Jose M Carrascosa

Universidad Autónoma de Madrid | UAM · Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM)

The prevalence of insulin resistance and type 2 diabetes increases with aging and these disorders are associated with inflammation. Insulin resistance and inflammation do not develop at the same time in all tissues. Adipose tissue is one of the tissues where inflammation and insulin resistance are established earlier during aging. Nevertheless, the...

Aged Wistar rats present central insulin resistance associated with ageing. Several steps of the insulin signaling pathway have been described to be impaired in aged rats at hypothalamic level. In the present article we have explored possible alterations in protein tyrosine phosphatases (PTPs) involved in insulin receptor dephosphorylation, as well...

Insulin resistance develops with aging in rats in parallel to fat mass accretion, central leptin resistance and hyperleptinemia. Previous studies demonstrated that insulin resistance appears earlier in adipose tissue than in muscle during aging and pointed to a role of hyperleptinemia in the impairment of insulin action. Here we explored the evolut...

Protein tyrosine phosphatase 1B (PTP1B) is a negative regulator of insulin signaling and a therapeutic target for type 2 diabetes (T2DM). In this study, we have evaluated the role of PTP1B in the development of aging-associated obesity, inflammation, and peripheral insulin resistance by assessing metabolic parameters at 3 and 16 months in PTP1B(-/-...

We have studied the effect of aging and late onset caloric restriction (CR) on the expression of SIRT1 in hippocampus and cerebral cortex of the rat. Quantitative analysis showed that there is a significant reduction of SIRT1 protein levels in hippocampus with aging. Late onset, moderate CR prevented the deleterious effect of aging on SIRT1 content...

Insulin resistance and type 2 Diabetes have been associated to a low grade of inflammation and their prevalence increase with ageing. To analyse the development of inflammation in adipose tissue, liver, muscle and hypothalamus during ageing and the effects of caloric restriction. We have analysed the expression of inflammatory cytokines (TNFα, IL1-...

Aging in mammals associates with the development of peripheral insulin resistance. Additionally, adiposity usually increases with aging and this could play a relevant role in the gradual impairment of insulin action. In fact, fat accretion leads to changes in the expression and circulating concentrations of factors originated in adipose tissue like...

Leptin enhances the glucose utilization in most insulin target tissues and paradoxically decreases it in white adipose tissue (WAT), but knowledge of the mechanisms underlying the inhibitory effect of central leptin on the insulin-dependent glucose uptake in WAT is limited. After 7 d intracerebroventricular leptin treatment (0.2 μg/d) of rats, the...

S-resistin is a non-secretable resistin spliced variant described in white adipose tissue from Wistar rats. Since resistin has been implicated in adipogenesis regulation, here we have investigated the possible role of this new isoform in this process. For that, we have studied the adipocyte development in 3T3-L1 pre-adipocyte cell line stably expre...

Food intake and energy balance are among the functions regulated by serotonin in the brain. Recent studies have shown an interaction of serotonergic system with leptin, a protein released from adipose tissue that inhibits feeding behavior and increases fuel expenditure. In this study, leptin labeled with digoxigenin was injected in the lateral cere...

Insulin resistance progressively increases with age, resulting in excessively high incidence of T2D in the elderly population. To investigate the molecular mechanisms underlying insulin resistance of aging, we carried out a comparative study of insulin signalling cascade in adipose tissue, liver and skeletal muscle. We measured the protein levels i...

Two variants of the adipose hormone resistin are generated by alternative splicing in Wistar rats. Here we analyzed the expression of these resistin variants in 2 main visceral adipose depots, epididymal and retroperitoneal, as well as the resistin serum concentration during aging and food restriction. Total protein levels of resistin were also ana...

Basal cell carcinoma (BCC) is a cutaneous, locally invasive, epidermal malignant tumor generally considered to originate from pluripotential immature cells of the epidermis and thus able to differentiate towards any of the epithelial skin structures. It is composed of cells similar to those in the basal layer of the epidermis and its appendages. Ev...

Energy balance in mammals is modulated by peripheral signals that inform the brain about the magnitude of fat stores, the amount of food in the gastrointestinal tract, and the level of nutrients such as glucose in the circulation. Among these, insulin and leptin are considered adiposity signals involved in the long-term maintenance of fat stores. H...

