Effects of Diets Based on Hydrolyzed Chicken Liver and Different Protein Concentrations on the Formation and Deamination of Biogenic Amines and Total Antioxidant Capacity of Dogs.

Biogenic amines are synthesized through the bacterial decarboxylation of amino acids, commonly found in high levels in animal by-product meals due to spoilage. Furthermore, biogenic amines and other metabolites can be produced by the fermentation of proteins in the hindgut according to the protein source and concentration of crude protein (CP) in the diet. Thus, this study aimed to evaluate two protein sources (poultry by-product meal (PBPM) and hydrolyzed chicken liver powder (HCLP)) and three CP concentrations (24, 32, and 40%) and their effects on the consumption and fecal excretion of biogenic amines, plasma monoamine oxidase (MAO) and diamine oxidase (DAO) activities, and total antioxidant capacity (TAC) of healthy adult dogs after 30 days of feeding the experimental diets. Twelve dogs were randomly distributed into six treatments (n = 6/treatment): PBPM24 (PBPM with 24% CP); PBPM32 (PBPM with 32% CP); PBPM40 (PBPM with 40% CP); HCLP24 (HCLP with 24% CP); HCLP32 (HCLP with 32% CP); HCLP40 (HCLP with 40% CP). The PBPM and PBPM-based diets had higher concentrations of putrescine, cadaverine, tyramine, histamine, agmatine, and total biogenic amines. In contrast, HCLP and HCLP-based diets contained higher concentrations of spermidine, phenylethylamine, and spermine. The PBPM and PBPM-diets had higher biogenic amine index (BAI) indicating lower quality due to the high content of putrescine, cadaverine and tyramine. Dogs fed diets with PBPM and higher protein concentrations consumed more putrescine, cadaverine, tyramine, agmatine, and total amines (p < 0.0001), while dogs fed with HCLP consumed more spermidine, phenylethylamine, and spermine (p < 0.0001). Fecal excretion of phenylethylamine was greater in dogs fed HCLP32 and HCLP40 diets (p = 0.045). Dogs fed with HCLP tended to excrete more spermidine and tryptamine via feces, while higher protein concentrations tended to increase fecal excretion of cadaverine (p < 0.10). Plasma MAO activity was higher in dogs fed HCLP24 and PBPM32 diets (p = 0.024). The plasma activities of DAO and TAC were not different between diets (p > 0.05). Although we did not evaluate the intestinal activities of MAO and DAO, our results suggest that healthy adult dogs have an efficient deamination process on the gut epithelium.

The impact of chasing stress on the metabolism of the Atlantic Ghost Crab Ocypode quadrata (Fabricius, 1787).

Ocypode quadrata, a Ghost crab species found along the western Atlantic coast, is considered a bioindicator of anthropogenic impact on sandy beaches. Ghost Crabbing, a touristic activity in which ghost crabs are chased just for fun, is a potentially threatening activity for this crab. In crustaceans, metabolites such as glucose and lactate, and the gene expression of crustacean hyperglycemic hormone (CHH) and heat shock proteins (HSPs) increase when the animals are exposed to several types of stress, including alterations in temperature, salinity, or exposure to xenobiotics. This work was developed to identify if being chased by humans would affect these markers of stress in this species of crab. The effects of chasing stress on hemolymph and tissue metabolites and the gene expression levels of CHH and HSP70 were investigated. The levels of lactate in the hemolymph of stressed crabs were six times higher than those of control crabs immediately after chasing and decreased progressively during recovery, indicating an active anaerobic metabolism during the stress. On the contrary, glucose levels in the hemolymph of the stressed crabs increased progressively from 30 to 60 min after chasing, indicating an inverse correlation between glucose and lactate and the conversion of lactate to glucose by gluconeogenesis. In stressed crabs, the levels of triglycerides in the hemolymph decreased 30 min after chasing, while the opposite tended to occur in the hepatopancreas, indicating that during recovery, the crabs use triglycerides as energy source to sustain aerobic metabolism. Finally, this study demonstrates that ghost crabs are stressed by minimum human contact and that "ghost crabbing" must not be encouraged as a tourist activity.

Acute effects of a single moderate-intensity exercise bout performed in fast or fed states on cell metabolism and signaling: Comparison between lean and obese rats.

