Heterogeneity among astroglial cells with respect to 5HT-evoked cytosolic Ca 2+ responses. A microspectrofluorimetric study on single cells in primary culture

Abstract

The effect of 5-hydroxytryptamine (5HT) on cytoplasmic Ca 2+ concentration was examined at the single cell level in astroglial enriched primary cultures from newborn rat cerebral cortex. Type 1 astroglial cells were identified and the Ca 2+ indicator dye fura 2/AM was used in a microspectrofluorimetric system. Pharmacological studies indicated that the Ca 2+ responses were mediated by 5HT 2 receptors. Four different patterns of 5HT evoked cytosolic Ca 2+ responses were identified including two different types of spike patterns and two types of Ca 2+ oscillations (low amplitude and base-line spiking behaviour). In addition, cells with spontaneous Ca 2+ oscillations were of two types, those responding to 5HT and those not responding to 5HT. The different responses were identified already on day 7 in culture and were followed up to day 21 with a concomitant increase in the number of responding cells, although the response patterns did not differ during culture. The triggering 5HT concentration was 1μM. The results suggest that subpopulations of astrocytes exist with respect to 5HT 2-evoked cytosolic Ca 2+ mobilization.