[Microelectrode arrays mapped tissue field action potential duration changes of thoracic spinal cord 1 - 5 nerves and heart in chronic stress rat model].
OBJECTIVE
To investigate chronic stress induced tissue action potential and pathological changes of thoracic spinal cord 1 - 5 nerves and heart in SD rats.


METHODS
SD rats (weighing 180 - 250 g) were randomly divided into depressive group and control group (n = 10 each). Depressive model (unpredicted chronic mild stress) was established according to Gronli's protocol. The heart rhythm, tissue field action potential duration (FAPD) of thoracic spinal cord 1 - 5 nerves, atrium and ventricle were mapped by microelectrode arrays (MEA) technique. Heart was sectioned and stained with Massion and HE for pathological analysis.


RESULTS
After 3 weeks chronic stress, P wave [(35.09 +/- 7.92) ms vs. (25.43 +/- 3.38) ms, P<0.05] and Q-T interval [(114.64 +/- 35.08) ms vs. (81.93 +/- 16.35) ms, P<0.01] were significantly increased, FAPD of thoracic spinal cord 1 - 5 nerves and heart was significantly prolonged, atrial field action potential duration dispersion (FAPDd) was significantly increased, atrial premature beats (n = 2) and ventricular premature beats ( n = 3) were also recorded in rats from depressive group. Moreover, increased collagen deposition was evidenced in Massion stained myocardium and increased inflammatory cell infiltration in the heart was found by both HE stain and electron microscope from depressive rats.


CONCLUSIONS
Chronic mild stress could activate sympathetic nerves system, promote inflammatory cell myocardial infiltration and myocardial fibrosis, induce arrhythmias by prolonging FAPD and increasing FADPd in thoracic spinal cord 1 - 5 nerves and/or heart tissue.
Hou
Yue-mei
YM
Cardiovascular Research Center, the First Teaching Hospital, Xinjiang Medical University, Urumuqi 830054, China. houyuemei@sina.com
Liu
Zheng-jiang
ZJ
Ma
Xiao-jie
XJ
Sun
Juan
J
Feng
Yan
Y
D000200:Action Potentials; D000818:Animals; D003866:Depressive Disorder / Q000175:diagnosis / Q000503:physiopathology*; D004195:Disease Models, Animal; D004562:Electrocardiography; D006321:Heart / Q000503:physiopathology*; D008839:Microelectrodes; D051381:Rats; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord / Q000503:physiopathology*; D013312:Stress, Physiological