Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P61278 (somatostatin)
 22,083 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Growth hormone secretion by the pituitary gland is dependent on the dual regulation exerted by growth hormone-releasing hormone and somatostatin, which are the final integrative pathways for several signals reaching the hypothalamus. Regulatory signals include neurotransmitters, neuropeptides, and peripheral signals such as hormones or nutrients. In the circulation, growth hormone is bound to specific binding proteins and, by activating specific receptors, exerts a variety of peripheral actions.
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PMID:Physiology of growth hormone secretion and action. 152 8

Growth hormone (GH) secretion is decreased during aging in humans and in rodents. This decrease may be due to increased hypothalamic somatostatin release, which is inhibited by cholinergic agonists, or to decreased secretion of GHRH. Alpha-glyceryl-phosphorylcholine (alpha-GFC) is a putative acetylcholine precursor used in the treatment of cognitive disorders in the elderly. In order to learn what effect alpha-GFC had on GH secretion, GH-release hormone (GHRH) was given to young and old human volunteers, with or without the addition of alpha-GFC. GH secretion was greater in the younger subjects than in the old individuals, and both groups had a greater GH response to the GHRH+alpha-GFC than to GHRH alone. The potentiating effect of alpha-GFC on GH secretion was more pronounced in the elderly subjects. These findings confirm the observation that aged individuals respond less well to GHRH than younger subjects, and provides further evidence that increased cholinergic tone enhances GH release.
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PMID:alpha-Glycerylphosphorylcholine administration increases the GH responses to GHRH of young and elderly subjects. 157

Some pituitary hormones secrete hormones while others do not. Nonsecreting tumors can interfere with normal pituitary hormone secretion and produce tumor symptoms and signs like headaches and visual field defects. The most frequent hormone-secreting tumors are prolactinomas. Growth hormone or ACTH or gonadotropin or gonadotropin-alpha and beta chain-producing tumors are less frequent, TSH producing tumors are extremely rare. The most important elements of the diagnostic work-up are clinical signs and symptoms, assessment of pituitary function (measurement of TSH, free T4, LH, FSH, oestradiol/free testosteron, growth hormone, IGF-1, prolactin, ACTH, Cortisol, serum and urine osmolality), CT and/or MRI and, in patients with large tumors, a visual field exam. The treatment of choice of pituitary tumors is often surgery. Alternative therapies are radiation treatment (in nonoperable patients or when hormone levels are persistently elevated after pituitary surgery) and drug treatment (dopamine agonists in hyperprolactinemia, somatostatin analogues in acromegaly). Pituitary hormone deficiencies are treated depending on the specific deficiency with thyroxine, cortisone, oestrogen/gestagen/testosterone gonadotropines or ADH analogues.
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PMID:[Hypophyseal dysfunction and tumors]. 158 68

Plasma growth hormone profiles in adolescents with Type 1 (insulin-dependent) diabetes mellitus are characterized by both increases in pulse amplitude and higher baseline concentrations. To determine which of these abnormalities adversely affect metabolic control, we studied six young adults overnight on three occasions. On each night somatostatin (50-100 micrograms.m2-1.h-1) and glucagon (1 ng.kg-1.min-1) were infused continuously and 18 mU/kg of growth hormone was given as either: three discrete pulses of 6 mU.kg-1.h-1 at 180-min intervals or a 12-h infusion (1.5 mU.kg-1.h-1) or buffer solution only on a control night. Euglycaemia was maintained by an insulin-varying clamp. Blood samples were taken every 15 min for glucose and growth hormone and every hour for intermediate metabolites and non-esterified fatty acids. Comparable normoglycaemic conditions were achieved on all three nights. Growth hormone levels achieved (mean +/- SEM) on study nights were: 32.8 +/- 2.2 mU/l (peak level during growth hormone pulses); 9.8 +/- 0.8 mU/l (continuous growth hormone) and 1.1 +/- 0.3 mU/l (control level). Pulsatile growth hormone administration led to an increase in insulin requirements (mean +/- SEM: 0.17 +/- 0.03 vs control 0.09 +/- 0.01 mU.kg-1.min-1, p less than 0.05) whereas insulin requirements following continuous growth hormone administration were unchanged. Cross-correlation confirmed an increase in insulin requirements occurring 135 min after a growth hormone pulse (r = 0.21, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Contrasting metabolic effects of continuous and pulsatile growth hormone administration in young adults with type 1 (insulin-dependent) diabetes mellitus. 161 27

