The M 1 -muscarinic acetylcholine receptor subtype may play a role in learning and memory performance in the hippocampus of neonatal monosodium glutamate-obese rats.

Here, we investigate the effects of obesity induced by monosodium glutamate (MSG) on cognitive impairment and whether this model induces any alteration in the affinity, density, and subtypes of muscarinic acetylcholine receptors (mAChRs) in rat hippocampus. Healthy rats were used as controls, and MSG-obese rats were selected via the Lee index > 0.300. The effects of MSG-induced obesity on hippocampal spatial learning and memory processes were evaluated by using the working memory versions of the Morris' water maze task and the evaluation of mAChRs by binding assay and their subtypes by immunoprecipitation assays. [ 3 H]Quinuclidinyl benzilate specific binding analysis showed that the equilibrium dissociation constant (K D ) did not differ between control and MSG, indicating that affinity is not affected by obesity induced by MSG. The maximum number of binding sites (B max ) obtained in MSG subjects was lower than that obtained from control rats, indicating a decrease in the expression of total mAChRs. Immunoprecipitation assays reveal a decrease in the expression of M 1 subtype of MSG when compared with control rats (M 2 to M 5 subtypes did not differ between control and MSG). We also observed that MSG promotes a disruption of the spatial working memory which was accompanied by a decrease in the M 1 mAChR subtype in rat hippocampus, thus suggesting deleterious long-term effects besides the obesity. In conclusion, these findings provide new insights into how obesity can influence spatial learning and memory that is hippocampal-dependent. The data suggest that the M 1 mAChR subtype protein expression is a potential therapeutic target.

The M1-muscarinic acetylcholine receptor subtype may play a role in learning and memory performance in the hippocampus of neonatal monosodium glutamate-obese rats

Here, we investigate the effects of obesity induced by monosodium glutamate (MSG) on cognitive impairment and whether this model induces any alteration in the affinity, density, and subtypes of muscarinic acetylcholine receptors (mAChRs) in rat hippocampus. Healthy rats were used as controls, and MSG-obese rats were selected via the Lee index > 0.300. The effects of MSG-induced obesity on hippocampal spatial learning and memory processes were evaluated by using the working memory versions of the Morris’ water maze task and the evaluation of mAChRs by binding assay and their subtypes by immunoprecipitation assays. [3H]Quinuclidinyl benzilate specific binding analysis showed that the equilibrium dissociation constant (KD) did not differ between control and MSG, indicating that affinity is not affected by obesity induced by MSG. The maximum number of binding sites (Bmax) obtained in MSG subjects was lower than that obtained from control rats, indicating a decrease in the expression of total mAChRs. Immunoprecipitation assays reveal a decrease in the expression of M1 subtype of MSG when compared with control rats (M2 to M5 subtypes did not differ between control and MSG). We also observed that MSG promotes a disruption of the spatial working memory which was accompanied by a decrease in the M1 mAChR subtype in rat hippocampus, thus suggesting deleterious long-term effects besides the obesity. In conclusion, these findings provide new insights into how obesity can influence spatial learning and memory that is hippocampal-dependent. The data suggest that the M1 mAChR subtype protein expression is a potential therapeutic target.

Monosodium glutamate administration early in life alters pineal melatonin nocturnal profile in adulthood

The pinealgland synthesizes melatonin exclusively at night, which gives melatonin the characteristic of a temporal synchronizer of the physiological systems. Melatonin is a regulator of insulin activities centrally and also peripherally and its synthesis is reduced in diabetes. Since monosodium glutamate (MSG) is often used to induce the type 2 diabetic and metabolic syndrome in animal models, the purpose of this work is to evaluate the potential effects of MSG given to neonates on the pineal melatonin synthesis in different agedmale and female rats. Wistar rats were subcutaneously injected with MSG (4mg/g/day) or saline solution (0.9%) from the second to eighth post-natal day. The circadian profiles both melatonin levels and AANAT activity were monitored at different ages. Body weight, naso-anal length, adipose tissues weight, GTT, ITT and serum insulin levels were also evaluated. Typical obesity with the neonatal MSG treatment was observed, indicated by a great increase in adipose depots without a concurrent increase in body weight. MSG treatment did not cause hyperglycemia or glucose intolerance, but induced insulin resistance. An increase of melatonin synthesis at ZT 15 with phase advance was observed in in some animals. The AANAT activity was positively parallel to the melatonin circadian profile. It seems that MSG causes hypothalamic obesity which may increase AANAT activity and melatonin production in pineal gland. These effects were not temporally correlated with insulin resistance and hyperinsulinemia indicating the hypothalamic lesions, particularly in arcuate nucleus induced by MSG in early age, as the principal cause of the increase in melatonin production.

