Biochemistry

Inositol triphosphate (IP₃) is an important second messenger that participates in signal transduction pathways in diverse cell types including hippocampal neurons. Stimulation of phospholipase C in response to various stimuli (hormones, growth factors, neurotransmitters, neurotrophins, neuromodulators, odorants, light, etc.) results in hydrolysis of phosphatidylinositol 4, 5-bisphosphate (PIP₂), a phospholipid that is located in the plasma membrane, and leads to the production of IP₃ and diacylglycerol. Binding of IP₃ to the IP₃ receptor (IP₃R) induces Ca²⁺ release from intracellular stores and enables the initiation of intracellular Ca²⁺-dependent signaling. Here we describe a procedure for the measurement of cellular IP₃ levels in tissue homogenates prepared from rat hippocampal slices.