AIMS: Although the benefits of exercise can be potentiated by fasting in healthy subjects, few studies evaluated the effects of this intervention on the metabolism of obese subjects. This study investigated the immediate effects of a single moderate-intensity exercise bout performed in fast or fed states on the metabolism of gastrocnemius and soleus of lean and obese rats. MAIN METHODS: Male rats received a high-fat diet (HFD) for twelve weeks to induce obesity or were fed standard diet (SD). After this period, the animals were subdivided in groups: fed and rest (FER), fed and exercise (30 min treadmill, FEE), 8 h fasted and rest (FAR) and fasted and exercise (FAE). Muscle samples were used to investigate the oxidative capacity and gene expression of AMPK, PGC1α, SIRT1, HSF1 and HSP70. KEY FINDINGS: In relation to lean animals, obese animals' gastrocnemius glycogen decreased 60 %, triglycerides increased 31 %; glucose and alanine oxidation decreased 26 % and 38 %, respectively; in soleus, triglycerides reduced 46 % and glucose oxidation decreased 37 %. Exercise and fasting induced different effects in glycolytic and oxidative muscles of obese rats. In soleus, fasting exercise spared glycogen and increased palmitate oxidation, while in gastrocnemius, glucose oxidation increased. In obese animals' gastrocnemius, AMPK expression decreased 29 % and SIRT1 increased 28 % in relation to lean. The AMPK response was more sensitive to exercise and fasting in lean than obese rats. SIGNIFICANCE: Exercise and fasting induced different effects on the metabolism of glycolytic and oxidative muscles of obese rats that can promote health benefits in these animals.

Female Wistar rats present particular glucose flux when submitted to classic protocols of experimental diabetes.

BACKGROUND: Type 1 diabetes mellitus is a prevalent autoimmune disease worldwide. The knowledge of female particularities in metabolic dysfunction is of fundamental importance, leading to better choices for human therapy candidates. The aim of this study is to investigate the glucose flux peculiarities of female rats submitted to two classic experimental diabetes protocols. METHODS: Female Wistar rats, 60 days old, were used to evaluate biochemical and hormonal serum parameters, in addition to skeletal muscle and liver energy stocks and 14C-glucose and 14C-alanine flux. Two different protocols, multiple (25 mg/kg dose) and single (65 mg/kg dose) intraperitoneal streptozotocin, were compared considering the alterations presented 48 h and 30 days after the drug administration. RESULTS: The results showed few indicators of muscle and liver metabolic imbalance. High-single streptozotocin dose promoted 97% and 41% lower glycogen levels in liver and muscle respectively. Multiple-low streptozotocin dose promoted 63% lower lipid synthesis in liver. After 30 days, diabetic animals presented hyperglycaemia in both protocols, 589.5 (529.3/642.3) mg/dL to high-single dose and 374.2 (339.3/530.6) mg/dL to multiple-low dose. However, they did not present lower insulin levels, alterations on muscle glucose uptake, nor higher hepatic gluconeogenesis. CONCLUSION: In conclusion, this study demonstrates that females, at least Wistar rats, are less responsive to classic diabetes protocols established in literature, so mechanisms of experimental diabetes for females need more investigation. After which, therapeutic candidates should be evaluated in such a way sex bias does not present itself as a factor that hinders reproducibility in human studies.

Liraglutide treatment counteracts alterations in adipose tissue metabolism induced by orchiectomy in rats.

AIMS: The reduction in androgens serum concentration is a physiological condition that accompanies age advancement but can also occur because of prostate cancer and gender affirming treatment or pathological conditions such as functional hypogonadism. However, androgen deficiency is related to a higher risk of developing metabolic disorders such as obesity and type 2 diabetes mellitus (T2DM). Considering that glucagon-like peptide 1 (GLP1) analogs are increasingly used in the treatment of T2DM, we investigated if liraglutide could also attenuate the metabolic changes caused by orchiectomy in rats. MAIN METHODS: Wistar rats were orchiectomized (ORC), and subdivided in four groups: sham saline, sham liraglutide, ORC saline, and ORC liraglutide. After sixty days, metabolic parameters were evaluated in blood, muscle, liver, brown (BAT) and white adipose tissue (WAT) visceral depots. Glucose utilization, oxidation, and conversion to lipids by de novo lipogenesis, and basal and adrenaline-stimulated lipolysis were evaluated in BAT and WAT depots. KEY FINDINGS: Orchiectomy increased triglyceridemia, BAT and rtWAT weight, and lipolysis and reduced glucose utilization. Liraglutide treatment reversed these effects. SIGNIFICANCE: These results indicate that liraglutide improves triglyceridemia and glucose metabolism in WAT depots, which suggests that it may be a promising therapeutic strategy to handle disruptions in energy metabolism caused by androgen deficiency.

