ABILITY OF VARIOUS FACTORS TO OPPOSE THE STIMULATORY EFFECT OF DIBUTYRYL CYCLIC AMP ON THE RELEASE OF MELANOCYTE-STIMULATING HORMONE BY THE RAT PITUITARY IN VITRO

1976 ◽  
Vol 68 (2) ◽  
pp. 283-287 ◽  
Author(s):  
BRIDGET I. BAKER
Keyword(s):  
Cyclic Amp ◽  
Cyclic Gmp ◽  
Inhibitory Effect ◽  
Aminobutyric Acid ◽  
Intermediate Lobe ◽  
Dibutyryl Cyclic Amp ◽  
Melanocyte Stimulating Hormone ◽  
Rat Pituitary ◽  
Stimulating Hormone

SUMMARY Various agents were tested for their ability to oppose the stimulatory effect of dibutyryl cyclic AMP on the release of the melanocyte-stimulating hormone from the rat neuro-intermediate lobe in vitro. Only dopamine exhibited an inhibitory effect; serotonin, γ-aminobutyric acid, tocinoic acid, tocinamide, the tripeptide Pro-Leu-Gly-NH2 and dibutyryl cyclic GMP were all ineffective.

EFFECT OF DIBUTYRYL CYCLIC AMP ON THE RELEASE OF MELANOCYTE-STIMULATING HORMONE FROM RAT NEUROINTERMEDIATE LOBES IN VITRO

1974 ◽  
Vol 63 (3) ◽  
pp. 533-538 ◽  
Author(s):  
BRIDGET I. BAKER
Keyword(s):  
Cyclic Amp ◽  
Gel Electrophoresis ◽  
Incubation Medium ◽  
Polyacrylamide Gel Electrophoresis ◽  
Polyacrylamide Gel ◽  
Dibutyryl Cyclic Amp ◽  
Melanocyte Stimulating Hormone ◽  
Low Concentrations ◽  
Stimulating Hormone

SUMMARY A method for measuring melanocyte-stimulating hormone (MSH) in rat neurointermediate lobe in vitro and in incubation medium, using polyacrylamide gel electrophoresis, is described. Using this technique, it was shown that dibutyryl cyclic AMP increased the release of MSH in vitro, the degree of stimulation depending on the concentration of the nucleotide. The effect of low concentrations of the nucleotide was potentiated by theophylline.

INTERACTION OF α-MELANOCYTE-STIMULATING HORMONE, MELATONIN, CYCLIC AMP AND CYCLIC GMP IN THE CONTROL OF MELANOGENESIS IN HAIR FOLLICLE MELANOCYTES IN VITRO

1981 ◽  
Vol 90 (1) ◽  
pp. 89-96 ◽  
Author(s):  
BRIAN WEATHERHEAD ◽  
ANN LOGAN
Keyword(s):  
Cyclic Amp ◽  
Cyclic Gmp ◽  
Phosphodiesterase Inhibitors ◽  
Hair Follicles ◽  
Tyrosinase Activity ◽  
Melanin Production ◽  
Melanocyte Stimulating Hormone ◽  
Dependent Mechanism ◽  
Stimulating Hormone

In short-term (48 h) cultures of hair follicles α-melanocyte-stimulating hormone (α-MSH) and cyclic AMP stimulated melanogenesis through an increase in tyrosinase activity. In contrast cyclic GMP mimicked the effects of melatonin by inhibiting melanin production without causing a concomitant decrease in tyrosinase activity. Both cyclic GMP and melatonin blocked the stimulatory effects of cyclic AMP and α-MSH on melanin production but they left the increased levels of tyrosinase activity unaffected. Phosphodiesterase inhibitors (3-isobutyl-1-methylxanthine and papaverine) simultaneously stimulated tyrosinase activity and inhibited melanin production, presumably by allowing endogenous cyclic AMP and cyclic GMP to accumulate intracellularly. It is suggested that whereas MSH stimulates melanogenesis through a cyclic AMP-dependent mechanism there must also be an inhibitory cyclic GMP-dependent mechanism, perhaps activated by melatonin, which operates at some post-tyrosinase step in the melanin biosynthetic pathway.

scholarly journals TWO ACTIONS OF CYCLIC AMP ON MELANOSOME MOVEMENT IN FROG SKIN

1973 ◽  
Vol 57 (3) ◽  
pp. 845-858 ◽  
Author(s):  
Bruce Magun
Keyword(s):  
Cyclic Amp ◽  
Frog Skin ◽  
Cytochalasin B ◽  
Motive Force ◽  
Dibutyryl Cyclic Amp ◽  
Hormonal Stimulation ◽  
Melanocyte Stimulating Hormone ◽  
Skin Lightening ◽  
Stimulating Hormone