Inhibitors of tumor necrosis factor synthesis as a new approach for the treatment of rheumatoid arthritis

Objective: The treatment of rheumatoid arthritis (RA) is based on the inhibition of TNF. Here we evaluated whether drugs that might inhibit TNF, such as pentoxifylline (PTX), rupatadine (RUP), rolipram (ROL) and thalidomide (THA), could be an alternative for RA treatment. Methods: In wistar male rats the changes in paw thickness, plasma TNF and by the activity of basic aminopeptidase (APB) in soluble fraction of synovial tissue and peripheral blood mononuclear cells (PBMC) evaluated after daily injection for 30 days were taken as anti-inflammatory outputs, while hepatotoxicity was assessed by measuring plasma alanine transaminase (ALT) and aspartate transaminase (AST) activity. The content of IL1-β, IL-6 in serum and synovial fluid and the histology of the injured tissue were determined only for ROL, THA and ROL+THA. Prednisolone was used as a standard drug. Results: Collagen treatment induced paw thickness, histological changes in the tibiotarsal joint, increase in synovial fluid of both cytokines and synovial tissue of APB activity. Furthermore, the APB activity in PBMC was reduced and ALT and AST activity were enhanced. The most effective drug schedule in reducing arthritis induced changes described above, as well as recovering from control levels TNF, IL1-β, APB in synovial tissue and AST activities were THA and the association of ROL and THA. However, only THA alone reduced the levels of ALT. Conclusion: The synthesis of TNF in RA models can be blocked by drugs acting at different targets. We show that THA and THA+ROL emerges as simple and effective therapeutic alternatives for RA.

Effects of obesity induced by high-calorie diet and its treatment with exenatide on muscarinic acetylcholine receptors in rat hippocampus.

Here, we described the effects of obesity induced by high-calorie diet and its treatment with exenatide, an anti-diabetogenic and potential anti-obesogenic drug derived from the venom of the Gila monster Heloderma suspectum, on the affinity, density, subtypes and intracellular signaling pathways linked to activation of muscarinic acetylcholine receptors (mAChRs) in rat hippocampus. Male Wistar rats were divided into three groups: control (CT), obese induced by high-calorie diet (DIO) and DIO treated with exenatide (DIO + E). [3H]Quinuclidinyl benzilate specific binding analysis showed that the equilibrium dissociation constant (KD) did not differ among CT, DIO and DIO + E, indicating that affinity is not affected by high-calorie diet or its treatment with exenatide. On the other hand, the density of mAChRs obtained in DIO animals was lower than that obtained from CT rats, and that DIO + E restored the density of mAChRs. Immunoprecipitation assays reveal a decrease in the expression of M1 and M3 subtypes of DIO animals when compared with CT. Treatment with exenatide (DIO + E) restored the expression of the two subtypes similar to obtained from CT. On the other hand, the M2, M4 and M5 mAChR subtypes expression did not differ among CT, DIO and DIO + E. Carbacol caused a concentration-dependent increase in the accumulation of total [3H] inositol phosphate in CT, DIO and DIO + E. However, the magnitude of the maximal response to carbachol was lower in DIO when compared with those obtained from CT and DIO + E animals, which did not differ from each other. Our results indicate that obesity induced by high-calorie diet strongly influences the expression and intracellular signaling coupled to M1-M3 mAChR subtypes. The exenatide ameliorated these effects, suggesting an important role on hippocampal muscarinic cholinergic system. This action of obesity induced by high-calorie diet and its treatment with exenatide might be a key step mediating cellular events important for learning and memory.

Exenatida e exendina(9-39) oriundos do lagarto venenoso Heloderma suspectum e seus efeitos sobre a qualidade espermática de ratos obesos e diabéticos / Exenatide and exendin(9-39) from the poisonous lizard Heloderma suspectum and its effects on sperm quality in obese and diabetic rats

