title: Prior cold water swim stress alters immobility in the forced swim test and associated activation of serotonergic neurons in the rat dorsal raphe nucleus.
abstract: Prior adverse experience alters behavioral responses to subsequent stressors. For example, exposure to a brief swim increases immobility in a subsequent swim test 24h later. In order to determine if qualitative differences (e.g. 19°C versus 25°C) in an initial stressor (15-min swim) impact behavioral, physiological, and associated neural responses in a 5-min, 25°C swim test 24h later, rats were surgically implanted with biotelemetry devices 1 week prior to experimentation then randomly assigned to one of six conditions (Day 1 (15 min)/Day 2 (5 min)): (1) home cage (HC)/HC, (2) HC/25°C swim, (3) 19°C swim/HC, (4) 19°C swim/25°C swim, (5) 25°C swim/HC, (6) 25°C swim/25°C swim. Core body temperature (Tb) was measured on Days 1 and 2 using biotelemetry; behavior was measured on Day 2. Rats were transcardially perfused with fixative 2h following the onset of the swim on Day 2 for analysis of c-Fos expression in midbrain serotonergic neurons. Cold water (19°C) swim on Day 1 reduced Tb, compared to both 25°C swim and HC groups on Day 1, and, relative to rats exposed to HC conditions on Day 1, reduced the hypothermic response to the 25°C swim on Day 2. The 19°C swim on Day 1, relative to HC exposure on Day 1, increased immobility during the 5-min swim on Day 2. Also, 19°C swim, relative to HC conditions, on Day 1 reduced swim (25°C)-induced increases in c-Fos expression in serotonergic neurons within the dorsal and interfascicular parts of the dorsal raphe nucleus. These results suggest that exposure to a 5-min 19°C cold water swim, but not exposure to a 5-min 25°C swim alters physiological, behavioral and serotonergic responses to a subsequent stressor.
authors.affiliation: Department of Psychology, University of New Hampshire, Durham, NH 03824-3567, USA.
authors.forename: R C
authors.initials: RC
authors.lastname: Drugan
authors.forename: P T
authors.initials: PT
authors.lastname: Hibl
authors.forename: K J
authors.initials: KJ
authors.lastname: Kelly
authors.forename: K F
authors.initials: KF
authors.lastname: Dady
authors.forename: M W
authors.initials: MW
authors.lastname: Hale
authors.forename: C A
authors.initials: CA
authors.lastname: Lowry
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000929:Antidepressive Agents, Tricyclic / Q000494:pharmacology; D002452:Cell Count; D003080:Cold Temperature / Q000009:adverse effects*; D003891:Desipramine / Q000494:pharmacology; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D046353:Immobility Response, Tonic / Q000187:drug effects / Q000502:physiology*; D008297:Male; D016761:Oncogene Proteins v-fos / Q000378:metabolism; D011903:Raphe Nuclei / Q000187:drug effects / Q000473:pathology*; D051381:Rats; D017208:Rats, Wistar; D059326:Serotonergic Neurons / Q000502:physiology*; D013315:Stress, Psychological / Q000188:drug therapy / Q000209:etiology* / Q000473:pathology*; D013550:Swimming / Q000523:psychology*; D013686:Telemetry; D013997:Time Factors; D014365:Tryptophan Hydroxylase / Q000378:metabolism
chemical_list: D000929:Antidepressive Agents, Tricyclic; D016761:Oncogene Proteins v-fos; D014365:Tryptophan Hydroxylase; D003891:Desipramine
keywords: 5-HT; 5-hydroxytryptamine, serotonin; ANOVA; DR; DRD; DRI; DRVL/VLPAG; FST; H(2)O(2); HC; LSD; NaN(3); PBS; PBS containing 0.1% Triton X-100; PBST; SS; T(b); Tph; analysis of variance; core body temperature; core body temperature (°C); dH(2)O; depression; distilled H(2)O; dorsal raphe nucleus; dorsal raphe nucleus, dorsal part; dorsal raphe nucleus, interfascicular part; dorsal raphe nucleus, ventrolateral part/ventrolateral periaqueductal gray; forced swim test; home cage; hydrogen peroxide; immunoreactive; ir; least significant difference; phosphate-buffered saline; raphe; serotonin; sodium azide; swim stress; tryptophan hydroxylase