William O. Reinhardt

Similarity of response of thymus and lymph nodes to administration of adrenocorticotropic hormone in the rat

Summary Administration of purified ACT to the male rat produces by its action on the adrenal cortex a striking reduction in the weight and size of the thymus gland and the cervical lymph nodes. This same effect is not manifest in the adrenalectomized animal. This finding furnishes further evidence for the existence of a definite relationship between adrenal cortex and thymus and lymph nodes. Functional interpretation of this relationship awaits further experimental and clinical study.

Rate of Flow and Cell Count of Rat Thoracic Duct Lymph.

Summary 1. A technic is described for obtaining lymph from the thoracic duct of the rat. 2. The average rate of flow of thoracic duct lymph in the adult, female, unfasted rat, anesthetized with sodium pentobarbital was approximately 0.45 cc/hour (range: 0.13-0.7 in 10 rats). 3. The white cell count of the thoracic duct lymph in 17 rats varied from 6,650-46,250 cells/cu mm and averaged 19,050 cells/cu mm. 4. The rat is a useful and convenient animal to employ in studies on physiology of the lymph.

Thymus and Lymph Nodes Following Adrenalectomy and Maintenance with NaCl in the Rat.

Summary 1. The thymus gland of adrenalectomized male rats maintained for 45 days on sodium chloride does not undergo the involution characterizing the gland in normal untreated animals or those treated with sodium chloride. Sodium chloride as employed appears to exert no consistent effect per se on the thymus or lymphoid tissues of the unoperated control. 2. The systemic lymph nodes of adrenalectomized animals maintained on sodium chloride were heavier than those of normal untreated animals or normal animals given sodium chloride. It is notable that the mesenteric lymph nodes do not undergo a comparable gravimetric increase.

Significance of Intermedin Activity in Adrenocorticotropic Hormone Preparations.

Summary The validity of claims reporting an identity of ACTH and intermedin is questioned by experiments in which assays by the melanophore expanding test in the hypophysectomized frog and the adrenal ascorbic acid depleting test in the hypophysectomized rat were employed. The results demonstrate: 1. Lack of correlation between the 2 activities in various ACTH preparations. 2. Partial separation of intermedin and ACTH activities using a discontinuous pH gradient on cellulose. 3. Differential migration of activities during zone electrophoresis on filter paper. 4. Potentiation of intermedin and inactivation of ACTH by alkali-heat treatment. 5. Differential concentration of ACTH and intermedin activities in the anterior and intermediate lobes of the frog pituitary.

Effect of Thyroidectomy, Castration, and Replacement Therapy on Thymus, Lymph Nodes, Spleen in Male Rats.∗

Summary 1. Evidence is presented that there is a relationship in the reactions of the thymus, spleen, and lymph nodes to the effects of castration, thyroidectomy, and treatment with thyroxin or testosterone propionate, or combinations of these in the male rat. 2. Castration and thyroxin cause comparable increases in the weights of thymus, lymph nodes and spleen. Thyroidectomy and treatment with testosterone propionate tend to decrease the weights of these tissues. Thyroidectomy and testosterone propionate prevent the increase in the weights of thymus, spleen and lymph nodes which follow castration. The order of decreasing sensitivity to the stimuli employed is as follows: thymus. cervical lymph nodes, mesenteric lymph nodes and spleen. 3. A positive coefficient of correlation of 0.591 ± 0.080 was calculated from the data derived from the above experiments for the thymus and the cervical lymph nodes. This is further evidence of a similarity in reaction of these tissues.

Cell Count, Rate of Flow, and Protein Content of Cervical Lymph in the Rat.

Summary The quiescent anaesthetized rat exhibits a free flow of lymph from the cervical lymphatic trunks. A method of collecting cervical lymph in the rat is described. The average rate of flow is approximately 40 mg/hr, the lymphocyte count averages 7,065/cmm, and the average protein content is 3.07 g %. These figures are compared with similar data for thoracic duct lymph.

Apparent discrepancies in evaluation of adrenocorticotrophic hormone (ACTH) activity by two assay methods.

Summary Evidence is presented to indicate that the assessment of the potency of various types of ACTH preparation may vary according to the assay method employed. The suggestion is advanced that ACTH preparations be routinely assayed by more than one method (ascorbic acid depletion, adrenal repair and maintenance, effect on thymus, lymph nodes, etc.) in order to avoid ministerpretation of the nature of the activity and biological responses to a particular preparation.

Method for Determining Completeness of Thyroidectomy Using Radioactive Iodine.

Summary A simple and rapid method is suggested for ascertaining the presence or absence of iodine concentrating tissue (thyroid gland) in thyroidectomized animals. Injected radioactive iodine is assayed by radioautography of the entire neck region, either in the fresh or the fixed state.

Lack of Correlation of Eosinopenic and Adrenal Ascorbic Acid-Depleting Activities of Various Adrenocorticotropic Preparations.∗

Summary Equivalent dose levels by weight of various ACTH preparations have been compared on the basis of their eosinopenic activity (EA) in normal and hypophysectomized rats with the adrenal ascorbic acid-depleting activity (AAA) in hypophysectomized rats. The data presented have been interpreted as indicating that: 1. No correlation exists between the EA and AAA of various ACTH fractions as tested either in normal or hypophysectomized rats. 2. EA in normal rats is not necessarily correlated with EA of the same preparations as tested in hypophysectomized rats. 3. Reduction of AAA by treatment with NaOH-heat under the conditions employed does not inactivate EA, suggesting that EA may be a separate and more stable component aLtKe ACTH preparations. Neither AAA nor EA were influenced by HCl-heat treatment in these experiments. 4. No ACTH compound has been tested which is completely free of AAA and yet exhibits EA? although the converse has been observed. 5. Some evidence suggests the presence of an eosinophilic component in certain ACTH preparations.

Effect of Pituitary Growth Hormone on the Thymectomized Rat

Summary 1. The growth in body weight of female rats thymectomized at the age of 8 days and followed to the age of 6 months is the same as that of sham operated littermate controls. 2. The response of hypophysectomized-thymectomized female rats to a preparation of the pituitary growth hormone is the same as that of similarly treated hypophysectomized littermate controls which had been subjected to a sham thymectomy. 3. The response of plateaued thymectomized female rats with intact pituitaries to a potent growth hormone preparation of the anterior pituitary is the same as that of sham operated littermate controls. 4. Under the conditions of this experiment, therefore, the thymus gland was not necessary either for the growth in weight of otherwise normal animals or for the marked increase in body weight produced by the administration of anterior pituitary growth hormone.