Effect of capsaicin on ligand binding activity of the hippocampal serotonin1A receptor.

The serotonin(1A) receptor is an important member of the G-protein coupled receptor family, and is involved in the generation and modulation of a variety of cognitive, behavioral, and developmental functions. In order to examine the role of membrane material properties in ligand binding activity of the hippocampal serotonin(1A) receptor, we monitored the function of the receptor in presence of capsaicin. Capsaicin has been previously shown to increase the elasticity of membrane bilayers. Our results show that the ligand binding activity of the hippocampal serotonin(1A) receptor is reduced in the presence of capsaicin in a linear concentration-dependent manner. This is accompanied by no appreciable change in G-protein coupling of the receptor and overall membrane order. We conclude that material properties of membrane bilayers could play an important role in the function of the serotonin(1A) receptor in particular, and membrane proteins in general.