The effects of exenatide (EXE) and exendin(9-39) (EXE9), peptides isolated from poisonous lizard H. suspectum on obesity and diabetes mellitus on male fertility are still poorly understood. The aim of this study was to evaluate the effects of EXE and EXE9 on parameters that contribute to sperm quality in hypothalamic injury-induced obesity (MSG) and hypercaloric diet (DIO) as well as streptozotocin-induced diabetes mellitus (STZ). Obese and diabetic rats received 10μg EXE / kg or 100μg EXE9 / kg sc daily or remained untreated for 20 days. Healthy rats at same age for each experimental models were used for comparison, only MSG model used healthy rats treated with exenatide. Biometric and glucoregulatory parameters treated with EXE (STZ) and EXE9 (STZ, DIO, MSG) were evaluated. Blood, testes and tail of the epididymis were collected. Sex hormones, leptin and insulin were evaluated by ELISA. Sperm were obtained from the epididymal tail by washing with HTF culture medium. The percentage of abnormal sperm morphology was analyzed under a phase contrast microscope. Functional analyzes of sperm were performed only STZ and MSG models. Sperm kinetics was evaluated by Computer Aided Analysis. The EXE-treated STZ group (STZ-E) improved the biometric parameters, glycemic control as well as the morphology, functionality and kinetics of mature sperm and EXE9 (STZ-E9) has an EXE effect on essential parameters for maintaining sperm quality. DIO showed impaired sperm quality, but there were occasional changes in the parameters that affect sperm quality. DIO-E improved sperm quality, suggesting that the antiobesogenic, antidislipidemic, and antidiabetogenic action of EXE restored the accuracy of the pathway of mature sperm, whereas treatment with EXE9 did not dramatically affect sperm kinetics, but was unable to restore path accuracy. EXE, through glucoregulatory improvement in MSG, has beneficial effects on hormone levels as well as sperm morphology, functionality and kinetics. Negative changes caused by EXE9 in glycorregulatory parameters, exacerbated increase in mass of periepididimal adipose tissue deposition, decreased testosterone and FSH plasma levels, with consequences on kinetics negatively affect sperm quality. EXE has been shown to be an excellent therapeutic agent to be used for beneficial effects on sperm quality in obese and diabetic patients. Results of treatment with EXE9 similar to those obtained with EXE in some evaluated parameters suggest two hypotheses (1) the use of an alternative to classical receptor; or (2) a dose-dependent situation if the dose of EXE9 administered is not sufficient for its action as an antagonist in a given organ and / or tissue. Therefore clinical research is needed to deepen the knowledge as well as the use of exenatide in a new incretinomimetic function as therapy.

Os efeitos da exenatida (EXE) e da exendina(9-39) (EXE9), peptídeos isolados do lagarto venenoso H. suspectum sobre a obesidade e diabetes melito na fertilidade masculina ainda são pouco compreendidos. O objetivo deste estudo foi avaliar os efeitos da EXE e da EXE9 sobre parâmetros que contribuem para a qualidade espermática na obesidade induzida por injúria hipotalâmica (MSG) e dieta hipercalórica (DIO) bem como no diabetes melito induzido por estreptozotocina (STZ). Ratos obesos e diabéticos receberam 10μg EXE/kg ou 100μg EXE9/kg sc diariamente ou permaneceram sem tratamento por 20 dias. Ratos saudáveis de mesma idade para cada modelo experimental foram utilizados para comparação, somente para o modelo MSG houve ratos saudáveis tratados com exenatida. Foram avaliados parâmetros biométricos e glicorregulatórios tratados com EXE (STZ) e EXE9 (STZ, DIO, MSG). Sangue, testículos e cauda do epidídimo foram coletados. Hormônios sexuais, leptina e insulina foram avaliados por ELISA. Os espermatozoides foram obtidos da cauda epididimal por lavagem com meio de cultura HTF. A porcentagem de morfologia anormal dos espermatozoides foi analisada sob um microscópio de contraste de fase. Foram realizadas análises funcionais dos espermatozoides somente para os modelos STZ e MSG. A cinética espermática foi avaliada pela Análise Assistida por Computador. O grupo STZ tratado com EXE (STZ-E) melhorou os parâmetros biométricos, controle glicêmico bem como a morfologia, funcionalidade e cinética de espermatozoides maduros e EXE9 (STZ-E9) possui efeito contrário a EXE em parâmetros essenciais para manutenção da qualidade espermática. DIO apresentou comprometimento da qualidade espermática, porém foram alterações pontuais nos parâmetros que afetam a qualidade espermática. DIO-E melhorou a qualidade espermática, sugerindo que a ação antiobesogênicao, antidislipidêmico e antidiabetogênico de EXE restaurou a acurácia da trajetória do espermatozoide maduro, já o tratamento com EXE9 não afetou drasticamente a cinética espermática, mas foi incapaz de restaurar a acurácia da trajetória. EXE, através da melhora glicorregulatória em MSG, tem efeitos benéficos nos níveis hormonais, bem como na morfologia, funcionalidade e cinética dos espermatozoides. As alterações negativas causadas por EXE9 nos parâmetros glicorregulatórios, aumento exacerbado da massa do depósito de tecido adiposo periepididimal, diminuição dos níveis plasmáticos de testosterona e FSH, com consequências sobre a cinética repercutem negativamente sobre a qualidade dos espermatozoides. A EXE mostrou-se um excelente agente terapêutico para ser utilizado em busca de efeitos benéficos sobre a qualidade espermática em obesos e diabéticos. Os resultados do tratamento com EXE9 similares aos obtidos com EXE em alguns parâmetros avaliados sugerem duas hipóteses (1) a utilização de um receptor alternativo ao clássico; ou (2) uma situação dose-dependente no caso da dose de EXE9 administrada não ser o suficiente para sua ação como antagonista em determinado órgão e/ou tecido. Portanto são necessário pesquisas clínicas para aprofundar o conhecimento bem como a utilização da exenatida em uma nova função incretinomimética como terapia.

