“…Besides their role in pain modulation on peripheral primary afferents [13,14], TRPV1 channels have also been involved in the control of pain transmission in the central nervous system [1,2,7,15]. There is also evidence suggesting the participation of vanilloid receptors in brainstem areas involved in the modulation of defensive reactions [3,6] and on the descending pain inhibitory system [2,16,17] in which the midbrain periaqueductal gray matter (PAG) plays a crucial role (e.g.…”