Somatostatin (SRIF) is a peptide hormone that is synthesized as part of a larger precursor, prepro-SRIF, consisting of a signal peptide and a proregion of 80-90 amino acids. The mature hormone exists as two different bioactive species. In addition to the most common form, which is a 14-residue peptide, there is also a 14-amino acid NH2-terminally extended form of the tetradecapeptide, SRIF-28. In mammals a single prepro-SRIF molecule undergoes tissue-specific processing to generate the mature hormone, whereas in some species of fish separate genes encode two distinct but homologous precursors, prepro-SRIF-I and -II, that give rise to SRIF-14 and -28, respectively. To investigate the molecular basis for differential processing of the prohormones, we have expressed their cDNAs in heterologous cells. Previously, we demonstrated that prepro-SRIF-I was efficiently and accurately processed in rat pituitary growth hormone (GH3) cells to generate the same hormone as synthesized in pancreatic islet D-cells, namely SRIF-14 (Stoller, T., and Shields, D. (1989) J. Biol. Chem. 264, 6922-6928). We have now compared the proteolytic processing of pro-SRIF-II to that of pro-SRIF-I in these cells. In contrast to pro-SRIF-I, pro-SRIF-II was neither processed nor secreted. Instead, greater than 70% of the precursor was degraded intracellularly in a post-trans Golgi network compartment which was inhibited by weak bases. Brefeldin A treatment prevented degradation, suggesting that turnover of the remaining pro-SRIF-II occurred after exit from the endoplasmic reticulum/intermediate compartment and prior to arrival at the trans Golgi network. The intracellular degradation of the precursor was unexpected, since heterologous cells which do not cleave prohormones generally secrete the unprocessed precursor. We speculate that unique structural domains within each precursor are recognized by the sorting apparatus in GH3 cells, thereby targeting the molecules to different intracellular organelles.
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PMID:Heterologous expression of preprosomatostatin. Intracellular degradation of prosomatostatin-II. 167 9

The aim of this study was to characterize the effects of prolonged infusion of growth hormone-releasing factor (1-29)NH2 (GRF) on plasma concentrations of hormones and metabolites when administered to control pigs and pigs immunized against somatostatin (SRIF). In the first experiment, eight purebred Yorkshire boars averaging 113 +/- 2 kg BW were immunized against SRIF conjugated to bovine serum albumin (BSA) (n = 4) or BSA alone (n = 4). Somatotropin (ST) response to four rates of GRF infusion (0, 1.66, 5 and 15 ng/min/kg BW) for 6 hr was evaluated using a double balanced 4 x 4 Latin square design. During the 4 hr before infusion, SRIF-immunized animals tended (P = 0.06) to have a higher ST release (613 vs 316 ng.min/ml, SE = 232) than controls. During infusion, GRF elicited a dose-dependent increase in ST release in both squares; the ST response was not better in SRIF-immunized animals than in controls (P greater than 0.05) (1435 vs 880 ng.min/ml; SE = 597). In the second experiment, ten purebred Yorkshire boars (5 controls and 5 SRIF-immunized animals) averaging 69 +/- 2 kg BW were continuously infused with GRF at the rate of 15 ng/min/kg BW for six consecutive d. Under GRF infusion, ST concentrations increased (P less than 0.05) from 805 to 4768 ng.min/ml (SE = 507) from day 1 to day 6 in both SRIF-immunized and control animals. Prolactin levels increased (P less than 0.05) with GRF infusion; pattern of increase was different (P less than .01) overtime in control and SRIF-immunized animals. Thyroxine levels increased from 2.53 to 3.45 micrograms/dl (SE = 0.16) after six d of infusion. Insulin-like growth factor I was higher (P less than 0.05) before (139 vs 90 ng/ml; SE = 11) and during (222 vs 185 ng/ml; SE = 11) GRF infusion in SRIF-immunized animals. A transient increase (P less than 0.05) in glucose and insulin was observed in both groups. Immunization against SRIF had no effect on blood metabolites; however, GRF infusion increased free fatty acids from 157 to 204 microEq/l (SE = 11) and decreased blood urea nitrogen from 4.1 to 3.5 mmol/l (SE = 0.2) from day 1 to day 6, respectively. In summary, active immunization against SRIF in growing pigs increased ST and IGF-I concentrations. Infusion of GRF continuously raised ST levels with days of infusion without any sign of decrease responsiveness.
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PMID:Effect of growth hormone-releasing factor infusion on somatotropin, prolactin, thyroxine, insulin, insulin-like growth factor I and blood metabolites in control and somatostatin-immunized growing pigs. 167 61

Growth hormone (GH) secretory patterns are disrupted in streptozotocin (STZ) diabetic rats. Alterations in hypothalamic growth hormone-releasing factor (GRF) or hypothalamic somatostatin (SRIF) secretion, increased systemic SRIF secretion, and changes in somatotroph sensitivity to these hypothalamic factors have been advanced as potential underlying mechanisms for the observed attenuation of GH secretion after STZ treatment. Two weeks after STZ treatment, the mean circulating GH level was attenuated by 58%, plasma glucose concentration was 4-fold higher, and systemic SRIF concentration was elevated 6.8-fold with respect to vehicle (VEH)-treated rats. The hypothalamic content of neither SRIF nor GRF was significantly different between VEH and STZ groups. Total hypophysial-portal SRIF concentration, which represents the sum of both peripheral and hypothalamic SRIF contributions, was significantly elevated in the STZ versus VEH group (p less than 0.007). However, when corrected for the contribution of peripheral SRIF, the mean portal SRIF concentration in STZ rats was only 44% of the mean portal SRIF in VEH rats. A reduction in hypophysial-portal GRF concentration in STZ diabetic rats was also observed. Overall, these observations suggest that elevated peripheral SRIF levels characteristic of STZ diabetic rats play a major role in mediating the suppression of GH secretion in this model. Furthermore, the data are suggestive of an inhibitory effect of peripheral SRIF on hypothalamic SRIF release.
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PMID:Hypothalamic secretion of somatostatin and growth hormone-releasing factor into the hypophysial-portal circulation is reduced in streptozotocin diabetic male rats. 167 93