Liraglutide improves lipid and carbohydrate metabolism of ovariectomized rats.

Considering that post-menopausal women and ovariectomized rodents develop obesity associated with increased visceral fat, this study was developed to investigate if liraglutide, a glucagon-like peptide 1 (GLP1) analogue, could improve the metabolism of estrogen (E2) deficient females. Wistar rats were ovariectomized (OVX), and subdivided in four groups: sham saline, sham liraglutide, OVX saline, and OVX liraglutide. After sixty days, metabolic parameters of blood, heart, liver, brown (BAT) and white adipose tissue (WAT) visceral depots, and, heart oxidative homeostasis, were evaluated. Castration increased the animals' body weight, the relative weight of the WAT depots, hepatic triglycerides and cardiac glycogen content. Liraglutide treatment reversed these effects, decreased WAT depots weight and increased glucose oxidation and lipogenesis in BAT and WAT. In addition, liraglutide enhanced adrenalin (A) lipolytic effect. These results indicate that liraglutide may be a promising treatment to restore lipid homeostasis and prevent weight gain associated with E2 deficiency.

Effects of stanniocalcin 1 hormone on lactate metabolism in rat kidney under fed and fasted conditions.

To test the hypothesis of STC-1 participation in maintenance of glucose homeostasis in fed and fasting (48 h) rats, we investigated that this hormone may be implicated in the regulation of renal gluconeogenesis pathway from lactate and lactate oxidation in renal cortex and medulla. Our results demonstrate the hSTC-1 role on lactate metabolism in the renal cortex and medulla from fed and fasting rats. hSTC-1 increased the gluconeogenesis activity in fed state in renal cortex, and this increase was induced by raise in Pck1 gene expression. In fasting animals hSTC-1 increase the renal medulla gluconeogenesis activity, but Pck1 gene expression was not alter. The stimulatory effect of hSTC-1 on 14C-lactate oxidation occurred only in the renal cortex from fed rats. These findings show the hSTC-1 contribution to lactate homeostasis and supplies glucose to other tissues. This response may represent a strategy of action of STC-1 in response to fasting stress as postulated by different authors. On the other hand, hSTC-1 acts downstream of adenylcyclase pathway, decreasing the gluconeogenesis activity induced by cAMP intracellular increase or stimulating the phosphodiesterase activity in the renal cortex. However, no hSTC-1 effect on 14C-lactate oxidation was found after increase in the intracellular cAMP. The findings also revealed that the renal cortex and medulla respond differently to hSTC-1, possibly due to the higher level of STC-1 gene expression in inner renal medulla than in renal cortex.

Diet composition and long-term starvation do not affect crustacean hyperglycemic hormone (CHH) transcription in the burrowing crab Neohelice granulata (Dana, 1851).

The burrowing crab Neohelice granulata is a key omnivorous species in intertidal areas along the southwestern Atlantic from southern Brazil to northern Argentinean Patagonia. This crab is adapted to starvation and can endure natural periods of food deprivation. The metabolic adjustments during starvation depend on the type of diet the crabs were fed previously. Since eyestalk-crustacean hyperglycemic hormone (CHH) is the principal regulator of glucose homeostasis in decapods, we investigated whether CHH transcription was affected by diet composition and starvation. Crabs were maintained in the laboratory for two weeks and subsequently divided in two groups. One received a high carbohydrate (HC) diet, and the other was fed a high protein (HP) diet. After this period, they were starved for four weeks. The full-length cDNA sequence of N. granulata CHH was determined and aligned with CHH sequences of other crabs. Levels of circulating glucose and glycogen were higher in the hepatopancreas and muscle of the HC-fed group and decreased after starvation. Glucose and glycogen concentrations were not altered by starvation in the HP group. Triglyceride levels within the hemolymph were not altered by diet or starvation. However, triglycerides concentration was higher in the hepatopancreas of HC compared to HP-fed group. Long-term starvation and diet composition did not affect CHH transcription.

