BACKGROUND:Glucagon plays a central role in hepatic adaptation during fasting, with the upregulation of hepatic phosphoenolpyruvate carboxykinase 1 (PCK1) traditionally associated with increased gluconeogenesis. However, recent experimental models and clinical studies have challenged this view, suggesting a more complex interplay between PCK1 and glucagon, which extends beyond gluconeogenesis and has broader implications for metabolic regulation in health and disease. SCOPE OF REVIEW:This review provides a comprehensive overview of the current evidence on the multifaceted roles of PCK1 in glucagon-dependent hepatic adaptation during fasting, which is crucial for maintaining systemic homeostasis not only of glucose, but also of lipids and amino acids. We explore the relationship between PCK1 deficiency and glucagon resistance in metabolic disorders, including inherited PCK1 deficiency and metabolic dysfunction-associated steatotic liver disease (MASLD), and compare findings from experimental animal models with whole-body or tissue-specific ablation of PCK1 or the glucagon receptor. We propose new research platforms to advance the therapeutic potential of targeting PCK1 in metabolic diseases. MAJOR CONCLUSIONS:We propose that hepatic PCK1 deficiency might be an acquired metabolic disorder linking alterations in lipid metabolism with impaired glucagon signaling. Our findings highlight interesting links between glycerol, PCK1 deficiency, elevated plasma alanine levels and glucagon resistance. We conclude that the roles of PCK1 and glucagon in metabolic regulation are more complex than previously assumed. In this (un)expected scenario, hepatic PCK1 deficiency and glucagon resistance appear to exert limited control over glycemia, but have broader metabolic effects related to lipid and amino acid dysregulation. Given the shift in glucagon research from receptor inhibition to activation, we propose that a similar paradigm shift is needed in the study of hepatic PCK1. Understanding PCK1 expression and activity in the glucagon-dependent hepatic adaptation to fasting might provide new perspectives and therapeutic opportunities for metabolic diseases.

Pancreatic beta-cells express the gluconeogenic enzymes glucose 6-phosphatase (G6Pase), fructose 1,6-bisphosphatase (FBP), and phosphoenolpyruvate (PEP) carboxykinase (PCK), which modulate glucose-stimulated insulin secretion (GSIS) through their ability to reverse otherwise irreversible glycolytic steps. Here, we review current knowledge about the expression and regulation of these enzymes in the context of manipulating them to improve insulin secretion in diabetics. Because the regulation of gluconeogenic enzymes in beta-cells is so poorly understood, we propose novel research avenues to study these enzymes as modulators of insulin secretion and beta-cell dysfunction, with especial attention to FBP, which constitutes an attractive target with an inhibitor under clinical evaluation at present.

The pancreatic islets of Langerhans, mainly formed by glucagon-producing α-cells and insulin-producing β-cells, are critical for glucose homeostasis. Insulin and glucagon oppositely modulate blood glucose levels in health, but a combined decline in insulin secretion together with increased glucagon secretion contribute to hyperglycemia in diabetes. Despite this bi-hormonal dysregulation, most studies have focused on insulin secretion and much less is known about glucagon secretion. Therefore, a deeper understanding of α-cell metabolism and glucagon secretion is of great interest. Here, we show that phosphoenolpyruvate carboxykinase (PCK1), an essential cataplerotic enzyme involved in metabolism and long considered to be absent from the pancreatic islet, is expressed in pancreatic α-cells of both murine and human. Furthermore, PCK1 transcription is induced by fasting and diabetes in rat pancreas, which indicates that the PCK1 activity is required for α-cell adaptation to different metabolic states. To our knowledge, this is the first evidence implicating PCK1 expression in α-cell metabolism.

Diabetes is a complex metabolic disorder triggered by the deficient secretion of insulin by pancreatic cells, the resistance of peripheral tissues to the action of the hormone, or both, and is characterized by chronic hyperglycemia leading to organ damage and failure. Tight glycemic control represents the best therapy to delay or stop progression of diabetes, with many antidiabetic drugs being commercially available nowadays. However, no ideal normoglycemic agent has been developed as yet, and those already available still induce hypoglycemia and/or weight gain as major side effects, worsening glycemic control. In this respect, the inorganic salt sodium tungstate (Na2WO4) has been proven to offer a good antidiabetic alternative in different animal models of diabetes, reducing body weight and normalizing glycemia without causing hypoglycemic episodes. The mechanisms of action mediating the potent antidiabetic actions but also the spectrum of undesirable effects of Na2WO4 are still poorly understood. In fact, along with its beneficial effects, Na2WO4 has been consistently reported to be toxic and even carcinogenic. Given that Na2WO4 is accumulated in the kidneys for elimination, here, we discuss a possible association between long-term Na2WO4 treatment and a higher risk of renal carcinogenesis in diabetic individuals.

