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Introduction: According to the theory of social learning, the behaviors and behaviors developed by children and adolescents are learned from the contexts where they live and are mediated by the parental practices of their caregivers. Objectives: In this sense, the objective of the present work is to identify the prosocial and aggressive behaviors of adolescents in the city of Santa Marta, Colombia. Methods: We developed a quantitative cross-sectional research where the CESC instrument was applied in a sample of 51 adolescents with an average age of 12.35 years. Results: 15.7% of adolescents reflected aggressive behaviors, however 84.3% of these do not have this behavior. On the other hand, related to prosocial behaviour, only 5.9% of the sample demonstrate this type of behaviour, on the other hand that 94.1% of these do not have prosociality within their interpersonal relationships and in social settings. Conclusions: There is a need to promote greater prosocial behaviour in adolescents based on the intervention of social scenarios such as family and school, in order to ensure the promotion of values and standards that allow them to be set up as adults comprehensive and peaceful in society that contribute positively to the development of communities. [ABSTRACT FROM AUTHOR]

Inflammatory Bowel Diseases (IBD) are a group of chronic, inflammatory disorders of the gut. The incidence and activity of IBD are determined by both genetic and environmental factors. Among these factors, polymorphisms in genes related to autophagy and the consumption of non-steroidal anti-inflammatory drugs (NSAIDs) have been consistently associated with IBD. We show that NSAIDs induce mitochondrial stress and mitophagy in intestinal epithelial cells. In an altered mitophagy context simulating that observed in IBD patients, NSAID-induced mitochondrial stress leads to the release of mitochondrial components, which act as Danger Associated Molecular Patterns with pro-inflammatory potential. Furthermore, colonic organoids from Crohn's disease patients and healthy donors show activation of the mitochondrial Unfolded Protein Response (UPR mt ) upon treatment with ibuprofen. Finally, colon biopsies from Crohn's disease patients in remission or with low-to-moderate activity also show expression of genes involved in UPR mt , while patients with severe activity show no increase compared to healthy donors. Our results suggest the involvement of mitochondria in the mechanisms triggering inflammation in IBD after NSAID use. Moreover, our results highlight the clinical relevance of mitochondrial stress and activation of the UPR mt pathway in the pathophysiology of Crohn's disease.

Clostridioides difficile infection (CDI) appears to be associated with different liver diseases. C. difficile secretes membrane vesicles (MVs), which may be involved in the development of nonalcoholic fatty liver disease (NALFD) and drug-induced liver injury (DILI). In this study, we investigated the presence of C. difficile -derived MVs in patients with and without CDI, and analyzed their effects on pathways related to NAFLD and DILI in HepG2 cells. Fecal extracellular vesicles from CDI patients showed an increase of Clostridioides MVs. C. difficile -derived MVs that were internalized by HepG2 cells. Toxigenic C. difficile -derived MVs decreased mitochondrial membrane potential and increased intracellular ROS compared to non-toxigenic C. difficile -derived MVs. In addition, toxigenic C. difficile -derived MVs upregulated the expression of genes related to mitochondrial fission (FIS1 and DRP1), antioxidant status (GPX1), apoptosis (CASP3), glycolysis (HK2, PDK1, LDHA and PKM2) and β-oxidation (CPT1A), as well as anti- and pro-inflammatory genes (IL-6 and IL-10). However, non-toxigenic C. difficile -derived MVs did not produce changes in the expression of these genes, except for CPT1A, which was also increased. In conclusion, the metabolic and mitochondrial changes produced by MVs obtained from toxigenic C. difficile present in CDI feces are common pathophysiological features observed in the NAFLD spectrum and DILI.

