Effects of prolactin on testosterone-induced growth and protein synthesis in rat accessory sex glands

1983 ◽  
Vol 96 (3) ◽  
pp. 407-416 ◽  
Author(s):  
R. Jones ◽  
P. R. Riding ◽  
M. G. Parker
Keyword(s):  
Protein Synthesis ◽  
Total Protein ◽  
Sodium Dodecyl ◽  
Chronic Administration ◽  
Specific Protein ◽  
Ventral Prostate ◽  
Plasma Prolactin ◽  
Accessory Sex Glands ◽  
Caput Epididymidis

The relative importance of testosterone and prolactin in regulating growth and protein synthesis in rat accessory sex glands has been investigated. Protein synthesis was measured by incubating tissue minces in vitro with [35S]methionine and analysing labelled proteins on polyacrylamide gels containing sodium dodecyl sulphate. Plasma prolactin was assayed by radioimmunoassay. Results showed that castration for 8 days significantly reduced wet weights and total protein synthesis in the ventral prostate, dorsolateral prostate and caput epididymidis, but that these effects could be reversed by exogenous testosterone. Similarly, the specific incorporation of [35S]methionine into four polypeptides in the ventral prostate, two polypeptides in the dorsolateral prostate and two polypeptides in the caput epididymidis was lowered by castration but markedly stimulated by testosterone. Acute or chronic administration of 2-bromo-α-ergocryptine to animals in combination with testosterone had no significant effect on any of the parameters measured, although the drug reduced circulating prolactin to undetectable levels. In addition, exogenous prolactin given alone, or in combination with testosterone, to hypophysectomized rats had no effect on general or specific protein synthesis. The induction of hyperprolactinaemia in immature or mature rats with pituitary homographs had no effect on testosterone-stimulated growth of any accessory gland, although it caused a significant stimulation of total protein synthesis in the dorsolateral prostate and coagulating glands. However, this was a generalized effect as it did not increase the specific incorporation of [35S]methionine into androgen-dependent proteins. The results do not indicate a major role for prolactin in regulating androgen responsiveness of male accessory sex glands in the rat.

scholarly journals Characterization of hormonally regulated secretory proteins from the caput epididymidis of the rabbit

1981 ◽  
Vol 196 (1) ◽  
pp. 105-114 ◽  
Author(s):  
R Jones ◽  
K I von Glos ◽  
C R Brown
Keyword(s):  
Protein Synthesis ◽  
Sodium Dodecyl ◽  
Secretory Proteins ◽  
Purification And Characterization ◽  
Ductus Deferens ◽  
Testosterone Treatment ◽  
Ductuli Efferentes ◽  
Caput Epididymidis

1. The incorporation of [35S]methionine into protein was investigated in tissue minces from different regions of the rabbit epididymis incubated in vitro. Rates of synthesis were in the order: epididymal regions 2-5 greater than region 7 greater than region 6 greater than region 1 greater than region 8 greater than ductus deferens greater than ductuli efferentes. 2. Separation of labelled proteins on polyacrylamide gels containing sodium dodecyl sulphate followed by fluorography revealed that one protein (mol.wt. approx. 90 000) was characteristic of region 1, four proteins (one of mol.wt. 54 000 and three of mol.wt. 20 000) were synthesized principally in regions 2-5, and one protein (mol.wt. 22 500) was produced mainly in regions 6, 7 and 8. 3. Castration for 14 days decreased incorporation of [35S]methionine into total protein to less than 10% of that in controls in all regions of the epididymis. However, testosterone treatment for a further period of 14 days restored protein synthesis to normal values in regions 6, 7 and 8, but not in region 1 or regions 2-5. In regions 2-5 the synthesis of three proteins of mol.wt. 20 000 declined after castration, but was not stimulated by exogenous testosterone. Since the 20 000-mol.wt. proteins were major tissue proteins, accounting for 16-25% of the total synthesized, they were used as markers for investigating hormone action in the epididymis. 4. Castration followed immediately by testosterone treatment or ligation of the ductuli efferentes resulted in a decrease in their synthesis, suggesting that they are partially dependent on factors in testicular fluid. Purification and characterization showed them to be acidic glycoproteins with a number of biochemical and immunological properties in common. 5. It is suggested that there is a synergistic action between blood androgens and factors in testicular fluid in regulating protein synthesis in the proximal regions of the rabbit epididymis.

scholarly journals Protein synthesis in chloroplasts. Characteristics and products of protein synthesis in vitro in etioplasts and developing chloroplasts from pea leaves

1975 ◽  
Vol 146 (3) ◽  
pp. 675-685 ◽  
Author(s):  
S G Siddell ◽  
R J Ellis
Keyword(s):  
Energy Source ◽  
Protein Synthesis ◽  
Large Subunit ◽  
Sodium Dodecyl ◽  
Supernatant Fraction ◽  
Pisum Sativum L ◽  
Fraction I ◽  
Plastid Ribosomes

