Phosphorylation of spinal signaling-regulated kinases by acute uterine cervical distension in rats.
BACKGROUND
Spinal extracellular signaling-regulated kinase 1 and 2 (ERK 1/2) have been found to contribute to nociceptive processing, but the role of spinal ERK 1/2 in visceral pain related to the uterine cervix, the source of pain during the first stage of labor, is unknown. The aim of this study was to investigate ERK activation (phosphorylation) in spinal dorsal horn neurons after acute uterine cervical distension.


METHODS
Under intraperitoneal anesthesia using chloral hydrate 300 mg/kg, female Sprague-Dawley rats were exposed to a 10-s uterine cervical distension of 25, 50, 75, and 100g or no distension (sham). The electromyographic response in the rectus abdominis muscle and mean arterial blood pressure and heart rate changes to uterine cervical distension were determined. The numbers of phosphorylated-ERK 1/2- immunoreactive (pERK 1/2-IR) dorsal horn neurons in cervical (C5-8), thoracic (T5-8), thoracolumbar (T12-L2) and lumbosacral (L(6)-S(1)) segments were counted using immunohistochemistry.


RESULTS
Compared with the non-distended sham rats, uterine cervical distension resulted in a stimulus-dependent increase in electromyographic activity and the number of pERK-IR neurons that selectively located to the thoracolumbar segment, mostly in the deep dorsal and the central canal regions. The time course study demonstrated that spinal ERK activation peaked at 60 min with a slow decline for 120 min after uterine cervical distension stimulation.


CONCLUSIONS
This study suggests that activation of spinal ERK might be involved in acute visceral pain arising from the uterine cervix.
Wang
L Z
LZ
Department of Anesthesiology, Jiaxing Maternity and Child Care Hospital, Jiaxing, Zhejiang Province, China. jxlzw@sina.com
Liu
X
X
Wu
W X
WX
Chai
R K
RK
Chang
X Y
XY
D000818:Animals; D004106:Dilatation; D004576:Electromyography; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D005260:Female; D006439:Hemodynamics / Q000502:physiology; D007150:Immunohistochemistry; D007700:Kinetics; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D009474:Neurons / Q000187:drug effects / Q000201:enzymology; D010766:Phosphorylation; D010812:Physical Stimulation; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction; D013116:Spinal Cord / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D014599:Uterus / Q000201:enzymology* / Q000502:physiology*
D048049:Extracellular Signal-Regulated MAP Kinases