5-hydroxytryptamine and glutamate modulate velocity and extent of intercellular calcium signalling in hippocampal astroglial cells in primary cultures

The effects of 5-hydroxytryptamine or glutamate treatment on mechanically i nduced intercellular calcium waves were studied in gap junction-coupled ast roglial cells using rat astroglial-neuronal primary cultures from hippocamp us. Imaging software was developed to study amplitude, velocity and extent of wave propagation. Velocity software was designed to find the cell contou rs automatically and to calculate travelled distance and time-delay of the calcium wave as it propagates from the stimulated cell to all other cells. Propagation analyses were performed to calculate the area of wave propagati on. Mechanical stimulation of a single astroglial cell induced an intercell ular calcium wave spreading from cell to cell in the astroglial syncytium. When registering the appearances of calcium signals in individual cells alo ng the wave path upon re-stimulation of the same cell, 44.7% of the cells r esponded with similar calcium signal appearances the second time as the fir st time. A second wave from the opposite direction resulted in similar calc ium signal appearances in 27.3% of the studied cells. Both amplitude and velocity of the calcium signal decreased most prominentl y in the first part and showed a later flattening out. Treatment with 5-hyd roxytryptamine or glutamate for 20-30 s before mechanical stimulation incre ased the velocity of the calcium waves. 5-Hydroxytryptamine treatment for v arying times decreased the propagation area of the calcium waves. In contra st, glutamate treatment increased the propagation area. (C) 1998 IBRO. Publ ished by Elsevier Science Ltd.