Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01189 (beta-endorphin)
 21,003 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In Araldite sections of male rat pituitaries, stained after embedding by the unlabeled antibody enzyme method with antisera to native luteinizing hormone-releasing hormone (LH-RH) or LH-RH azo-conjugated to bovine serum albumin, localization is confined mainly to the interior of the large, and to a lesser extent to that of the small, secretion granules of the gonadotrophic cells. Plasma membranes are not demonstrated. Except for weak staining in the granules of corticotrophs, no other pituitary cell is stained. Pretreatment of sections with LH-RH (to dilutions of 4 pg/mul) increases staining intensity in the gonadotrophic granules. Other cells are unaffected. The lesser the gonadotroph staining intensity without pretreatment, the greater the increase (more than 23-fold reactivity). Augmented staining is measurable (P less than 0.001) to antiserum dilutions of 1:240000. Pretreatment with des-Glu-1-LH-RH, porcine corticotropin or rat prolactin has no effect. LH-RH-Gly-10(des-amide) inhibits. Rat glycoprotein hormones enhance staining with anti-azo-conjugated LH-RH. With antinative LH-RH these hormones enhance weak staining, but inhibit strong staining. Thick vibrotome sections of male rat or rabbit pituitaries stained before embedding reveal specific localization on plasma membrane and gonadotrophic secretion granules provided the sections have been pretreated with LH-RH (250 pg/mul). The data show that LH-RH after reaction with receptor is not sterically hindered from binding specific antibodies. Receptor may be found in secretion granules, both in the free state or combined with LH-RH. Plasma membrane receptor, on the other hand, was free under the conditions of the experiments. Immunization with LH-RH elicits not only heteroimmune antibodies specific for LH-RH, but also a group of still ill defined autoimmune antibodies, some of which may conceivably be reactive with glycoprotein hormone alpha-chains.
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PMID:Quantitative immunocytochemistry of pituitary receptors for luteinizing hormone-releasing hormone. 5 7

Thyrotropin-releasing hormone (TRH) immunoreactivity was localized in the rat anterior pituitary with rabbit anti-TRH sera and the unlabeled antibody peroxidase-antiperoxidase complex (PAP) technique. Stain was present in secretory granules of cells possessing morphological characteristics of thyrotropes, gonadotropes and lactotropes. Antibody absorption studies with anti-TRH sera absorbed with TRH, 3 diastereoisomeric analogues of TRH, gonadotropin-releasing hormone (GnRH), bovine serum albumin, thyrotropin, prolactin, adrenocorticotropin, luteinizing hormone, follicle stimulating hormone were performed to determine the specificity of the staining reaction. Only absorption with TRH resulted in a significant reduction in staining intensity. In vitro experiments were then begun with hemipituitaries to ascertain if intrapituitary TRH might originate by sequestration of exogenous, plasma membrane bound TRH or by de novo synthesis. The results suggest that anterior pituitary TRH is of endogenous origin.
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PMID:Endogenous thyrotropin-releasing hormone in the anterior pituitary: sites of activity as identified by immunocytochemical staining. 8 70

A radioimmunoassay is described for the measurement of alpha-melanocyte-stimulating hormone (alpha-MSH). The antibody was produced in rabbits by immunization with alpha-MSH coupled to bovine serum albumin with carbodiimide. The antibody did not react significantly with ACTH, beta-MSH, or 6 fragments of ACTH. The sensitivity and reliability of the assay were improved by employing a simple plasma extraction procedure. When applied to a 2 ml plasma sample, the detection limit of the radioimmunoassay was 6 pg/ml. ACTH was measured with a sensitive and specific radioimmunoassay previously described for humans and adapted for the rat. The anti-ACTH serum cross-reacted with the biologically active portion of alpha-p ACTH and not with alpha-MSH, beta-MSH or the alpha-p 17-39 and alpha-p 25-39 fragments of ACTH. The detection limit was 20 pg/ml. Plasma and pituitary alpha-MSH and ACTH had the same immunoreactivity as synthetic alpha-MSH and ACTH. alpha-MSH and ACTH contents of the rat neurointermediate lobe were 1398 +/- 360 (SE) ng and 28.2 +/- 2.9 ng, respectively, while in the anterior lobe they were 102 +/- 31 ng and 551 +/- 36 ng, respectively. The plasma alpha-MSH concentration at 8 AM in male rats was 64 +/- 8 pg/ml when the plasma ACTH concentration was 92 +/- 15 pg/ml. Over a 24-hour period two peaks of plasma alpha-MSH were observed, one at 4 AM (142 +/- 35 pg/ml) and the other at 4 PM (139 +/- 26 pg/ml). Plasma ACTH was higher at noon (151 +/- 43 pg/ml) and 4 PM (130 +/- 48 pg/ml). Short-term exposure to ether induced a transient increase in alpha-MSH level 5 min later and a rapid return to normal levels. Plasma ACTH increased significantly 2.5 min after the onset of ether stress and remained high for 30 min. Two hours' exposure to ether did not change plasma alpha-MSH, although a 3-fold increase in plasma ACTH was observed. Haloperidol injection was followed by a large increase in plasma alpha-MSH, whereas ACTH levels increased similarly after saline and Haloperidol injection. Corticoid administration reduced ACTH, but not alpha-MSH. Three weeks after adrenalectomy, alpha-MSH levels had not changed but ACTH levels had increased ten-fold. These data indicate that alpha-MSH is secreted in the rat, and that the regulation of its secretion is different from that of ACTH.
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PMID:Immunoreactive alpha-MSH and ACTH levels in rat plasma and pituitary. 17 89