Inhibitors of intestinal glucosidases have been shown to improve glycaemic control in diabetic and obese humans and animals. In the present study, we have investigated the effect of 3 months treatment with acarbose on adiposity, food intake and the modulation of hypothalamic neuropeptide Y (NPY) in obese diabetic Wistar (WDF) rats and the possible...

Leptin reduces adiposity and exerts antisteatotic effects on nonadipose tissues. However, the mechanisms underlying leptin effects on lipid metabolism in liver and white adipose tissue have not been fully clarified. Here, we have studied the effects of central leptin administration on key enzymes and transcription factors involved in lipid metaboli...

Insulin, like leptin, is considered as a lipostatic signal acting at a central level. Aging and age-associated adiposity have been related to the development of leptin resistance in Wistar rats. In the present article, hypothalamic insulin response during aging has been studied in Wistar rats. Thus, the effects of intracerebroventricular infusion o...

Insulin resistance develops with ageing in humans and rodents. Here, we have studied the evolution of insulin sensitivity with ageing trying to discriminate the role of adiposity from that of ageing in this process. We performed oral glucose tolerance tests and determined overall and tissue-specific glucose utilization under euglycemic-hyper-insuli...

Insulin receptor signal transduction depends on the precise intracellular localization of signalling molecules. This study examines the compartmentalization and the insulin-induced translocation and tyrosine phosphorylation of insulin receptor substrates (IRS-1 and IRS-3) in epididymal white adipose tissue from adult and insulin-resistant old rats....

It is essential to develop a consensus document on phototherapy in order to adapt this procedure to the specific characteristics, needs and reality of our milieu. Using a review of existing literature on the subject and the experience of its own members as a reference, the Spanish Photobiology Group (GEF) of the Spanish Academy of Dermatology and V...

It is essential to develop a consensus document on phototherapy in order to adapt this procedure to the specific characteristics, needs and reality of our milieu.Using a review of existing literature on the subject and the experience of its own members as a reference, the Spanish Photobiology Group (GEF) of the Spanish Academy of Dermatology and Ve...

In rodents, soluble leptin receptor (SLR) may be generated by alternative splicing of ObR mRNA and/or as a cleavage product of ObR membrane-anchored receptors. In this study, we investigated the contribution of both processes on the generation of SLR in 3-, 8-, and 24-month-old Wistar rats fed ad libitum (AL) or under food restriction (FR). To this...

The insulin receptor (IR) occurs as two alternatively spliced isoforms, IR-A (exon 11-) and IR-B (exon 11+), which exhibit functional differences and are expressed in a tissue-specific manner. The IR substrate (IRS) proteins 1, 2 and 3 also differ in function and tissue distribution. Here we show the differential gene expression of IRs and IRSs in...

Leptin modulates glucose homeostasis by acting as an insulin-sensitizing factor in most insulin target tissues. Nevertheless, insulin-dependent glucose uptake in white adipose tissue decreases after in vivo treatment with leptin. Moreover, elevated leptin concentrations inhibit insulin metabolic effects in adipocytes. Here we studied both, direct a...

Resistin is a secreted adipose tissue hormone that belongs to the resistin-like molecule family. We report here a new alternatively spliced isoform of the rat resistin gene, named S-resistin (short resistin), detected in adipose tissue by reverse transcription-polymerase chain reaction (RT-PCR). A comparison of this cDNA variant and genomic sequenc...

A protein with insulin-like effects was isolated from the hepatopancreas of the lobster Panulirus argus following a classic method for mammalian insulin purification from the pancreas. After acid-alcoholic extraction and ethanol-ether precipitation followed by molecular filtration chromatography, a protein with an apparent molecular weight of 6 kDa...

Aged Wistar rats are characterized by leptin and insulin resistance. The expression of SOCS-3 in hypothalamus increases with ageing. Food restriction during 3 months decreases obesity Lee index in aged rats with respect to their ad libitum aged-mates and brings serum leptin concentrations to values close to those of young rats. Food restriction par...

Ageing is associated with insulin and leptin resistance in mammals. These alterations might be caused by the increased adiposity associated with ageing, by ageing alone or both. We studied whether leptin resistance occurs at the central level in the Wistar rat and we aimed to discriminate between the effects of ageing from those of the increased ad...

Vanadate has insulin-like effects in adipocytes without stimulating insulin receptor kinase activity. However, it activates IRS-1 associated PI 3-kinase, suggesting that it mimics insulin effects by stimulating signaling elements downstream of PI 3-kinase. Here we analysed the stimulation of MAPK by insulin and vanadate and observed that both elici...

