Postnatal developmental pattern of thyrotrophin releasing hormone-degrading activity in rat plasma, hypothalamus and liver: role of tri-iodothyronine

1983 ◽  
Vol 97 (3) ◽  
pp. 409-418 ◽  
Author(s):  
Sonia Aratan-Spire ◽  
Kari Moilanen ◽  
Paul Czernichow
Keyword(s):  
Degradation Products ◽  
Rat Plasma ◽  
Developmental Pattern ◽  
Adult Rats ◽  
Thyrotrophin Releasing Hormone ◽  
Releasing Hormone ◽  
Degrading Enzyme ◽  
Liver And Kidney ◽  
Layer Chromatography

Thyrotrophin releasing hormone-degrading activity (TRH-DA) is present in plasma, hypothalamus, pituitary gland, liver and kidney of adults of several species. Each of these tissues contains more than one TRH-degrading enzyme but only one, pyroglutamate aminopeptidase, isolated from the blood, is a TRH-specific enzyme. The aim of this study was to describe the developmental pattern of TRH-DA in the plasma, hypothalamus and liver and the role of tri-iodothyronine (T3) in the development of TRH-DA in the rat. Based on the hypothesis that thyroid hormones stimulate plasma TRH-DA in adult rats, degradation of TRH was studied in hypo- or hyperthyroid rats induced by 6-n-propyl-2-thiouracil or T3 respectively. Tritiated TRH was incubated with plasma and homogenates of hypothalamus or liver. After separation of degradation products by thin-layer chromatography, the amount of degraded [3H]TRH (pmol/50 μl plasma or homogenate) was taken as a comparative index of TRH-DA. Plasma TRH-DA was not detectable before day 9 while hypothalamic and hepatic TRH-DA was already active at birth. Furthermore, the maturation pattern of total TRH-DA was different in plasma compared with other tissues and T3 appeared to play a significant role in its development. The absence of plasma TRH-DA in the neonatal period, its special thyroid-dependent developmental pattern and the presence of a specific TRH-degrading enzyme in adult blood suggest a physiological regulatory role for this activity.

Effects of antiserum to thyrotrophin-releasing hormone on the concentrations of plasma prolactin, thyrotrophin and LH in the pro-oestrous rat

1985 ◽  
Vol 104 (2) ◽  
pp. 205-209 ◽  
Author(s):  
A. M. Horn ◽  
H. M. Fraser ◽  
G. Fink
Keyword(s):  
Plasma Concentrations ◽  
Passive Immunization ◽  
Immune Serum ◽  
Female Rats ◽  
Plasma Prolactin ◽  
Thyrotrophin Releasing Hormone ◽  
Blood Samples ◽  
Releasing Hormone ◽  
Sheep Blood

ABSTRACT The possible role of thyrotrophin-releasing hormone (TRH) in causing the pro-oestrous surge of prolactin was investigated in conscious female rats by passive immunization with a specific anti-TRH serum raised in sheep. Blood samples were withdrawn through a previously implanted intra-atrial cannula. The i.p. injection of 1 ml anti-TRH serum, but not non-immune sheep serum, at 13.00 h of pro-oestrus delayed by about 1 h the onset of the prolactin surge, but the peak of the surge was similar to that in animals injected with the non-immune serum. The plasma concentrations of TSH were significantly reduced by the anti-TRH serum, but plasma concentrations of LH were not significantly affected. These results show that TRH may play an important role in the timing and initiation, but not the maintenance of the prolactin surge in the pro-oestrous rat. J. Endocr. (1985) 104, 205–209

scholarly journals Purified recombinant insulin-degrading enzyme degrades amyloid β-protein but does not promote its oligomerization

2000 ◽  
Vol 351 (2) ◽  
pp. 509-516 ◽  
Author(s):  
Valérie CHESNEAU ◽  
Konstantinos VEKRELLIS ◽  
Marsha Rich ROSNER ◽  
Dennis J. SELKOE
Keyword(s):  
Culture Media ◽  
Degradation Products ◽  
Amyloid Β ◽  
Amyloid Β Protein ◽  
Insulin Degrading Enzyme ◽  
Degrading Enzyme ◽  
Β Protein ◽  
Recombinant Insulin ◽  
Molecular Masses

