EFFECT OF TRICHLORACETIC ACID ON BASOPHILS AND ON CORTICOTROPHIN CONTENT OF HUMAN PITUITARY GLANDS: EXTRACTION OF LOW MOLECULAR WEIGHT CORTICOTROPHIN

Abstract

ABSTRACT Experiments are reported which show that 2.5% trichloracetic acid (TCA) causes marked loss of periodic acid-Schiff staining of the basophil granules of the pituitary gland and that there is extraction of some ACTH into the TCA. There is, however, no direct correlation between the basophil changes and the extraction of the hormone from the gland. The vesiculate chromophobe, the colloid and the cytoplasmic granules of the acidophils are not apparently affected by TCA treatment. Little is known about the chemical state of storage of ACTH in the human adenohypophysis. The amino acid structure and sequence of human ACTH has recently been proposed but there is as yet no chemical basis for a histochemical technique specific for ACTH. The 2.5% TCA-extractable ACTH, which represents about 30% of the total ACTH activity of batches of 'old' pituitary glands, has been characterized by ultrafiltration, Sephadex column chromatography and ultracentrifugation as a single component of minimum molecular weight about 3200. This is a simple method for extracting low molecular weight ACTH-extraction in 2.5% TCA (or water acidified to pH 5.0) for 1 hour at 4° C followed by ultrafiltration and Sephadex column chromatography. About 68% of the original activity in the TCA extract is recovered in the final product. Extraction was equally efficient whether 'pieces' or homogenates were used and in the presence or absence of posterior lobe tissue. Autolysis results in a decrease of both residual gland and TCA-extractable hormone.