A corticotropin antiserum was obtained from rabbits immunized with synthetic 1--24 corticotropin conjugated with bovine serum albumin. The antiserum did not cross react with synthetic alpha-melanotropin or with synthetic beta-endorphin and had a cross reactivity of 0.23% with human beta-lipotropin. We developed a radioimmunoassay with the antiserum obtained, in which we used polyethylene glycol in conjunction with a second precipitating antibody for fast (15-min) separation of antibody-bound and free corticotropin. The assay had a sensitivity of 16 ng/L and was validated on patients with various pituitary and adrenal diseases. From 103 normal subjects, the median value for corticotropin in specimens collected during the morning was 34 ng/L of plasma; the upper 95% confidence limit of the normal range was 98 ng/L.
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PMID:Human corticotropin (ACTH) radioimmunoassay with synthetic 1--24 ACTH. 22 3

Acrylamide is an efficient quencher of tryptophanyl fluorescence which we report to be very discriminating in sensing the degree of exposure of this residue in proteins. The quenching reaction involves physical contact between the quencher and an excited indole ring, and can be kinetically described in terms of a collisional and a static component. The rate constant for the collisional component is a kinetic measure of the exposure of a residue in a protein, and values ranging from 4 X 10(9) M-1 S-1 for the fully exposed tryptophan in the polypeptide, adrenocorticotropin, to less than 5 X 10(8) M-1 S-1 for the buried residue in azurin have been found. Static quenching is readily detected in proteins that are denatured, or contain only a single fluorophor. Quenching patterns for most multi-tryptophan containing proteins are difficult to analyze precisely, but qualitative information can, nevertheless, be extracted. Applications of this probing technique for monitoring protein conformational changes, such as the acid-induced expansion of human serum albumin, and inhibitor binding to enzymes, are presented. The value of this method lies in its ability to sense not only the steady-state exposure of a residue in a protein, but also its dynamic exposure.
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PMID:Exposure of tryptophanyl residues in proteins. Quantitative determination by fluorescence quenching studies. 125 18

Several experiments were designed to evaluate a secondary humoral response following limbic seizures. After baseline antigen binding capacity (ABC) had been determined for the primary response, a second subcutaneous injection of the antigen (human serum albumin) was accompanied by an injection of either lithium (3 mEq/kg)-pilocarpine (30 mg/kg) or one of two comparator treatments: metrazol (30 mg/kg) or cyclophosphamide (50 mg/kg); other rats served as drug controls. Only the groups that received the lithium-pilocarpine (status epilepticus) or cyclophosphamide (no seizure) displayed significant immunosuppression after 5 but not 10 days. The results support the hypothesis that seizure activity within the amygdaloid-hippocampal complex modulates immunocompetence through corticotropin mechanisms.
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PMID:Transient suppression of a secondary humoral response in rats is evoked by lithium-pilocarpine-induced limbic seizures. 132 17

A method for primary culturing of rat anterior and intermediate/posterior pituitary cells in complete serum-free defined medium (CSFM) is described. Dispersed pituitary cells were prepared by using a multiple enzyme digestion system. Insulin, transferrin and serum albumin were essential additives for maintenance of primary rat pituitary cells in CSFM. Morphological immunocytochemical and RIA studies during three weeks' culture indicated that beta-endorphin-like immunoreactivity (beta-End-IR) was contained in and released from pituitary cells. The secretion rate remained almost constant for 2 weeks after the 5th day in culture. This method provides an ideal in vitro model for studying the effects of various factors on the synthesis and release of beta-endorphin in pituitary cells and the mechanism of regulation of other target gland hormones.
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PMID:[Primary culture of rat pituitary cells in serum-free medium]. 139 42

