Sucrose drinking mimics effects of nucleus accumbens µ-opioid receptor stimulation on fat intake and brain c-Fos-expression.

Objectives: We have previously shown that the combined consumption of fat and a sucrose solution induces overeating, and there is evidence indicating that sucrose drinking directly stimulates fat intake. One neurochemical pathway by which sucrose may enhance fat intake is through the release of endogenous opioids in the nucleus accumbens (NAC).Methods: To test this hypothesis, we provided rats with a free-choice high-fat diet for two weeks. During the second week, rats had access to an additional bottle of water or a 30% sucrose solution for five minutes per day. After these two weeks, we infused vehicle or the µ-opioid receptor agonist [D-Ala2, N-MePhe4, Gly-ol]-enkephalin (DAMGO) into the NAC 30 min after their daily access to the additional bottle of water or the sucrose solution.Results: Sucrose drinking had two effects, (1) it stimulated fat intake in the absence of DAMGO infusion, (2) it diminished sensitivity to DAMGO, as it prevented the rapid increase in fat intake typically seen upon DAMGO infusion in the nucleus accumbens. In a second experiment, we confirmed that these results are not due to the ingested calories of the sucrose solution. Lastly, we investigated which brain areas are involved in the observed effects on fat intake by assessing c-Fos-expression in brain areas previously linked to DAMGO's effects on food intake. Both intra-NAC DAMGO infusion and sucrose consumption in the absence of DAMGO infusion had no effect on c-Fos-expression in orexin neurons and the central amygdala but increased c-Fos-expression in the NAC as well as the basolateral amygdala.Discussion: In conclusion, we confirm that sucrose drinking stimulates fat intake, likely through the release of endogenous opioids.

A free-choice high-fat diet modulates the effects of a sucrose bolus on the expression of genes involved in glucose handling in the hypothalamus and nucleus accumbens.

The consumption of saturated fat and sucrose can have synergistic effects on the brain that do not occur when either nutrient is consumed by itself. In this study we hypothesize that saturated fat intake modulates glucose handling in the hypothalamus and nucleus accumbens, both brain areas highly involved in the control of food intake. To study this, male Wistar rats were given a free-choice high fat diet (fcHFD) or a control diet for two weeks. During the last seven days rats were given a daily bolus of either a 30% sucrose solution or water. Rats were sacrificed on day eight, 30 minutes after the onset of drinking. mRNA and protein levels of genes involved in glucose handling were assessed in the hypothalamus and nucleus accumbens. We found increased Glut3 and Glut4 mRNA in the hypothalamus of fcHFD-fed rats without an additional effect of the sucrose bolus. In the nucleus accumbens, the sucrose bolus increased Glut3 mRNA and decreased Glut4 mRNA independent of prior diet exposure. The ATP-sensitive potassium channel subunit Kir6.1 in the nucleus accumbens tended to be affected by the synergistic effects of a fcHFD and a sucrose bolus. These data suggest that acute glucose handling in the hypothalamus and nucleus accumbens may be affected by prior high fat exposure.

Infusion of fluoxetine, a serotonin reuptake inhibitor, in the shell region of the nucleus accumbens increases blood glucose concentrations in rats.

The brain is well known to regulate blood glucose, and the hypothalamus and hindbrain, in particular, have been studied extensively to understand the underlying mechanisms. Nuclei in these regions respond to alterations in blood glucose concentrations and can alter glucose liver output or glucose tissue uptake to maintain blood glucose concentrations within strict boundaries. Interestingly, several cortico-limbic regions also respond to alterations in glucose concentrations and have been shown to project to hypothalamic nuclei and glucoregulatory organs. For instance, electrical stimulation of the shell of the nucleus accumbens (sNAc) results in increased circulating concentrations of glucose and glucagon and activation of the lateral hypothalamus (LH). Whether this is caused by the simultaneous increase in serotonin release in the sNAc remains to be determined. To study the effect of sNAc serotonin on systemic glucose metabolism, we implanted bilateral microdialysis probes in the sNAc of male Wistar rats and infused fluoxetine, a serotonin reuptake inhibitor, or vehicle after which blood glucose, endogenous glucose production (EGP) and glucoregulatory hormones were measured. Fluoxetine in the sNAc for 1h significantly increased blood glucose concentrations without an effect on glucoregulatory hormones. This increase was accompanied by a higher EGP in the fluoxetine infused rats compared to the controls. These data provide further evidence for a role of sNAc-serotonin in the regulation of glucose metabolism.

