الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
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Abstract
Disturbed immunological response to stress is a major problem facing our society nowadays. The defective defense mechanism during stress is due to the inability of the involuted spleen to perform its proper function.
Many attempts to restore an effective immunological response were in vain. Propolis administration before stress waved for new hope in the correction of stress-induced disturbed immunological response.
Our work aimed to study the effect of stress on the splenic structure and to prove the possible protective effect of propolis on the spleen of physically stressed rats.
The stress technique was performed by placing rats in plastic restraints with a ventilation pore that allowed complete restraint for two hours/day for ten consecutive days (restraint stress test).
The experiment was conducted on 32 male rats (6 to 8 weeks old) with an average weight of 100 to 120 gm. Rats were randomly subdivided into four groups, with 8 animals each.
group I (Control group): It included 8 rats that served as the control untreated group and were sacrificed on the 10th day.
group II: It included rats that were treated with propolis orally with a dose of (3g/kg) per day for 10 consecutive days.
group III (stress group): It included rats that underwent the stress restraint test. The animals were restrained for 2 hours daily for 10 consecutive days.
group IV (stress with propolis): It included rats that were treated with propolis 2 h before the start of the immobilization for 10 days. Rats underwent the stress restraint test as group III.
Animals were sacrificed on the 10th day. The spleen from the previous groups was excised and, the specimens were prepared for LM examination using H&E and immunohistochemical stains. Other specimens were prepared for EM study.
Results:
• Examination of H&E sections revealed changes in the histological structure of the spleen of group III. Atrophy of the white pulp components occurred. This was confirmed by a significant decrease in the surface area of the lymphoid follicle. Moreover, there was a significant decrease in CD3 +ve cells in PALS compared with the control group. A significant increase in MZ led to a nonsignificant decrease in CD20+ve cells. Some specimens showed a normal white pulp component. In other specimens predominance of the red pulp was observed. The red pulp appeared with congested dilated splenic sinusoids. EM examination of group III of the present study showed signs of mitosis in the lymphoid follicle cells. The apparent increase in the number of apoptotic cells was observed. The apparent increase in the number of dendritic cells and macrophages was detected. This result was confirmed by a significant increase in CD68+ve cells. Numerous collagen fibers could be detected in parenchyma especially under the splenic capsule. However, group IV showed remarkable improvement in the histological picture of the spleen with propolis.
• In the current study, stress could induce histological and immunohistochemical changes in the structure of the spleen. Propolis administration before restraint stress test provides protective effects against stress-induced histological and immunohistochemical changes in the spleen.