Zeng YJ, Yang J, Zhao JB, Liao DH, Zhang EP, Gregersen H, Xu XH, Xu H, Xu CQ. Morphologic and biomechanical changes of rat oesophagus in experimental diabetes. World J Gastroenterol 2004; 10(17): 2519-2523 [PMID: 15300896 DOI: 10.3748/wjg.v10.i17.2519]
Corresponding Author of This Article
Yan-Jun Zeng, Forensic Medicine Department, Medical College, Shantou University, Shantou 515031, Guangdong Province, China. yjzeng@bjut.edu.cn
Article-Type of This Article
Basic Research
Open-Access Policy of This Article
This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Yan-Jun Zeng, Xiao-Hu Xu, Hong Xu, Chuan-Qing Xu, Forensic Medicine Department, Medical College, Santou University, Santou 515031, Guangdong Province, China
Jian Yang, En-Ping Zhang, Beijing University of Technology, Beijing 100022, China
Jing-Bo Zhao, Dong-Hua Liao, Hans Gregersen, Department of Gastrointestinal Surgery, Aalborg University, Denmark
ORCID number: $[AuthorORCIDs]
Author contributions: All authors contributed equally to the work.
Correspondence to: Yan-Jun Zeng, Forensic Medicine Department, Medical College, Shantou University, Shantou 515031, Guangdong Province, China. yjzeng@bjut.edu.cn
Telephone: +86-10-67391685 Fax: +86-10-67391738
Received: August 23, 2003 Revised: October 4, 2003 Accepted: October 22, 2003 Published online: September 1, 2004
Abstract
AIM: To study morphologic and biomechanical changes of oesophagus in diabetes rats.
METHODS: Diabetes was induced by a single injection of streptozotocin (STZ). The type of diabetes mellitus induced by parenteral STZ administration in rats was insulin-dependent (type I). The samples were excised and studied in vitro using a self-developed biomaterial test machine.
RESULTS: The body mass was decreased after 4 d with STZ treatment. The length of esophagus shortened after 4, 7, 14 d. The opening angle increased after 14 d. The shear, longitudinal and circumferential stiffness were obviously raised after 28 d of STZ treatment.
CONCLUSION: The changes of passive biomechanical properties reflect intra-structural alteration of tissue to a certain extent. This alteration will lead to some dysfunction of movement. For example, tension of esophageal wall will change due to some obstructive disease.
Key Words: $[Keywords]
Citation: Zeng YJ, Yang J, Zhao JB, Liao DH, Zhang EP, Gregersen H, Xu XH, Xu H, Xu CQ. Morphologic and biomechanical changes of rat oesophagus in experimental diabetes. World J Gastroenterol 2004; 10(17): 2519-2523
Esophagus is a distensible muscular tube that connects pharynx and stomach. The function of the esophagus is to transport food by peristaltic movement, which is the result of the interaction of the tissue forces in the esophageal wall and the hydrodynamic forces in the food bolus. Esophagus has been studied by radiography[1], concurrent videofluoroscopy and manometry[2,3], high-frequency ultrasonography[4-6], and endoscopic sclerotherapy[7,8]. Motility disorders[9], bolus transport[10,11], systemic sclerosis[12], pain[13], wall distensibility[8], impedance planimetric characterization[14] and the effects of epidermal growth factor[15] on esophagus have been reported in many papers. Since the function of esophagus is mainly mechanical, our work was focused on providing quantitative measurement of passive biomechanical properties of esophagus. Many investigations on biomechanics of esophagus are available in the literature[16,17]. Gregersen et al[18] studied strain distribution in the layered wall[19], relation between pressure and cross-sectional area[20] and other biomechanical properties[21-23] of esophagus. A more recent work used a novel ultrasound technique to study the biomechanics of the human esophagus in vivo[24]. Patel represented biomechanical and sensory parameters of the human esophagus at four levels[25]. Researchers have done a lot biomechanical studies on gastrointestinal tract such as intestine[26,27], small intestine[28-32], ileum[33], duodenum[34] and large intestine[35,36].
