beta-Lipotropin: localization of cells and axons in rat brain by immunocytochemistry.
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Using specific antisera to human beta-lipotropin, we have visualized cells and axons with beta-lipotropin-like immunoreactivity in rat brain and pituitary. The beta-lipotropin so localized is well delineated and contained in the cytoplasm of cells and in beaded axons. Areas of greatest beta-lipotropin content are hypothalamus (with cell bodies in the medial basal hypothalamus and arcuate regions), periventricular nucleus of the thalamus, ansa lenticularis, zona compacta of the substantia nigra, medial amygdaloid nucleus, zona incerta, periaqueductal central gray area, locus ceruleus, and a few fibers in the reticular formation. The question of the exact relationship of beta-lipotropin and methionine-enkephalin remains open, because some brain areas contain both substances and some areas contain only one or the other. (+info)
Human beta-endorphin and beta-lipotropin levels in maternal and fetal plasma and amniotic fluid.
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We measured beta-endorphin (beta-EP) and beta-lipotropin (beta-LPH) levels in human maternal and fetal plasma and amniotic fluid, simultaneously. It appeared evident that maternal circulating levels of beta-EP (n = 11, 163.9 +/- 12.9 pg/ml, mean +/- S.E.) and beta-LPH (n = 11, 413.0 +/- 25.9 pg/ml) at delivery were significantly (p less than 0.01) higher than those of maternal plasma at term (beta-EP; n = 4, 18.3 +/- 2.1 pg/ml, beta-LPH; 213.4 +/- 24.3 pg/ml) and those of amniotic fluid (beta-EP; n = 5, 8.5 +/- 1.2 pg/ml, beta-LPH; 215.1 +/- 44.9 pg/ml). Fetal beta-EP levels (n = 11, 79.1 +/- 5.8 pg/ml) were significantly (p less than 0.01) higher than those of amniotic fluid. These data suggest that the origin of amniotic fluid beta-EP may be an increased synthesis in the maternal and fetal pituitary gland but not in the placenta. (+info)
Distribution of active and inactive forms of endorphins in rat pituitary and brain.
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The recent isolation and identification of alpha-N-acetyl forms of the C-Fragment of lipotropin (beta-endorphin, residues 61-91) and the C'-Fragment (residues 61-87) [Smyth, D.G., Massey, D.E., Zakarian, S. & Finnie, M. (1979) Nature (London) 279, 252-254] has led to a study of their distribution in the pituitary and brain of the rat. Regions were mapped by the method of immunofluorescent staining and the reactive peptides were determined by immunoassay after extraction, gel filtration, and ion exchange chromatography. The major immunoreactive peptides in both lobes of the pituitary were found to be C'-Fragment and N-acetyl C'-Fragment, which are weakly active or inactive as opiates; the C-Fragment and its N-acetyl derivative represented minor components. This indicates that in the rat the circulating "endorphins" released from pituitary would have little morphinomimetic activity. The same four immunoreactive peptides were observed in rat brain. In the hippocampus the C'-Fragment was the principal component in the midbrain there was more C-Fragment but C'-Fragment predominated; in the hypothalamus the C-Fragment was the major peptide, almost to the exclusion of the other peptides. The results demonstrate that the processing of lipotropin is under differential control in anatomically distinct regions of the central nervous system. The processing of lipotropin in the hypothalamus is directed specifically to the production of lipotropin C-Fragment. (+info)
The mechanism of functional vasodilatation in rabbit epigastric adipose tissue.
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1. The effect of close-arterial infusions of fat-mobilizing substances has been examined on the release of free fatty acids and blood flow in the epigastric adipose tissue of rabbits.2. All the fat mobilizers in addition to causing the release of free fatty acids also caused an increased blood flow in the fat tissue.3. Both the fat mobilization and the vasodilatation continued for an hour or so after the end of infusion.4. Although no vasodilator substance could be detected in the venous effluent from the activated adipose tissue, a vasodilator could be detected in acid-ether extracts of adipose tissue excised during a period of fat mobilization.5. It is suggested that a vasodilator substance is released or formed in adipose tissue during fat mobilization and that this substance accounts for the vasodilatation accompanying activity in the tissue. (+info)
Human somatotropin and lipotropin: relation between structure and activity.
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Hormones of the anterior pituitary gland have been divided into three groups according to their chemical and biologic properties. Recent advances in knowledge of the relation between structure and activity of human somatotropin and beta-lipotropin are discussed. (+info)
Adrenocorticotrophic and melanocyte-stimulating peptides in the human pituitary.
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The adrenocorticotrophic and melanocyte-stimulating peptides of the human pituitary were investigated by means of radioimmunoassay, bioassay and physicochemical procedures. Substantial amounts of adrenocorticotrophin and a peptide resembling beta-lipotrophin were identified in pituitary extracts, but alpha-melanocyte-stimulating hormone, beta-melanocyte-stimulating hormone and corticotrophin-like intermediate lobe peptide, which have been identified in the pars intermedia of pituitaries from other vertebrates, were not found. The absence of beta-melanocyte-stimulating hormone appears to contradict previous chemical and radioimmunological studies. Our results suggest, however, that it is not a natural pituitary peptide but an artefact formed by enzymic degradation of beta-lipotrophin during extraction. (+info)
Synthesis of a pentekontapeptide with high lipolytic activity corresponding to the carboxyl-terminal fifty amino acids of ovine beta-lipotropin.
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The synthesis of a peptide, composed of fifty amino-acid residues, corresponding to positions 42-91 in ovine beta-lipotropin has been accomplished by the solidphase method. The preformed symmetrical anhydride and active ester coupling methods were used exclusively. The synthetic product was purified by gel filtration, carboxymethylcellulose chromatography, and partition chromatography on Sephadex G-50. Its lipolytic activity in isolated rabbit fat cells was about six times that of beta-lipotropin on a weight basis. (+info)
Characterization of mouse tumor cell beta-lipotropin.
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Mouse tumor cell beta-lipotropin (beta LPH) and gamma-lipotropin (gamma LPH) were purified from mouse pituitary tumor cell culture medium by ion exchange chromatography and gel filtration. The mouse tumor cell beta LPH was identified by immunoprecipitation with several antisera to beta-endorphin, generation of opioid bioactivity upon brief treatment with trypsin, and its identity with the molecule previously shown to serve as an intermediate in the biosynthesis of beta-endorphin. Mouse tumor cell beta LPH (Mr = 8200 +/- 250) and gamma LPH (Mr = 4600 +/- 200) are significantly smaller than known mammalian beta LPH (Mr = 10,000) and gamma LPH (Mr = 6300) molecules. The beta-endorphin region of mouse tumor cell beta LPH has the same amino acid composition as ovine, bovine, and camel beta-endorphin, and species-specific differences are thus located in the gamma LPH region of the molecule. Mouse tumor cell beta LPH and gamma LPH lack a methionine residue at what had been considered to be a highly conserved site in their beta-melanotropin-like region. A species-specific radioimmunoassay for mouse tumor cell gamma LPH was developed. Rat pituitary beta LPH and gamma LPH were shown to be similar to the corresponding mouse tumor cell molecules in size and lack of methionine in their beta-melanotropin-like segment. (+info)