STIMULATION OF ANTERIOR PITUITARY AND CEREBRAL CORTICAL GLUCOSE OXIDATION BY NEUROHUMORAL AGENTS

Endocrinology ◽  
1961 ◽  
Vol 69 (4) ◽  
pp. 809-818 ◽  
Author(s):  
SAMUEL H. BARONDES ◽  
PHYLLIS JOHNSON ◽  
JAMES B. FIELD
Keyword(s):  
Anterior Pituitary ◽  
Glucose Oxidation ◽  
Stimulation Of

scholarly journals Biosynthesis of growth hormone in the rat anterior pituitary gland. Stimulation of biosynthesis in vitro by insulin

1973 ◽  
Vol 134 (4) ◽  
pp. 1103-1113 ◽  
Author(s):  
A. Betteridge ◽  
M. Wallis
Keyword(s):  
Growth Hormone ◽  
Anterior Pituitary ◽  
Rna Synthesis ◽  
Glucose Utilization ◽  
Actinomycin D ◽  
Hormone Synthesis ◽  
Pituitary Glands ◽  
Hormone Biosynthesis ◽  
Stimulation Of

The effect of insulin on the incorporation of radioactive leucine into growth hormone was investigated by using rat anterior pituitary glands incubated in vitro. A 50% stimulation over control values was observed at insulin concentrations above 2μm (280munits/ml). The effect was specific for growth hormone biosynthesis, over the range 1–5μm-insulin (140–700munits/ml). Lower more physiological concentrations had no significant effect in this system. Above 10μm (1.4 units/ml) total protein synthesis was also increased. The stimulation of growth hormone synthesis could be partially blocked by the addition of actinomycin D, suggesting that RNA synthesis was involved. Insulin was found to stimulate the rate of glucose utilization in a similar way to growth hormone synthesis. 2-Deoxyglucose and phloridzin, which both prevented insulin from stimulating glucose utilization, also prevented the effect of insulin on growth hormone synthesis. If glucose was replaced by fructose in the medium, the effect of insulin on growth hormone synthesis was decreased. We conclude that the rate of utilization of glucose may be an important step in mediating the effect of insulin on growth hormone synthesis.

scholarly journals Subplasmalemmal hydrogen peroxide triggers calcium influx in gonadotropes

2018 ◽  
Vol 293 (41) ◽  
pp. 16028-16042 ◽  
Author(s):  
An K. Dang ◽  
Nathan L. Chaplin ◽  
Dilyara A. Murtazina ◽  
Ulrich Boehm ◽  
Colin M. Clay ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Calcium Channels ◽  
Nadph Oxidase ◽  
Calcium Channel ◽  
Anterior Pituitary ◽  
Calcium Influx ◽  
Ros Generation ◽  
Primary Mouse ◽  
The Impact ◽  
Stimulation Of

Gonadotropin-releasing hormone (GnRH) stimulation of its eponymous receptor on the surface of endocrine anterior pituitary gonadotrope cells (gonadotropes) initiates multiple signaling cascades that culminate in the secretion of luteinizing and follicle-stimulating hormones, which have critical roles in fertility and reproduction. Enhanced luteinizing hormone biosynthesis, a necessary event for ovulation, requires a signaling pathway characterized by calcium influx through L-type calcium channels and subsequent activation of the mitogen-activated protein kinase extracellular signal-regulated kinase (ERK). We previously reported that highly localized subplasmalemmal calcium microdomains produced by L-type calcium channels (calcium sparklets) play an essential part in GnRH-dependent ERK activation. Similar to calcium, reactive oxygen species (ROS) are ubiquitous intracellular signaling molecules whose subcellular localization determines their specificity. To investigate the potential influence of oxidant signaling in gonadotropes, here we examined the impact of ROS generation on L-type calcium channel function. Total internal reflection fluorescence (TIRF) microscopy revealed that GnRH induces spatially restricted sites of ROS generation in gonadotrope-derived αT3-1 cells. Furthermore, GnRH-dependent stimulation of L-type calcium channels required intracellular hydrogen peroxide signaling in these cells and in primary mouse gonadotropes. NADPH oxidase and mitochondrial ROS generation were each necessary for GnRH-mediated stimulation of L-type calcium channels. Congruently, GnRH increased oxidation within subplasmalemmal mitochondria, and L-type calcium channel activity correlated strongly with the presence of adjacent mitochondria. Collectively, our results provide compelling evidence that NADPH oxidase activity and mitochondria-derived hydrogen peroxide signaling play a fundamental role in GnRH-dependent stimulation of L-type calcium channels in anterior pituitary gonadotropes.

THE GROWTH OF THE VENTRAL AND DORSOLATERAL PROSTATE, THE COAGULATING GLANDS AND THE SEMINAL VESICLES IN FORCE-FED HYPOPHYSECTOMIZED CASTRATED ADRENALECTOMIZED RATS INJECTED WITH CORTISONE AND/OR INSULIN

1972 ◽  
Vol 71 (1) ◽  
pp. 179-190 ◽  
Author(s):  
Lars-Eric Tisell ◽  
Lennart Angervall
Keyword(s):  
Histological Examination ◽  
Anterior Pituitary ◽  
Adrenal Glands ◽  
Reproductive Organs ◽  
Seminal Vesicles ◽  
The Other ◽  
Protamine Zinc Insulin ◽  
Adrenalectomized Rats ◽  
Stimulation Of