The composition and impact of fecal-microbe-derived extracellular vesicles (EVs) present in different diseases has not been analyzed. We determined the metagenomic profiling of feces and fecal-microbe-derived EVs from healthy subjects and patients with different diseases (diarrhea, morbid obesity and Crohn's disease (CD)) and the effect of these fecal EVs on the cellular permeability of Caco-2 cells. The control group presented higher proportions of Pseudomonas and Rikenellaceae_RC9_gut_group and lower proportions of Phascolarctobacterium , Veillonella and Veillonellaceae_ge in EVs when compared with the feces from which these EVs were isolated. In contrast, there were significant differences in 20 genera between the feces and EV compositions in the disease groups. Bacteroidales and Pseudomonas were increased, and Faecalibacterium , Ruminococcus , Clostridium and Subdoligranum were decreased in EVs from control patients compared with the other three groups of patients. Tyzzerella , Verrucomicrobiaceae , Candidatus_Paracaedibacter and Akkermansia were increased in EVs from the CD group compared with the morbid obesity and diarrhea groups. Fecal EVs from the morbid obesity, CD and, mainly, diarrhea induced a significant increase in the permeability of Caco-2 cells. In conclusion, the metagenomic composition of fecal-microbe-derived EVs changes depending on the disease of the patients. The modification of the permeability of Caco-2 cells produced by fecal EVs depends on the disease of the patients.

The effect of oleic acid (OA) on the regulation of the circadian rhythm present in human visceral (VAT) and subcutaneous (SAT) adipose tissue from patients with morbid obesity has not been analyzed yet. VAT and SAT explants from patients with morbid obesity were incubated with OA to analyze the circadian regulation of clock and other genes related to lipid metabolism (SREBP-1c, FAS, LPL and CPT1), and their association with baseline variables and the improvement of these patients after bariatric surgery. There were significant differences in amplitude and acrophase in VAT with respect to SAT. In VAT, body weight negatively correlated with BMAL1 and CRY1 amplitude, and REVERBα acrophase; body mass index (BMI) negatively correlated with REVERBα acrophase; and waist circumference negatively correlated with PER3 acrophase. In SAT, BMI negatively correlated with CLOCK amplitude, and CLOCK, REVERBα and CRY2 MESOR; and waist circumference negatively correlated with PER3 amplitude and acrophase. A greater short-term improvement of body weight, BMI and waist circumference in patients with morbid obesity after bariatric surgery was associated with a lower CRY1 and CRY2 amplitude and an earlier PER1 and PER3 acrophase in SAT. OA produced a more relevant circadian rhythm and increased the amplitude of most clock genes and lipid metabolism-related genes. OA regulated the acrophase of most clock genes in VAT and SAT, placing CLOCK/BMAL1 in antiphase with regard to the other genes. OA increased the circadian rhythmicity, although with slight differences between adipose tissues. These differences could determine its different behavior in obesity., Competing Interests: Declaration of interest None., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: Little is known about the relation between morbid obesity and duodenal transcriptomic changes. We aimed to identify intestinal genes that may be associated with the development of obesity regardless of the degree of insulin resistance (IR) of patients., Material and Methods: Duodenal samples were assessed by microarray in three groups of women: non-obese women and women with morbid obesity with low and high IR., Results: We identified differentially expressed genes (DEGs) associated with morbid obesity, regardless of IR degree, related to digestion and lipid metabolism, defense response and inflammatory processes, maintenance of the gastrointestinal epithelium, wound healing and homeostasis, and the development of gastrointestinal cancer. However, other DEGs depended on the IR degree. We mainly found an upregulation of genes involved in the response to external organisms, hypoxia, and wound healing functions in women with morbid obesity and low IR., Conclusions: Regardless of the degree of IR, morbid obesity is associated with an altered expression of genes related to intestinal defenses, antimicrobial and immune responses, and gastrointestinal cancer. Our data also suggest a deficient duodenal immune and antimicrobial response in women with high IR.