Effects of obesity induced by high-calorie diet and its treatment with exenatide on muscarinic acetylcholine receptors in rat hippocampus

Here, we described the effects of obesity induced by high-calorie diet and its treatment with exenatide, an anti-diabetogenic and potential anti-obesogenic drug derived from the venom of the Gila monster Heloderma suspectum, on the affinity, density, subtypes and intracellular signaling pathways linked to activation of muscarinic acetylcholine receptors (mAChRs) in rat hippocampus. Male Wistar rats were divided into three groups: control (CT), obese induced by high-calorie diet (DIO) and DIO treated with exenatide (DIO+E). [3H]Quinuclidinyl benzilate specific binding analysis showed that the equilibrium dissociation constant (KD) did not differ among CT, DIO and DIO+E, indicating that affinity is not affected by high-calorie diet or its treatment with exenatide. On the other hand, the density of mAChRs obtained in DIO animals was lower than that obtained from CT rats, and that DIO+E restored the density of mAChRs. Immunoprecipitation assays reveal a decrease in the expression of M1 and M3 subtypes of DIO animals when compared with CT. Treatment with exenatide (DIO+E) restored the expression of the two subtypes similar to obtained from CT. On the other hand, the M2, M4 and M5 mAChR subtypes expression did not differ among CT, DIO and DIO+E. Carbacol caused a concentration-dependent increase in the accumulation of total [3H] inositol phosphate in CT, DIO and DIO+E. However, the magnitude of the maximal response to carbachol was lower in DIO when compared with those obtained from CT and DIO+E animals, which did not differ from each other. Our results indicate that obesity induced by high-calorie diet strongly influences the expression and intracellular signaling coupled to M1-M3 mAChR subtypes. The exenatide ameliorated these effects, suggesting an important role on hippocampal muscarinic cholinergic system. This action of obesity induced by high-calorie diet and its treatment with exenatide might be a key step mediating cellular events important for learning and memory.Here, we described the effects of obesity induced by high-calorie diet and its treatment with exenatide, an anti-diabetogenic and potential anti-obesogenic drug derived from the venom of the Gila monster Heloderma suspectum, on the affinity, density, subtypes and intracellular signaling pathways linked to activation of muscarinic acetylcholine receptors (mAChRs) in rat hippocampus. Male Wistar rats were divided into three groups: control (CT), obese induced by high-calorie diet (DIO) and DIO treated with exenatide (DIO+E). [3H]Quinuclidinyl benzilate specific binding analysis showed that the equilibrium dissociation constant (KD) did not differ among CT, DIO and DIO+E, indicating that affinity is not affected by high-calorie diet or its treatment with exenatide. On the other hand, the density of mAChRs obtained in DIO animals was lower than that obtained from CT rats, and that DIO+E restored the density of mAChRs. Immunoprecipitation assays reveal a decrease in the expression of M1 and M3 subtypes of DIO animals when compared with CT. Treatment with exenatide (DIO+E) restored the expression of the two subtypes similar to obtained from CT. On the other hand, the M2, M4 and M5 mAChR subtypes expression did not differ among CT, DIO and DIO+E. Carbacol caused a concentration-dependent increase in the accumulation of total [3H] inositol phosphate in CT, DIO and DIO+E. However, the magnitude of the maximal response to carbachol was lower in DIO when compared with those obtained from CT and DIO+E animals, which did not differ from each other. Our results indicate that obesity induced by high-calorie diet strongly influences the expression and intracellular signaling coupled to M1-M3 mAChR subtypes. The exenatide ameliorated these effects, suggesting an important role on hippocampal muscarinic cholinergic system. This action of obesity induced by high-calorie diet and its treatment with exenatide might be a key step mediating cellular events important for learning and memory.