Leptin interacts with specific receptors in hypothalamic nuclei and modulates energy balance. Growing evidence has shown the association of obesity and hyperleptinaemia with non-insulin-dependent diabetes mellitus and insulin resistance. The aged Wistar rat shows peripheral insulin resistance in the absence of obesity and alterations of glucose hom...

The effect of chronic treatment with acarbose on fasting plasma glucose, insulin, triglyceride, cholesterol and free fatty acid (FFA) concentrations, as well as on the glucose and insulin excursions during oral glucose tolerance test (OGTT), in obese diabetic Wistar (WDF) rats was investigated. Forty-five mature male WDF rats were randomly distribu...

Vanadate stimulates adipocyte 2-deoxyglucose transport and GLUT-4 translocation to the membrane through an insulin receptor-independent but wortmannin-inhibitable pathway. Vanadate stimulates PI 3-kinase in anti-IRS-1 immunoprecipitates and the binding between IRS-1 and the p85alpha subunit of PI 3-kinase. In insulin-resistant adipocytes from old r...

Mammary gland is an organ that undergoes cycles of growth, differentiation, and function during pregnancy and lactation. Although it is known that the gland enhances its sensitivity to insulin during lactation, it remains to be investigated whether this increased sensitivity develops during pregnancy and which are the molecular mechanisms underlyin...

Mammary gland is an organ that undergoes cycles of growth, differentiation, and function during pregnancy and lactation. Although it is known that the gland enhances its sensitivity to insulin during lactation, it remains to be investigated whether this increased sensitivity develops during pregnancy and which are the molecular mechanisms underlyin...

Aging has been associated with peripheral insulin resistance in both humans and rats. However, the specific tissues that become insensitive to insulin before glucose homeostasis is altered remain to be elucidated. In the present work we studied the glucose metabolic index of a number of tissues known to be insulin sensitive in 3- and 24-month-old W...

Aging has been associated with peripheral insulin resistance in both humans and rats. However, the specific tissues that become insensitive to insulin before glucose homeostasis is altered remain to be elucidated. In the present work we studied the glucose metabolic index of a number of tissues known to be insulin sensitive in 3- and 24-month-old W...

Partially purified liver insulin receptors from full-term pregnant rats show decreased autophosphorylation rates if compared with receptors from virgins. We studied the molecular mechanism of this phenomenon, looking at possible structural and functional changes of several domains. The ATP-binding domain seems to be unaltered in receptors from preg...

Cyclic AMP (cAMP) is known to play a key role in regulating insulin action, and it is well documented that in several cases of physiological insulin resistance its concentration is increased. Since late pregnancy in the rat is associated with liver insulin resistance, we have studied possible alterations of some cellular mechanisms regulating the c...

The effect of aging on the insulin binding parameters and on the kinetic characteristics of the insulin receptor autophosphorylation in rat adipose tissue has been investigated. Using solubilized receptors from adipocyte plasma membranes, no significant differences were identified in either affinity or receptor number in adult vs old rats. Time cou...

Insulin resistance of the skeletal muscle is a key feature of Type 2 (non-insulin-dependent) diabetes mellitus. To determine whether a decrease of glucose carrier proteins or an altered subcellular distribution of glucose transporters might contribute to the pathogenesis of the insulin resistant state, we measured glucose transporter numbers in mem...

Human insulin receptor (HIR) is expressed in two isoforms which differ in the C-terminal end of the alpha-subunit (HIR-A = -12 aa, HIR-B = +12 aa). We studied internalization kinetics of HIR-A and HIR-B in Rat1 fibroblasts. Internalized receptors were quantified by 125I-insulin binding after cell trypsinisation and solubilization, surface receptors...

Activation of a phosphatidylinositol-3-kinase (PI-3-kinase) is one of the earliest consequences of insulin binding to the receptor. The human insulin receptor exists in two isoforms which differ in the length of the alpha-subunit (HIR-A = 719 aa, HIR-B = 731 aa). To test whether both isoforms transduce an insulin signal on PI-3-kinase we used rat-1...

A slight but significant short-term incorporation (15 and 60 min) of glucose-carbon into DNA and RNA was detected in Ehrlich ascites tumour cells incubated in the presence of labelled glucose (5 mM). Glutamine (0.5 mM) increased the incorporation of glucose but did not modify the glycolytic flux.

