The effect of Nigella sativa on the thymus of young andadult rats: Histological, immunohistochemical, andmorphometric study

BackgroundThe thymic microenvironment plays a central role in T-cell differentiation. Involutionof the thymus begins relatively early in life, resulting in decreased immunity. Nigellasativa is known for its immunopotentiating effects.Aim of the workThe aim of the study was to elucidate the effect of N. sativa on the structure of thethymus in young and mature adult rats.Materials and methodsTwenty-eight male Wistar albino rats were divided into two groups: group I andgroup II. Group I was further divided into subgroup Ia and subgroup Ib. SubgroupIa included seven 1-month-old young rats weighing 50–60 g that received plainwater by gavage for 15 days. Subgroup Ib included seven young rats that received2 ml/kg body weight of 1% petroleum ether extract of N. sativa by gavage for 15days. Group II was further divided into subgroup IIa and subgroup IIb. Subgroup IIaincluded seven mature 12-month-old adult rats weighing 600–650 g that receivedplain water by gavage for 15 days. Subgroup IIb included seven mature adult ratsthat received 2 ml/kg body weight of 1% petroleum ether extract of N. sativa bygavage for 15 days. Thymi from different subgroups were processed for histological,immunohistochemical, and morphometric studies.ResultsIn subgroup Ib, the thymus of N. sativa-treated rats revealed a significant increasein the number of CD3-positive cells in the cortex. Some CD3-positive cells were seenin the medulla. In subgroup IIa, signs of thymic involution in the form of expansion ofperivascular spaces containing adipocytes and stromal cells with a significant decreasein the number of CD3-positive cells were noticed. In addition, CI cells non reticularthymulin secreting cells along the capillaries were detected. In N. sativa-treatedadult rats (subgroup IIb), restoration of the normal stroma and parenchyma occurred.Moreover, a significant increase in the number of CD3-positive cells in the cortex andmedulla with an increase in the secretory activity of reticuloepithelial cells was noticed.ConclusionOral administration of the petroleum ether extract of N. sativa for 15 days to youngand mature adult rats results in enhanced proliferation of thymocytes and increasedactivity of reticuloepithelial cells.