Effects of obesity induced by high-calorie diet and its treatment with exenatide on muscarinic acetylcholine receptors in rat hippocampus

Here, we described the effects of obesity induced by high-calorie diet and its treatment with exenatide, an anti-diabetogenic and potential anti-obesogenic drug derived from the venom of the Gila monster Heloderma suspectum, on the affinity, density, subtypes and intracellular signaling pathways linked to activation of muscarinic acetylcholine receptors (mAChRs) in rat hippocampus. Male Wistar rats were divided into three groups: control (CT), obese induced by high-calorie diet (DIO) and DIO treated with exenatide (DIO+E). [3H]Quinuclidinyl benzilate specific binding analysis showed that the equilibrium dissociation constant (KD) did not differ among CT, DIO and DIO+E, indicating that affinity is not affected by high-calorie diet or its treatment with exenatide. On the other hand, the density of mAChRs obtained in DIO animals was lower than that obtained from CT rats, and that DIO+E restored the density of mAChRs. Immunoprecipitation assays reveal a decrease in the expression of M1 and M3 subtypes of DIO animals when compared with CT. Treatment with exenatide (DIO+E) restored the expression of the two subtypes similar to obtained from CT. On the other hand, the M2, M4 and M5 mAChR subtypes expression did not differ among CT, DIO and DIO+E. Carbacol caused a concentration-dependent increase in the accumulation of total [3H] inositol phosphate in CT, DIO and DIO+E. However, the magnitude of the maximal response to carbachol was lower in DIO when compared with those obtained from CT and DIO+E animals, which did not differ from each other. Our results indicate that obesity induced by high-calorie diet strongly influences the expression and intracellular signaling coupled to M1-M3 mAChR subtypes. The exenatide ameliorated these effects, suggesting an important role on hippocampal muscarinic cholinergic system. This action of obesity induced by high-calorie diet and its treatment with exenatide might be a key step mediating cellular events important for learning and memory.Here, we described the effects of obesity induced by high-calorie diet and its treatment with exenatide, an anti-diabetogenic and potential anti-obesogenic drug derived from the venom of the Gila monster Heloderma suspectum, on the affinity, density, subtypes and intracellular signaling pathways linked to activation of muscarinic acetylcholine receptors (mAChRs) in rat hippocampus. Male Wistar rats were divided into three groups: control (CT), obese induced by high-calorie diet (DIO) and DIO treated with exenatide (DIO+E). [3H]Quinuclidinyl benzilate specific binding analysis showed that the equilibrium dissociation constant (KD) did not differ among CT, DIO and DIO+E, indicating that affinity is not affected by high-calorie diet or its treatment with exenatide. On the other hand, the density of mAChRs obtained in DIO animals was lower than that obtained from CT rats, and that DIO+E restored the density of mAChRs. Immunoprecipitation assays reveal a decrease in the expression of M1 and M3 subtypes of DIO animals when compared with CT. Treatment with exenatide (DIO+E) restored the expression of the two subtypes similar to obtained from CT. On the other hand, the M2, M4 and M5 mAChR subtypes expression did not differ among CT, DIO and DIO+E. Carbacol caused a concentration-dependent increase in the accumulation of total [3H] inositol phosphate in CT, DIO and DIO+E. However, the magnitude of the maximal response to carbachol was lower in DIO when compared with those obtained from CT and DIO+E animals, which did not differ from each other. Our results indicate that obesity induced by high-calorie diet strongly influences the expression and intracellular signaling coupled to M1-M3 mAChR subtypes. The exenatide ameliorated these effects, suggesting an important role on hippocampal muscarinic cholinergic system. This action of obesity induced by high-calorie diet and its treatment with exenatide might be a key step mediating cellular events important for learning and memory.

Anti-obesogenic and hypolipidemic effects of a glucagon-like peptide-1 receptor agonist derived from the saliva of the Gila monster.

