Histological changes induced by exogenous human growth hormone in the thymus of male albino mice

Abstract

It is well documented that hormones of the pituitary gland affect lymphoid organs both structurally and physiologically. This experiment has been conducted to practically confirm the effect of Growth Hormone (a major pituitary hormone) on the histological changes that occur in the thymus (a primary lymphoid organ) in relation to age-related and steroid-induced atrophy.Male albino mice of 8, 28 and 41 weeks of age were used. Each age group was subdivided into 4 subgroups, two of which as controls while the other two received human Growth Hormone for one and two week periods. The young mice were given high dose Dexamethasone to induce thymic atrophy before starting Growth Hormone treatment. Growth Hormone was given as a single daily subcutaneous injection in the morning.Statistical analysis of the results and histological examination of the GH-treated groups revealed that GH was effective in restoring histological structure and possibly the function of the thymus following steroid-induced and age-related atrophy. This was evident by the finding of deceleration of fatty infiltration of thymic tissue and maintenance of the clear thymic architecture, increased thymic weight/ body weight ratio and increased numbers of thymocytes and epitheliocytes in cortical and medullary zones.