Effect of Irradiation and Cortisol on Thymus Fraction.

Abstract

Summary Rabbits were exposed to 650 r of radiation or were injected with 10 mg cortisol for 3 days. Two methods were used for fractionation of thymus from control and treated animals. Method I was based on sequential extraction with water and saline. Nuclear and cytoplasmic fractions of lymphocytes were prepared by Method II. Minced tissue was stirred in sucrose-CaCl₂ and residual material homogenized in saline. Method I does not distinguish cytoplasmic and nuclear components. The weights of all fractions except Fraction A were lower in experimental animals when data are expressed as g/100 g thymus. A large portion of Fraction A was found to be serum proteins as determined by the large increase in albumin in electrophoretic patterns. RNA was lower in most fractions from experimental animals. Electrophoretic analysis of the S₁ cytoplasmic fraction from lymphocytes obtained by Method II, again shows a higher weight fraction of albumin in the extract from treated animals. Decreases in fractions attributed to nuclear material were noted in treated animals. Nuclear fractions were attributed largely to lymphocytes. Saline extracts and final residue show little change following irradiation, indicating these fractions are from radioresistant elements. Both fractions are more sensitive to hormone treatment.