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1.
Diabetes Obes Metab ; 18(9): 930-5, 2016 09.
Artículo en Inglés | MEDLINE | ID: mdl-27097971

RESUMEN

Gastrointestinal (GI) adverse events (AEs) are the most frequently reported treatment-related AEs associated with glucagon-like peptide-1 receptor agonists (GLP-1RAs) in the treatment of type 2 diabetes mellitus. The GI safety of albiglutide, a once-weekly GLP-1RA, was assessed using data from five phase III studies. In a pooled analysis of four placebo-controlled trials, the most common GI AEs were diarrhoea (albiglutide, 14.5% vs. placebo, 11.5%) and nausea (albiglutide, 11.9% vs. placebo, 10.3%), with most patients experiencing 1-2 events. The majority were mild or moderate in intensity and their median duration was 3-4 days. Vomiting occurred in 4.9% of patients in the albiglutide vs. 2.6% in the placebo group. For both albiglutide and placebo, serious GI AEs (2.0% vs. 1.5%) and withdrawals attributable to GI AEs (1.7% vs. 1.5%) were low. In a 32-week trial of albiglutide 50 mg weekly versus liraglutide 1.8 mg daily, nausea occurred in 9.9% of patients in the albiglutide group vs. 29.2% in the liraglutide group. Vomiting occurred in 5.0% in the albiglutide vs. 9.3% in the liraglutide group. In conclusion, albiglutide has an acceptable GI tolerability profile, with nausea and vomiting rates slightly higher than those for placebo but lower than those for liraglutide.


Asunto(s)
Estreñimiento/inducido químicamente , Diabetes Mellitus Tipo 2/tratamiento farmacológico , Diarrea/inducido químicamente , Péptido 1 Similar al Glucagón/análogos & derivados , Incretinas/efectos adversos , Náusea/inducido químicamente , Vómitos/inducido químicamente , Dolor Abdominal/inducido químicamente , Ensayos Clínicos Fase III como Asunto , Reflujo Gastroesofágico/inducido químicamente , Enfermedades Gastrointestinales/inducido químicamente , Péptido 1 Similar al Glucagón/efectos adversos , Humanos , Índice de Severidad de la Enfermedad
2.
Diabetes Obes Metab ; 17(1): 82-90, 2015 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-25263215

RESUMEN

AIM: To determine if the glucagon-like peptide-1 (GLP-1) receptor agonist albiglutide, once weekly, impairs counter-regulatory responses during hypoglycaemia. METHODS: We conducted a randomized, double-blind, parallel, placebo-controlled study in subjects with type 2 diabetes mellitus. A single dose of albiglutide 50 mg (n = 22) or placebo (n = 22) was administered on day 1. Glucose was clamped on day 4 (to coincide with the approximate albiglutide maximum plasma concentration) at 9.0, 5.0, 4.0, 3.3 and 2.8 mmol/l (162, 90, 72, 59.4 and 50.4 mg/dl), with a post-clamp recovery period to 3.9 mmol/l (70 mg/dl). Hormone measurements were made at each plateau and adverse events (AEs) were recorded. RESULTS: The counter-regulatory hormones glucagon, epinephrine, norepinephrine, growth hormone and cortisol were appropriately suppressed when plasma glucose levels were >4.0 mmol/l (>72 mg/dl), but increased in the albiglutide and placebo groups with glucose levels <3.3 mmol/l (<59.4 mg/dl) in response to hypoglycaemia. The area under the curve geometric mean ratios (albiglutide : placebo), calculated from the clamped plateau of 4.0 mmol/l (72 mg/dl) to the glucose recovery point, were not significantly different for any of the counter-regulatory hormones. When plasma glucose levels were >5.0 mmol/l (>90 mg/dl), albiglutide increased pancreatic ß-cell secretion of C-peptide in a glucose-dependent manner to a greater extent than did placebo, and it was suppressed in each group when levels were <4.0 mmol/l (<72 mg/dl). No significant difference between groups was observed in the recovery time to glucose level ≥3.9 mmol/l (≥70 mg/dl). There were no clinically relevant differences in AEs or other safety variables. CONCLUSIONS: A single 50-mg dose of albiglutide was well tolerated and did not impair the counter-regulatory response to hypoglycaemia. These data provide mechanistic evidence supporting the low intrinsic hypoglycaemic potential of albiglutide.


Asunto(s)
Diabetes Mellitus Tipo 2/tratamiento farmacológico , Péptido 1 Similar al Glucagón/análogos & derivados , Péptido 1 Similar al Glucagón/agonistas , Glucagón/metabolismo , Hipoglucemia/prevención & control , Páncreas/efectos de los fármacos , Regulación hacia Arriba/efectos de los fármacos , Adulto , Glucemia/análisis , Diabetes Mellitus Tipo 2/sangre , Método Doble Ciego , Regulación hacia Abajo/efectos de los fármacos , Femenino , Glucagón/sangre , Péptido 1 Similar al Glucagón/administración & dosificación , Péptido 1 Similar al Glucagón/efectos adversos , Péptido 1 Similar al Glucagón/genética , Péptido 1 Similar al Glucagón/uso terapéutico , Técnica de Clampeo de la Glucosa , Humanos , Hiperglucemia/prevención & control , Hipoglucemia/inducido químicamente , Hipoglucemiantes/administración & dosificación , Hipoglucemiantes/efectos adversos , Hipoglucemiantes/uso terapéutico , Insulina/sangre , Insulina/metabolismo , Secreción de Insulina , Masculino , Persona de Mediana Edad , Páncreas/metabolismo , Proteínas Recombinantes/administración & dosificación , Proteínas Recombinantes/efectos adversos , Proteínas Recombinantes/uso terapéutico
3.
Diabetes Obes Metab ; 16(12): 1257-64, 2014 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-25155146

