title: Exaggerated adrenomedullary response to immobilization in mice with targeted disruption of the serotonin transporter gene.
abstract: This study examined whether serotonin transporter (5-HTT) gene knockout influences adrenomedullary, sympathoneural, or hypothalamo-pituitary-adrenal responses to acute immobilization. In conscious, cannulated mice, arterial plasma concentrations of catecholamines, ACTH, and corticosterone were measured at baseline and after 15 min of immobilization. Tissue levels of serotonin (5-HT), catecholamines, and hormones were also measured in pituitary and adrenal glands. At baseline, adrenal and pituitary 5-HT concentrations in knockout (5-HTT(-/-)) mice were markedly lower than those in littermate control (5-HTT(+/+)) mice, whereas the groups did not differ in levels of catecholamines or hormones in plasma or tissue. Immobilization increased plasma levels of catecholamines, ACTH, and corticosterone in all genotypes. 5-HTT(-/-) mice had exaggerated responses of plasma epinephrine to immobilization and significant reductions in adrenal epinephrine, norepinephrine, and 5-HT contents compared with values in littermate controls. Pituitary ACTH was significantly reduced after immobilization in 5-HTT(-/-) mice only, but increases in plasma ACTH and corticosterone levels did not differ between genotypes. The results suggest that one 5-HTT function is to restrain adrenomedullary activation in response to immobilization. Exaggerated adrenomedullary responses seem to be an autonomic correlate of the anxiety-like behaviors in 5-HTT knockout mice.
authors.affiliation: Laboratory of Clinical Science, National Institute of Mental Health, and Clinical Neurocardiology Section, National Institutes of Health, Bethesda, Maryland 20892, USA. ot3d@nih.gov
authors.forename: Olga A
authors.initials: OA
authors.lastname: Tjurmina
authors.forename: Ines
authors.initials: I
authors.lastname: Armando
authors.forename: Juan M
authors.initials: JM
authors.lastname: Saavedra
authors.forename: David S
authors.initials: DS
authors.lastname: Goldstein
authors.forename: Dennis L
authors.initials: DL
authors.lastname: Murphy
mesh_terms: D015102:3,4-Dihydroxyphenylacetic Acid / Q000097:blood; D000311:Adrenal Glands / Q000737:chemistry / Q000503:physiopathology; D000313:Adrenal Medulla / Q000503:physiopathology*; D000324:Adrenocorticotropic Hormone / Q000032:analysis / Q000097:blood; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology; D003345:Corticosterone / Q000097:blood; D004295:Dihydroxyphenylalanine / Q000097:blood; D004837:Epinephrine / Q000032:analysis / Q000097:blood; D008562:Membrane Glycoproteins / Q000172:deficiency* / Q000235:genetics / Q000502:physiology; D026901:Membrane Transport Proteins; D008734:Methoxyhydroxyphenylglycol / Q000031:analogs & derivatives* / Q000097:blood; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009419:Nerve Tissue Proteins; D009638:Norepinephrine / Q000032:analysis / Q000097:blood; D010902:Pituitary Gland / Q000737:chemistry / Q000503:physiopathology; D012149:Restraint, Physical; D012701:Serotonin / Q000032:analysis; D050486:Serotonin Plasma Membrane Transport Proteins; D013312:Stress, Physiological / Q000503:physiopathology*
chemical_list: D002352:Carrier Proteins; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D050486:Serotonin Plasma Membrane Transport Proteins; C493231:Slc6a4 protein, mouse; D015102:3,4-Dihydroxyphenylacetic Acid; D012701:Serotonin; D008734:Methoxyhydroxyphenylglycol; D004295:Dihydroxyphenylalanine; D000324:Adrenocorticotropic Hormone; C010117:3,4-dihydroxyphenylglycol; D003345:Corticosterone; D009638:Norepinephrine; D004837:Epinephrine