Receptor-Mediated Release of Inositolphosphates in Brain Slices
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Target-cell response to a number of neurotransmitters, growth factors, hormones, and other stimuli are initiated by cell-surface
receptor-mediated activation of phospholipase C (PLC) and the rapid hydrolysis of phosphoinositides (1
–3
). The activation of PLC by receptors for most neurotransmitters and growth factors occurs through a mechanism involving a
guanine nucleotide regulatory protein or G protein. The PLC-catalyzed hydrolyses of phosphatidylinositol 4,5-bisphosphate
(PI(4,5)P2) results in the formation of inositol 1,4,5 trisphosphate (Ins(l,4,5)P3) and diacylglycerol (DAG). Both Ins(l,4,5)P3
and DAG have second-messenger functions inside the cell. Ins(l,4,5)P3 mobilizes intracellular Ca2+
by binding to specific intracellular receptors that promote opening of calcium channels in vesicular storage sites associated
with endoplasmic reticulum (4
,5
), whereas DAG binds to and activates protein kinase C (PKC), resulting in the phosphorylation of a number of intracellular
proteins (1
,2
).