RESUMEN

AIMS: To show that albiglutide, a glucagon-like peptide-1 receptor agonist, is an effective and generally safe treatment to improve glycaemic control in patients with type 2 diabetes mellitus whose hyperglycaemia is inadequately controlled with pioglitazone (with or without metformin). METHODS: In this 3-year, randomized, double-blind, placebo-controlled study, 310 adult patients on a regimen of pioglitazone (with or without metformin) were randomly assigned to receive additional treatment with albiglutide [30 mg subcutaneous (s.c.) once weekly, n = 155] or matching placebo (n = 155). The primary efficacy endpoint was change from baseline to week 52 (intention-to-treat) in glycated haemoglobin (HbA1c). RESULTS: The model-adjusted change from baseline in HbA1c at week 52 was significantly better with albiglutide than with placebo (-0.8%, 95% confidence interval -1.0, -0.6; p < 0.0001). Change from baseline fasting plasma glucose was -1.3 mmol/l in the albiglutide group and +0.4 mmol/l in the placebo group (p < 0.0001); a significantly higher percentage of patients reached the HbA1c goals with albiglutide (p < 0.0001), and the rate of hyperglycaemia rescue up to week 52 for albiglutide was 24.4 versus 47.7% for placebo (p < 0.0001). Albiglutide plus pioglitazone had no impact on weight, and severe hypoglycaemia was observed rarely (n = 2). With few exceptions, the results of safety assessments were similar between the groups, and most adverse events (AEs) were mild or moderate. The 52-week incidence rates for gastrointestinal AEs for albiglutide and placebo were: 31.3 and 29.8%, respectively (diarrhoea: 11.3 and 8.6%; nausea: 10.7 and 11.3%; vomiting: 4.0 and 4.0%). CONCLUSIONS: Albiglutide 30 mg administered once weekly as an add-on to pioglitazone (with or without metformin) provided effective and durable glucose lowering and was generally well tolerated.


Asunto(s)
Glucemia/efectos de los fármacos , Diabetes Mellitus Tipo 2/tratamiento farmacológico , Péptido 1 Similar al Glucagón/análogos & derivados , Hipoglucemia/prevención & control , Hipoglucemiantes/uso terapéutico , Metformina/uso terapéutico , Glucemia/metabolismo , Método Doble Ciego , Esquema de Medicación , Quimioterapia Combinada , Femenino , Péptido 1 Similar al Glucagón/administración & dosificación , Péptido 1 Similar al Glucagón/efectos adversos , Péptido 1 Similar al Glucagón/uso terapéutico , Humanos , Hipoglucemia/inducido químicamente , Hipoglucemiantes/administración & dosificación , Hipoglucemiantes/efectos adversos , Incretinas , Masculino , Metformina/administración & dosificación , Metformina/efectos adversos , Persona de Mediana Edad , Pioglitazona , Tiazolidinedionas/administración & dosificación , Resultado del Tratamiento
4.
Eur J Cancer ; 37(7): 835-42, 2001 May.
Artículo en Inglés | MEDLINE | ID: mdl-11313170

RESUMEN

Substance P is localised in brainstem regions associated with emesis. Based on studies in the ferret, it was postulated that a neurokinin-1 (NK1) receptor antagonist would have antiemetic activity as monotherapy in humans receiving chemotherapy. L-758,298 is a water-soluble, intravenous (i.v.) prodrug for L-754,030, a potent and selective NK1 receptor antagonist. This double-blind, randomised, active-agent (ondansetron)-controlled study enrolled 53 cisplatin-naïve patients and evaluated the prevention of both acute (0-24 h) and delayed (days 2-7) emesis after cisplatin treatment (50-100 mg/m(2)). All patients received i.v. L-758,298 (60 or 100 mg) (n=30) or ondansetron (32 mg) (n=23) before cisplatin and efficacy was evaluated up to day 7 post-cisplatin. Nausea was assessed by means of a four-point ordinal scale at intervals over the 7 day period. In the acute period, the proportion of patients without emesis in the L-758,298 and ondansetron groups was 37 and 52%, respectively (no significant difference between the groups). Comparing the distribution of average nausea scores over the entire first 24 h revealed no significant difference between the groups. In the delayed period, the proportion of patients without emesis in the L-758,298 and ondansetron treatment groups was 72 and 30%, respectively (P=0.005). The distribution of average nausea scores in the delayed period was lower in the L-758,298 group compared with the ondansetron group (P=0.15 for the entire delayed period and P=0.043 for day 2 only). No serious adverse events were attributed to L-758,298. A single dose of L-758,298 substantially suppressed the delayed nausea and vomiting characteristic of high dose cisplatin and also appeared to reduce acute emesis post-cisplatin. The data also support the proposition that the underlying mechanism(s) of acute and delayed emesis are different.