INTRODUCTION: Glucagon-like peptide-1 (GLP-1) receptor (R) agonists are a class of incretin mimetic drugs that have been used for the treatment of type 2 diabetes mellitus and also considered strong candidates for the treatment of obesity. The original prototypical drug in this class is the exenatide, a synthetic peptide with the same structure as the native molecule, exendin-4, found in the saliva of the Gila monster (Heloderma suspectum suspectum lizard). OBJECTIVES: To identify and compare the anti-obesogenic, antidyslipidemic and antidiabetogenic effects of agonism in GLP-1R by exenatide on two distinct models of obesity: induced by hypothalamic injury (MSG) or high-calorie diet (DIO). METHODS: To obtain MSG, neonatal rats were daily subcutaneously injected with 4 g monosodium glutamate/kg, for 10 consecutive days. To obtain DIO, 72-75 days old rats received hyperlipid food and 30% sucrose for drinking up to 142-145 days old. Untreated healthy rats with the same age were used as control. General biometric and metabolic parameters were measured. RESULTS: MSG was characterized by decreased naso-anal length, food and fluid intake, plasma protein and glucose decay rate per minute after insulin administration (KITT), as well as increased Lee index (body mass0.33/naso-anal length), mass of retroperitoneal and periepididymal fat pads, glycemia, triglycerides (TG), LDL and VLDL. Exenatide ameliorated KITT and food and fluid intake, and it also restored glycemia in MSG. DIO was characterized by glucose intolerance, increased body mass, Lee index, fluid intake, mass of retroperitoneal and periepididymal fat pads, glycemia, glycated hemoglobin (HbA1c), TG, VLDL and total cholesterol, as well as decreased food intake and KITT. Exenatide restored glycemia, HbA1c, TG, VLDL, total cholesterol and body mass, and it also ameliorated food and fluid intake, KITT and mass of retroperitoneal fat pad in DIO. CONCLUSIONS: The hypothalamic injury and the high-calorie diet induce dyslipidemia and glycemic dysregulation in addition to obesity in rats. The usual therapeutic dose of exenatide in humans is antidiabetogenic in both these obesity models, but is anti-obesogenic and hypolipidemic only in diet-induced obesity. Agonists of GLP-1R are promising anti-obesogenic and antidyslipidemic drugs in the early stages of the obesity, in which the integrity of the nervous system was unaffected.

Anti-obesogenic and hypolipidemic effects of a glucagon-like peptide-1 receptor agonist derived from the saliva of the Gila monster

Introduction: Glucagon-like peptide-1(GLP-1) receptor (R) agonists are a class of incretin mimetic drugs that have been used for the treatment of type 2 diabetes mellitus and also considered strong candidates for the treatment of obesity. The original prototypical drug in this class is the exenatide, a synthetic peptide with the same structure as the native molecule, exendin-4, found in the saliva of the Gila monster (Heloderma suspectum suspectum lizard). Objectives: To identify and compare the anti-obesogenic, antidyslipidemic and antidiabetogenic effects of agonism in GLP-1R by exenatide on two distinct models of obesity: induced by hypothalamic injury (MSG) or high-calorie diet (DIO). Methods: To obtain MSG, neonatal rats were daily subcutaneously injected with 4 g monosodium glutamate/kg, for 10 consecutive days. To obtain DID, 72-75 days old rats received hyperlipid food and 30% sucrose for drinking up to 142-145 days old. Untreated healthy rats with the same age were used as control. General biometric and metabolic parameters were measured. Results: MSG was characterized by decreased naso-anal length, food and fluid intake, plasma protein and glucose decay rate per minute after insulin administration (K-ITT), as well as increased Lee index (body mass(0.33)/naso-anal length), mass of retroperitoneal and periepididymal fat pads, glycemia, triglycerides (TG), LDL and VLDL. Exenatide ameliorated K-ITT and food and fluid intake, and it also restored glycemia in MSG. DIO was characterized by glucose intolerance, increased body mass, Lee index, fluid intake, mass of retroperitoneal and periepididymal fat pads, glycemia, glycated hemoglobin (HbAlc), TG, VLDL and total cholesterol, as well as decreased food intake and K-ITT. Exenatide restored glycemia, HbA1c, TG, VLDL, total cholesterol and body mass, and it also ameliorated food and fluid intake, K-ITT and mass of retroperitoneal fat pad in DIO. Conclusions: The hypothalamic injury and the high-calorie diet induce dyslipidemia and glycemic dysregulation in addition to obesity in rats. The usual therapeutic dose of exenatide in humans is anti-diabetogenic in both these obesity models, but is anti-obesogenic and hypolipidemic only in diet-induced obesity. Agonists of GLP-1R are promising anti-obesogenic and antidyslipidemic drugs in the early stages of the obesity, in which the integrity of the nervous system was unaffected.

