Histological and immunohistochemical study on the effect ofnoise stress on the spleen of adult albino rat and the possiblerole of Ginkgo biloba extract

IntroductionIt is widely accepted that stress has an immunosuppressive effect. Ginkgo bilobaextract has a broad spectrum of pharmacological properties.AimThe aim of the study was to determine the effect of noise stress on the structureof the spleen and to detect the efficacy of G. biloba extract in counteracting theseeffects.Materials and methodsThirty adult albino rats were divided equally into five groups. Group I was thecontrol group; group II was the noise group, in which rats were exposed to noisefor 4 weeks; and in group III (protected), rats were exposed to noise and receivedG. biloba (orally 100 mg/kg/day) from the beginning of the experiment for 4 weeks.In group IV (recovery), rats were exposed to noise for 4 weeks and then alloweda recovery period for another 4 weeks; in group V (treated), rats were exposed tonoise for 4 weeks and then administration of G. biloba was continued for another4 weeks after stoppage of noise stress. At the end of the experiment, specimensfrom the spleen were taken and prepared for H E and immunohistochemical stains(CD4 and CD68).ResultIn group II, there was a significant decrease in the size of the lymphatic folliclesand many of them appeared to have focal areas of cellular depletions. There wasa significant decrease in the number of both CD4+ T helper cells and CD68+macrophages in comparison with the control group. In group III, a few follicles stillshowed small areas of cellular depletion. In groups IV and V (recovery and treatedgroups), a relative improvement in the structure of the spleen was observed, but amore or less complete improvement in group V was observed. However, the numberof both CD4+ and CD68+ cells was still less than that in the control group.ConclusionNoise stress had an immunosuppressive effect. Treatment with G. biloba was foundto be more effective than its protective role.