Most previous studies have explained the relationship between the diabetes and gastrointestinal tract function[37,38]. Some researches studied relationship between esophageal dysfunction and neuropathy[39], oesophagus scintigraphy[40] and the relationship between esophageal motility and transit[41] in diabetic patients. More recently, Jorgensen reported tension-strain relations and morphometry of rat small intestine in experimental diabetes[42]. Zhao introduced the remodeling of zero-stress state of small intestine in streptozotocin-induced diabetic rats[43].
This paper presents the effect of experimental diabetes on the morphologic and biomechanical properties of the esophagus. The result of this study indicated that experimental type I diabetes caused significant changes in the passive biomechanical properties in the rat esophagus.
MATERIALS AND METHODS
Materials
Diabetes was induced by a single injection of streptozotocin (STZ). The form of diabetes mellitus induced by parenteral STZ administration in rats is insulin-dependent (type I). Twenty-seven rats were divided into 4 groups according to the survival time after STZ treatment: 4 d (n = 7), 7 d (n = 7), 14 d (n = 7), 28 d (n = 6). Another 8 rats were used as normal controls. The samples were taken from the middle part of esophagus. Two rings were cut from each end of the sample to measure the geometric parameters of the no-load state and the opening angle at zero-stress state. The remaining part was excised and studied in vitro using a self-developed biomaterial test machine.
Methods
Using this machine, the esophagus was stepwise elongated and inflated and continuously twisted in circumferential-longitudinal direction. In the normal controls and 28 d of diabetes group, after the intact esophagus was tested, the mucosa and muscle layers were separated using microsurgery and tested in the same loading procedure as mentioned above. The esophagus was treated as a membrane when the stress and strain were calculated, the longitudinal and circumferential stresses were considered to be evenly distributed along the wall thickness while the radial stress and other transverse shear stresses were ignored. The torque vs twist-angle relation was approximately linear at a specified pressure and longitudinal stretch ratio. Thus, the shear modulus can be computed by the torque, twist angle and polar moment of inertial at this state. However, the shear modulus varied greatly with the changing inflation pressure and longitudinal stretch ratio(Figure 1).
Figure 1 Simplified diagram of biomaterial test machine.
1: Linear stage, 2: Torque transducer, 3: Organ bath, 4: Specimen, 5: Force transducer, 6: Motor for axial rotation, 7: Pressure transducer, 8: Infusion channel, 9: Motor for linear stage, 10: Rails for linear stage, 11: CCD camera, 12: Plastic rod.
RESULTS
Type I diabetes could induce the following effect on the biomechanical and morphologic properties of esophagus: body weight and morphology, shear modulus, circumferential and longitudinal stress-strain relationship, stress-strain relationship of muscle layer and mucosa layer.
Body weight and morphology
The body mass kept a steady increase in the control rats. But it went down after 4 d in the diabetes rat (Figure 2A). The length of esophagus in vivo obviously declined after 4, 7, 14 d, but it would return to normal level after 28 d (Figure 2B). The mass per unit lengh in vitro changed little (Figure 2C). In the intact esophagus, the opening angle increased after 14 d of STZ treatment (Figure 2D).
Figure 2 Changes of body mass and esophagus morphology and opening angle at zero-stress state in the process of diabetes development.
Dunner’s test result: significant difference vs normal control (aP < 0.05). A: Change of body mass, B: Change of in vivo length, C: Change of mass per unit length, D: Change of opening angle.
Shear modulus
Changes of elastic shear moduli in the course of diabetes development at longitudinal stretch ratio λzz = 1.5 and various transmural pressure are shown in Figure 3A. Elastic shear modulus would rise with increased transmural pressure. Especially when transmural pressure was more than 0.25 kPa, the shear moduli for various transmural pressure were remarkably different. And diabetes has notably affected the shear modulus. This effect showed that shear moduli are obviously increased after 28 d.
Figure 3 Change of elastic shear modulus in the process of diabetes development.
A: Change at λzz = 1.5 and various transmural pressure, B: Change at P = 1 kPa and various longitudinal stretch ratio.
