|(1)||Department of Pharmacology, Karolinska Institute, Box 60 400, S-104 01 Stockholm, Sweden|
"Locus coeruleus (LC) is located in the ventrallateral side of the fourth ventricle in the pontine, most of which are noradrenergic neurons projecting to the cortex, cingulate cortex, amygdala nucleus, thalamus, hypothalamus, olfactory tubercles, hippocampus, cerebellum, and spinal cord (Swanson and Hartman, 1975). Norepinephrine (NE) released from the nerve terminal of LC neurons contributes to about 70% of the total extracellular NE in primates brain (Svensson, 1987). It plays important roles not only in arousal, attention, emotion control, and stress (reviewed in Aston-Jones and Cohen, 2005; Berridge and Waterhouse, 2003; Bouret and Sara, 2005; Nieuwenhuis et al., 2005; Sara and Devauges, 1989; Valentino and Van Bockstaele, 2008), but also in sensory information processing (Svensson, 1987). LC directly modulates the somatosensory information from the peripheral system. Under the stress condition, LC could completely inhibit the input from painful stimuli through the descending projection to the spinal cord (Stahl and Briley, 2004). Dys-regulations of LC neurotransmission have been suggested to be involved in physical painful symptoms, attention deficit hyperactivity disorder (ADHD), sleep/arousal disorder, post-traumatic stress disorder, depression, schizophrenia, and Parkinson's disease (reviewed in Berridge and Waterhouse, 2003; Grimbergen et al., 2009; Mehler and Purpura, 2009)."