Introduction: This study evaluates the effects of 25 mL of three types of oils [extra-virgin olive oil (EVOO), olive oil (OO), and sunflower oil (SO)] on postprandial (3 h) satiety markers and variables related to metabolic status and inflammation in non-obese patients (n = 6) and in those with morbid obesity (n = 6), before and 1 year after Roux-en-Y gastric by-pass (RYGB)., Methods and Results: After EVOO intake, serum acylated ghrelin decreases and GLP1 increases more than with OO and SO. EVOO causes a higher increase of insulin and lower postprandial hypertriglyceridemia and free fatty acid levels than with OO and SO. EVOO decreases TNFα and IL6 expression in peripheral blood mononuclear cells, with OO inducing intermediate effects and SO inducing an increase of these proinflammatory markers. These results are observed in non-obese patients and in those with morbid obesity after RYGB. However, patients with morbid obesity before RYGB show a profound alteration of this response., Conclusion: EVOO produces more beneficial effects than OO, which has lower amounts of minor components, and SO, which has PUFA as its main component. RYGB produces an improvement in the metabolic response to all three types of oils in patients with morbid obesity., (© 2021 Wiley-VCH GmbH.)

Background & Aims: We investigated whether oleic acid (OA), one of the main components of the Mediterranean diet, participates in the regulation of the intestinal circadian rhythm in patients with morbid obesity., Methods: Stomach and jejunum explants from patients with morbid obesity were incubated with oleic acid to analyze the regulation of clock genes., Results: Stomach explants showed an altered circadian rhythm in CLOCK, BMAL1, REVERBα, CRY1, and CRY2, and an absence in PER1, PER2, PER3 and ghrelin (p > 0.05). OA led to the emergence of rhythmicity in PER1, PER2, PER3 and ghrelin (p < 0.05). Jejunum explants showed an altered circadian rhythm in CLOCK, BMAL1, PER1 and PER3, and an absence in PER2, REVERBα, CRY1, CRY2 and GLP1 (p > 0.05). OA led to the emergence of rhythmicity in PER2, REVERBα, CRY1 and GLP1 (p < 0.05), but not in CRY2 (p > 0.05). OA restored the rhythmicity of acrophase and increased the amplitude for most of the genes studied in stomach and jejunum explants. OA placed PER1, PER2, PER3, REVERBα, CRY1 and CRY2 in antiphase with regard to CLOCK and BMAL1., Conclusions: There is an alteration in circadian rhythm in stomach and jejunum explants in morbid obesity. OA restored the rhythmicity of the genes related with circadian rhythm, ghrelin and GLP1, although with slight differences between tissues, which could determine a different behaviour of the explants from jejunum and stomach in obesity., Competing Interests: Conflict of interest The authors declare that they have no conflict of interest., (Copyright © 2021 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.)

Objective: The study aim was to identify changes in duodenal gene expression associated with the development of insulin resistance according to the BMI of women., Methods: Duodenal samples were assessed by microarray in four groups of women, nonobese women and women with severe obesity, with both low and high insulin resistance., Results: There was a group of shared downregulated differentially expressed genes (DEGs) related to tissue homeostasis and antimicrobial humoral response in women with higher insulin resistance both with severe obesity and without obesity. In the exclusive DEGs found in severe obesity, downregulated DEGs related to the regulation of the defense response to bacterium and cell adhesion, involving pathways related to the immune system, inflammation, and xenobiotic metabolism, were observed. In the exclusive DEGs from nonobese women with higher insulin resistance, upregulated DEGs mainly related to the regulation of lipoprotein lipase activity, very low-density lipoprotein particle remodeling, lipid metabolic process, antigen processing, and the presentation of peptide antigen were found., Conclusions: Independent of BMI, higher insulin resistance was associated with a downregulation of duodenal DEGs mainly related to the immune system, inflammation, and xenobiotic metabolism. Also, intestinal lipoprotein metabolism may have a certain relevance in the regulation of insulin resistance in nonobese women., (© 2020 The Obesity Society.)