Changes of elastic shear modulus in the course of diabetes development at transmural pressure P = 1 kPa and various longitudinal stretch ratio are pictured in Figure 3B. Elastic shear modulus would rise with increased longitudinal stretch ratio. Shear moduli were remarkably different at various longitudinal stretch ratios. And diabetes has notably affected the shear modulus. This effect demonstrated that shear moduli were obviously increased after 28 d of STZ treatment.
Circumferential and longitudinal stress-strain relationship
Figure 4A shows the changes of circumferential stress-strain relationship in the course of diabetes development at longitudinal stretch ratio λzz = 1.5 and various transmural pressure. All curves of experimental group inclined to left side except that after 4 d. The curve after 28 d was on the most left side. The circumferential stiffness increased after 7, 14, 28 d of diabetes.
Figure 4 A: Change of circumferential stress-strain relation in the course of diabetes development at λzz = 1.
5 and various transmural pressure. B: Change of longitudinal stress-strain relation in the course of diabetes development at P = 0.25 kPa and various longitudinal stretch ratio.
The changes of longitudinal stress-strain relationship in the course of diabetes development at transmural pressure P = 0.25 kPa and various longitudinal stretch ratio are pictured in Figure 4B.The stress-strain curve after 28 d was obviously inclined to left side. So the longitudinal stiffness notably increased after 28 d.
Stress-strain relationship of muscle layer and mucosa layer
The circumferential stress-strain relationship of muscle layer and mucosa layer in the process of inflation at a longitudinal stretch ratio of 1.5 is pictured in Figure 5A. And the experimental diabetes was after 28 d. For muscle layer, there was no obvious difference between the control and diabetes groups. For mucosa layer, the stress-strain curve moved to left side in parallel. So circumferential stiffness of mucosa layer with diabetes was larger than that of control.
Figure 5 A: Circumferential stress-strain relation between muscle layer and mucosa layer in the process of inflation at a longitudinal stretch ratio of 1.
5. N: Normal control, D: 28 d of diabetes. B: Longitudinal stress-strain relation between muscle layer and mucosa layer in the process of elongation at a transmural pressure of 0.25 kPa. N: Normal control, D: 28 d of diabetes.
Figure 5B shows longitudinal stress-strain relationship of muscle layer and mucosa layer in the process of elongation at a transmural pressure of 0.25 kPa. For muscle layer, there was no obvious difference between control and diabetes groups. There was no notable difference for mucosa layer either.
DISCUSSION
A large number of studies have discovered that diabetes can affect the movement of oesophagus. Transportation of oesophagus may delay or slow down, and movement of esophagus can not coordinate.
This dysfunction of movement can be a result of muscle and nerve cooperative failure[39-41,44-47]. Histologic research has proved that diabetes can destroy vagus nerve[48]. Though there are many papers on movement and function of oesophagus in diabetes, few data on morphologic and passive biomechanical properties are seen. The change of passive biomechanical properties reflects intra-structural alteration of tissue to a certain extent. This alteration will result in some dysfunction of movement, for example, tension of esophageal wall will change due to some obstructive disease[49,50], and therefore, it is necessary to study biomechanics and morphology together.
The body mass is decreased in rat with diabetes. This is consistent with other studies[43,51]. Diabetes will lead to hyperplasia of some organs. Hyperplasia of esophagus is less frequent than that of small intestine[52,53]. Diabetes has caused rise of the opening angle of small intestine[44], also it is seen for esophagus.
In this paper, the shear, longitudinal and circumferential stiffnesses were obviously elevated after 28 d with STZ treatment. Jorrensen[42], Liu[54] and Zhao[51] have discovered that stiffness is raised in diabetes in small intestine, blood vessel and arterial wall.
We can draw a conclusion that the changes of passive biomechanical properties reflect intra-structural alteration of tissue to a certain extent. This alteration will lead to some dysfunction of movement.
Narawane NM, Bhatia SJ, Mistry FP, Abraham P, Dherai AJ. Manometric mapping of normal esophagus and definition of the transition zone.Indian J Gastroenterol. 1998;17:55-57.