Metabolic effects of epinephrine on the crab Neohelice granulata.

Although widely known for their involvement in the control of carbohydrate and lipid metabolism of vertebrates, the participation of catecholamines (CAs) in the metabolism of invertebrates is less understood. This study was designed to identify the physiological role of Epinephrine (E) in the intermediary metabolism of the burrowing crab Neohelice granulata and how E regulates the metabolism in crabs fed with a high-carbohydrate (HC) or a high-protein (HP) diet. To answer these questions, we evaluated in vivo the effects of E injections on glucose and triglycerides in the hemolymph and tissue glycogen levels of crabs fed with HC or HP diet. An in vitro investigation was carried out to assess the direct effects of E on glycogenolysis, lipolysis and glycolysis pathways in the hepatopancreas, mandibular muscle and anterior and posterior gills of this crab. E injections increased glucose and did not affect triglycerides levels in the hemolymph of either group of crabs, and E decreased glycogen in the hepatopancreas and mandibular muscle only in HP crabs, suggesting that these effects may be mediated by the crustacean hyperglycemic hormone (CHH). When the tissues were incubated with different concentrations of E, the concentration of glucose released to the medium decreased in the hepatopancreas and posterior gills, while glucose oxidation increased in the posterior gills of HP crabs. Incubation with E did not alter any parameter in tissues of HC crabs. These effects suggest that E may be involved in the metabolic response to osmotic stress.

Effect of yerba mate (Ilex paraguariensis) extract on the metabolism of diabetic rats.

The relationship between metabolic disturbances and clinical events related to diabetes is well known. Yerba mate has presented a potential use as preventive and therapeutic agent on diabetes. The aim of this study was to evaluate the effect of yerba mate on different tissues of diabetic rats, focusing on energetic metabolism. Diabetes was induced by streptozotocin, followed by daily yerba mate treatment. After 30 days, the animals were euthanized to evaluate metabolic parameters on liver, adipose tissue, muscle and serum. The results showed mate treatment promoted a decrease in retroperitoneal adipose tissue in healthy animals. Muscle weight returned to control levels in diabetic rats treated with mate. There was improvement on serum glucose, creatinine, urea and total protein levels associated with mate treatment. Muscle parameters, such as glucose uptake and carbon dioxide production, were improved by mate treatment to control levels. The results evidenced the beneficial actions mate can have on metabolic disturbances of diabetes.

Serotonin effects in the crab Neohelice granulata: Possible involvement of two types of receptors in peripheral tissues.

In crustaceans, serotonin (5-HT) controls various physiological processes, such as hormonal secretion, color changes, reproduction, and metabolism. Since 5-HT injections cause hyperglycemia, this study was designed to further investigate this action of 5-HT in the crab Neohelice granulate, fed with a high-carbohydrate (HC) or a high-protein (HP) diet. The effects of pre-treatment with mammalian 5-HT receptor antagonists, cyproheptadine and methiothepin, were also investigated. A series of in vivo experiments with (3)H-5-HT was carried out in order to investigate the presence of putative receptors in peripheral tissues. Since gills were the tissue with the highest labeling in in vivo experiments, in vitro studies with isolated anterior and posterior gills were also conducted. Cyproheptadine blocked the hyperglycemic effect of 5-HT in HP-fed crabs. Methiothepin reduced glycogen levels in the anterior gills of HP crabs and partially blocked the 5-HT-like posture. The injection of (3)H-5-HT identified specific binding sites in all the tissues studied and revealed that the binding can be influenced by the type of diet administered to the crabs. Incubation of the anterior and posterior gills with (3)H-5-HT and 5-HT confirmed the specificity of the binding sites. Both antagonists inhibited (3)H-5-HT binding. In conclusion, this study highlights the importance of serotonin in the control of glucose homeostasis in crustaceans and provides evidences of at least two types of 5-HT binding sites in peripheral tissues. Further studies are necessary to identify the structure of these receptors and their signaling pathways.