Diabetes is a complex metabolic disorder triggered by the deficient secretion of insulin by pancreatic β cells, the resistance of peripheral tissues to the action of the hormone, or both, and is characterized by chronic hyperglycemia leading to organ damage and failure. Tight glycemic control represents the best therapy to delay or stop progression of diabetes, with many antidiabetic drugs being commercially available nowadays. However, no ideal normoglycemic agent has been developed as yet, and those already available still induce hypoglycemia and/or weight gain as major side effects, worsening glycemic control. In this respect, the inorganic salt sodium tungstate (Na2WO4) has been proven to offer a good antidiabetic alternative in different animal models of diabetes, reducing body weight and normalizing glycemia without causing hypoglycemic episodes. The mechanisms of action mediating the potent antidiabetic actions but also the spectrum of undesirable effects of Na2WO4 are still poorly understood. In fact, along with its beneficial effects, Na2WO4 has been consistently reported to be toxic and even carcinogenic. Given that Na2WO4 is accumulated in the kidneys for elimination, here, we discuss a possible association between long‐term Na2WO4 treatment and a higher risk of renal carcinogenesis in diabetic individuals.

The kidney is an insulin-sensitive organ involved in glucose homeostasis. One major effect of insulin is to induce glycogen storage in the liver and muscle. However, no significant glycogen stores are detected in normal kidneys, but diabetic subjects present a characteristic renal histopathological feature resulting from extensive glycogen deposition mostly in nonproximal tubules. The mechanism of renal glycogen accumulation is yet poorly understood. Here, we studied in situ glycogen accumulation in the kidney from diabetic IRS2-knockout mice and the effect of the insulin-mimetic agent sodium tungstate (NaW). IRS2-knockout mice displayed hyperglycemia and hyperinsulinemia. NaW only normalized glycemia. There was no evident morphological difference between kidneys from untreated wild-type (WT), NaW-treated WT, and untreated IRS2-knockout mice. However, NaW-treated IRS2-knockout mice showed tubular alterations resembling clear cells in the cortex, but not in the outer medulla, that were correlated with glycogen accumulation. Immunohistochemical detection of the gluconeogenic enzyme phosphoenolpyruvate carboxykinase, mostly expressed by renal proximal tubules, showed that altered tubules were of proximal origin. Our preliminary study suggests that IRS2 differentially regulates glycogen accumulation in renal tubules and that NaW treatment in the context of IRS2 ablation induces abnormal glycogen accumulation in cortical proximal tubules.

A sedentary lifestyle is associated with decreased insulin sensitivity and accumulation of visceral adipose tissue. Which combined with poor eating habits, explain the overall increase in overweight and obesity. In Chile overweight it affects 64.4% and 88.6% sedentary population. The objective was to determine the levels of sedentarism in Nutrition and Dietetics students's and evaluate whether there is an association with eating habits. 607 students from Nutrition and Dietetics were evaluated by applying an anthropometric weight and height assessment, a food assessment survey and a physical activity survey. Results: The percentage of sedentary women was significantly higher than in men (74.3% v / s 40.5%), also women who never eat dinner nearly twice the percentage observed in men. Finally, students who performed some type of physical activity had a significantly higher percentage in the frequency of consumption of breakfast and dinner, with respect to sedentary students. Determining an association between physical activity and eating behaviour (integral 2= 10,56; p-0.001). This study determined that young sedentary individuals had a worse eating habits than those who performed some type of physical activity. Our results suggest that perform some type of physical activity is associated with better eating pattern.

Diabetic nephropathy (DN) is a major complication of diabetic patients and the leading cause of end-stage renal disease. Glomerular dysfunction plays a critical role in DN, but deterioration of renal function also correlates with tubular alterations. Human DN is characterized by glycogen accumulation in tubules. Although this pathological feature has long been recognized, little information exists about the triggering mechanism. In this study, we detected over-expression of muscle glycogen synthase (MGS) in diabetic human kidney. This enhanced expression suggests the participation of MGS in renal metabolic changes associated with diabetes. HK2 human renal cell line exhibited an intrinsic ability to synthesize glycogen, which was enhanced after over-expression of protein targeting to glycogen. A correlation between increased glycogen amount and cell death was observed. Based on a previous transcriptome study on human diabetic kidney disease, significant differences in the expression of genes involved in glycogen metabolism were analyzed. We propose that glucose, but not insulin, is the main modulator of MGS activity in HK2 cells, suggesting that blood glucose control is the best approach to modulate renal glycogen-induced damage during long-term diabetes.