How we do: optimizing bone marrow biopsy logistics for sign-out within 2 days.

Since the introduction of fast diagnostic tracks in many areas of oncology, the traditional processing of bone marrow biopsies (BMB), requiring either resin embedding or lengthy fixation and decalcification, is due to an upgrade. Thanks to a growing number of new commercially available tissue processors, microwave-enhanced processing is becoming a standard tool in the pathology laboratory, allowing rapid fixation and decalcification of BMB with preserved morphology and antigens. In this short report, we describe the use of a commercially available EDTA-based decalcification fluid (USEDECALC, Medite, Orlando, USA) in combination with the LOGOS J (Milestone, Bergamo, Italy), a closed microwave-enhanced tissue processor, for overnight fixation, decalcification, and paraffin impregnation of the BMB. This allows next-day reporting without impaired morphology or immunohistochemistry, and even improved DNA quality of the BMB.

Dataset of liver proteins changed in eu- and hypothyroid female rats upon in vivo exposure to hexabromocyclododecane (HBCD).

Female Wistar rats with different thyroid status (eu-, hypothyroid) were exposed to 0, 3 or 30 mg/kg body weight of the flame retardant HBCD for 7 days. Changes in protein patterns obtained by 2D-DIGE were evaluated, and different animal groups compared taking into account their exposure and thyroid status. Proteins significantly altered in abundance in any of these comparisons were identified by mass spectrometry. These data, together with hormone data of the animals, are discussed in "Hexa-bromocyclododecane (HBCD) induced changes in the liver proteome of eu- and hypothyroid female rats" (Miller et al., 2016) [1].

Hexabromocyclododecane (HBCD) induced changes in the liver proteome of eu- and hypothyroid female rats.

Hexabromocyclododecane (HBCD) is a brominated flame retardant known for its low acute toxicity as observed in animal experiments. However, HBCD exposure can affect liver functioning and thyroid hormone (TH) status. As exact mechanisms are unknown and only limited toxicological data exists, a gel-based proteomic approach was undertaken. In a eu- and hypothyroid female rat model, rats were exposed to 3 and 30 mg/kg bw/day HBCD for 7 days via their diet, and exposure was related to a range of canonical endpoints (hormone status, body weight) available for these animals. Alterations in the liver proteome under HBCD exposure were determined in comparison with patterns of control animals, for both thyroid states. This revealed significantly changed abundance of proteins involved in metabolic processes (gluconeogenesis/glycolysis, amino acid metabolism, lipid metabolism), but also in oxidative stress responses, in both euthyroid and hypothyroid rats. The results provide a more detailed picture on the mechanisms involved in these alterations, e.g. at the protein level changes of the proposed influence of HBCD on the lipid metabolism. Present results show that proteomic approaches can provide further mechanistic insights in toxicological studies.

Gender specific differences in the liver proteome of rats exposed to short term and low-concentration hexabromocyclododecane (HBCD).

The influence of short term (7-day) exposure of male rats to the brominated flame retardant hexabromocyclododecane (HBCD) was studied by investigation of the liver proteome, both in euthyroid and hypothyroid rats and by comparing results with general data on animal physiology and thyroid hormone, leptin, insulin and gonadotropin concentrations determined in parallel. Proteome analysis of liver tissue by two-dimensional fluorescence difference gel electrophoresis (2D-DIGE) revealed that only small protein pattern changes were induced by exposure in males, on just a few proteins with different functions and not involved in pathways in common. This is in contrast to previous findings in similarly exposed eu- and hypothyroid female rats, where general metabolic pathways had been shown to be affected. The largest gender-dependent effects concerned basal concentrations of liver proteins already in control and hypothyroid animals, involving mainly the pathways which were also differently affected by HBCD exposure. Among them were differences in lipid metabolism, which - upon exposure to HBCD - may also be the reason for the considerably higher ratio of γ-HBCD accumulated in white adipose tissue of exposed female rats compared to males. The results further elucidate the already suggested different sensitivity of genders towards HBCD exposure on the protein level, and confirm the need for undertaking toxicological animal experiments in both genders.