ABSTRACT The growth of the ventral and dorsolateral prostate, the coagulating glands and the seminal vesicles was studied in force-fed hypophysectomized castrated adrenalectomized rats following daily injections for fourteen days of protamine zinc insulin or cortisone acetate alone or in combination. Cortisone was given in daily doses of 3 mg and insulin was administered in increasing daily doses of protamine zinc insulin up to 8 IU. Cortisone alone induced slight histological stimulation of the epithelium of the coagulating glands, while no stimulation was demonstrated in the other accessory reproductive organs. After insulin alone the weight of the accessory reproductive organs was slightly increased but no stimulation was demonstrated histologically. Cortisone and insulin given in combination induced distinct signs of stimulation of all the accessory reproductive organs as assesed by histological examination and weight determination of the organs. The results indicate that in the rat the growth stimulating effect of cortisone on the male accessory reproductive organs is markedly decreased or abolished in the absence of the anterior pituitary. Insulin can act synergistically with cortisone in promoting the growth of the accessory reproductive organs through effects which are not dependent on the presence of the adrenal glands or the anterior pituitary.

scholarly journals Increase in pituitary adenosine 3′:5′-cyclic monophosphate content and potentiation of growth-hormone release from heifer anterior pituitary slices incubated in the presence of 3-isobutyl-1-methylxanthine

1974 ◽  
Vol 142 (2) ◽  
pp. 295-300 ◽  
Author(s):  
J. George Schofield ◽  
Margaret McPherson
Keyword(s):  
Growth Hormone ◽  
Cyclic Amp ◽  
Prostaglandin E2 ◽  
Anterior Pituitary ◽  
Phosphodiesterase Inhibitor ◽  
Secretory Process ◽  
Hormone Release ◽  
Growth Hormone Release ◽  
Inhibitor Concentration ◽  
Stimulation Of

The release of growth hormone from heifer anterior pituitary slices and the cyclic AMP content of the slices were increased by the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine, both increases being related to inhibitor concentration over the range 0.1–1.0mm. Neither Ba2+(6.9 or 2.3mm), K+(72mm), nor p-chloromercuribenzoate (20μm) had any effect on pituitary cyclic AMP content over a 20min period. 3-Isobutyl-1-methylxanthine potentiated the release of growth hormone in response to Ba2+(2.3mm) and K+(24mm), but the degree of potentiation did not depend on inhibitor concentration in the same way as did tissue cyclic AMP content. 3-Isobutyl-1-methylxanthine decreased the concentration of K+required to give maximum stimulation of growth-hormone release, but did not significantly increase the maximum response to Ba2+. Growth-hormone release in the presence of prostaglandin E2 (1μm) was increased by 3-isobutyl-1-methylxanthine and was inhibited by the prostaglandin antagonist, 7-oxa-13-prostynoic acid, although this antagonist increased the pituitary cyclic AMP concentration and potentiated the prostaglandin E2-induced rise in cyclic AMP content. The stimulation of growth-hormone release by p-chloromercuribenzoate was not potentiated by 3-isobutyl-1-methylxanthine. The data suggest that Ba+and K+act at the same point in the secretory process as 3-isobutyl-1-methylxanthine, although by a different mechanism, and that p-chloromercuribenzoate has a different point of action.

scholarly journals Insulin directly stimulates mitochondrial glucose oxidation in the heart

2020 ◽  
Vol 19 (1) ◽  
Author(s):  
Qutuba G. Karwi ◽  
Cory S. Wagg ◽  
Tariq R. Altamimi ◽  
Golam M. Uddin ◽  
Kim L. Ho ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Glucose Uptake ◽  
Glucose Oxidation ◽  
Glycogen Synthase ◽  
Acid Oxidation ◽  
Mouse Heart ◽  
Insulin Stimulation ◽  
Direct Stimulation ◽  
Gsk 3Β ◽  
Stimulation Of

Abstract Background Glucose oxidation is a major contributor to myocardial energy production and its contribution is orchestrated by insulin. While insulin can increase glucose oxidation indirectly by enhancing glucose uptake and glycolysis, it also directly stimulates mitochondrial glucose oxidation, independent of increasing glucose uptake or glycolysis, through activating mitochondrial pyruvate dehydrogenase (PDH), the rate-limiting enzyme of glucose oxidation. However, how insulin directly stimulates PDH is not known. To determine this, we characterized the impacts of modifying mitochondrial insulin signaling kinases, namely protein kinase B (Akt), protein kinase C-delta (PKC-δ) and glycogen synthase kinase-3 beta (GSK-3β), on the direct insulin stimulation of glucose oxidation. Methods We employed an isolated working mouse heart model to measure the effect of insulin on cardiac glycolysis, glucose oxidation and fatty acid oxidation and how that could be affected when mitochondrial Akt, PKC-δ or GSK-3β is disturbed using pharmacological modulators. We also used differential centrifugation to isolate mitochondrial and cytosol fraction to examine the activity of Akt, PKC-δ and GSK-3β between these fractions. Data were analyzed using unpaired t-test and two-way ANOVA. Results Here we show that insulin-stimulated phosphorylation of mitochondrial Akt is a prerequisite for transducing insulin’s direct stimulation of glucose oxidation. Inhibition of mitochondrial Akt completely abolishes insulin-stimulated glucose oxidation, independent of glucose uptake or glycolysis. We also show a novel role of mitochondrial PKC-δ in modulating mitochondrial glucose oxidation. Inhibition of mitochondrial PKC-δ mimics insulin stimulation of glucose oxidation and mitochondrial Akt. We also demonstrate that inhibition of mitochondrial GSK3β phosphorylation does not influence insulin-stimulated glucose oxidation. Conclusion We identify, for the first time, insulin-stimulated mitochondrial Akt as a prerequisite transmitter of the insulin signal that directly stimulates cardiac glucose oxidation. These novel findings suggest that targeting mitochondrial Akt is a potential therapeutic approach to enhance cardiac insulin sensitivity in condition such as heart failure, diabetes and obesity.

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