Functional organization of the dorsal raphe efferent system with special consideration of nitrergic cell groups

• Published in: Journal of chemical neuroanatomy 2011-07, Vol.41 (4), p.281-293
• Main Authors: Vasudeva, Rani K., Lin, Rick C.S., Simpson, Kimberly L., Waterhouse, Barry D.
• Format: Article
• Language: English
• Subjects: Animals; Anxiety; Anxiety - metabolism; Cats; Cerebral Cortex - metabolism; Efferent Pathways - metabolism; Immunohistochemistry; Lateral wing; Limbic System - metabolism; Neurons - metabolism; Nitric oxide; Nitric Oxide - metabolism; Nitric Oxide Synthase - metabolism; Raphe Nuclei - cytology; Raphe Nuclei - metabolism; Rats; Serotonin; Serotonin - metabolism; Stress, Physiological; Stress, Psychological - metabolism; Trigeminal Nuclei - metabolism
• ISSN: 0891-0618; 1873-6300
• DOI: 10.1016/j.jchemneu.2011.05.008

► We review the intranuclear organization of dorsal raphe nucleus (DRN). ► The DRN maintains an internal topography with respect to its efferent projections. ► The lateral wing of the DRN projects exclusively to sub-cortical targets. ► DRN lateral wing includes serotonin- and nitric oxide synthase-containing neurons. ► Nitric oxide-producing cells in the caudal lateral wing are activated by stressors. The serotonin (5HT) system of the brain is involved in many CNS functions including sensory perception, stress responses and psychological disorders such as anxiety and depression. Of the nine 5HT nuclei located in the mammalian brain, the dorsal raphe nucleus (DRN) has the most extensive forebrain connectivity and is implicated in the manifestation of stress-related psychological disturbances. Initial investigations of DRN efferent connections failed to acknowledge the rostrocaudal and mediolateral organization of the nucleus or its neurochemical heterogeneity. More recent studies have focused on the non-5HT contingent of DRN cells and have revealed an intrinsic intranuclear organization of the DRN which has specific implications for sensory signal processing and stress responses. Of particular interest are spatially segregated subsets of nitric oxide producing neurons that are activated by stressors and that have unique efferent projection fields. In this regard, both the midline and lateral wing subregions of the DRN have emerged as prominent loci for future investigation of nitric oxide function and modulation of sensory- and stressor-related signals in the DRN and coinciding terminal fields.