Six insulin-like growth factor binding proteins (IGFBP) have been identified in the conditioned medium from sheep thyroid cells cultured under serum-free conditions. IGFBPs of 32, 28, 23 and 19 kDa were secreted by cells cultured for 14 days in serum-free and hormone-free medium. The constitutive secretion of IGFBP was inhibited by thyrotropin (TSH, 0.3 mU per mL). The effect was most marked on the secretion of the 28 kDa BP. High insulin concentrations stimulated the secretion of this IGFBP. The stimulatory effects of insulin were inhibited by TSH. Growth hormone treatment decreased the secretion of the 28 kDa protein. Tetradecanoylphorbol-13 acetate (TPA) and epidermal growth factor (EGF) both of which stimulate thyroid cell growth but inhibit differentiated function, markedly stimulated IGFBP secretion and induced the appearance of a 46 and a 150 kDa IGFBP. The effects of EGF and TPA were not identical. A rat IGFBP-2 cDNA reacted with sheep thyroid RNA of approximate size 1.6 kb. TPA treatment increased IGFBP-2 mRNA. Other hormones used to enhance differentiation and growth in thyroid cells in culture i.e. transferrin, somatostatin, cortisol and glycyl-histidyl-lysine acetate had no marked effects on IGFBP secretion nor on TSH-dependent, insulin-mediated iodide uptake and organification and cell growth. We show a correlation between secretion of high molecular weight IGFBP with enhanced growth but decreased function. Conversely, we find a correlation between decreased secretion of the 28 kDa BP and increased growth and function.
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PMID:Thyrotropin inhibits while insulin, epidermal growth factor and tetradecanoyl phorbol acetate stimulate insulin-like growth factor binding protein secretion from sheep thyroid cells. 172 84

Hormonal changes and whole blood free amino acid levels and their relation to renal function were measured in 12 insulin-dependent diabetic patients after two 10-day periods with a diet consisting of 10% and 20% respectively of the energy as protein. The patients were 15-21 years old and mean duration of diabetes was 12 (5-20) years. Glomerular filtration rate, renal plasma flow, and albumin excretion rate were measured together with plasma concentrations of glucagon, growth hormone, insulin-like growth factor 1 (IGF-1), somatostatin, serum insulin and free amino acids in blood. Glomerular filtration rate was 123 +/- 3 ml/min/1.73 m2 on high protein diet and 113 +/- 3 ml/min/1.73 m2 on low protein diet (p = 0.02). Renal plasma flow was unchanged. Glucagon, IGF-1, branch chained amino acids (BCAA), tyrosine, phenylalanine, lysine, and methionine were increased after the high protein diet. Growth hormone, somatostatin, insulin, and other amino acids remained unchanged. The increase in glomerular filtration rate was significantly correlated to the increase in glucagon, isoleucine, and valine (glucagon r = 0.71, p = 0.01, isoleucine r = 0.59, p = 0.04, valine r = 0.62, p = 0.03). In a multiple regression model the increase in glomerular filtration correlated most strongly to the increase in isoleucine, followed by valine and glucagon. Together these variables explained 88% of the total variance of the change in glomerular filtration rate (r2 = 0.88, p = 0.001). Albumin excretion rate was correlated to IGF-1 (r = 0.86, p less than 0.001) on the high protein diet.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Indications that branched chain amino acids, in addition to glucagon, affect the glomerular filtration rate after a high protein diet in insulin-dependent diabetes. 180 76

Growth hormone (GH) synthesis is known to be impaired by either abnormally high or low levels of thyroid hormone. To determine the effects of these conditions on the central regulation of GH secretion, we have examined their effects on the hypothalamic regulatory peptides GH-releasing hormone (GH-RH) and somatostatin (SRIF). In thyroidectomized rat hypothalamus, a dramatic increase in GH-RH mRNA occurred in parallel with a decrease in peptide content. The significance of this phenomenon is uncertain and might possibly reflect some posttranscriptional derangement of GH-RH synthesis or an increased rate of GH-RH synthesis and release. In the hyperthyroid group, GH-RH showed significant decreases in both peptide and mRNA levels that might possibly reflect a decrease in GH-RH synthesis and secretion. No change was observed in SRIF peptide or mRNA levels in either thyroidectomized or T4-treated animals. As expected, GH mRNA levels in the anterior pituitary were dramatically decreased by thyroidectomy and unaffected by T4 treatment. In addition, in thyroidectomized pituitaries, the mature GH mRNA was observed to alter its structure, increasing in size by approximately 100 nucleotides. This increase in size was found to result from an increase in poly(A) tail length, the significance of which is as yet unclear.
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PMID:The influence of thyroid hormone status on the hypothalamo-hypophyseal growth hormone axis. 196 79


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