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At least 19 recordsLinked to original sources
PubMed1978

Ultrastructure and morphometry of ACTH-producing cell in the rat anterior pituitary gland stimulated by lysin-vasopressin and prostaglandin E1.

The aim of this study was to investigate the qualitative and quantitative changes of ACTH-cells in the rat after application of a specific and a non-specific stimulus. A CRF-analog (lysin-vasopressin) and a prostaglandin (prostaglandin E1) were used. 40 rats were injected lysin-vasopressin or prostaglandin E1, respectively, for 4 weeks. The pituitary glands were investigated by means of light microscopy, electron microscopy and morphometry. Activation of the ACTH-cells could be observed after use of both substances, the effect of lysin-vasopressin being more intense than that of prostaglandin E1. Enlargement of the nucleus, the cytoplasm and the organelles involved in hormone-production and -transport were found and verified by morphometry. Additionally an increase in number of the cells could be demonstrated. Prostaglandin influenced not only ACTH-cells, but also other cells of the anterior pituitary.

Adrenocorticotropic Hormone↗
PubMed1978

Hypothalamic-pituitary functions in patients with idiopathic pituitary dwarfism. Further evidence for hypophysiotropic human deficiencies.

Somatotropic, thyrotropic, gonadotropic and corticotropic functions in 10 patients with idiopathic hypopituitary dwarfism (IH) were investigated. The patients were divided into two groups: Group I (5 patients) had normal plasma T4 levels, and Group II (5 patients) had T4 levels of less than 4.6 microgram/dl. In Group I three cases had isolated growth hormone (GH) deficiency and two cases had GH and gonadotropin (Gn) deficiencies; in Group II the 5 cases showed multiple anterior pituitary hormone deficiencies. In Group II, the plasma thyroid stimulating hormone (TSH) was 4.1-9.4 muU/ml and the response to thyrotropin releasing hormone (TRH) was greatly delayed and prolonged, with a maximum after 120 min instead of 15 min. The basal prolactin (PRL) level in Group II was 12-31 ng/ml, which was significantly higher than normal (P less than 0.001). In 4 cases in Group II, the plasma cortisol level increased 120 min after the infusion of lysine-vasopressin, whereas oral administration of metyrapone and hypoglycemia induced by insulin did not increase the plasma cortisol levels. From these findings it is concluded that hypothalamic lesions caused the pituitary hormone deficiencies in 4 Group II cases, and Group I may tentatively be differentiated from Group II by T4 determinations.

Adolescent↗
PubMed1976

Partial purification and characterization of post-proline cleaving enzyme: enzymatic inactivation of neurohypophyseal hormones by kidney preparations of various species.

The inactivation of the neurohypophyseal hormones arginine vasopressin and oxytocin, both 14C-labelled in the C-terminal glycine residue, by enzymes present in kidney homogenates of various species has been investigated, and some of the enzymes responsible have been partially purified and characterized. The Leu-Gly peptide bond of oxytocin is generally most effectively cleaved by kidney homogenates, although with certain species enzymic activity hydrolyzing the Pro-Leu bond is significant. Degradation of arginine vasopressin is slower than oxytocin in all species studied, and appears to occur by a different overall mechanism since cleavage of the Pro-Arg bond is more significant than hydrolysis of the Arg-Gly bond. The enzyme releasing glycinamide from oxytocin and the "Post-Proline Cleaving Enzyme", which releases C-terminal dipeptide from oxytocin and arginine vasopressin, were partially purified from lamb kidney by ammonium sulfate fractionation and column chromatography. The two enzymes are shown to be separate entities with different pH profiles. The prolyl peptidase activity released the C-terminal dipeptides from oxytocin and arginine vasopressin at similar rates and was inhibited by p-chloromercuriphenylsulfonic acid, 1,10-phenanthroline, L-1-tosylamido-2-phenylethylchloromethyl ketone, Co2+, Ca2+, and Zn2+, but significantly enhanced by dithiothreitol. The prolyl peptidase preparation cleaves proline-containing peptide substrates at the Pro-X bond. The rate of cleavage is dependent on the nature of residue X and with the conditions used there is no cleavage when X equals Pro; however, cleavage occurs when X is a D isomer: [Mpr1, D-Arg8] vasopressin is inactivated at a rate similar to [Mpr1, Arg8]- and [Mpr1, Lys8] vasopressin, suggesting that the known prolonged biological action of [Mpr1, D-Arg8] vasopressin is not due to resistance to the prolyl peptidase. In all characteristics tested the lamb kidney prolyl peptidase was identical to the post-proline cleaving enzyme isolated earlier from human uterus. In vivo experiments in the cat suggested that both the glycinamide-releasing enzyme and post-proline cleaving enzyme are present and effective in inactivating neurohypophyseal hormones in the intact animal.