Asunto(s)
Acetales/uso terapéutico , Antieméticos/uso terapéutico , Antineoplásicos/efectos adversos , Cisplatino/efectos adversos , Morfolinas/uso terapéutico , Náusea/prevención & control , Ondansetrón/uso terapéutico , Vómitos/prevención & control , Adulto , Anciano , Aprepitant , Método Doble Ciego , Femenino , Humanos , Masculino , Persona de Mediana Edad , Náusea/inducido químicamente , Satisfacción del Paciente , Profármacos , Vómitos/inducido químicamente
5.
J Clin Oncol ; 19(6): 1759-67, 2001 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-11251007

RESUMEN

PURPOSE: The NK1-receptor antagonist MK-869 (L-754,030) has demonstrated antiemetic activity in humans receiving chemotherapy. Objectives of the present trial included the first assessment of oral MK-869 plus dexamethasone compared with a 5HT(3) antagonist plus dexamethasone for prevention of acute and delayed emesis after high-dose cisplatin. Furthermore, the study sought to confirm that addition of MK-869 to a 5HT(3) antagonist plus dexamethasone was more effective than just the 5HT(3) antagonist plus dexamethasone for prevention of acute and delayed emesis. METHODS: This multicenter, double-blind, parallel-group trial in 351 cisplatin-naïve patients evaluated prevention of acute (0 to 24 hours) and delayed emesis (primary efficacy parameter; days 2 to 5) after cisplatin (> or =70 mg/m(2)). Patients were randomized to four groups (I to IV) (n = number randomized; number evaluable): granisetron (10 microg/kg intravenously) pre-cisplatin followed by placebo on days 2 to 5 (group I) (n = 90; 90); granisetron and MK-869 (400 mg PO [by mouth]) pre-cisplatin, followed by MK-869 (300 mg PO) on days 2 to 5 (group II) (n = 86; 84); MK-869 (400 mg PO) the evening before and pre-cisplatin, followed by MK-869 (300 mg PO) on days 2 to 5 (group III) (n = 89; 88); or MK-869 (400 mg PO) pre-cisplatin, followed by MK-869 (300 mg PO) on days 2 to 5 (group IV) (n = 86; 84). All patients also received dexamethasone (20 mg PO) before cisplatin. Additional medication was available to treat emesis or nausea at any time. RESULTS: In the acute period, 57%, 80%, 46%, and 43% of patients were without emesis in groups I, II, III, and IV, respectively (P <.01 for group II v group I). In the delayed period, the proportion of patients without emesis in groups I, II, III, and IV was 29%, 63%, 51%, and 57%, respectively (P <.01 for groups II, III, and IV v group I). The distribution of nausea scores in the delayed period was lower when comparing group II with group I (P <.05 for days 1 to 5 and days 2 to 5). One serious adverse event (dizziness) was rated as possibly related to MK-869. CONCLUSION: Once daily oral administration of MK-869 was effective in reducing delayed emesis and nausea after high-dose cisplatin. However, the combination of the 5HT3 antagonist plus dexamethasone was numerically superior to MK-869 plus dexamethasone in reducing acute emesis. Confirming and extending previous findings, the triple combination of a 5HT(3) antagonist, MK-869, and dexamethasone provided the best control of acute emesis.


Asunto(s)
Antidepresivos de Segunda Generación/farmacología , Antieméticos/farmacología , Cisplatino/efectos adversos , Dexametasona/farmacología , Granisetrón/farmacología , Morfolinas/farmacología , Vómitos/inducido químicamente , Vómitos/prevención & control , Adulto , Anciano , Antidepresivos de Segunda Generación/administración & dosificación , Antieméticos/administración & dosificación , Aprepitant , Cisplatino/uso terapéutico , Dexametasona/administración & dosificación , Método Doble Ciego , Quimioterapia Combinada , Femenino , Granisetrón/administración & dosificación , Humanos , Masculino , Persona de Mediana Edad , Morfolinas/administración & dosificación , Neoplasias/tratamiento farmacológico
6.
Proc Natl Acad Sci U S A ; 97(18): 10236-41, 2000 Aug 29.
Artículo en Inglés | MEDLINE | ID: mdl-10954733

RESUMEN

The brain has enormous anabolic needs during early postnatal development. This study presents multiple lines of evidence showing that endogenous brain insulin-like growth factor 1 (Igf1) serves an essential, insulin-like role in promoting neuronal glucose utilization and growth during this period. Brain 2-deoxy-d- [1-(14)C]glucose uptake parallels Igf1 expression in wild-type mice and is profoundly reduced in Igf1-/- mice, particularly in those structures where Igf1 is normally most highly expressed. 2-Deoxy-d- [1-(14)C]glucose is significantly reduced in synaptosomes prepared from Igf1-/- brains, and the deficit is corrected by inclusion of Igf1 in the incubation medium. The serine/threonine kinase Akt/PKB is a major target of insulin-signaling in the regulation of glucose transport via the facilitative glucose transporter (GLUT4) and glycogen synthesis in peripheral tissues. Phosphorylation of Akt and GLUT4 expression are reduced in Igf1-/- neurons. Phosphorylation of glycogen synthase kinase 3beta and glycogen accumulation also are reduced in Igf1-/- neurons. These data support the hypothesis that endogenous brain Igf1 serves an anabolic, insulin-like role in developing brain metabolism.