GH (growth hormone) secretion/action is modulated by alterations in energy homeostasis, such as malnutrition and obesity. Recent data have uncovered the mechanism by which hypothalamic neurons sense nutrient bioavailability, with a relevant contribution of AMPK (AMP-activated protein kinase) and mTOR (mammalian Target of Rapamycin), as sensors of cellular energy status. However, whether central AMPK-mediated lipid signaling and mTOR participate in the regulation of pituitary GH secretion remains unexplored. We provide herein evidence for the involvement of hypothalamic AMPK signaling, but not hypothalamic lipid metabolism or CPT-1 (carnitine palmitoyltransferase I) activity, in the regulation of GH stimulatory responses to the two major elicitors of GH release in vivo, namely GHRH (growth hormone-releasing hormone) and ghrelin. This effect appeared to be GH-specific, as blocking of hypothalamic AMPK failed to influence GnRH (gonadotropin-releasing hormone)-induced LH (luteinizing hormone) secretion. Additionally, central mTOR inactivation did not alter GH responses to GHRH or ghrelin, nor this blockade affected LH responses to GnRH in vivo. In sum, we document here for the first time the indispensable and specific role of preserved central AMPK, but not mTOR, signaling, through a non-canonical lipid signaling pathway, for proper GH responses to GHRH and ghrelin in vivo.

Background: The effects of different types of fatty acids on the gene expression of key players in the IRS1/PI3K signaling pathway have been poorly studied., Material and Methods: We analyzed IRS1, p85α, and p110β mRNA expression and the fatty acid composition of phospholipids in visceral adipose tissue from patients with morbid obesity and from non-obese patients. Moreover, we analyzed the expression of those genes in visceral adipocytes incubated with oleic, linoleic, palmitic and dosahexaenoic acids., Results: We found a reduced IRS1 expression in patients with morbid obesity, independent of insulin resistance, and a reduced p110β expression in those with lower insulin resistance. A positive correlation was found between p85α and stearic acid, and between IRS1 and p110β with palmitic and dosahexaenoic acid. In contrast, a negative correlation was found between p85α and oleic acid, and between IRS1 and p110β with linoleic, arachidonic and adrenic acid. Incubation with palmitic acid decreased IRS1 expression. p85α was down-regulated after incubation with oleic and dosahexaenoic acid and up-regulated with palmitic acid. p110β expression was increased and decreased after incubation with oleic and palmitic acid, respectively. The ratio p85α/p110β was decreased by oleic and dosahexaenoic acid and increased by palmitic acid., Conclusions: Our in vitro results suggest a detrimental role of palmitic acid on the expression of gene related to insulin signaling pathway, with oleic acid being the one with the higher and more beneficial effects. DHA had a slight beneficial effect. Fatty acid-induced regulation of genes related to the IRS1/PI3K pathway may be a novel mechanism by which fatty acids regulate insulin sensitivity in visceral adipocytes.

Little is known about the jejunal insulin signalling pathways in insulin resistance/diabetes states and their possible regulation by insulin/leptin. We study in jejunum the relation between insulin signalling and insulin resistance in morbidly obese subjects with low (MO-low-IR) or with high insulin resistance (MO-high-IR), and with type 2 diabetes treated with metformin (MO-metf-T2DM)), and the effect of insulin/leptin on intestinal epithelial cells (IEC). Insulin receptor substrate-1 (IRS1) and the catalytic p110β subunit (p110β) of phosphatidylinositol 3-kinase (PI3K) were higher in MO-high-IR than in MO-low-IR. The regulatory p85α subunit of PI3K (p85α)/p110β ratio was lower in MO-high-IR and MO-metf-T2DM than in MO-low-IR. Akt-phosphorylation in Ser473 was reduced in MO-high-IR compared with MO-low-IR. IRS1 and p110-β were associated with insulin and leptin levels. The improvement of body mass index (BMI) and HOMA-IR (homeostasis model assessment of insulin resistance index) after bariatric surgery was associated with a higher IRS1 and a lower p85α/p110β ratio. IEC (intestinal epithelial cells) incubation with a high glucose + insulin dose produced an increase of p85α and p110β. High dose of leptin produced an increase of IRS1, p85α and p110β. In conclusion, despite the existence of insulin resistance, the jejunal expression of genes involved in insulin signalling was increased in MO-high-IR. Their expressions were regulated mainly by leptin. IRS1 and p85α/p110β ratio was associated with the evolution of insulin resistance after bariatric surgery., Competing Interests: The authors declare that they have no conflict of interest.