Animals↗
PubMed1978

Specificity and inhibition studies of Armillaria mellea protease.

The action of Armillaria mellea protease has been evaluated on a number of polypeptide substrates. It has been shown to split the Pro7-Lys8 bonds in both native and oxidised lysine-vasopressin and the Ser11-Lys12 bond in glucagon. No other splits were detected in these substrates. The enzyme also caused extensive degradation of S-carboxymethyl lysozyme, S-carcoxymethyl pepsinogen and oxidised ribonuclease. A. In each case the only new amino-terminal residue to appear was lysine. A. mellea protease was inhibited by the chelating agents 1,10-phenanthroline, alpha, alpha'-bipyridine and imidazole. The pK1 values (negative log10 of concentration required for 50% inhibition) for these three inhibitors were 3.9, 3.4 and 1.1, respectively. Lysine, S-2-aminoethylcysteine and short chain aliphatic amines also proved to be relatively good inhibitors of A. mellea protease while arginine was a poor inhibitor.

Amines↗
PubMed1977

Parallel changes in behaviour and hippocampal serotonin metabolism in rats following treatment with desglycinamide lysine vasopressin.

Application of a foot shock during the acquisition trial of a one-trial passive avoidance task is associated with a rise in the concentration of serotonin in the hippocampus 24 h after conclusion of the acquisition trial. Carbon dioxide (CO2) induces amnesia for the passive avoidance response when administered immediately upon termination of the acquisition trial. In rats subjected to CO2 treatment following foot shock the rise in hippocampal serotonin is not observed 24 h later. The vasopressin analogue desglycinamide lysine vasopressin attenuates CO2-induced amnesia for the passive avoidance response when given prior to either the acquisition or the retrieval test (24 h after acquisition). This attenuation of the passive avoidance response is associated with a rise in the hippocampal serotonin concentration similar to the one observed in non-amnesic animals. It is suggested that a correlation exists between changes in hippocampal serotonin metabolism and the retrievability of the passive avoidance response.

Amnesia, Retrograde↗
PubMed1978

Some biological properties of an "irreversible" antagonist of neurohypophyseal hormones, deamino-[Phe(4-BrCH2CONH)2]-oxytocin, and its isosteric analogue, deamino-[Phe(4-CH3CH2CONH)2]-oxytocin.

The 2-p-bromoacetylaminophenylalanine analogue of deamino-oxytoxin displayed some features of an irreversible inhibitor of oxytocin on rat uterus (long persistence of inhibitory effect, slow wash-out from the tissue). An isosteric analogue with a propionylamino group at the same position was, under similar experimental conditions, also an antagonist of oxytocin, but the features of an irreversible inhibitor were lacking. pA2 values of the two substances are between 6.5 and 6.9. The "irreversibility" of the former compound is concentration dependent and it is concluded that it cannot be entirely caused by a covalent binding of the inhibitor to the uterus receptor for oxytoxin. Like many other similar inhibitors, the substances display only an inefficient in vivo inhibition of the vasopressor effect of lysine vasopressin in rats.

Animals↗
PubMed1976

Dorsal hippocampus: a site of action of neuropeptides on avoidance behavior?

Vasopressin and ACTH 4-10 induce a dose dependent long-term, respectively short-term inhibition of extinction of a pole jumping avoidance response in animals with sham lesions in the antero-dorsal hippocampus. Small lesions, causing a restricted damage in this area of the brain, partly inhibit the behavioral effect of vasopressin. Extensive lesions in the antero-dorsal hippocampus completely prevent the inhibitory effects of vasopressin and of ACTH 4-10 on extinction of the avoidance response. The extensive lesions in the dorsal hippocampus complex do not interfere with the rate of extinction, but acquisition of the response is retarded. These observations do not allow the conclusion that the hippocampal complex is the locus of action of neuropeptides in relation to avoidance behavior; it is more likely that this brain region is but one site of behavioral action of these hormones, and that the limbic system needs to be intact to permit the neuropeptides to exert their behavioral effects.

Adrenocorticotropic Hormone↗