Asunto(s)
Encéfalo/fisiología , Desoxiglucosa/farmacocinética , Glucosa/metabolismo , Factor I del Crecimiento Similar a la Insulina/fisiología , Proteínas Musculares , Neuronas/fisiología , Proteínas Serina-Treonina Quinasas , Animales , Encéfalo/efectos de los fármacos , Encéfalo/crecimiento & desarrollo , Proteínas Quinasas Dependientes de Calcio-Calmodulina/metabolismo , Regulación de la Expresión Génica , Transportador de Glucosa de Tipo 4 , Glucógeno/biosíntesis , Glucógeno Sintasa Quinasa 3 , Glucógeno Sintasa Quinasas , Factor I del Crecimiento Similar a la Insulina/deficiencia , Factor I del Crecimiento Similar a la Insulina/genética , Factor I del Crecimiento Similar a la Insulina/farmacología , Masculino , Ratones , Ratones Noqueados , Proteínas Asociadas a Microtúbulos/genética , Proteínas Asociadas a Microtúbulos/metabolismo , Proteínas de Transporte de Monosacáridos/genética , Proteínas de Transporte de Monosacáridos/metabolismo , Fosforilación , Proteínas Proto-Oncogénicas/metabolismo , Proteínas Proto-Oncogénicas c-akt , Ratas , Ratas Sprague-Dawley , Transducción de Señal , Transcripción Genética
7.
N Engl J Med ; 340(3): 190-5, 1999 Jan 21.
Artículo en Inglés | MEDLINE | ID: mdl-9917226

RESUMEN

BACKGROUND: The localization of substance P in brain-stem regions associated with vomiting, and the results of studies in ferrets, led us to postulate that a neurokinin-1-receptor antagonist would be an antiemetic in patients receiving anticancer chemotherapy. METHODS: In a multicenter, double-blind, placebo-controlled trial involving 159 patients who had not previously received cisplatin, we evaluated the prevention of acute emesis (occurring within 24 hours) and delayed emesis (on days 2 to 5) after a single dose of cisplatin therapy (70 mg or more per square meter of body-surface area). Before receiving cisplatin, all the patients received granisetron (10 microg per kilogram of body weight intravenously) and dexamethasone (20 mg orally). The patients were randomly assigned to one of three treatments in addition to granisetron and dexamethasone: 400 mg of an oral trisubstituted morpholine acetal (also known as L-754,030) before cisplatin and 300 mg on days 2 to 5 (group 1), 400 mg of L-754,030 before cisplatin and placebo on days 2 to 5 (group 2), or placebo before cisplatin and placebo on days 2 to 5 (group 3). Additional medication was available at any time to treat occurrences of vomiting or nausea. RESULTS: In the acute-emesis phase, 93 percent of the patients in groups 1 and 2 combined and 67 percent of those in group 3 had no vomiting (P<0.001). In the delayed-emesis phase, 82 percent of the patients in group 1, 78 percent of those in group 2, and 33 percent of those in group 3 had no vomiting (P<0.001 for the comparison between group 1 or 2 and group 3). The median nausea score in the delayed-emesis phase was significantly lower in group 1 than in group 3 (P=0.003). No serious adverse events were attributed to L-754,030. CONCLUSIONS: The neurokinin-1-receptor antagonist L-754,030 prevents delayed emesis after treatment with cisplatin. Moreover, combining L-754,030 with granisetron plus dexamethasone improves the prevention of acute emesis.


Asunto(s)
Acetales/uso terapéutico , Antieméticos/uso terapéutico , Cisplatino/efectos adversos , Morfolinas/uso terapéutico , Antagonistas del Receptor de Neuroquinina-1 , Vómitos/prevención & control , Acetales/efectos adversos , Anciano , Antieméticos/efectos adversos , Aprepitant , Dexametasona/uso terapéutico , Método Doble Ciego , Quimioterapia Combinada , Femenino , Granisetrón/uso terapéutico , Humanos , Masculino , Persona de Mediana Edad , Morfolinas/efectos adversos , Satisfacción del Paciente , Antagonistas de la Serotonina/uso terapéutico , Vómitos/inducido químicamente
8.
J Neurosci ; 18(15): 5673-81, 1998 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-9671658

RESUMEN

To elucidate the role of insulin-like growth factor 1 (IGF1) in the normal development of brain myelination, we used behavioral, biochemical, and histological analyses to compare the myelination of brains from Igf1(-/-) and wild-type (WT) littermate mice. The studies were conducted at postnatal day 40, at which time the Igf1(-/-) mice weighed approximately 66% less than wild-type mice. However, the Igf1(-/-) brain weight was only reduced by approximately 34%. Formal neurological testing showed no sign of central or peripheral myelinopathy in Igf1(-/-) mice. Myelin composition was not significantly different, and myelin concentration, normalized to brain weight or protein, was equal in Igf1(-/-) and WT mice. Likewise, concentrations of myelin-specific proteins (MBP, myelin proteolipid protein, MAG, and 2',3'-cyclic nucleotide,3'-phosphodiesterase) were not significantly different in Igf1(-/-) and WT mice. The myelin-associated lipids galactocerebroside and sulfatide were modestly reduced in Igf1(-/-) brains. Regional oligodendrocyte populations and myelin staining patterns were comparable in Igf1(-/-) and WT brains, with the notable exception of the olfactory system. The Igf1(-/-) olfactory bulb was profoundly reduced in size and was depleted of mitral neurons and oligodendrocytes, and its efferent tracts were depleted of myelin. In summary, this study shows that myelination of the Igf1(-/-) brain is proportionate to its neuronal composition. Where projection neurons are preserved despite the deletion of IGF1, as in the cerebellar system, oligodendrocytes and myelination are indistinguishable from wild type. Where projection neurons are depleted, as in the olfactory bulb, oligodendrocytes are also depleted, and myelination is reduced in proportion to the reduced projection neuron mass. These data make a strong case for the primacy of axonal factors, not including IGF1, in determining oligodendrocyte survival and myelination.


