 2006
- Tongue
- English
- Weight
- 392 KB
- Volume
- 53
- Category
- Article
- ISSN
- 0894-1491
No coin nor oath required. For personal study only.
✦ Synopsis
Glial cells in the brain are capable of responding to hormonal signals. The ovarian steroid hormone 17beta-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 (Ca(2+)). Using simultaneous electrophysiology and calcium imaging techniques, we monitored neuronal activity evoked astrocyte (Ca(2+)) 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+)) elevations in astrocytes, which could be blocked by 200 microM MCPG and also 1 microM TTX. We compared astrocytic (Ca(2+)) transients in control and 24-hour estradiol treated cultures. The amplitude of the (Ca(2+)) transient, the number of responsive astrocytes, and the (Ca(2+)) wave velocity were all significantly reduced in estradiol treated cultures. (Ca(2+)) 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+)) response seen following estradiol treatment could have functional consequences on astrocyte-neuron signaling.