Photomicrography and reflectance microphotometry were used to monitor melanosome movement in frog skin melanocytes in vitro in response to hormonal stimulation and cytochalasin B (CB). Melanocyte-stimulating hormone (MSH), theophylline, and dibutyryl cyclic AMP (DiBcAMP) induced melanosome dispersion (darkening) which was promptly arrested by cytochalasin B in concentrations of 5–20 µg/ml. Melanosome aggregation (skin lightening) occurred only after removal of the darkening agent (MSH, theophylline, or DiBcAMP) and proceeded in the presence or absence of CB. When CB was added to darkened skins, they did not lighten and melanosomes remained in the dispersed state. Use of CB has permitted the dissection of cyclic AMP-mediated melanosome dispersion into two distinct events. The first, induction of melanosome dispersion, is CB sensitive. The second action of intracellular cyclic AMP involves an uncoupling of the centripetal motive force, and is CB insensitive. In the latter process, production of cyclic AMP appears to produce the same result as application of microtubule-disrupting agents.

INCORPORATION OF 14C-LABELLED AMINO ACIDS INTO CORTICOTROPHIN-LIKE INTERMEDIATE LOBE PEPTIDE AND α-MELANOCYTE-STIMULATING HORMONE BY THE RAT PITUITARY NEUROINTERMEDIATE LOBE IN VITRO, AND THE IDENTIFICATION OF FOUR NEW PARS INTERMEDIA PEPTIDES

1976 ◽  
Vol 70 (2) ◽  
pp. 197-205 ◽  
Author(s):  
A. P. SCOTT ◽  
P. J. LOWRY ◽  
TJ. B. VAN WIMERSMA GREIDANUS
Keyword(s):  
Amino Acids ◽  
The Other ◽  
Pars Intermedia ◽  
Intermediate Lobe ◽  
Melanocyte Stimulating Hormone ◽  
Neurointermediate Lobe ◽  
Rat Pituitary ◽  
Stimulating Hormone

SUMMARY At least seven radioactive peptides, which fractionated on Biogel P6, were found in rat neurointermediate lobes after incubation for 6 h with [14C]proline. Only three of these could be tentatively identified; one as α-melanocyte-stimulating hormone (α-MSH) and two as forms of corticotrophin-like intermediate lobe peptide (CLIP). One other crossreacted partially with a β-melanocyte-stimulating hormone (β-MSH) antiserum, was acidically charged and eluted on Biogel P6 in roughly the same position as ACTH. The other three peptides showed no resemblance to α-MSH, CLIP, β-MSH or ACTH.

Effect of Cyclic AMP and Cyclic GMP on Thromboplastin (Factor III) Synthesis in Human Monocytes In Vitro

1983 ◽  
Vol 50 (04) ◽  
pp. 804-809 ◽  
Author(s):  
Torstein Lyberg
Keyword(s):  
Cyclic Amp ◽  
Cyclic Gmp ◽  
Immune Complexes ◽  
Phosphodiesterase Inhibitors ◽  
Inhibitory Effect ◽  
Intracellular Camp ◽  
Human Monocytes ◽  
Purified Protein Derivative ◽  
A 23187

SummaryHuman monocytes in vitro respond to various agents (immune complexes, lectins, endotoxin, the divalent ionophore A 23187, 12-0-tetradecanoyl-phorbol 13-acetate [TPA], purified protein derivative [PPD] of Bacille Calmette-Guerin) with an increased synthesis of the protein component of thromboplastin. The effect of cyclic AMP and cyclic GMP on this response has been studied. Dibutyryl-cyclic AMP, prostaglandin E1 and the phosphodiesterase inhibitors 3-butyl-1-methyl-xanthine (MIX) and rac -4-(3-butoxy-4-methoxybenzyl)-2-imidazolidinone (Ro 201724), separately and in combination have a pronounced inhibitory effect on the response to immune complexes and PPD, and a moderate effect on the response to endotoxin and lectins. The effect on TPA response and on the response to A 23187 was slight. Dibutyryl-cyclic GMP (1 mM) gave a slight inhibition of the TPA arid IC response, but had essentially no effect on the response to other inducers. The intracellular cAMP level increased when monocytes were incubated with IC, TPA or A 23187 followed by a decrease to basal levels within 1-2 hr, whereas lectin (PHA) and PPD did not induce such changes. The cAMP response to endotoxin varied. Stimulation with IC induced an increase in monocyte cGMP levels, whereas the other stimulants did not cause such changes.