Asunto(s)
Encéfalo/metabolismo , Factor I del Crecimiento Similar a la Insulina/fisiología , Vaina de Mielina/fisiología , Neuronas/química , Animales , Encéfalo/patología , Lípidos/análisis , Ratones , Ratones Endogámicos , Proteínas de la Mielina/análisis , Oligodendroglía/ultraestructura
9.
Neuroscience ; 72(2): 567-78, 1996 May.
Artículo en Inglés | MEDLINE | ID: mdl-8737425

RESUMEN

Cyclic GMP-inhibited phosphodiesterases are characterized by sensitivity of cAMP hydrolysis to inhibition by cGMP. This phosphodiesterase family contains at least two different isoforms (PDE3A and PDE3B) encoded by distinct genes and serving tissue-specific roles in regulation of lipolysis, glycogenolysis, myocardial contractility, and smooth muscle relaxation. Our previous work indicated an abundance of these two phosphodiesterase messenger RNAs in the embryonic rat brain, and therefore, to elucidate the potential functions of these enzymes in brain development as well as in mature brain function, the present study mapped cellular patterns of gene expression for these two enzymes from embryonic day 15 to adulthood using in situ hybridization histochemistry. Phosphodiesterase 3B isoform messenger RNA is uniformly expressed in germinal neuroepithelium and mature neurons, with distribution generally reflecting cell density. Phosphodiesterase isoform 3A messenger RNA, in contrast, demonstrates striking spatiotemporal specificity of expression, with three distinct patterns being evident. Firstly, this mRNA is highly abundant in both primary and secondary neuroepithelial germinal zones. Secondly, during early postnatal development PDE3A mRNA is transiently but highly expressed in neurons localized in basal forebrain, deep cerebellar, pontine, interpeduncular and a variety of thalamic, midbrain and brainstem nuclei. Thirdly, PDE3A mRNA is focally expressed in isolated large striatal and hippocampal neurons from the perinatal period without attenuation into adulthood. In summary, two cGMP-inhibited phosphodiesterase isoforms show distinctive patterns of gene expression in brain: PDE3B gene expression is uniform without evidence of system specificity or developmental stage specificity, suggesting that this isoform has a constitutive role in neuroepithelial metabolism, while PDE3B gene expression demonstrates a high level of spatiotemporal heterogeneity, suggesting that this isoform subserves a variety of developmental stage-specific and system-specific functions.


Asunto(s)
3',5'-AMP Cíclico Fosfodiesterasas/biosíntesis , Encéfalo/enzimología , Regulación del Desarrollo de la Expresión Génica/fisiología , Regulación Enzimológica de la Expresión Génica/fisiología , Isoenzimas/biosíntesis , 3',5'-AMP Cíclico Fosfodiesterasas/genética , Animales , Encéfalo/anatomía & histología , Fosfodiesterasas de Nucleótidos Cíclicos Tipo 3 , Células Epiteliales , Epitelio/enzimología , Femenino , Hibridación in Situ , Isoenzimas/genética , Embarazo , Ratas , Ratas Sprague-Dawley
10.
J Clin Invest ; 95(4): 1528-38, 1995 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-7706458

RESUMEN

Type III cGMP-inhibited phosphodiesterases (PDE3s) play important roles in hormonal regulation of lipolysis, platelet aggregation, myocardial contractility, and smooth muscle relaxation. We have recently characterized two PDE3 subtypes (PDE3A and PDE3B) as products of distinct but related genes. To elucidate their biological roles, in this study we compare cellular patterns of gene expression for these two enzymes during rat embryonic and postnatal development using in situ hybridization. PDE3B [corrected] mRNA is abundant in adipose tissue and is also expressed in hepatocytes throughout development. This mRNA is also highly abundant in embryonic neuroepithelium including the neural retina, but expression is greatly reduced in the mature nervous system. Finally, PDE3B [corrected] mRNA is localized in spermatocytes and renal collecting duct epithelium in adult rats. PDE3B mRNA is highly expressed in the cardiovascular system, including myocardium and arterial and venous smooth muscle, throughout development. It is also abundant in bronchial, genitourinary and gastrointestinal smooth muscle and epithelium, megakaryocytes, and oocytes. PDE3A [corrected] mRNA demonstrates a complex, developmentally regulated pattern of gene expression in the central nervous system. In summary, the two different PDE3s show distinctive tissue-specific patterns of gene expression suggesting that PDE3B [corrected] is involved in hormonal regulation of lipolysis and glycogenolysis, while regulation of myocardial and smooth muscle contractility appears to be a function of PDE3A [corrected]. In addition, the present findings suggest previously unsuspected roles for these enzymes in gametogenesis and neural development.


Asunto(s)
Hidrolasas Diéster Fosfóricas/aislamiento & purificación , ARN Mensajero/aislamiento & purificación , Animales , Secuencia de Bases , GMP Cíclico/farmacología , Embrión de Mamíferos/anatomía & histología , Expresión Génica , Hibridación in Situ , Datos de Secuencia Molecular , Inhibidores de Fosfodiesterasa/farmacología , Hidrolasas Diéster Fosfóricas/genética , Ratas , Distribución Tisular
11.
Endocrinology ; 135(5): 1753-61, 1994 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-7525251