Novel adipocyte aminopeptidases are selectively upregulated by insulin in healthy and obese rats.

The lack of a complete assembly of the sensitivity of subcellular aminopeptidase (AP) activities to insulin in different pathophysiological conditions has hampered the complete view of the adipocyte metabolic pathways and its implications in these conditions. Here we investigated the influence of insulin on basic AP (APB), neutral puromycin-sensitive AP (PSA), and neutral puromycin-insensitive AP (APM) in high and low density microsomal and plasma membrane fractions from adipocytes of healthy and obese rats. Catalytic activities of these enzymes were fluorometrically monitoring in these fractions with or without insulin stimulus. Canonical traffic such as insulin-regulated AP was not detected for these novel adipocyte APs in healthy and obese rats. However, insulin increased APM in low density microsomal and plasma membrane fractions from healthy rats, APB in high density microsomal fraction from obese rats and PSA in plasma membrane fraction from healthy rats. A new concept of intracellular compartment-dependent upregulation of AP enzyme activities by insulin emerges from these data. This relatively selective regulation has pathophysiological significance, since these enzymes are well known to act as catalysts and receptor of peptides directly related to energy metabolism. Overall, the regulation of each one of these enzyme activities reflects certain dysfunction in obese individuals.

Novel adipocyte aminopeptidases are selectively upregulated by insulin in healthy and obese rats

The lack of a complete assembly of the sensitivity of subcellular aminopeptidase (AP) activities to insulin in different pathophysiological conditions has hampered the complete view of the adipocyte metabolic pathways and its implications in these conditions. Here we investigated the influence of insulin on basic AP (APB), neutral puromycin-sensitive AP (PSA), and neutral puromycin-insensitive AP (APM) in high and low density microsomal and plasma membrane fractions from adipocytes of healthy and obese rats. Catalytic activities of these enzymes were fluorometrically monitoring in these fractions with or without insulin stimulus. Canonical traffic such as insulin-regulated AP was not detected for these novel adipocyte APs in healthy and obese rats. However, insulin increased APM in low density microsomal and plasma membrane fractions from healthy rats, APB in high density microsomal fraction from obese rats and PSA in plasma membrane fraction from healthy rats. A new concept of intracellular compartment-dependent upregulation of AP enzyme activities by insulin emerges from these data. This relatively selective regulation has pathophysiological significance, since these enzymes are well known to act as catalysts and receptor of peptides directly related to energy metabolism. Overall, the regulation of each one of these enzyme activities reflects certain dysfunction in obese individuals

Comparação do perfil metabólico e funcionalidade de ilhotas pancreáticas, sob efeito da exenatida, em modelos experimentais de obesidade e diabetes melito no rato / Comparison of the metabolic profile and functionality of pancreatic islets, under the effect of exenatide, in experimental models of obesity and diabetes mellitus in rats

Exenatide, a synthetic exendin-4 peptide isolated from the venom of Heloderma suspectum lizard is among the most recent pharmacological resources for the treatment of type 2 diabetes mellitus (DM2), with agonist effect on the receptor of glucagon-like type 1 peptide hormone (GLP-1), and resistance to the hydrolysis by dipeptidyl-peptidase IV (DPPIV). This drug has also been suggested as effective in reducing food intake and body weight. However, its differential action on the metabolic and morphometric profiles in animals models of DM induced by streptozotocin (STZ) and obesity induced by monosodium glutamate (MSG) or high calorie diet (DIO) is not fully understood. The present study compared these models in relation to the gain of body weight (MC), as well as naso-anal length (CNA), Lee index, food and fluid intake, oral glucose tolerance (OGTT), insulin tolerance (ITT), mass of periepididymal and retroperitoneal fat pads, preprandial glucose, triglycerides (TG), cholesterol (total, HDL, LDL and VLDL), glycated hemoglobin (HbA1c), plasma protein, plasma osmolality, glucagon and insulin secreted by isolated islets, and about the effects of exenatide on all these parameters (STZ-E, MSG-E, DIO-E). DIO presented higher MC and CNA gain, Lee index, mass of retroperitoneal fat pad, preprandial glucose, TG, total cholesterol, VLDL and HbA1c, as well as lower food intake, glucose disappearance rate for ITT (Kitt) than healthy control (C-S). MSG presented higher Lee index, mass of retroperitoneal and periepididymal fat pads, preprandial glucose, TG, LDL and VLDL, as well as lower food and fluid intake, Kitt and plasma protein than C-S. STZ presented lower MC gain, mass of periepididyma and retroperitoneal fat pad, secreted insulin, tolerance to glucose and insensitivity to insulin, as well as higher HDL, preprandial glucose and HbA1c than C-S. The treatment with exenatide, for 20 consecutive days at human therapeutic dose, had beneficial effects on important metabolic and morphometric parameters in all groups, mainly in DIO-E, where it decreased MC gain, food intake, mass and retroperitoneal fat pad, preprandial glucose, HbA1c, TG, VLDL, total cholesterol and promoted insulin sensitivity. In MSG-E the preprandial glucose and secreted insulin were increased, and the insulin sensitivity was ameliorated. In STZ-E was increased and preprandial blood glucose and HbA1c were ameliorated without changing in the secretion of insulin and glucagon. Data contribute to the knowledge of the comparative pharmacology and physiology of compounds from animal venoms and to elucidate new mechanisms involved in the etiology and development of obesity, as well as to the prevention and treatment of obesity and DM.