Aims: The paraoxonase-1 (PON1) enzyme could play an important role in the anti-oxidant capacity of high-density lipoprotein. However, there are no studies which analyse the evolution of the three activities of PON1 (PON arylesterase, PON paraoxonase and PON lactonase) after Roux-en-Y Gastric Bypass (RYGB) in morbidly obese subjects. We analysed the association of PON concentration and activities with the evolution of morbidly obese subjects who underwent RYGB, and its relationship with biochemical variables and different atherogenic indices., Methods: Twenty-seven non-obese and 82 morbidly obese subjects were studied before and 6 months after RYGB., Results: Before RYGB, morbidly obese subjects had a lower PON1 concentration (P < 0.05) and higher PON lactonase activity (P < 0.001) than non-obese subjects, with no differences in PON arylesterase and PON paraoxonase activities. After RYGB, PON1 concentration (P < 0.05) and PON lactonase activity (P < 0.001) decreased with regard to the presurgery state. PON lactonase activity correlated with the atherogenic index of plasma before (r = 0.19, P = 0.047) and after RYGB (r = 0.27, P = 0.035). In different multiple lineal regression analysis models, presurgery PON lactonase activity was associated with total cholesterol (β = 0.909, P < 0.001), LDL (β = 0.632, P = 0.006) and DBP (β = 0.230, P = 0.030) (R 2  = 0.295), postsurgery PON lactonase activity was associated with esterified cholesterol (β = 0.362, P = 0.011) (R 2  = 0.131), and the change (Δ) in PON lactonase activity after RYGB was associated with Δesterified cholesterol (β = 0.304, P = 0.030) (R 2  = 0.093)., Conclusions: PON lactonase activity is associated with the presence of morbid obesity and with an impaired lipid profile. All associations found could indicate the relationship between PON lactonase activity and the development of atherosclerosis., (© 2019 John Wiley & Sons Ltd.)

Background: The immune response of visceral adipose tissue (VAT) in obesity, in particular the role of invariant natural killer T (iNKT) cells, has not yet been fully elucidated., Objective: To characterize iNKT cells and its activation status in VAT and peripheral blood mononuclear cells (PBMC) in morbidly obese subjects (MO), and to analyze their association with metabolic parameters., Subjects and Methods: Twenty non-obese and 20 MO subjects underwent Roux-en-Y gastric bypass (RYGB) and were studied before and 6 months after RYGB. VAT and PBMC were obtained., Results: A decrease in VAT iNKT cells from MO was found, however, not in PBMC. Visceral adipocytes from MO presented increased CD1d expression (p = 0.032). MO presented an increase in early activated CD69+ iNKT cells in PBMC before RYGB (p < 0.001), but not after RYGB nor in VAT, and an increase in later activated CD25+ iNKT in VAT (p = 0.046), without differences in PBMC. The co-expression of early and later markers (CD69+CD25+) in iNKT cells was increased in MO in VAT (p = 0.050) and PBMC (p = 0.006), decreasing after RYGB (p = 0.050). CD69+ iNKT and CD69+CD25+ iNKT cells in PBMC after RYGB correlated negatively with glucose, insulin, and insulin resistance levels., Conclusions: There is a tissue-specific phenotype and activation of iNKT cells in VAT in morbid obesity, which could be involved in VAT immunometabolism dysregulation. Also, the increase in CD1d expression could be to offset the lack of VAT iNKT cells.