RESUMEN

Although evidence exists that insulin may cross the blood-brain barrier, little is known about the ability of insulin-like growth factors (IGF-I and -II) to cross this barrier. In the present studies, equimolar concentrations of equal specific activity 125I-labeled IGF-I, IGF-II, or insulin were infused into the carotid artery of anesthetized adult rats. The perfusions were carried out for 3 min in the presence or absence of excess unlabeled ligand or insulin, with three or more animals in each group. Immediately after the perfusion, brains were frozen and sectioned for autoradiography. All ligands were detected in choroid plexus, median eminence, and blood vessels, but [125I]IGF-I and -II were also prominently localized in brain parenchyma. Densitometric analysis of film autoradiographs (28-day exposure for all ligands) revealed that radiolabeled IGFs, especially IGF-I, were significantly more abundant throughout the forebrain than [125I]insulin, especially in the paraventricular nucleus, where [125I]IGF-I was 10-fold and [125I]IGF-II was 5-fold more abundant than [125I]insulin. The difference in [125I]IGF-I vs. [125I]insulin accumulation was confirmed by parallel measurements of radioactivity in anatomically matched brain sections using a gamma-spectrometer. The uptake of radiolabeled IGF-I, IGF-II, and insulin by brain parenchyma and vasculature was completely inhibited by excess (1,000-fold) unlabeled ligand; however, insulin (10,000-fold excess) did not completely abolish [125I]IGF-I and -II accumulation. Microscopic evaluation of nuclear emulsion-coated brain sections revealed that radioactivity associated with [125I]IGF-I and -II perfusions was selectively concentrated in capillaries and medium-sized parenchymal cells in the paraventricular nucleus and, to a lesser extent, the supraoptic nucleus and anterior nucleus of the thalamus, whereas in other brain regions the radioligands were mostly bound to capillaries. These results suggest that radiolabeled IGF-I and -II bind to brain capillaries and cross the blood-brain barrier into brain parenchyma more readily than radiolabeled insulin.


Asunto(s)
Barrera Hematoencefálica/fisiología , Factor II del Crecimiento Similar a la Insulina/metabolismo , Factor I del Crecimiento Similar a la Insulina/metabolismo , Animales , Autorradiografía , Transporte Biológico/fisiología , Hibridación in Situ , Factor I del Crecimiento Similar a la Insulina/genética , Factor II del Crecimiento Similar a la Insulina/genética , Radioisótopos de Yodo , Ligandos , Masculino , ARN/análisis , ARN/genética , Ratas , Ratas Sprague-Dawley , Factores de Tiempo
12.
J Neurosci ; 14(8): 4674-83, 1994 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-8046442

RESUMEN

The insulin receptor-related receptor (IRR) has recently been identified as a member of the insulin receptor tyrosine kinase family; however, its endogenous ligand and biological function are still unknown. In contrast to the very widespread pattern of expression of the homologous insulin and IGF-I receptors, IRR demonstrates a very restricted cellular distribution. Using in situ hybridization and immunohistochemistry, we now show that the expression of this receptor is selectively concentrated in a subset of neurons where its appearance is closely associated with that of the NGF receptor TRK. IRR and TRK demonstrate synchronized patterns of coexpression in neural crest-derived sensory and sympathetic neurons and in non-neural crest basal forebrain and striatal neurons. Both appear early in the embryonic development of dorsal root and trigeminal neurons and somewhat later, near the time of birth, in sympathetic neurons. Expression of both IRR and TRK appears perinatally in basal forebrain neurons, reaching maximal levels about postnatal day 20. This association is highly selective, since TRK mRNA is not detected anywhere in the developing nervous system in the absence of coordinate IRR expression, and the same is true for IRR expression with respect to TRK. In the adult rat, the majority of TRK-positive sensory neurons still express IRR mRNA, and coexpression in sympathetic and forebrain neurons continues without evidence of diminution. These findings are consistent with a functional linkage of the IRR and TRK receptors in NGF-sensitive neurons.


Asunto(s)
Encéfalo/metabolismo , Neuronas/metabolismo , Proteínas Proto-Oncogénicas/metabolismo , Proteínas Tirosina Quinasas Receptoras/metabolismo , Receptor de Insulina/metabolismo , Receptores de Factor de Crecimiento Nervioso/metabolismo , Animales , Encéfalo/embriología , Femenino , Técnica del Anticuerpo Fluorescente , Expresión Génica , Hibridación in Situ , Factores de Crecimiento Nervioso/fisiología , Embarazo , Sondas ARN , ARN Mensajero/metabolismo , Ratas , Ratas Sprague-Dawley , Receptor trkA
13.
J Clin Invest ; 93(3): 966-73, 1994 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-8132782

RESUMEN

Insulin-degrading enzyme (IDE) hydrolyzes both insulin and IGFs and has been proposed to play a role in signal termination after binding of these peptides to their receptors. In situ hybridization was used to investigate the cellular distribution of IDE mRNA and to compare it with insulin receptor (IR) and IGF-I receptor (IGFR) gene expression in serial thin sections from a variety of tissues in embryonic and adult rats. IDE mRNA is highly abundant in kidney and liver, tissues known to play a role in insulin degradation. IDE and IR mRNAs are highly coexpressed in brown fat and liver. The highest level IDE gene expression, on a per cell basis, is found in germinal epithelium. IDE and IGFR mRNAs are colocalized in oocytes, while IDE is colocalized with the IGF-II receptor in spermatocytes, suggesting that IDE may be involved with degradation of IGF-II in the testis. In summary, IDE expression demonstrates significant anatomical correlation with insulin/IGF receptors. These data are compatible with a role for IDE in degrading insulin and IGFs after they bind to and are internalized with their respective receptors and may also suggest a novel role for IDE in germ cells.