A exenatida, peptídeo sintético da exendina-4 isolada do veneno do lagarto Heloderma suspectum, está entre os mais recentes recursos farmacológicos para o tratamento do diabetes melito tipo 2 (DM2), apresentando ação agonista do receptor do hormônio peptídico glucagon-símile tipo 1 (GLP-1) e resistência à hidrólise pela dipeptidil-peptidase IV (DPPIV). Há evidências de que este fármaco também seja eficaz na redução da ingestão de alimento e do peso corporal. Todavia, não estão completamente caracterizadas suas ações diferenciais sobre o perfil metabólico e morfométrico em modelos animais de DM induzido por estreptozotocina (STZ) e de obesidade induzida por glutamato monossódico (MSG) e dieta hipercalórica (DIO). O presente estudo comparou estes modelos em relação ao ganho de massa corporal (MC) e comprimento naso-anal (CNA), índice de Lee, ingestão de alimento e líquido, tolerância oral à glicose (OGTT), tolerância à insulina (ITT), massa dos depósitos de tecidos adiposos periepididimal e retroperitoneal, glicemia de jejum, triglicérides (TG), colesterol (total, HDL, LDL e VLDL), hemoglobina glicada (HbA1c), proteína plasmática, osmolalidade plasmática, glucagon e insulina secretados pelas ilhotas isoladas, e quanto aos efeitos da exenatida sobre todos estes parâmetros (STZ-E, MSG-E, DIO-E). Comparativamente aos controles sadios (C-S), o grupo DIO apresentou ganho de MC e CNA, maiores índice de Lee, massa do depósito adiposo retroperitoneal, glicemia de jejum, TG, colesterol total, VLDL e HbA1c, bem como menores ingestão de alimentos, taxa de decaimento de glicose (Kitt). O grupo MSG apresentou maiores índice de Lee, massa dos depósitos adiposos retroperitoneal e periepididimal, glicemia de jejum, TG, LDL e VLDL, bem como menores ingestões de alimento e líquido, Kitt e de proteína plasmática, relativamente a C-S. O grupo STZ apresentou menores ganho de MC, massa dos depósitos adiposos periepididimal e retroperitoneal, insulina secretada e maiores HDL, glicemia de jejum e HbA1c, bem como menores tolerância à glicose e insensibilidade à insulina, relativamente a C-S. Utilizando dose terapêutica para humanos, o tratamento com exenatida, por 20 dias consecutivos, teve efeitos benéficos em parâmetros metabólicos e morfométricos relevantes nos grupos estudados, principalmente no DIO-E, onde o ganho de MC, ingestão de alimento, massa do depósito adiposo retroperitoneal, glicemia de jejum, HbA1c, TG, VLDL e colesterol total foram diminuídos além de haver melhora da sensibilidade à insulina. Em MSG-E houve melhora da glicemia de jejum, insulina secretada e da sensibilidade à insulina. Em STZ-E houve melhora da glicemia de jejum e HbA1c, sem alterar a secreção de insulina e glucagon. Esses dados contribuem com o conhecimento da farmacologia e fisiologia comparativa de componentes de venenos animais e para elucidar novos mecanismos relacionados à etiologia e desenvolvimento da obesidade, bem como para a prevenção e tratamento da obesidade e do DM.