The factors regulating TNF alpha (TNFa) levels could be considered therapeutic targets against metabolic syndrome development. DNA methylation is a potent regulator of gene expression and may be associated with protein levels. In this study we investigate whether the effect of dietary fatty acids on TNFa released from adipocytes might be associated with modifications of the TNFa promoter DNA methylation status. A group of rats was assigned to three diets with a different composition of saturated, monounsaturated and polyunsaturated fatty acids. Samples of visceral adipose tissues were taken for adipocyte isolation, in which released TNFa levels were measured, and for methylation and expression studies. In addition, 3 T3-L1 cells were treated with palmitic, oleic and linoleic acids, with and without 5-Azacitydine (5-AZA). After treatments, cells and supernatants were included in the same analyses as rat samples. TNFa promoter methylation levels, gene expression and secretion were different according to the diets and fatty acid treatments associated with them. Cells treated with 5-AZA displayed higher TNFa levels than in the absence of 5-AZA, without differences between fatty acids. According to our results, dietary fatty acid regulation of adipocyte TNFa levels may be mediated by epigenetic modifications of the TNFa promoter DNA methylation levels., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Purpose: We have investigated the epigenetic regulation by dietary fatty acids of Vegfb levels in rats' white adipose tissue and 3T3-L1 cells., Methods: A group of rats were assigned to three diets, each one with a different composition of saturated, monounsaturated and polyunsaturated fatty acids. Samples of white adipose tissues were taken for the methylation and expression studies. Additionally, 3T3-L1 cells were treated with palmitic, oleic, and linoleic fatty acids. After treatment, cells were harvested and genetic material was extracted for the analysis of Vegfb levels., Results: We report evidence of changes in the methylation levels of the CpG island at the Vegfb promoter and in the Vegfb expression levels in vivo and in vitro by dietary fatty acid, with the main contribution of the linoleic fatty acid. Vegfb promoter methylation levels were closely related to the Vegfb gene expression., Conclusion: According to our results, the regulation of Vegfb gene expression by dietary fatty acids may be mediated, at least in part, by epigenetic modifications on Vegfb promoter methylation. Considering the deep association between angiogenesis and tissue growth, we suggest the nutriepigenetic regulation of Vegfb as a key target in the control of the adipose tissue expansion.

Objective: The effects of C-peptide on adipose tissue, an organ involved in the development of obesity and insulin resistance, are not yet well known. The aim of this study was to determine whether C-peptide could be involved in the regulation of the adipocytokine synthesis in human visceral adipose tissue., Methods: The association between C-peptide and different serum adipocytokines, with an intravenous glucose tolerance test (IVGTT), and in an in vitro study in subjects without obesity and in subjects with morbid obesity were analyzed., Results: In different multiple regression analysis models, C-peptide and C-peptide increase above basal levels during total IVGTT and between 0 and 10 min were associated positively with leptin and negatively with visfatin. Rhodamine-labeled C-peptide binds to human adipocytes, and this binding was blocked with excess of unlabeled C-peptide. Exposure of human visceral explants and adipocytes from subjects with morbid obesity to C-peptide at 1 and 10 nM induced a significant increase in leptin and a decrease in visfatin secretion. In subjects without obesity, these C-peptide effects were found mainly at 10 nM. These effects can be inhibited by phosphatidylinositol 3-kinase (PI3K) or protein kinase B (PKB) inhibitors., Conclusions: C-peptide may be involved in the regulation of leptin and visfatin secretion, molecules intimately involved in energy homeostasis processes, through PI3K or PKB pathways., (© 2015 The Obesity Society.)

Little is known about the association between iodine and human milk composition. In this study, we investigated the association between iodine and different markers of oxidative stress and obesity-related hormones in human breast milk. This work is composed of two cross-sectional studies (in lactating women and in the general population), one prospective and one in vitro. In the cross-sectional study in lactating women, the breast milk iodine correlated negatively with superoxide dismutase (SOD), catalase, and glutathione peroxidase (GSH-Px) activities, and with adiponectin levels. An in vitro culture of human adipocytes with 1 μM potassium iodide (KI, dose similar to the human breast milk iodine concentration) produced a significant decrease in adiponectin, GSH-Px, SOD1, and SOD2 mRNA expression. However, after 2 months of treatment with KI in the prospective study, a positive correlation was found between 24-h urinary iodine and serum adiponectin. Our observations lead to the hypothesis that iodine may be a factor directly involved in the regulation of oxidative stress and adiponectin levels in human breast milk.