[PubMed] [DOI][Cited in This Article: ]
Nicosia MA, Brasseur JG, Liu JB, Miller LS. Local longitudinal muscle shortening of the human esophagus from high-frequency ultrasonography.Am J Physiol Gastrointest Liver Physiol. 2001;281:G1022-G1033.
[PubMed] [DOI][Cited in This Article: ]
Pehlivanov N, Liu J, Kassab GS, Puckett JL, Mittal RK. Relationship between esophageal muscle thickness and intraluminal pressure: an ultrasonographic study.Am J Physiol Gastrointest Liver Physiol. 2001;280:G1093-G1098.
[PubMed] [DOI][Cited in This Article: ]
Hewson EG, Ott DJ, Dalton CB, Chen YM, Wu WC, Richter JE. Manometry and radiology. Complementary studies in the assessment of esophageal motility disorders.Gastroenterology. 1990;98:626-632.
[PubMed] [DOI][Cited in This Article: ]
Patel RS, Rao SS. Biomechanical and sensory parameters of the human esophagus at four levels.Am J Physiol. 1998;275:G187-G191.
[PubMed] [DOI][Cited in This Article: ]
Zhao J, Yang J, Vinter-Jensen L, Zhuang F, Gregersen H. The morphometry and biomechanical properties of the rat small intestine after systemic treatment with epidermal growth factor.Biorheology. 2002;39:719-733.
[PubMed] [DOI][Cited in This Article: ]
Zeng YJ, Qiao AK, Yu JD, Zhao JB, Liao DH, Xu XH, Hans G. Collagen fiber angle in the submucosa of small intestine and its application in Gastroenterology.World J Gastroenterol. 2003;9:804-807.
[PubMed] [DOI][Cited in This Article: ]
Yang J, Zhao JB, Zeng YJ, Gregersen H. Biomechanical properties of ileum after systemic treatment with epithelial growth factor.World J Gastroenterol. 2003;9:2278-2283.
[PubMed] [DOI][Cited in This Article: ]
Clouse RE, Lustman PJ, Reidel WL. Correlation of esophageal motility abnormalities with neuropsychiatric status in diabetics.Gastroenterology. 1986;90:1146-1154.
[PubMed] [DOI][Cited in This Article: ]
Gregersen H, Giversen IM, Rasmussen LM, Tøttrup A. Biomechanical wall properties and collagen content in the partially obstructed opossum esophagus.Gastroenterology. 1992;103:1547-1551.
[PubMed] [DOI][Cited in This Article: ]
Mittal RK, Ren J, McCallum RW, Shaffer HA, Sluss J. Modulation of feline esophageal contractions by bolus volume and outflow obstruction.Am J Physiol. 1990;258:G208-G215.
[PubMed] [DOI][Cited in This Article: ]
Zhao J, Lu X, Zhuang F, Gregersen H. Biomechanical and morphometric properties of the arterial wall referenced to the zero-stress state in experimental diabetes.Biorheology. 2000;37:385-400.
[PubMed] [DOI][Cited in This Article: ]
Mayhew TM, Carson FL, Sharma AK. Small intestinal morphology in experimental diabetic rats: a stereological study on the effects of an aldose reductase inhibitor (ponalrestat) given with or without conventional insulin therapy.Diabetologia. 1989;32:649-654.
[PubMed] [DOI][Cited in This Article: ][Cited by in Crossref: 13][Cited by in F6Publishing: 16][Article Influence: 0.5][Reference Citation Analysis (0)]
Zoubi SA, Williams MD, Mayhew TM, Sparrow RA. Number and ultrastructure of epithelial cells in crypts and villi along the streptozotocin-diabetic small intestine: a quantitative study on the effects of insulin and aldose reductase inhibition.Virchows Arch. 1995;427:187-193.
[PubMed] [DOI][Cited in This Article: ][Cited by in Crossref: 23][Cited by in F6Publishing: 27][Article Influence: 0.9][Reference Citation Analysis (0)]
Liu SQ, Fung YC. Changes in the rheological properties of blood vessel tissue remodeling in the course of development of diabetes.Biorheology. 1992;29:443-457.
[PubMed] [DOI][Cited in This Article: ]