The function of plastid ribosomes in pea (Pisum sativum L.) was investigated by characterizing the products of protein synthesis in vitro in plastids isolated at different stages during the transition from etioplast to chloroplast. Etioplasts and plastids isolated after 24, 48 and 96h of greening in continuous white light, use added ATP to incorporate labelled amino acids into protein. Plastids isolated from greening leaves can also use light as the source of energy for protein synthesis. The labelled polypeptides synthesized in isolated plastids were analysed by electrophoresis in sodium dodecyl sulphate-ureapolyacrylamide gels. Six polypeptides are synthesized in etioplasts with ATP as energy source. Only one of these polypeptides is present in a 150 000g supernatant fraction. This polypeptide has been identified as the large subunit of Fraction I protein (3-phospho-D-glycerate carboxylyase EC 4.1.1.39) by comparing the tryptic ‘map’ of its L-(35S)methionine-labelled peptides with the tryptic ‘map’ of large subunit peptides from Fraction I labelled with L-(35S)methionine in vivo. The same gel pattern of six polypeptides is seen when plastids isolated from greening leaves are incubated with either added ATP or light as the energy source. However, the rates of synthesis of particular polypeptides are different in plastids isolated at different stages of the etioplast to chloroplast transition. The results support the idea that plastid ribosomes synthesize only a small number of proteins, and that the number and molecular weight of these proteins does not alter during the formation of chloroplasts from etioplasts.

The initial synthesis of haemoglobin in de-embryonated chick blastoderms.

Development ◽  
1964 ◽  
Vol 12 (4) ◽  
pp. 609-619
Author(s):  
Anna Hell
Keyword(s):  
Protein Synthesis ◽  
Deoxyribonucleic Acid ◽  
Primitive Streak ◽  
Specific Protein ◽  
In Vitro System ◽  
Embryonic Tissues ◽  
Different Types ◽  
Excellent Tool ◽  
Made In

Enormous progress has been made in the last few years towards the elucidation of the mechanism of protein synthesis, and great interest is centred on the steps leading to cellular differentiation and specific protein synthesis. We know that genetic information is passed on from one generation of cells to the next by deoxyribonucleic acid (DNA), and that this material directs all protein synthesis by the intermediary of the different types of ribonucleic acid (RNA). A simple in vitro system described by O'Brien (1959) seemed to offer an excellent tool for the study of the differentiation of the blood islands, and the initial formation of a well-known protein, haemoglobin (Hb), in chick embryonic tissues. After de-embryonation, chick blastoderms, from the stage of primitive streak onwards, can be cultured in vitro on a saline agar medium supplemented with glucose.

Development of Haemoglobin by De-embryonated Chick Blastoderms Cultured in vitro and the Effect of Abnormal RNA upon its Synthesis

Development ◽  
1961 ◽  
Vol 9 (1) ◽  
pp. 202-221
Author(s):  
B. R. A. O'Brien
Keyword(s):  
Protein Synthesis ◽  
Developmental Stages ◽  
Specific Protein ◽  
Cytoplasmic Protein ◽  
Whole Cells ◽  
Restricted Group ◽  
Dividing Cells ◽  
First Time ◽  
Structural Code

The embryo provides a sequence of developmental stages in which proteins both structural and enzymatic appear or become detectable for the first time in a restricted group of dividing cells. The cells or tissues can be maintained in vitro for a period that may precede and include the synthesis of a specific ‘cytoplasmic’ protein. In this way systems of protein synthesis within the cells of higher organisms can be studied during those stages in which current hypotheses suggest that some structural code is passed on from the DNA of the nucleus to the cytoplasm where the synthesis of the protein becomes maximal. Acellular preparations have contributed much to the elucidation of protein synthesis, but it is doubtful whether actual net synthesis has been obtained in systems less complex than the ‘protoplast’ developed by Spiegelman (1957). In order to study the synthesis of a specific protein it seems necessary at this stage to use whole cells.

Effects of calcium on synthesis and secretion of parathyroid hormone and secretory protein I

1988 ◽  
Vol 255 (3) ◽  
pp. E299-E305
Author(s):  
R. R. MacGregor ◽  
D. A. Hinton ◽  
R. D. Ridgeway
Keyword(s):  
Protein Synthesis ◽  
Steady State ◽  
Parathyroid Hormone ◽  
Total Protein ◽  
Secretory Protein ◽  
Hormone Synthesis ◽  
Synthesis And Degradation

Bovine parathyroid organoids were cultured for up to 3 wk in medium containing 1.4 or 1.8 mM calcium. Steady-state secretion of parathyroid hormone and secretory protein I was two- to fourfold greater at 1.4 mM. At the end of culture, organoids were incubated 3.5 h in 1 or 2 mM calcium to examine maximum and minimum acute secretory rates. Relative to organoids cultured at 1.8 mM calcium, culture at 1.4 mM induced a hypersecretory state, i.e., both the maximum and minimum acute secretory rates of organoids previously cultured at 1.4 mM calcium were up to threefold greater than those of organoids previously at 1.8 mM calcium. Proparathyroid hormone synthesis was up to 50% greater in organoids cultured at 1.4 mM calcium, whereas secretory protein I and total protein synthesis were unaltered. The results showed that parathyroid hypersecretion can be induced by chronic hypocalcemic conditions in vitro. We conclude that the secretory adaptation to chronic hypocalcemia in vitro involves alterations in both synthesis and degradation of parathyroid hormone.

