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WJOLS
Effects of CO Pneumoperitoneum and Enteric Disturbance on β-endorphin in SD Rats
ORIGINAL ARTICLE 2
Effects of CO Pneumoperitoneum and Enteric
2
Disturbance on ββ ββ β-endorphin in SD Rats

Wu Gang, Cai Duan, Lu Lei, Ma Bao-Jin, Zhang Yan-Ling

Department of General Surgery, Huashan Hospital, Fudan University, Wulumuqi, Shanghai, China
Correspondence: Wu Gang, Department of General Surgery, Huashan Hospital, Fudan University, Wulumuqi, Road No. 12
Shanghai-200040, China, e-mail: wugang66916@yahoo.com.cn

Abstract
Objective: To study the effects of enteric disturbance and CO 2 pneumoperitoneum on serum β-endorphin (β-EP) in SD rats, and discuss
their influences on perioperative stress responses.
Methods: 120 SPF-grade male SD rats were anesthetized intraperitoneally and equally randomized to four groups: group A, CO 2
pneumoperitoneum at 1.0 kPa; group B, a 5 cm abdominal incision without enteric disturbance; group C, a 5 cm abdominal incision with
enteric disturbance; and group D, control Group. Serum β-EP was measured at 10, 20 and 40 minutes after initiation of surgery.
Results: The serum β-EP concentration of group A was 2.74 ± 0.67 ng/ml, 1.57 ± 0.64 ng/ml and 1.64 ± 0.74 ng/ml at 10, 20 and
40 minutes of CO 2 pneumoperitoneum respectively, which was significantly higher than that of the control group (P < 0.01). The serum
β-EP concentration of group B was 2.53 ± 0.86 ng/ml, 1.46 ± 0.11 ng/ml and 1.34 ± 0.14 ng/ml at 10, 20 and 40 minutes after the 5 cm
abdominal incision was made, which was very significantly higher than that of the control group (P < 0.01). The serum –EP concentration
of group C was 3.77 ± 0.51 ng/ml, 2.99 ± 0.70 ng/ml and 2.67 ± 0.54 ng/ml at 10, 20 and 40 minutes after the 5 cm abdominal incision was
made with enteric disturbance. There was a very significant difference in the concentration of serum β-EP at 10, 20 and 40 minutes
between Group C and Group B (P < 0.01).
Conclusion: Both enteric disturbance and CO 2 pneumoperitoneum are important stimulating factors inducing stress responses in rats.
Enteric disturbance may accentuate the severity of stress responses in laparotomy.
Keywords: β-endorphin, pneumoperitoneum, laparoscopy, stress responses.

INTRODUCTION including perioperative procedures. Increased generation of
β-EP and cortisol contributes to trauma-related acute phase
Carbon dioxide (CO ) pneumoperitoneum, abdominal
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incision and especially enteric disturbance are very important reaction and hypermetabolic response. Secretion of β-EP
stressful stimuli of abdominal surgery including laparoscopy. and cortisol plays a central role in mediating metabolic
Surgery is a stressful stimulus that elicits inflammatory, responses to stress, and there is a linear correlation between
endocrine and metabolic responses as represented by cortisol values and the severity of injury. As β-EP is positively
increased levels of stress hormones, leading to substrate correlated with cortisol, and both hormones are the result of
mobilization. These changes together constitute the stress corticotropin-releasing hormone (CRH) activation, increased
response. The stress response caused by surgery is circulating β-EP seems to be part of the response to stress.
conditioned by several factors such as anxiety, incision size, In this experimental study, the effect of enteric
enteric disturbance (enteric exposure and drawing), disturbance and carbon dioxide (CO ) pneumoperitoneum
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exposure of abdominal organs to air, temperature change, on stress response was studied in a rat model. Serum β-EP
operation duration, pain, hemorrhage, and infection. To
of SPF-grade male SD rats was measured at different time
obtain excellent exposure in laparotomy, it is necessary to
points after initiation of surgery under the experimental
incise the abdomen and pull the intestine. Avoidance of condition of CO pneumoperitoneum at 1.0 kPa, a 5 cm
enteric disturbance, less hemorrhage, smaller incisional size 2
abdominal incision without enteric distrubance, or a 5 cm
and shorter operation duration contribute to lowering stress
abdominal incision with enteric disturbance to see whether
responses in laparoscopic surgery. Laparoscopic surgery
intestinal disturbance as an important factor increased the
and induction of pneumoperitoneum cause minimal activation
of stress hormones, resulting in a lower stress response on degree of stress response, and whether reducing intraoperative
the part of the patient, and possibly a shorter recovery time. traction on the intestine reduced the extent and shortened the
Serum β-endorphin (β-EP) and cortisol levels are often duration of perioperative stress response, thus reducing
elevated in animals and humans under major stress conditions trauma and promoting patient rehabilitation.
World Journal of Laparoscopic Surgery, January-April 2010;3(1):49-53 49