Asunto(s)
Regulación de la Expresión Génica , Insulina/metabolismo , Receptor de Insulina/genética , Receptores de Somatomedina/genética , Animales , Embrión de Mamíferos/metabolismo , Femenino , Masculino , ARN Mensajero/análisis , Ratas , Ratas Sprague-Dawley , Somatomedinas/metabolismo
14.
Endocrinology ; 133(1): 3-10, 1993 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-8319578

RESUMEN

The insulin receptor-related receptor (IRR) demonstrates striking structural homology to the insulin receptor (IR) and insulin-like growth factor-I receptor (IGFR), suggesting that IRR is a member of the IR family. However, the endogenous ligand and biological role for this "orphan" receptor are unknown. To identify potential sites of action for the IRR, in situ hybridization was employed to reveal cellular patterns of IRR gene expression in the developing and adult rat and in the adult human kidney. From embryonic days 15-20, IRR mRNA is most abundant in sensory neurons of the trigeminal and dorsal root ganglia and, to a lesser extent, neurons of the autonomic system. IRR gene expression diminishes in the majority of sensory neurons postnatally, but remains abundant in a subpopulation of adult rat trigeminal and dorsal root ganglion neurons. IRR mRNA is localized in peripheral autonomic ganglia localized in the adrenal medulla and renal hilum in the adult. From birth to maturity, IRR mRNA is abundant in renal epithelial cells focally localized in the distal tubule in both rat and human kidney. The specificity of this pattern of IRR gene expression was demonstrated by hybridization of serial tissue sections with two different nonoverlapping cRNA probes. Nonspecific signal, as measured by IRR sense probe hybridization, was negligible. This highly restricted pattern of IRR gene expression is in marked contrast to the very widespread pattern of gene expression demonstrated by the IR and IGFR. This study showed that IRR, IR, and IGFR mRNAs were colocalized in some sensory neurons, suggesting the possibility for hybrid receptor formation in these cells. In summary, IRR gene expression is focally localized in sensory and autonomic neurons and renal distal tubule cells. These observations suggest that the IRR, in contrast to the related IR and IGFR, serves a narrow cell-specific role.


Asunto(s)
Expresión Génica , Túbulos Renales Distales/inervación , Neuronas/metabolismo , ARN Mensajero/metabolismo , Receptor de Insulina/genética , Animales , Epitelio/metabolismo , Femenino , Hibridación in Situ , Túbulos Renales Distales/embriología , Túbulos Renales Distales/metabolismo , Neuronas Aferentes/metabolismo , Sondas ARN , ARN sin Sentido , Ratas , Ratas Sprague-Dawley , Sistema Nervioso Simpático/metabolismo
15.
J Neurochem ; 50(6): 1945-51, 1988 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-2836562

RESUMEN

The main objective of these studies was to determine whether adenosine inhibits choline kinase in rat striata, leading to a decreased incorporation of choline into phosphorylcholine, a mechanism that may mediate seizure-induced increases in the levels of free choline in brain. Incubation of particulate and soluble fractions of striatal synaptosomes with adenosine or its metabolically stable analogues significantly inhibited enzyme activity. The inhibition was noncompetitive versus choline and competitive versus MgATP. Inhibitor constants for adenosine, 2-chloroadenosine, and 2',5'-dideoxyadenosine at the MgATP site were 94, 49, and 207 microM, respectively; these values were less than the Michaelis constant for MgATP (340 microM). To determine whether adenosine altered the phosphorylation of choline in an intact preparation, synaptosomes were incubated with [3H]choline in the presence or absence of adenosine or its analogues and the amount of [3H]-phosphorylcholine formed from the [3H]choline taken up was measured. All compounds tested significantly reduced the synthesis of [3H]phosphorylcholine. Results suggest that following seizures or hypoxia, when levels of adenosine increase and the concentration of ATP decreases, inhibition of choline phosphorylation may be manifest, resulting in increased levels of free choline in brain.


Asunto(s)
Adenosina/farmacología , Colina Quinasa/antagonistas & inhibidores , Colina/metabolismo , Cuerpo Estriado/enzimología , Didesoxiadenosina/análogos & derivados , Fosfotransferasas/antagonistas & inhibidores , Sinaptosomas/enzimología , 2-Cloroadenosina , Adenosina/análogos & derivados , Adenosina Trifosfato/metabolismo , Animales , Cuerpo Estriado/efectos de los fármacos , Desoxiadenosinas/análogos & derivados , Desoxiadenosinas/farmacología , Cinética , Masculino , Fosforilación , Fosforilcolina/metabolismo , Ratas , Ratas Endogámicas
16.
J Pharmacol Exp Ther ; 232(3): 754-9, 1985 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-3882936

RESUMEN

The isolated working rat heart exhibits dynamic changes in the cholinergic muscarinic receptor in response to perfusion with the acetylcholine congener methacholine. For example, perfusion with 4 microM methacholine for 2.5 hr mediates a statistically significant and reversible 10 to 15% decrease in receptor content in right atrium and left atrium and ventricle. The muscarinic receptor exhibits a single affinity state for antagonists but multiple affinity states for receptor agonists. When agonist 3H-antagonist competition experiments are performed, the concentration dependence of displacement by agonists is flattened and extends over more than 2 log units. From such curves, it is difficult to extract values for the relative proportions of the multiple receptors or their KD values by inspection. We have developed a procedure for plotting the competition curves so that the KD values and proportion of multiple receptor forms can be estimated graphically. We determined these more accurately by computer using a nonlinear least-squares analysis. After perfusion of methacholine for 1 hr, there were increases in the KD of the low and high affinity forms of the receptor in the right and left atria. After 2.5 hr of perfusion, the KD of the high-affinity form increased further in the left atrium. In the right atrium, the two affinity states were converted into a single state of low affinity. Although there was a significant decrease in the amount of receptor in left ventricle, there were no changes in the KD values or proportions of the two states. All changes in receptor reversed during an additional 2.5 hr of perfusion without methacholine.


