title: Does exposure to chronic stress influence blood pressure in rats?
abstract: The principal aim of this study was to determine whether prolonged chronic footshock stress can evoke sustained changes in blood pressure in rats and to elucidate possible underlying neurochemical mechanisms as mediated by the sympathoadrenal system. Adult male Wistar rats instrumented for telemetric recording of arterial pressure, heart rate and locomotor activity were subjected to six weeks of inescapable unpredictable electrical footshocks (FS+) or were exposed to shock chambers but were not shocked (FS-). Compared to FS- animals, FS+ animals had significantly reduced body weight gain (by 30%), locomotor activity (by 25%) and social interaction time (by 30%)--symptoms commonly induced by chronic stress and depression in humans. These changes were associated with small, but significant increases in systolic blood pressure (by 7%) and pulse pressure (by 11%) in FS+ rats relative to FS- rats. We have also found neurochemical alterations in sympathoadrenal pathways (that lasted for at least one week post-stress) including about 2-3 fold increases in the levels of tyrosine hydroxylase phosphorylation in the sympathetic ganglia and adrenal gland and a 1.8-fold increase in the expression of the Angiotensin II receptor type 1 protein in the adrenal gland of FS+ rats relative to FS- rats. We conclude that uncontrollable and unpredictable footshock stress can lead to elevation in systolic blood pressure when applied for an extended period of time (six weeks) in Wistar rats, and that these changes could be mediated by stress-induced modifications in sympathoadrenal pathways.
authors.affiliation: School of Biomedical Sciences and Pharmacy, Hunter Medical Research Institute, University of Newcastle, Callaghan, NSW, Australia. Electronic address: Larisa.Bobrovskaya@unisa.edu.au.
authors.forename: Larisa
authors.initials: L
authors.lastname: Bobrovskaya
authors.forename: Daniel
authors.initials: D
authors.lastname: Beard
authors.forename: Evgeny
authors.initials: E
authors.lastname: Bondarenko
authors.forename: Mirza I
authors.initials: MI
authors.lastname: Beig
authors.forename: Phillip
authors.initials: P
authors.lastname: Jobling
authors.forename: Frederick R
authors.initials: FR
authors.lastname: Walker
authors.forename: Trevor A
authors.initials: TA
authors.lastname: Day
authors.forename: Eugene
authors.initials: E
authors.lastname: Nalivaiko
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000502:physiology*; D002908:Chronic Disease; D006339:Heart Rate / Q000502:physiology; D008297:Male; D009043:Motor Activity / Q000502:physiology; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D013315:Stress, Psychological / Q000503:physiopathology* / Q000523:psychology*
keywords: AP; AT1R; Adrenal gland; Ang II; Angiotensin II; Angiotensin II receptor type 1; Angiotensin receptor; Blood pressure; FS; Footshock stress; Ser; Sympathetic ganglia; TH; Tyrosine hydroxylase; arterial pressure; footshock; serine residue; tyrosine hydroxylase