scholarly journals Studies on the form and synthesis of messenger ribonucleic acid in the rat ventral prostate gland, including its tissue-specific stimulation by androgens

1974 ◽  
Vol 137 (3) ◽  
pp. 513-524 ◽  
Author(s):  
W. Ian P. Mainwaring ◽  
Peter A. Wilce ◽  
Allan E. Smith
Keyword(s):  
Prostate Gland ◽  
Sodium Dodecyl ◽  
Ventral Prostate ◽  
Experimental Conditions ◽  
Free System ◽  
Cell Free System ◽  
Messenger Ribonucleic Acid ◽  
Selective Incorporation

1. When prostate polyribosomes are labelled with radioactive precursors in vivo and subsequently dissociated with sodium dodecyl sulphate, a heterogeneous 6–15S RNA species may be identified that possesses all of the distinctive properties of mRNA. 2. Apart from the selective incorporation of 5′-fluoro-orotic acid into this 6–15S RNA component, it is bound by nitrocellulose filters under experimental conditions where only poly(A)-rich species of RNA are specifically retained. Most importantly, however, only the 6–15S RNA fraction is capable of promoting the incorporation of amino acids into peptide linkage in an mRNA-depleted cell-free system derived from ascites-tumour cells. 3. With the development of a simpler method for labelling the total RNA fraction of the prostate gland in vitro, the poly(A)-enriched RNA fraction may be readily isolated by adsorption and elution from oligo(dT)-cellulose. The synthesis of the poly(A)-enriched 6–15S RNA fraction is stringently controlled by androgens in a highly tissue- and steroid-specific manner. 4. From an analysis of the proteins synthesized in the ascites cell-free system in the presence of the poly(A)-rich RNA fraction, it appears that protein synthesis in the prostate gland is stimulated in a rather general way, even during the earliest phases of the androgenic response. This conclusion may require modification when more specific means of analysis are available than those used in the present investigation. 5. The implications of these findings to the mechanism of action of androgens are discussed.

Electrophoretic determination of sulfhydryl groups and its application to complex protein samples, in vitro protein synthesis mixtures, and cross-linked proteins

1986 ◽  
Vol 64 (2) ◽  
pp. 154-160 ◽  
Author(s):  
Helga Stan-Lotter ◽  
Philip D. Bragg
Keyword(s):  
Protein Synthesis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Sulfhydryl Groups ◽  
Additional Parameter ◽  
In Vitro Protein Synthesis ◽  
Molecular Weights ◽  
Complex Protein ◽  
Vitro Protein

Without prior fractionation, the number of sulfhydryl groups of individual polypeptides in a protein mixture can be determined, provided their molecular weights and approximate isoelectric points are known. Urea-denatured protein samples are reacted with iodoacetamide and iodoacetate in a modified version of Creighton's procedure. After separation by sodium dodecyl sulfate – polyacrylamide gel electrophoresis and isoelectric focusing, the number of sulfhydryl groups is determined by counting the protein bands which have additional negative charges. This method requires little material and provides an additional parameter, besides the molecular weight and isoelectric point, for the identification and characterization of a protein. The sensitivity may be enhanced for nonradioactive proteins by using 14C-labeled iodoacetamide and iodoacetate. The procedure has been applied to prokaryotic in vitro protein synthesis mixtures, bacterial membrane protein, and trypsin-cleaved or chemically cross-linked subunits of the F1 ATPase from Escherichia coli.

Prolactin as a luteotrophin

1985 ◽  
Vol 63 (3) ◽  
pp. 257-264 ◽  
Author(s):  
Bruce D. Murphy ◽  
Kadaba Rajkumar
Keyword(s):  
Protein Synthesis ◽  
Specific Protein ◽  
Membrane Receptors ◽  
Direct Role ◽  
Receptor Proteins ◽  
Progesterone Synthesis ◽  
Intracellular Changes ◽  
Time Required ◽  
Stimulation Of

This review summarizes evidence suggesting a direct luteotrophic role for the hypophyseal hormone prolactin (PRL). This direct role consists of the capability to stimulate progesterone synthesis in vitro, the capability to maintain the membrane fluidity and receptors for luteinizing hormone and the capability to import substrate for progesterone synthesis. The time required for PRL-induced luteotrophic events is in the order of hours and sometimes days, and it appears that the effects are not associated with acute intracellular changes. The relatively slow responses and the stimulation of specific protein synthesis by PRL in target tissues other than the ovary suggest that PRL may function primarily through activation of the genome. PRL may induce the synthesis of specific luteal proteins, including enzymes for the regulation of intracellular substrate pools, membrane receptors for LH, or receptor proteins for lipoproteins, a major extracellular source of substrate.

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