Receptor-mediated binding of leukocyte chemotactic peptide, N-formylMet-Leu-Phe (fMLP), occurs in the ciliated protozoon Tetrahymena thermophila. In vivo labelling of the cells with N-formylMet-Leu-[3H]Phe ([3H]fMLP) shows that the cells bind the ligand with high affinity (KD = 4 x 10(-9) M to 1 x 10(-8) M). Moreover, Scatchard transformations of the binding data show that there are about 5 x 10(5) binding sites per cell on the cell surface. Two fluorescent derivatives of leukocyte chemotactic peptide, N-dansylMet-Leu-Phe (dansMLP) and N-formylMet-Leu-Phe-(N-dansyl-)Lys (fMLPdanLys) compete for the N-formylMet-Leu-Phe (fMLP) binding sites on the cell surface. Moreover, both derivatives have retained significant chemoattracting potentials. Fluorescence from dansMLP, but not from fMLPdansLys and dansyl-beta-endorphin, is internalized preferentially into small vesicles. The differences may, however, reflect that the fluorescence from the dansyl group is strongly quenched by a hydrophilic microenvironment when using the two latter peptide derivatives. In contrast, the dansyl group from dansMLP must be assumed to be embedded in a hydrophobic microenvironment in the vesicular membrane or membrane protein. Rhodamine-labelled bovine serum albumin, egg albumin and cytochrome c as well as dansylated bovine serum albumin, which are poor chemoattractants, are preferentially seen to be internalized into large vesicles (food vacuoles).
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PMID:Chemotactic properties, cellular binding and uptake of peptides and peptide derivatives: studies with Tetrahymena thermophila. 147 55

To determine direct effects of epinephrine on adrenal cortisol secretion, bilateral adrenal glands were isolated from guinea pigs, together with bilateral kidneys, aorta, and inferior caval vein for influent and effluent routes. The preparation was perfused with oxygenated Krebs-Ringer bicarbonate solution (pH 7.4) containing 10 mM glucose, 0.2% bovine serum albumin, and 4.6% dextran. The perfusate cortisol level was elevated by the addition of epinephrine in a dose-dependent manner at concentrations greater than 100 pg/ml and increased eightfold as high as the basal level at 1 micrograms/ml epinephrine. The stimulatory effect of epinephrine on cortisol secretion was completely abolished by phentolamine, an alpha-adrenergic antagonist but was not affected by propranolol, a beta-adrenergic antagonist. These results demonstrate that epinephrine has a direct stimulatory effect on adrenal cortisol secretion via an alpha-adrenergic mechanism and also suggest that not only adrenocorticotropin but also epinephrine is a most important factor for the regulation of cortisol secretion.
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PMID:Epinephrine augments cortisol secretion from isolated perfused adrenal glands of guinea pigs. 161 17

Albumin binds circulating glucocorticoids such as cortisol and consequently may modify the biological activity of these steroids by altering access to target cells. Because albumin is likely present in pituitary interstitial fluid, this study was designed to compare the negative feedback effect of cortisol on pituitary adrenocorticotropic hormone (ACTH) secretion from isolated sheep pituitary cells perifused with media containing 0.25% or 2% bovine serum albumin (BSA). Pituitary cells released less (P less than 0.05) immunoreactive ACTH in response to a 10-min treatment with 10 nM ovine corticotropin-releasing hormone (oCRH) after 45 min pretreatment with 0.5 microM cortisol when media contained 2% BSA vs. 0.25% BSA. A similar enhancement in negative feedback potency was observed when cells were treated with cortisol followed by 1 nM oCRH for 60 min, with an additional 10 min co-addition of arginine vasopressin. This potentiation was not observed when a noncortisol binding protein, ovalbumin, was substituted for BSA. However, the potentiating effect of albumin was present in perifused rat pituitary cells, indicating that the effect was not species specific. We conclude that albumin enhances the negative feedback potency of cortisol in anterior pituitary corticotrophs and that the process may operate under physiological conditions to enhance cell specific delivery of this steroid to appropriate targets.
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PMID:Albumin enhances negative feedback effect of cortisol on ACTH release from sheep pituitary cells. 165 90


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