Amyloid β-protein (Aβ) has been implicated as an early and essential factor in the pathogenesis of Alzheimer's disease. Although its cellular production has been studied extensively, little is known about Aβ clearance. Recently, insulin-degrading enzyme (IDE), a 110-kDa metalloendopeptidase, was found to degrade both endogenously secreted and synthetic Aβ peptides. Surprisingly, IDE-mediated proteolysis of [125I]Aβ(1-40) in microglial cell-culture media was accompanied by the formation of 125I-labelled peptides with higher apparent molecular masses, raising the possibility that the degradation products act as ‘seeds’ for Aβ oligomerization. To directly address the role of IDE in Aβ degradation and oligomerization, we investigated the action of purified recombinant wild-type and catalytically inactive IDEs. Our data demonstrate that (i) IDE alone is sufficient to cleave purified Aβ that is either unlabelled, iodinated or 35S-labelled; (ii) the initial cleavage sites are His14–Gln15, Phe19–Phe20 and Phe20–Ala21; and (iii) incubation of IDE with [125I]Aβ, but not with [35S]-Aβ, leads to the formation of slower migrating species on gels. Since iodination labels N-terminal fragments of Aβ, and 35S labels C-terminal products, we analysed unlabelled synthetic fragments of Aβ and determined that only the N-terminal fragments migrate with anomalously high molecular mass. These results indicate that IDE alone is sufficient to degrade Aβ at specific sites, and that its degradation products do not promote oligomerization of the intact Aβ peptide.

DEVELOPMENTAL CHANGES IN THE DEGRADATION OF THYROTROPHIN RELEASING HORMONE BY THE SERUM AND BRAIN TISSUES OF THE MALE RAT

1977 ◽  
Vol 74 (2) ◽  
pp. 339-340 ◽  
Author(s):  
C. OLIVER ◽  
C. R. PARKER ◽  
J. C. PORTER
Keyword(s):  
Medical School ◽  
Developmental Changes ◽  
Male Rats ◽  
Male Rat ◽  
Obstetrics And Gynecology ◽  
Adult Rats ◽  
Thyrotrophin Releasing Hormone ◽  
Releasing Hormone ◽  
Old Rats ◽  
Phosphate Buffered Saline

*Laboratoire de Médecine Expérimentale, UER Médecine Nord, Boulevard Pierre Dramard, 13326 Marseille Cedex 3, France and †Department of Obstetrics and Gynecology, Southwestern Medical School, 5323 Harry Hines Boulevard, Dallas, Texas 75235, U.S.A. (Received 15 March 1977) Thyrotrophin releasing hormone (TRH) is rapidly degraded when incubated at 37 °C with plasma (Redding & Schally, 1969) or brain homogenates (Bassiri & Utiger, 1974) from adult rats. However, immunoreactive TRH is stable in serum obtained from rats less than 2 weeks old (Oliver, Taurog & Porter, 1974). No loss of biological or immunological TRH activity occurs during incubation with serum from 4- or 16-day-old rats (Neary, Kieffer, Federico, Mover, Maloof & Soodak, 1976). In this report, we have determined the TRH degrading activity of brain homogenates and serum obtained from male rats at various stages of development after birth. Synthetic TRH (1 ng, Beckman Instruments, Inc.) diluted in 50 μl phosphate-buffered saline (0·01

scholarly journals Toxicity Induced after Subchronic Administration of the Synthetic Food Dye Tartrazine in Adult Rats, Role of Oxidative Stress

2016 ◽  
Vol 02 ◽  
pp. 20 ◽  
Author(s):  
Narges El Golli ◽  
Ines Bini-Dhouib ◽  
Aicha Jrad ◽  
Imene Boudali ◽  
Basma Nasri ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Adult Rats ◽  
Adult Rat ◽  
Food Dye ◽  
Antioxidant Defense Enzymes ◽  
Male Wistar Rats ◽  
Liver And Kidney ◽  
Endogenous Antioxidant ◽  
Toxic Potential

The present study was conducted to evaluate the toxic potential of tartrazine, a food color, in different tissues in adult rat: blood, liver, kidneys, and spleen. Tartrazine was administered orally at a dose of 300 mg/kg of body weight to adult male Wistar rats during a period of 30 days. Tartrazine treatment led to an increase in platelets count, a reduction in peripheral lymphocytes and in spleen T CD8-lymphocytes. Furthermore, tartrazine increased the activities of hepatocellular enzymes and promoted changes in kidney biomarkers. In order to explore the possible mechanism involved, oxidative-stress assessment was performed. Results identified critical oxidative alterations in all tested organs, as shown by the promotion of lipid peroxidation and the modification of endogenous antioxidant-defense enzymes. Thus, tartrazine is able to induce in adult rats’ hematotoxicity, immunotoxicity, and liver and kidney injuries by changing the whole balance between oxidants and antioxidants.

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