PALABRAS CLAVE: Sexualidad, trabajadoras sexual, mujer SUMMARY Background: Sexuality is displayed as a reflection of the level of physical, psychological and social wellbeing. Therefore, negative sexual experiences can affect the entire development as human beings. In Chile, there are no studies that investigate the presence of sexual dysfunctions in the sex worker. Aim: To evaluate the Female Sexual Function Index (FSFI) in women sex workers about their sexual performance with his regular partner and compared with women not sex workers. Methods: Sexually active women over 18 years. We work with purposive intentional non probabilistic sampling. The final number of women studied was 58, of which 23 women were sex workers (study group) and 35 women were not involved in the sex trade (control group). Results: The average age was 33 years for the control group and 35 years in the case of sex workers. 4% of sex workers had university education, 70% were unmarried and used as main contraceptive the IUD. Meanwhile, 34% of the control group had university education, 57% were single and used as primary contraceptive the hormone method. There were no significant differences in overall

Diabetes is the major cause of end stage renal disease, and tubular alterations are now considered to participate in the development and progression of diabetic nephropathy (DN). Here, we report for the first time that expression of the insulin receptor (IR) in human kidney is altered during diabetes. We detected a strong expression in proximal and distal tubules from human renal cortex, and a significant reduction in type 2 diabetic patients. Moreover, isolated proximal tubules from type 1 diabetic rat kidney showed a similar response, supporting its use as an excellent model for in vitro study of human DN. IR protein down-regulation was paralleled in proximal and distal tubules from diabetic rats, but prominent in proximal tubules from diabetic patients. A target of renal insulin signaling, the gluconeogenic enzyme phosphoenolpyruvate carboxykinase (PEPCK), showed increased expression and activity, and localization in compartments near the apical membrane of proximal tubules, which was correlated with activation of the GSK3β kinase in this specific renal structure in the diabetic condition. Thus, expression of IR protein in proximal tubules from type 1 and type 2 diabetic kidney indicates that this is a common regulatory mechanism which is altered in DN, triggering enhanced gluconeogenesis regardless the etiology of the disease.

Of 125 embryos (category I and II) recovered from 1 8 does, 25 were maintained intact as control, 25 bisected using a simplified splitting protocol, 25 frozen thawed according to a vitrification method, 25 bisected-vitrified, and 25 vitrified-bisected. The survivability of intact embryos and demiembryos were evaluated after 24 hours of in vitro culture by development ability, morphological asse ssment, and cell count with double staining method. The dev elopment rate after in vitro culture of intact control embryos (96%) was higher (P<0.001) than vit rified embryos (36%). The development rate of demiembryos was higher (74%) than bisected-vitrifie d embryos (34%), and vitrified-bisected embryos (10%) as well (P<0.001). A higher number of cells a nd percentage of surviving cells was observed in control embryos (91%), followed by fresh demiembrio s (84%), vitrified embryos (74%) (P<0.01), bisected-vitrified demiembryos (67%), and vitrified -bisected demiembryos (61%). Embryos and demiembryos originated from category I embryos show ed higher development rate than those obtained from category II. The reduced survivability for the vitrified-bisected embryos might be due to the combined effects of loss of cohesion and reduction of cells as a result of the bisection and to the crioprotectant toxicity during hydratation. In conc lusion, bisection and vitrification can be used together without micromanipulation and freezing com plex systems, but the embryo quality is the main factor in the success of these procedures .

With the aim of obtaining pregnancies from nuclear transfer embryos reconstituted with somatic cells and enucleated oocytes, bovine oocytes from slaughterhouse were matured in vitro and enucleated by micromanipulation. Nuclear donor cells were obtained from the ear of an adult cow, cultured for 9 to 14 days and cryopreserved in liquid nitrogen. Confluent cells were inserted individually in the perivitelline space of enucleated oocytes and treated with 2 electric pulses to induce fusion. The reconstituted zygotes were then cultured for 2 hours and treated with ionomycin and 6-dimethylaminopurine for their activation. The embryos were cultured in synthetic oviduct fluid for 8 to 9 days to obtain the blastocyst stage. These blastocysts were transferred to recipient heifers 7 to 9 days after oestrus. The ultrasound pregnancy diagnosis was done about 30 days after recipient oestrus. Five pregnancies were obtained from 25 transfers (20%). Two of them were lost at 42 days and a third at 120 days. This seems to be the first report on pregnancies obtained by cloned embryos in Chile.

With the aim of obtaining pregnancies from nuclear transfer embryos reconstituted with somatic cells and enucleated oocytes, bovine oocytes from slaughterhouse were matured in vitro and enucleated by micromanipulation.Nuclear donor cells were obtained from the ear of an adult cow, cultured for 9 to 14 days and cryopreserved in liquid nitrogen.Confluent cells were inserted individually in the perivitelline space of enucleated oocytes and treated with 2 electric pulses to induce fusion.The reconstituted zygotes were then cultured for 2 hours and treated with ionomycin and 6-dimethylaminopurine for their activation.The embryos were cultured in synthetic oviduct fluid for 8 to 9 days to obtain the blastocyst stage.These blastocysts were transferred to recipient heifers 7 to 9 days after oestrus.The ultrasound pregnancy diagnosis was done about 30 days after recipient oestrus.Five pregnancies were obtained from 25 transfers (20%).Two of them were lost at 42 days and a third at 120 days.This seems to be the first report on pregnancies obtained by cloned embryos in Chile.

