Herbert Sheppard

Metabolism of the accessory sex organs of the immature male rat: Changes in nucleic acid composition and uptake of thymidine-3H induced by castration and methandrostenolone☆

Abstract The administration of methandrostenolone to both castrated and control immature male rats for seven days resulted in dose-dependent increases in the RNA, DNA, and protein of the levator ani, ventral prostate, and seminal vesicles. The effect of this anabolic agent on these tissues was observable after only two days of treatment and was readily detectable in an increased incorporation of thymidine- 3 H into the hot acid-soluble fractions containing desoxyribonucleic acid. No effects were noted with the adrenal, thymus, or leg muscle, but a decreased uptake of thymidine- 3 H was noted in the kidney. The changes in 3 H uptake seen after two days of treatment decreased with continued treatment so that after seven days the effect of the drug had almost disappeared. Autoradiograms and general histological examination suggested that the observed changes in the uptake of thymidine- 3 H paralleled those for rates of mitosis.

Distribution and elimination of methylphenidate-C14

Abstract Methylphenidate labeled with C14 in the carboxyl carbon was administered intraperitoneally to guinea pigs and its distribution studied. The concentration of C14 in the brain and other tissues was higher when increased motor activity was evident than when no such drug effects could be noted. The C14 in the tissues was found to be distributed in several chemical forms including the intact drug, its product of hydrolysis, and a water-soluble conjugate. Most of this C14, however, was associated with the metabolic products rather than the unaltered drug. Over a 24-hour collection period, approximately 70% of the injected dose appeared in the urine while only 2% appeared in the feces. Most of the C14 in the excreta was composed of degradation products similar in certain respects to those found in the tissues.

Distribution and fate of hydrochlorothiazide-H3

Abstract Hydrochlorothiazide was labeled with tritium by the reduction of chlorothiazide with tritium-labeled sodium borohydride. Its distribution and metabolism were studied in saline-loaded, fasted rats. The drug was rapidly absorbed and 43 and 69% was excreted into the urine in 48 hours with doses of 4.7 and 0.15 mg/kg, respectively. No evidence could be found for the metabolic alteration of hydrochlorothiazide by the rat.

Determination of H3 and C14 in biological materials using oxygen bomb combustion

Abstract A method has been presented which makes possible the determination of 0.4 and 0.1 mμc of H3 and C14, respectively, in 1–15 gm of lyophilized tissue. The sample is combusted in a Parr oxygen bomb under 25 atm pressure of oxygen and the resulting water and carbon dioxide collected and counted in a liquid scintillation spectrometer.

The influence of NADPH on the hydroxylation of progesterone by rat adrenal homogenates

Abstract Variations in the pattern of steroids produced from progesterone were found to be dependent on the concentration of pyridine nucleotides used. At relatively low concentrations 21-hydroxylation predominated. As the concentrations were increased 21-hydroxylation decreased and 11- and 18-hydroxylations became stimulated. At very high concentrations, hydroxylations of progesterone at positions 11- and 18- were maximal and at 21- minimal yielding 11-hydroxyprogesterone as the major product. A greater effectiveness was noted for generated as compared to added reduced coenzyme.

Metabolism of Reserpine-C14. II. Species Differences as Studied in vitro

Summary 1. Liver slices of rat, mouse, dog, guinea pig, rabbit and pigeon were incubated with reserpine-C14. 2. Demethylation of the 4-methoxy position of trimethoxyben-zoic acid moiety of reserpine was observed to occur, with rat liver slices most active in this respect. 3. Hydrolysis of reserpine was observed to occur with liberation of free tri-methoxybenzoic acid. Guinea pig liver slices were most active in this respect. 4. Esteratic activity resides chiefly in the microsomes of guinea pig liver. 5. Demethylation or hydrolysis or both by liver slices is not correlated with dose requirement for typical tranquilizing response. 6. Rate of excretion of C14 by the guinea pig was studied in vivo after intravenous injection of reserpine-C14.

A Suggested Effect on Levels of Catecholamine in Brain produced by Small Doses of Reserpine

THE preceding communication contains data refuting the rise in catecholamines which we had observed 20 min. after the subcutaneous injection of reserpine (0.1 mgm./kgm.). In repeating the experiment in order to check the questioned specificity of the analytical method, we found that we were unable to reproduce our original findings. Instead, the brain catecholamine-levels expressed as percentage of controls were found to be 105, 100, 64, 26, 37 and 31 per cent after 1/3, 2, 4, 6, 8 and 72 hr. The shape of the curve was very much like that observed for serotonin and the 4-hr. values agreed with those reported by Orlans and Brodie. We are, at present, unable to detect the factors in the original experiments which gave us the values we reported, but we intend to pursue this matter further. In spite of this discrepancy, the serotonin values remain undisputed and the main conclusion remains valid, namely, that there exists no correlation between the levels of brain amines and the intensity of observable effects.

Chapter 25. Factors Affecting Adrenal Steroidogenesis

Publisher Summary Sulfated steroids are produced by human adrenals. This chapter discusses the mechanism and pathways of synthesis of adrenal corticosteroids because they may be affected by the natural hormone, ACTH as well as various chemical agents. For orientation, an outline of the pathways of synthesis is included. Mitochondrial fractions from the adrenals of several species contain enzymes necessary for steroid production. These include a solubilizable cholesterol side chain splitting complex, a non-soluble cytochrome P-450, 18-hydroxylase and 18-ol dehydrogenase from sheep and bullfrog adrenals, and enzymes from the guinea pig adrenal that 11- and 21-hydroxylate, reduce ring 11-dehydro (11, 21-diOH) progesterone and remove side chain of 17, 21-diOH progesterone. The 11β-hydroxylase in adrenal homogenates of the guinea pig is maximally stimulated by Krebs-cycle acids in the absence of NADPH while that of the rat is stimulated by both. Bullfrog adrenal homogenates synthesizing Aldo at the high rate of 250 μg/g/hr require NADPH, fumarate, and Mg that can be replaced by Ca or Mn. Phosphate, ATP, Na, and K are not required. Rat and bovine homogenates contain an inhibitor of Aldo synthesis. The production of 18-OH (11, 21-diOH) Progesterone and Aldo by rat adrenal quarters increases linearly for 20 hours but, if the animals drink 1% NaCl for 8 days, the production plateaus after 2 hours.

Parr Bomb Combustion of Tissues for C 14 and Tritium Analysis

The determination of low levels of C14 and H3 (tritium) in biological samples has been a problem for some time. For certain reasons it became necessary to think in terms of analyzing at least 1 g of tissue. This suggested the use of the Parr Oxygen bomb, which readily combusts 1 g of dried compressed material. The feasibility of oxygen bomb combustion was illustrated in a report by Payne [1] in which he described the use of a small hand-built metal bomb capable of handling a few hundred milligrams of tissue. The use of a metal oxygen bomb offers several advantages over any available glass apparatus. These include rapidity of combustion, safety, lack of “memory” effect, and compactness. The extensive use of the Parr Oxygen bomb in calorimetry has testified to the safety, durability, and reliability of this apparatus.