It is now well established that in humans and rats late pregnancy is associated with a state of insulin resistance, manifested by decreased sensitivity and responsiveness to the hormone of target tissues (1,2). The growth of the conceptus requires supply of substrates like glucose from the mother, and this is only possible if a mechanism develops t...

Late gestation is associated with insulin resistance in rats and humans. It has been reported that rats at term gestation show active hepatic gluconeogenesis and glycogenolysis, and diminished lipogenesis, despite normal or mildly elevated plasma insulin concentrations, indicating a state of resistance to the hormone action. Since autophosphorylati...

The tyrosine kinase activity of the insulin receptor derived from rat adipocyte plasma membranes was examined during aging. In the absence of insulin, autophosphorylation and histone H2B phosphorylation activities, measured with equal numbers of insulin receptors, were comparable among 3- and 24-month-old rats. In contrast, insulin-stimulated kinas...

The addition of 10 mM fructose or 10 mM tagatose to a suspension of hepatocytes caused respiratory inhibition, whereas no change in oxygen uptake was observed following the addition of glucose. However, incubations in the presence of fructose showed a high, aerobic glycolytic activity. Tagatose is phosphorylated to tagatose 1-phosphate but is not f...

The beta-subunit of the insulin receptor contains a tyrosine-specific protein kinase. Insulin binding activates this kinase and causes phosphorylation of the beta-subunit of the insulin receptor. It is believed that phosphorylation of other proteins might transmit the insulin signal from the receptor to the cell. In the present study we used a poly...

Partially purified phospholipid- and Ca2+-dependent protein kinase C from human placenta catalyzes the Mg-ATP-dependent phosphorylation of serine residues of purified rabbit muscle actin. Two tryptic [32P]-phosphopeptides were found on HPLC separation. Confirming the previous report by Machicao and Wieland [(1985) Curr. Top. Cell. Regul. 27, 95-105...

The digitonin method for the study of cellular compartmentation in mitochondrial and cytosolic fractions was applied to Ehrlich ascites tumor cells. The volume of mitochondrial and cytosolic water spaces are calculated to be 1.62 microliter/30 x 10(6) cells respectively, by the technique of 3H2O permeable and (14C)-sucrose impermeable spaces. The v...

Tumors function as a nitrogen trap, and they compete with the host for nitrogen compounds. In experiments with whole animals infected with Ehrlich ascitic tumor cells, the glutamine, glutamate, asparagine, and aspartate concentrations were determined for host plasma, ascitic liquid, and tumor cells, throughout the period of tumor growth. Concentrat...

The amount of ammonium ion in both plasma and ascites fluid from mice inoculated with Ehrlich ascites cancer was studied. The ammonium ion increases as tumor grows and is probably produced during the glutamine metabolism of cancer cells.

The flow through pyruvate dehydrogenase was assayed in glycolysing cells by the evolution of 14CO2 from [1-14C] pyruvate. Parallel incubations were carried out in high bicarbonate buffer (25 mM) and in bicarbonate-free buffer. The activation of the complex by NH+4 was only observed in high bicarbonate buffer, because the dilution of labelled CO2 in...

Oxygen uptake and glycolytic activity were studied in hepatocytes isolated from fed rats. The addition of fructose or tagatose resulted in a 38% and 31% inhibition of cellular respiration respectively. The addition of 10 mM D-glyceraldehyde caused a slight Crabtree effect. Glucose, L-sorbose, or glycerol failed to modify oxygen consumption. Only in...

The NH4+ concentrations in plasma and ascitic liquid of mice bearing tumor were determined over the time of tumor growth. A significant ammonia increase in the host's blood was detected in 13-14th days after inoculations. NH4+ in the ascitic liquid rose to 0.63 mM. Preliminary results suggested that NH4+ found in ascitic liquid and in the host's bl...

Brettanomyces abstinens growing on different initial glucose concentrations showed an anaerobic inhibition of fermentation. This Custers effect decreased as the initial glucose concentration in the medium increased. Two aldehyde dehydrogenases, one NAD+-linked and the other NADP+-linked were observed. The results suggest that the NAD+-linked enzyme...

NTRODUCCIÓN: El envejecimiento en la rata Wistar se asocia a una resistencia central y periférica a insulina que es revertida parcialmente con una restricción calórica. Teniendo en cuenta que la resistencia a insulina se ha asociado también a un estado de inflamación subcrónico en el presente trabajo hemos querido estudiar el estado inflamatorio de...