الفهرس 
Depression
Cytokines and Cardiovascular diseasesOnly 14 pages are availabe for public view
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Abstract
Recent evidence indicated that depression may be an independent risk factor for cardiac events in patients without known cardiovascular diseases. The current study was conducted to examine the hypothesis that a pro-inflammatory state might be the common underlying pathology linking depression and atherosclerotic cardiovascular disease which might account for the increased incidence of coexistence of these disorders.
In the current study, male Wistar rats were exposed to multiple unpredictable mild stressors over a period of 5 weeks for induction of the chronic mild stress (CMS) model of depression. Since depressed patients have a predilection to food with high fat content, which in itself is a sort of stress, rats were fed a high fat diet (CCT diet) as an extra stressor.
Pentoxifylline, a known suppressor of the pro-inflammatoy cytokine TNF- α was used as a pharmacological tool to investigate the possible involvement of TNF-α in the anhedonia, the core symptom of depression in the CMS model. The involvement of TNF-α in the endothelial destruction and in the subsequent atherosclerotic changes predisposing to cardiac disease, was also investigated. The effects of pentoxifylline were compared to those of the prototype tricyclic antidepressant ”imipramine”.
Study design:
Sixty rats were used and divided into 6 equal groups:
Group I: control (Naïve rats)
Group II (CMS): rats were exposed to CMS protocol for 5weeks then were examined.
Group III (CCT): rats were exposed to high fat diet ’CCT diet’ for 5 weeks then were examined Group IV (CMS-CCT): rats were exposed to CMS protocol while fed on high fat diet for 5 weeks then were examined.
Group V (CMS-CCT-Imipramine): rats were exposed to CMS and high fat diet for 5 weeks and treated with the imipramine (tricyclic anti-depressant) in the last 2 weeks then were examined.
Group VI (CMS-CCT-Pentoxifylline): rats were exposed to CMS and high fat diet for 5 weeks and treated with the pentoxifylline in the last 2 weeks then were examined.
Outcome measurements:
A. Behavioral level:
1- Anhedonia [sucrose preference test (SPT)].
2- Behavioral despair [immobility time in forced swim test (FST)].
3- Exploratory activity [number of crossed squares, frequency of rearing in open field test (OFT)].
4- Social activity [social interaction time in social interaction test (SIT)].
B. Body weight changes.
C. Histological Level:
Sections from thoracic aorta were studied by evaluating the aortic tissue integrity, changes in elasticity and possible stiffness of the wall. Anesthetized animals were sacrificed, the chest and abdomen were rapidly opened and the thoracic aortae with the associated perivascular fat were dissected, cut into 2 unequal pieces. The larger potion was fixed in 10% formalin, dehydrated and cleared and cut into sections at thickness of 5-7 μm. Paraffin sections of the thoracic aortae were stained with:
Haematoxylin & Eosin (H & E) stain
Orcein stain
Masson trichrome stain
D. Flow cytometric assessment of circulating endothelial progenitor cells“CEPCs” level in peripheral blood.
E. Immunohistochemical level:
Immunohistochemical staining was carried out to estimate the regenerative potential of endothelial cells. The smaller portions of the previously obtained aortae were immersed in liquid nitrogen, until completely frozen. Fresh frozen sections from the specimens were prepared and subsequently cut at 10m by the cryostate to be stained with immunohistochemical stains to determine the immunoreactivity of CD133, VEGFR-2 and TNF-α.
The results of the present study could be summarized as:
A. Changes associated with CMS and high fat (CCT) diet:
I. Behavioral changes:
The CMS-CCT rats (group IV) exhibited a significant decrease in sucrose preference by the end of the 2nd week. Both the CMS (group II) and CMS-CCT (group IV) rats exhibited an increased immobility time FST and a decreased exploratory activity in OFT compared to control (group I); rats.
II. Body weight changes:
CMS (group II) failed to gain weight as those of control (group I); however this finding wasn’t confirmed statistically. Surprisingly, CCT (group III) lost weight significantly III. Histological changes in aorta:
Examination of sections of of CMS (group II), CCT (group III) and CMS-CCT (group IV) rats showed damaged thoracic aortae in different histological stains. Hx & E stained sections revealed attached blood elements to luminal surface of endothelium, focally desquamated endothelial lining, appearance of foam cells in intima, and vacuolated cytoplasm of smooth muscle cells in media with some showing shrunken pyknotic nuclei. The elastic lamellae of the aortae were mutilated in the form of branching, splitting and discontinuity of internal elastic laminae together with branching and fraying of elastic lamellae in media. The collagen content was increased in intima, media and adventitia of rats of the previous groups when compared to that of the control (group I). Intima to media ratio (IMR) was significantly increased in CMS-CCT (group IV) animals.
IV. Flow cytometric assessment of changes in peripheral blood:
The effect of exposure of Wistar rats to CMS protocol and/or high fat diet on the level of CEPCs in blood was detected. No statistical significance was identified, however CMS-CCT rats (group IV) was on the verge of statistical significance when compared to control rats (group I).
V. Immunohistochemical changes:
CMS, CCT, and CMS-CCT rats (groups II, III, and IV) showed decreased expression of VEGFR-2 in endothelial cells, increased expression of TNF-α in intima and media compared with those of the control (group I).
Also, CD133 immunoreactivity was increased in intima, media and adventitia when compared with that of the control (group I). B. Effect of medication on the changes induced by chronic mild stress (CMS) and the CCT diet:
I. Effect of medication on behavioral changes:
Both imipramine (group V) and pentoxifylline (group VI) rats showed similar results in SPT, FST and OFT when compared to the untreated CMS-CCT (group IV) animals. Only pentoxifylline (group VI) treatment succeeded in improving the social behavior of rats as demonstrated in SIT.
II. Body weight changes in response to stress:
Pentoxifylline treated animals (group VI) showed no change in weight when compared to CMS-CCT rats (group IV), in contrast to imipramine treated (group V) which showed a marked weight reduction by the end of the experiment.
III. Effect of medication on histological changes in aorta:
Imipramine treated animals (group V) failed to correct the damage in rat aortic wall as evident in different histological stains. However, pentoxifylline treated rats (group VI) seemed to show some improvement. This was evident by a reduction in IMR when compared with CMS-CCT rats, while imipramine failed to show similar improvement.
Haematoxylin and Eosin-stained sections of imipramine treated animals (group V) showed adherence of blood elements to luminal surface of endothelium, persistence of foam cells in intima and vacuolations in cytoplasm of smooth muscle cells in the media. Pentoxifylline rats (group VI), on the other hand, showed sparse foam cells and vacuolations.
Imipramine treated animals (group V) did not succeed in correcting the damage in elastic and collagen contents as manifested by orcein and masson trichrome stains respectively. This was seen in the form of persistent splitting of internal elastic lamina together with splitting and fraying of some elastic lamellae in the media and increased collagen content of the intima, media and adventitia. Conversely, pentoxifylline rats (group VI) showed an improved structure as compared to imipramine (group V) in the form of less encountered elastic damage and decreased collagen content.
IV. Effect of medication on CEPCs level:
Both the chronic administration of imipramine (group V) and pentoxifylline (group VI) drugs failed to significantly affect CEPCs level in the peripheral blood in comparison to the untreated CMS-CCT rats group (group IV), though pentoxifylline (group VI) seemed to increase their number.
V. Immunohistochemical changes:
Pentoxifylline (group VI) administration amended the endothelium as evident by decreasing TNF-α and increasing the expression of both VEGFR-2 and CD133. Meanwhile, imipramine (group V) failed to increase CD133 expression.