title: Serotonergic systems, anxiety, and affective disorder: focus on the dorsomedial part of the dorsal raphe nucleus.
abstract: Depressed suicide patients have elevated expression of neuronal tryptophan hydroxylase 2 (TPH2) mRNA and protein in midbrain serotonergic neurons, as well as increases in brain serotonin turnover. The mechanisms underlying these changes are uncertain, but increased TPH2 expression and serotonin turnover could result from genetic influences, adverse early life experiences, or acute stressful life events, all of which can alter serotonergic neurotransmission and have been implicated in determining vulnerability to major depression. Emerging evidence suggests that there are several different stress-related subsets of serotonergic neurons, each with a unique role in the integrated stress response. Here we review our current understanding of how genetic and environmental factors may influence TPH2 mRNA expression and serotonergic neurotransmission, focusing in particular on the dorsomedial part of the dorsal raphe nucleus. This subdivision of the dorsal raphe nucleus is selectively innervated by key forebrain structures implicated in regulation of anxiety states, it gives rise to projections to a distributed neural system mediating anxiety states, and serotonergic neurons within this subdivision are selectively activated by a number of stress- and anxiety-related stimuli. A better understanding of the anatomical and functional properties of specific stress- or anxiety-related serotonergic systems should aid our understanding of the neural mechanisms underlying the etiology of anxiety and affective disorders.
authors.affiliation: Department of Integrative Physiology, University of Colorado at Boulder, Boulder, Colorado 80309-0354, USA. Christopher.Lowry@colorado.edu
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Lowry
authors.forename: Matthew W
authors.initials: MW
authors.lastname: Hale
authors.forename: Andrew K
authors.initials: AK
authors.lastname: Evans
authors.forename: Jasper
authors.initials: J
authors.lastname: Heerkens
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Staub
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Gasser
authors.forename: Anantha
authors.initials: A
authors.lastname: Shekhar
mesh_terms: D000818:Animals; D001007:Anxiety / Q000378:metabolism* / Q000503:physiopathology; D003346:Corticotropin-Releasing Hormone / Q000378:metabolism; D006801:Humans; D019964:Mood Disorders / Q000378:metabolism* / Q000503:physiopathology; D009434:Neural Pathways / Q000378:metabolism; D011903:Raphe Nuclei / Q000033:anatomy & histology / Q000378:metabolism; D012701:Serotonin / Q000378:metabolism*; D013312:Stress, Physiological; D014365:Tryptophan Hydroxylase / Q000235:genetics / Q000378:metabolism
chemical_list: D012701:Serotonin; D003346:Corticotropin-Releasing Hormone; C494784:TPH2 protein, human; D014365:Tryptophan Hydroxylase