الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 172 |  |  |
| | | from | 172 | | |
Abstract
Depression is one of the commonest psychiatric diseases. It is one of severe emotional, clinical, socioeconomic burden on a person’s life and society as a whole. Approximately 300 million people worldwide suffer from depression. Hence, comprehensive studies on depression and its pathognomonic mechanisms are one of the major interests of medical science.
Forty percent of patients do not respond adequately to the currently available antidepressant medications. Hence, one drug or combination of more than one are associated with high rate of non-response, partial, or delayed response onset from weeks to months. Thus, the need for new and better treatment is mandatory.
The aim of the present study is to evaluate the mechanisms and effects of novel anti-depressant drugs and possible contribution of NO in the control of depression like behavior in adult male rats.
We got 60 adult male albino rats (Sprague-Dawley strain) from the National Research Center in Cairo, Egypt. Their average weight was 200 ± 20 gm. They were kept at room temperature in twelve stainless steel cages, with each group split into six. They were given two weeks to acclimate upon arrival. The following was the procedure for randomly assigning 10 rats each to one of six groups:
1. Control group (C); where rats were allowed unrestricted access to food and drink and allowed to roam freely within their cages.
2. Chronic unpredictable mild stress group (CUMS); in which rats were exposed to different physical stressors for six weeks. Stressors like water deprivation, food deprivation, illumination overnight, wet cage, tilted cage at 30° from the horizontal, noise, forced swimming at 4 °C and tail pinch were used to induce depression. These stressors were administered daily and to make the procedure unpredictable, 2 stressors were randomly applied each day.
3. Ketamine treated CUMS group (Ket+CUMS); in which rats were exposed to different physical stressors for six weeks then every rat received a single sub-anesthetic intraperitoneal injection of ketamine at a dose of 10 mg/kg, 24 hours prior to the end of the experiment.
4. Ketamine and Amino guanidine treated CUMS group (Ket+AG+CUMS);
in The experiment involved subjecting rats to various physical stressors for a duration of six weeks. Subsequently, each rat was administered a solitary sub-anesthetic intraperitoneal injection of ketamine at a dosage of 10 mg/kg. Thirty minutes later, each rat was administered a solitary intraperitoneal injection of amino guanidine, a specific inhibitor of iNOS, at a dosage of 200 mg/kg. This injection was given 24 hours before the conclusion of the experiment.
5. Agmatine treated CUMS group (Agm+CUMS); in which rats were exposed to different physical stressors for six weeks then every rat received a single oral dose of agmatine in a dose of 0.1mg/kg, 24 hours prior to the end of experiment.
6. Agmatine + Amino guanidine treated CUMS group (Agm+AG+CUMS); in which rats were exposed to different physical stressors for six weeks then every rat received a single oral dose of agmatine in a dose of 0.1mg/kg. Half an hour later, rats received a single intra-peritoneal injection of amino guanidine at a dose of 200mg/kg, 24hour prior to the end of experiment.
Behavioral tests were conducted both before and after medication delivery, following the conclusion of the CUMS phase. The Sucrose preference test and Forced swimming test were conducted from 08:00 am to 14:00 pm, ensuring consistency among the experimental groups.
After the entire trial period, the rats were euthanized by means of cervical dislocation. The heads of the sacrificed rats were immediately dissected, and the brains were meticulously removed. The hippocampal brain tissue was sectioned and its mass was determined. The sample was subjected to homogenization in order to ascertain the levels of malondialdehyde (MDA), nitric oxide (NO), catecholamines (norepinephrine, dopamine, and serotonin), and brain-derived neurotrophic factor (BDNF). The back half of the brain hemispheres were immediately placed in a 10% formalin solution for a period of 24 hours. Afterwards, it was subjected to paraffin embedding and processed for histological investigation using the H&E staining technique. Stained tissue sections were observed using a light microscope. The expression of inducible nitric oxide synthase (iNOS) was demonstrated using immunohistochemical labeling, following a previously described methodology.
