¹¹C-Labeled Capsaicin and Its in Vivo Molecular Imaging in Rats by Positron Emission Tomography

Miki Goto¹, Hiroshi Mizuma¹, Yasuhiro Wada¹, Masaaki Suzuki², Yasuyoshi Watanabe¹, Hirotaka Onoe^1*, Hisashi Doi^1*

¹Division of Bio-Function Dynamics Imaging, RIKEN Center for Life Science Technologies (CLST), Kobe, Japan.
²National Center for Geriatrics and Gerontology, Obu, Japan.

DOI: 10.4236/fns.2015.62022                

Abstract

Synthesis of ¹¹C-labeled capsaicin ([¹¹C]-2) was accomplished by O-[¹¹C]methylation with [¹¹C]-methyl iodide to a corresponding catechol precursor (1). In Vivo whole-body distribution of [¹¹C]-2 in rats was investigated by positron emission tomography after intravenous injection. The results showed that [¹¹C]-2 accumulated in the brain and body surface, which was closely associated with the expression of transient receptor potential vanilloid 1.

Keywords

PET, Capsaicin, ¹¹C-Labeling, TRPV1, Blood-Brain Barrier

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	Caterina, M.J., Schumacher, M.A., Tominaga, M., Rosen, T.A., Levine, J.D. and Julius, D. (1997) The Capsaicin Receptor: A Heat-Activated Ion Channel in the Pain Pathway. Nature, 389, 816-824. http://dx.doi.org/10.1038/39807
[2]	Bandell, M., Macpherson, L.J. and Patapoutian, A. (2007) From Chills to Chilis: Mechanisms for Thermosensation and Chemesthesis via ThermoTRPs. Current Opinion in Neurobiology, 17, 490-497. http://dx.doi.org/10.1016/j.conb.2007.07.014
[3]	Gharat, L. and Szallasi, A. (2007) Medicinal Chemistry of the Vanilloid (Capsaicin) TRPV1 Receptor: Current Knowledge and Future Perspectives. Drug Development Research, 68, 477-497. http://dx.doi.org/10.1002/ddr.20218
[4]	Miller, P.W., Long, N.J., Vilar, R. and Gee, A.D. (2008) Synthesis of 11C, 18F, 15O, and 13N Radiolabels for Positron Emission Tomography. Angewandte Chemie International Edition, 47, 8998-9033. http://dx.doi.org/10.1002/anie.200800222
[5]	Roberts, J.C., Davis, J.B. and Benham, C.D. (2004) [3H]Resiniferatoxin Autoradiography in the CNS of Wild-Type and TRPV1 Null Mice Defines TRPV1 (VR-1) Protein Distribution. Brain Research, 995, 176-183. http://dx.doi.org/10.1016/j.brainres.2003.10.001
[6]	Wang, B., Yang, F., Shan, Y., Qiu, W. and Tang, J. (2009) Highly Efficient Synthesis of Capsaicin Analogues by Condensation of Vanillylamine and Acyl Chlorides in a Biphase H2O/CHCl3 System. Tetrahedron, 65, 5409-5412. http://dx.doi.org/10.1016/j.tet.2009.04.046