The prion protein (PrP) is best known for its mis-folded, pathogenic isoform, which is widely regarded as the infectious agent in transmissable spongiform encephalopathies. However, the role of normal, cellular PrP, a host-encoded 29-kD glycoprotein tethered to the cell membrane by a phosphatidyl-inositol glycane (GPI) anchor, is poorly understood. PrP binds copper with high affinity, has antioxidant activity and may play a role in cell adhesion and/or signaling. PrP is expressed in mouse embryos on 6.5 days post-coitum in extra-embryonic tissue and at 13.5 days in the central and peripheral nervous system, intestine, and dental lamina. Our previous data revealed PrP gene expression in bovine embryos throughout pre-implantation embryo development. As part of a larger effort to map the ontogeny of cellular PrP expression in cattle, we sought here to analyze in early bovine fetuses (1) total PrP gene expression by real-time quantitative PCR (QPCR), and (2) tissue-specific PrP expression by immunohistochemistry. Fetuses were obtained from donor cattle bred by artificial insemination (AI; Day 0) and subjected to mid-ventral laparotomy on Days 32 (n = 2) and 39 (n = 2). Immediately upon recovery, one fetus from each stage was placed in RNAlater for RNA isolation and the other fixed in 10% formalin for immunohistochemistry. RNA was isolated using an RNeasy� mini kit (Qiagen, Valencia, CA, USA). cDNA was generated by reverse transcription with random hexamer priming and used the ΔΔcT method for estimation of PrP expression by QPCR. Tissue-specific expression was determined by immunohistochemistry. Formalin-fixed fetuses were embedded in paraffin, sagittally sectioned, dehydrated, and subjected to an unmasking protocol that employed Vectorlab unmasking solution and autoclaving. Tissues were then probed with a primary anti-PrP monoclonal antibody (SAF 32; Cayman Chemical Company, Ann Arbor, MI, USA). Bound primary antibody was detected with a biotinylated horse anti-mouse secondary antibody complexed to horseradish peroxidase using the ABC kit (Vector Laboratories, Burlingame, CA, USA). Probed sections were then counterstained with hematoxolin and eosin. Neighboring sections, processed identically but to which no primary antibody was added, served as controls. PrP gene expression was detected by QPCR at both stages examined and tended to be higher in Day 39 compared to Day 32 fetuses. PrP immunoreactivity was found throughout the central and peripheral nervous systems, ganglia, nerve trunks, and neural cell populations of sensory organs in both Day 32 and Day 39 fetuses. PrP immunolabeling was also observed in the mesonephric kidney, liver, and heart in the Day 39 fetus. At both stages, immunoreactivity was most intense in the nervous system. Thus, PrP is expressed in a tissue-specific pattern in early bovine fetuses. Tissue distribution of fetal PrP expression appears similar to that of adult PrP. Moreover, PrP appears to be expressed in a developmentally regulated fashion in some tissues.

The expression of aldolase A and B isoenzyme transcripts was confirmed by RT‐PCR in rat kidney and their cell distribution was compared with characteristic enzymes of the gluconeogenic and glycolytic metabolic pathway: fructose‐1,6‐bisphosphatase (FBPase), phosphoenol pyruvate carboxykinase (PEPCK), and pyruvate kinase (PK). We detected aldolase A isoenzyme in the thin limb and collecting ducts of the medulla and in the distal tubules and glomerula of the cortex. The same pattern of distribution was found for PK, but not for aldolase B, PEPCK, and FBPase. In addition, co‐localization studies confirmed that aldolase B, FBPase, and PEPCK are expressed in the same proximal cells. This segregated cell distribution of aldolase A and B with key glycolytic and gluconeogenic enzymes, respectively, suggests that these aldolase isoenzymes participate in different metabolic pathways. In order to test if FBPase interacts with aldolase B, FBPase was immobilized on agarose and subjected to binding experiments. The results show that only aldolase B is specifically bound to FBPase and that this interaction was specifically disrupted by 60 μM Fru‐1,6‐P 2 . These data indicate the presence of a modulated enzyme–enzyme interaction between FBPase and isoenzyme B. They affirm that in kidney, aldolase B specifically participates, along the gluconeogenic pathway and aldolase A in glycolysis. © 2004 Wiley‐Liss, Inc.