Signal Transduction in Astrocytes during Chronic or Acute Treatment with Drugs (SSRIs, Antibipolar Drugs, GABA-ergic Drugs, and Benzodiazepines) Ameliorating Mood Disorders

Figure 5

Aspects of Ca²⁺ homeostasis in astrocytes discussed in this paper. Many transmitters increase [Ca²⁺] in astrocytes by triggering release of intracellularly bound Ca²⁺ (brown) by stimulation of inositol trisphosphate (IP₃) receptors. Highly elevated extracellular K⁺ concentrations (≥15 mM) cause L-channel-mediated Ca²⁺ entry, and additional Ca²⁺ is released by stimulation of Ca²⁺-activated ryanodine receptors (RyR). Free intracellular Ca²⁺ (red) is accumulated by ER or mitochondria or leaves the cell via a Ca²⁺/Na⁺ exchanger. This creates a need for Ca²⁺ entry via store-operated channels (Socs), of which TRPC1 is an important component in astrocytes.