Background: Insulin has several biological functions besides glycaemic control. We investigated and compared the effects of six different commercial insulins on adipocyte cell differentiation, the lipolytic activity of differentiated cells, and the expression levels of genes involved in adipogenesis and associated with insulin activity., Materials and Methods: 3T3-L1 cells were induced to differentiate with six commercial insulins: glargine, lispro, aspart, detemir, NPH and regular recombinant human insulin (used as control). Cell differentiation, lipolysis and gene expression were measured at day 7 (D7) and day 10 (D10) after induction of differentiation in these cells., Results: The highest values of cell differentiation and lipolysis were found at D10 for all the insulins used. Preadipocyte differentiation differed at both times depending on the insulin used, with detemir insulin being the least adipogenic. The PPARγ mRNA level varied according to the insulin and was a good genetic marker of adipogenesis at D7. Cells treated with glargine insulin showed the highest lipolysis and HSL expression on both days. Gene expression levels of InsR, SREBP-1c and SCD-1 differed depending on the insulin studied., Conclusions: Detemir insulin was the least adipogenic of the insulins tested, whereas treatment with glargine insulin tended to produce the highest lipolysis levels. Under these experimental conditions, the modifications made in commercial insulins to improve glycaemic control also affect adipocyte differentiation, the lipolysis level of differentiated cells, and the expression of different genes that can modify metabolic pathways independently of glucose metabolism., (© 2011 The Authors. European Journal of Clinical Investigation © 2011 Stichting European Society for Clinical Investigation Journal Foundation.)

The adipokine resistin is an insulin-antagonizing factor that also plays a regulatory role in inflammation, immunity, food intake, and gonadal function. Although adipose tissue is the primary source of resistin, it is also expressed in other tissues and organs, including the pituitary. However, there is no information on whether resistin, as described previously for other adipokines such as leptin and adiponectin, could regulate this gland. Likewise, the molecular basis of resistin actions remains largely unexplored. Here we show that administration of resistin to dispersed rat anterior pituitary cells increased GH release in both the short (4 h) and long (24 h) term, decreased mRNA levels of the receptor of the somatotrope regulator ghrelin, and increased free cytosolic Ca(2+) concentration in single somatotropes. By means of a pharmacological approach, we found that the stimulatory action of resistin occurs through a Gs protein-dependent mechanism and that the adenylate cyclase/cAMP/protein kinase A pathway, the phosphatidylinositol 3-kinase/Akt pathway, protein kinase C, and extracellular Ca(2+) entry through L-type voltage-sensitive Ca(2+) channels are essential players in mediating the effects of resistin on somatotropes. Taken together, our results demonstrate for the first time a regulatory role for resistin on somatotrope function and provide novel insights on the intracellular mechanisms activated by this protein.

Ghrelin is a newly discovered peptide that binds the receptor for GH secretagogues (GHS-R). The presence of both ghrelin and GHS-Rs in the hypothalamic-pituitary system, together with the ability of ghrelin to increase GH release, suggests a hypophysiotropic role for this peptide. To ascertain the intracellular mechanisms mediating the action of ghrelin in somatotropes, we evaluated ghrelin-induced GH release from pig pituitary cells both under basal conditions and after specific blockade of key steps of cAMP-, inositol phosphate-, and Ca2+-dependent signaling routes. Ghrelin stimulated GH release at concentrations ranging from 10-10 to 10-6 m. Its effects were comparable with those exerted by GHRH or the GHS L-163,255. Combined treatment with ghrelin and GHRH or L-163,255 did not cause further increases in GH release, whereas somatostatin abolished the effect of ghrelin. Blockade of phospholipase C or protein kinase C inhibited ghrelin-induced GH secretion, suggesting a requisite role for this route in ghrelin action. Unexpectedly, inhibition of either adenylate cyclase or protein kinase A also suppressed ghrelin-induced GH release. In addition, ghrelin stimulated cAMP production and also had an additive effect with GHRH on cAMP accumulation. Ghrelin also increased free intracellular Ca2+ levels in somatotropes. Moreover, ghrelin-induced GH release was entirely dependent on extracellular Ca2+ influx through L-type voltage-sensitive channels. These results indicate that ghrelin exerts a direct stimulatory action on porcine GH release that is not additive with that of GHRH and requires the contribution of a multiple, complex set of interdependent intracellular signaling pathways.