The blood samples obtained from the jugular vein were left to clot at room temperature and then underwent centrifugation at 3000 rpm for 15 minutes using a cooling centrifuge (Sigma Aldrich centrifuge). The serum layer was thereafter transferred into designated Eppendorf tubes and stored at a temperature of -20 °C until the assay for Corticosterone and TNF-α levels.
The results obtained clearly demonstrated that:
• CUMS induced depression in all experimental animals with an incidence of 100% after an average period of 6 weeks which proved in the present study by performing behavioral tests before animals scarifying. CUMS reduced the sucrose test as compared with control group in both the baseline and the preference tests. Additionally, CUMS produced the lowest struggling and the highest floating movement frequencies when compared with all experimental studied groups. Moreover, CUMS showed remarkably higher levels of serum corticosterone, serum TNF-α, hippocampal MDA, and hippocampal NO if compared to all experimental groups. However, hippocampal BDNF, and hippocampal catecholamines levels in CUMS group were significant decreased as compared with all the experimental groups.
• The administration of sub-anesthetic dose of ketamine produced a significant improvement of behavioral responses evidenced in the present study by elevation of true preference test with increasing of struggling movement frequencies and attenuation of floating movement frequencies as compared with CUMS group. In addition, ketamine treated CUMS group showed a significant higher hippocampal levels of BDNF and catecholamines with lower levels of serum TNF-α, serum corti¬costerone and hippocampal MDA as compared with CUMS group. On the other hand, the intra peritoneal injection of ketamine showed a non-significant change of hippocampal NO concentration as compared to the CUMS group.
• The data of the present data showed that agmatine administration produced a significant higher values of the true preference test and struggling movement frequencies, while floating movement frequencies were significantly decreased in comparable to CUMS and ketamine treated CUMS groups. Agmatine treated CUMS group showed a significant higher hippocampal levels of BDNF and catecholamines with lower levels of serum TNF-α, serum corti¬costerone, hippocampal MDA and hippocampal NO as compared with both CUMS and ketamine treated CUMS groups.
• The data of the present study showed that co-administration of aminoguanidine with ketamine showed significant improvement of behavioral responses evidenced by elevation of true preference test with increasing of struggling movement frequencies and attenuation of floating movement frequencies as compared with both ketamine and agmatine treated CUMS group. In addition, ketamine with aminoguanidine treated CUMS group showed a significant higher levels of hippocampal BDNF and hippocampal catecholamines with lower levels of serum TNF-α, serum corti¬costerone, hippocampal MDA and hippocampal NO as compared with ketamine treated CUMS group.
• The data of the present study clearly demonstrated that the
co-administration of aminoguanidine with agmatine produced the highest neuroprotective action against development of depression evidenced by the highest significant improvement of true preference test with increasing of struggling movement frequencies and attenuation of floating movement frequencies as compared with CUMS. These values were significantly lower in true preference test, struggling movement and significantly higher in floating movement frequencies as compared to control group. In addition, agmatine with aminoguanidine treated CUMS group showed the highest hippocampal levels of BDNF and catecholamines with the lowest levels of serum TNF-α, serum corti-costerone, hippocampal MDA and hippocampal NO among all the stressed groups.
• H&E sections of the hippocampus in CUMS group showed that there was an apparent hippocampal sclerosis and pyramidal neurons distortion with an areas of neuronal loss, while on administration of ketamine, different hippocampal areas showed the least improvement in the degenerative changes among all the experimental groups. As regard ketamine and amino guanidine treated CUMS group, cells showed improved histological appearance of most of its pyramidal and granular cells. Moreover, the administration of agmatine produced remarkable improvement in most of the granular cells, while the combination between agmatine and amino guanidine produced approximately normal morphological appearance.
• Immunohistochemically study of iNOS antibody expression of the rat hippocampus in both the endothelium of cerebral blood vessels and intraluminal neutrophils showed negative reaction to the immune-stain in control group, while CUMS group showed densely expressed iNOS. On the other hand, ketamine treated CUMS group showing strong immune-staining of vascular endothelium while the combination between ketamine and amino guanidine, produced a moderate reaction in endothelial lining. Agmatine treated CUMS group, showed a minimal reaction in the endothelial lining while agmatine and amino guanidine treated CUMS group showed a very faint reaction.