Asunto(s)
Compuestos de Metacolina/farmacología , Miocardio/metabolismo , Receptores Muscarínicos/metabolismo , Animales , Unión Competitiva , Atrios Cardíacos/metabolismo , Ventrículos Cardíacos/metabolismo , Técnicas In Vitro , Masculino , Cloruro de Metacolina , Compuestos de Metacolina/metabolismo , Modelos Biológicos , Perfusión , Quinuclidinil Bencilato/metabolismo , Ratas , Ratas Endogámicas , Receptores Muscarínicos/efectos de los fármacos
17.
J Biol Chem ; 259(12): 7446-52, 1984 Jun 25.
Artículo en Inglés | MEDLINE | ID: mdl-6330058

RESUMEN

The kinetic mechanism of choline kinase associated with both the cytosolic and membrane fractions of synaptosomes isolated from rat striata was studied. The velocity of choline kinase was measured using various concentrations of MgATP at several concentrations of uncomplexed Mg2+ and a single concentration of choline. This experiment was repeated using different concentrations of choline. Analysis of these data according to a terreactant mechanism indicates that MgATP binds in rapid equilibrium prior to Mg2+, but the binding of MgATP and choline is random. Product inhibition by phosphorylcholine was noncompetitive versus both choline and MgATP. Hemicholinium-3 (HC-3), an analog of choline and competitive inhibitor of the sodium-dependent high affinity choline transport system, was noncompetitive versus choline and uncompetitive versus MgATP at high levels of Mg2+. However, when the concentration of Mg2+ was decreased below the KMg2 +, HC-3 was noncompetitive versus MgATP. Thiocholine, another analog of choline, gave slope-linear intercept hyperbolic inhibition versus choline. Mg-5'-adenylyl imidodiphosphate, an analog of MgATP, was competitive versus MgATP and noncompetitive versus choline. Virtually identical results were obtained using either soluble or particulate forms of choline kinase from rat striata. All data are consistent with the mechanism suggested by initial velocity studies alone and additionally suggest that the release of MgADP is slow, occurs last, and may limit the overall rate of the reaction.


Asunto(s)
Colina Quinasa/metabolismo , Cuerpo Estriado/enzimología , Fosfotransferasas/metabolismo , Adenosina Trifosfato/metabolismo , Animales , Hemicolinio 3/farmacología , Cinética , Masculino , Matemática , Fosforilcolina/farmacología , Ratas , Ratas Endogámicas , Tiocolina/farmacología
18.
J Neurochem ; 41(3): 623-9, 1983 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-6308165

RESUMEN

The distribution of choline kinase (EC 2.7.1.32) activity was investigated in subcellular fractions of rat striatum. Enzyme activity in the crude mitochondrial fraction, determined after dissolution in Triton X-100, was 5.90 mumol/g initial wet weight/h. When a crude mitochondrial preparation was hypoosmotically shocked and fractionated, followed by the addition of Triton X-100, choline kinase activity in the soluble and particulate fractions was 4.58 and 1.40 mumol/g initial wet weight/h, respectively. Enzyme activity in the particulate fraction was not detected in the absence of Triton X-100 or in the presence of NaCl (up to 1.5 M). Subcellular enzyme markers indicated that the membrane-associated activity was not attributable to mitochondrial or microsomal contamination. Kinetic analysis of the activity of soluble and membrane-solubilized choline kinase indicated Km values of 0.74 mM and 0.68 mM, respectively. Results indicate that choline kinase activity may be measured in both the soluble and the particulate fractions of rat striatum, the latter most likely involving enzyme associated with membrane through hydrophobic or covalent interactions. The specific function of the membrane-associated enzyme has not yet been determined.


Asunto(s)
Colina Quinasa/metabolismo , Cuerpo Estriado/enzimología , Fosfotransferasas/metabolismo , Adenosina Trifosfato/farmacología , Animales , Membranas Intracelulares/enzimología , Cinética , Magnesio/farmacología , Masculino , Octoxinol , Polietilenglicoles , Ratas , Ratas Endogámicas , Cloruro de Sodio , Distribución Tisular
19.
J Pharmacol Exp Ther ; 226(1): 135-9, 1983 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-6345753

RESUMEN

The regulation of the muscarinic receptor by the agonist methacholine was investigated in the perfused working rat heart. After 2.5 hr of perfusion with 4 microM methacholine, the number of (-)-[3H]-quinuclidinyl benzilate binding sites was significantly reduced (10-18%) in the right and left atria and left ventricle when compared with controls (2.5 hr of perfusion in the absence of methacholine). Scatchard analysis revealed that there was no change in the apparent dissociation constant for quinuclidinyl benzilate. Furthermore, when hearts were perfused for 2.5 hr with methacholine in the presence of (-)-scopolamine, a muscarinic receptor antagonist, no significant loss of receptor was observed. After perfusing with methacholine for 2.5 hr followed by 2.5 hr in the absence of agonist, the number of quinuclidinyl benzilate binding sites returned to control levels. These results suggest that agonist-induced receptor decreases or down regulation requires receptor activation and not just simple receptor occupancy. This decrease, moreover, is reversible. The perfused working rat heart represents a physiological system in which the mechanisms of muscarinic receptor regulation can be studied.


Asunto(s)
Compuestos de Metacolina/farmacología , Miocardio/metabolismo , Receptores Colinérgicos/metabolismo , Receptores Muscarínicos/metabolismo , Animales , Técnicas In Vitro , Cinética , Masculino , Cloruro de Metacolina , Perfusión , Quinuclidinil Bencilato/metabolismo , Ratas , Ratas Endogámicas , Receptores Muscarínicos/efectos de los fármacos , Escopolamina/farmacología
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