Curcumin inhibits bTREK-1 K+ channels and stimulates cortisol secretion from adrenocortical cells.
Biochem Biophys Res Commun. 2008 Jun 13;370(4):623-8. Epub 2008 Apr 10. PMID: 18406348
Department of Neuroscience, The Ohio State University, College of Medicine and Public Health, 5196 Graves Hall, 333 W.10th Avenue, Columbus, OH 43210-1239, USA. firstname.lastname@example.org
Bovine adrenal zona fasciculata (AZF) cells express bTREK-1 K(+) channels that set the resting membrane potential. Inhibition of these channels by adrenocorticotropic hormone (ACTH) is coupled to membrane depolarization and cortisol secretion. Curcumin, a phytochemical with medicinal properties extracted from the spice turmeric, was found to modulate both bTREK-1 K(+) currents and cortisol secretion from AZF cells. In whole-cell patch clamp experiments, curcumin inhibited bTREK-1 with an IC(50) of 0.93muM by a mechanism that was voltage-independent. bTREK-1 inhibition by curcumin occurred through interaction with an external binding site and was independent of ATP hydrolysis. Curcumin produced a concentration-dependent increase in cortisol secretion that persisted for up to 24h. At a maximally effective concentration of 50muM, curcumin increased secretion as much as 10-fold. These results demonstrate that curcumin potently inhibits bTREK-1 K(+) channels and stimulates cortisol secretion from bovine AZF cells. The inhibition of bTREK-1 by curcumin may be linked to cortisol secretion through membrane depolarization. Since TREK-1 is widely expressed in a variety of cells, it is likely that some of the biological actions of curcumin, including its therapeutic effects, may be mediated through inhibition of these K(+) channels.