Follicle-stimulating hormone-induced prostaglandin E formation in isolated rat ovarian theca

1983 ◽  
Vol 97 (1) ◽  
pp. 43-49 ◽  
Author(s):  
U. Zor ◽  
B. Strulovici ◽  
R. Braw ◽  
H. R. Lindner ◽  
A. Tsafriri
Keyword(s):  
Cyclic Amp ◽  
Cyclic Gmp ◽  
Follicle Stimulating Hormone ◽  
Fold Increase ◽  
Prostaglandin E ◽  
Β Subunit ◽  
Biochemical Effects ◽  
Isolated Rat ◽  
Stimulating Hormone

The aim of this study was to search for direct biochemical effects of highly purified FSH on isolated ovarian follicular theca in vitro. Granulosa cells (GC; approximately 1 × 105 cells per follicle) were flushed from isolated follicles of pro-oestrous rats. The remaining theca layer and the isolated GC were incubated with highly purified ovine FSH. Prostaglandin E (PGE) accumulation was measured by radioimmunoassay. Follicle-stimulating hormone induced a 15-fold increase in PGE accumulation over the basal level in the follicular theca, the stimulated rate exceeding threefold that observed in the GC fraction derived from the same follicle. Follicle-stimulating hormone caused no significant increase in cyclic AMP level or steroidogenesis in the theca layer, but was active on these parameters in the GC. In contrast, LH increased the accumulation of cyclic AMP, progesterone and testosterone, as well as of PGE, in follicular theca. Exogenous 8-bromo cyclic AMP or cyclic GMP also stimulated PGE production in follicular theca or GC, but FSH was without any effect on the level of endogenous cyclic GMP in GC or follicular theca. Antibodies to FSH prevented the effect of FSH (but not that of LH) on PGE formation by follicular theca and GC, while antibodies to the β-subunit of LH blocked the effect of LH but not of FSH. We conclude that highly purified FSH has a stimulatory effect on PGE formation by the follicular theca.

scholarly journals Effect of phenylpyruvate on enzymes involved in fatty acid synthesis in rat brain

1973 ◽  
Vol 134 (2) ◽  
pp. 557-563 ◽  
Author(s):  
D. J. Deery ◽  
K. W. Taylor
Keyword(s):  
Cyclic Amp ◽  
Insulin Release ◽  
Acid Synthesis ◽  
Inhibitory Effect ◽  
Dibutyryl Cyclic Amp ◽  
Cell Content ◽  
Nad Synthesis ◽  
Arginine Hydrochloride ◽  
Rat Islets Of Langerhans

1. The effects of azaserine and nicotinamide, agents which inhibit and stimulate hepatic NAD synthesis respectively, on the content of NAD+ and NADH in isolated rat islets of Langerhans incubated in vitro were studied. The effects of these compounds on the rates of insulin release, from isolated islets incubated in vitro, in response to various secretagogues were also measured. 2. Preincubation of islets in the presence of azaserine (0.3mm) caused a marked depletion of the normal islet-cell content of both NAD+ and NADH and prevented the secretion of insulin in response to stimulatory concentrations of d-glucose, xylitol, d-xylulose, l-arginine hydrochloride and l-leucine. 3. Preincubation of islets in the presence of nicotinamide (2mm) increased the islet content of NAD+ and enhanced the rate of release of insulin in response to d-glucose. Also when nicotinamide was present the inhibitory effect of azaserine on insulin release and the azaserine-induced depletion of the islet content of NAD+ and NADH was prevented. 4. Preincubation with azaserine was without effect on the stimulation of insulin release caused by theophylline or dibutyryl cyclic AMP. 5. It is suggested that insulin release caused by sugars and amino acids is dependent on the maintenance of NAD concentrations, though this may not be the case for release due to theophylline and dibutyryl cyclic AMP.

Effects of an ATP analogue (α,β-methylene-adenosine-5′-triphosphate) on cyclic AMP and cyclic GMP levels, 45Ca efflux, and protein secretion from rat pancreas

1976 ◽  
Vol 54 (5) ◽  
pp. 692-697 ◽  
Author(s):  
Seymour Heisler
Keyword(s):  
Cyclic Amp ◽  
Cyclic Gmp ◽  
Calcium Ionophore ◽  
Competitive Inhibitor ◽  
The Other ◽  
Dibutyryl Cyclic Amp ◽  
Onset Of Action ◽  
Rat Pancreas ◽  
A 23187

The effects of the α,β-methylene analogue of ATP (Ap(CH2)pp), described as a competitive inhibitor of adenylate cyclase (EC 4.6.1.1), were studied in the rat pancreas in vitro. The analogue did not alter basal cyclic AMP production and basal or carbachol-stimulated efflux of 45Ca from isotope-preloaded glands. On the other hand, Ap(CH2)pp reduced the secretory responses to carbachol, carbachol in the presence of dibutyryl cyclic AMP, pancreozymin (PZ), and the calcium ionophore, A-23187. Release of pancreatic protein in response to dibutyryl cyclic AMP itself was unaffected by the ATP analogue, suggesting that the other secretagogues tested share a common, Ap(CH2)pp-inhibitable pathway in their respective stimulatory actions. Though carbachol, PZ, and A-23187 all stimulated a rapid production (30 s) of pancreatic cyclic GMP, these responses were not affected by Ap(CH2)pp. Additional studies with the analogue indicated that it has a slow onset of action (30–45 min), i.e., its effect on secretion is preceded by secretagogue-induced changes in nucleotide levels and calcium efflux. Nonetheless, the analogue may affect cellular calcium homeostasis, if not during the initial events triggering secretion, then during those events which maintain continued secretory output in the presence of a stimulus.

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