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Type-2 diabetes (T2D) is a metabolic disorder that is considered a risk factor for Alzheimer's disease (AD). Cognitive impairment can arise due to hypoglycemia associated with T2D, and hyperamylinemia associated with insulin resistance can enhance AD pathology. We explored whether changes occur in the hippocampus in aging (6-12 months old) female V-Lep◦b-/- transgenic (tg) mice, comprising an animal model of T2D. We also investigated whether an increase in vulnerability to Aβ (1-42), a known pathological hallmark of AD, is evident. Using magnetic resonance imaging we detected significant decreases in hippocampal brain volume in female tg-mice compared to wild-type (wt) littermates. Long-term potentiation (LTP) was impaired in tg compared to wt mice. Treatment of the hippocampus with Aβ (1-42) elicited a stronger debilitation of LTP in tg compared to wt mice. Treatment with an amylin antagonist (AC187) significantly enhanced LTP in wt and tg mice, and rescued LTP in Aβ (1-42)-treated tgmice. Taken together our data indicate that a T2D-like state results in an increased vulnerability of the hippocampus to the debilitating effects of Aβ (1-42) and that effects are mediated in part by changes in amylin receptor signaling. [ABSTRACT FROM AUTHOR]

Obesity is characterized by immoderate fat accumulation leading to an elevated risk of neurodegenerative disorders, along with a host of metabolic disturbances. Chronic neuroinflammation is a main factor linking obesity and the propensity for neurodegenerative disorders. To determine the cerebrometabolic effects of diet-induced obesity (DIO) in female mice fed a long-term (24 weeks) high-fat diet (HFD, 60% fat) compared to a group on a control diet (CD, 20% fat), we used in vivo PET imaging with the radiotracer [18F]FDG as a marker for brain glucose metabolism. In addition, we determined the effects of DIO on cerebral neuroinflammation using translocator protein 18 kDa (TSPO)-sensitive PET imaging with [18F]GE-180. Finally, we performed complementary post mortem histological and biochemical analyses of TSPO and further microglial (Iba1, TMEM119) and astroglial (GFAP) markers as well as cerebral expression analyses of cytokines (e.g., Interleukin (IL)-1β). We showed the development of a peripheral DIO phenotype, characterized by increased body weight, visceral fat, free triglycerides and leptin in plasma, as well as increased fasted blood glucose levels. Furthermore, we found obesity-associated hypermetabolic changes in brain glucose metabolism in the HFD group. Our main findings with respect to neuroinflammation were that neither [18F]GE-180 PET nor histological analyses of brain samples seem fit to detect the predicted cerebral inflammation response, despite clear evidence of perturbed brain metabolism along with elevated IL-1β expression. These results could be interpreted as a metabolically activated state in brain-resident immune cells due to a long-term HFD. [ABSTRACT FROM AUTHOR]

Cytotoxic T lymphocytes and their granule components, such as perforin and granzyme, play an important role in the defense of hepatic infections caused by different pathogens. Moreover, it has been shown in vitro that hepatocytes can initiate cell death via a perforin-dependent mechanism. Although it is well known that hepatocellular apoptosis in D-galactosamine/lipopolysaccharide (D-Gal/LPS)-associated liver failure is mediated by TNF-[alpha]-dependent Fas/FasL cytotoxicity, there is no information on the role of perforin-mediated mechanisms in vivo. Therefore, we studied whether the cytolytic perforin/granzyme pathway contributes to the D-Gal/LPS-associated hepatotoxicity. Perforin knockout (Pko) mice showed significantly higher hepatic TNF-[alpha] and IL-6 mRNA expression as well as plasma TNF-[alpha] and IL-6 concentrations within the first hour upon D-Gal/LPS challenge compared with perforin wild-type (Pwt) mice. At 6 h upon D-Gal/LPS challenge, Pko mice further presented with higher transaminase release and onconecrotic tissue damage, whereas hepatocellular apoptosis and caspase-3 cleavage remained unaffected by the perforin deficiency. Pretreatment with a recombinant human TNF-[alpha] receptor fusion protein attenuated necrotic and apoptotic tissue damage and reduced plasma transaminase activities as well as cytokine release, thereby preventing acute liver failure in Pko mice as effectively as in Pwt mice. These data do not only confirm the significance of TNF-[alpha] as distal mediator of hepatic injury in this model but simultaneously reveal a contribution of a perforin-dependent immunoregulation, limiting the D-Gal/LPS-induced overwhelming cytokine release and onconecrotic tissue injury. apoptosis; caspase-3; immunoregulation; interleukin-6; necrapoptosis; tumor necrosis factor-[alpha]

The endocannabinoids (ECs) N-arachidonylethanolamide (anandamide; AEA) and 2-arachidonoylglycerol (2-AG) participate in the control of feed intake and energy metabolism. Most mammals increase their feed intake after parturition to cope with the increased energy and nutrient requirements for milk synthesis, thereby increasing their metabolic rate. Here we investigated in experiment 1 the regulation of plasma AEA and 2-AG concentrations during the transition from late pregnancy to early lactation in dairy cows, and analyzed in experiment 2 the expression of the EC system in the paraventricular nucleus (PVN) and the arcuate nucleus (ARC) of the hypothalamus of late and early lactating cows using immunohistochemistry. Cows in experiment 1 were retrospectively grouped based on peak plasma fatty acid concentrations to a high (H) or low (L) group. Feed intake was not different between groups before parturition, but was lower in H than L cows during early lactation. Plasma AEA and 2-AG concentrations increased 2.2- to 2.4-fold during early lactation, in which time plasma AEA concentrations rose faster in H cows than in L cows postpartum. Upregulation of N-acyl phosphatidylethanolamine-specific phospholipase D together with tending increased cannabinoid receptor 1 (CB1) expression, and downregulation of fatty acid amide hydrolase in early lactating cows suggested an increased PVN AEA tone. The abundance of CB1 in the ARC and diacylglycerol lipase-alpha was not different between late and early lactating cows, but PVN monoacylglycerol lipase expression was 30% higher in early lactating cows, indicating diminished PVN 2-AG concentrations. The results show a potential involvement of AEA in stimulating feed intake and of 2-AG in regulating energy metabolism of early lactating cows. [ABSTRACT FROM AUTHOR]

In many animal experiments scientists and local authorities define a body-weight reduction of 20% or more as severe suffering and thereby as a potential parameter for humane endpoint decisions. In this study, we evaluated distinct animal experiments in multiple research facilities, and assessed whether 20% body-weight reduction is a valid humane endpoint criterion in rodents. In most experiments (restraint stress, distinct models for epilepsy, pancreatic resection, liver resection, caloric restrictive feeding and a mouse model for Dravet syndrome) the animals lost less than 20% of their original body weight. In a glioma model, a fast deterioration in body weight of less than 20% was observed as a reliable predictor for clinical deterioration. In contrast, after induction of chronic diabetes or acute colitis some animals lost more than 20% of their body weight without exhibiting major signs of distress. In these two animal models an exclusive application of the 20% weight loss criterion for euthanasia might therefore result in an unnecessary loss of animals. However, we also confirmed that this criterion can be a valid parameter for defining the humane endpoint in other animal models, especially when it is combined with additional criteria for evaluating distress. In conclusion, our findings strongly suggest that experiment and model specific considerations are necessary for the rational integration of the parameter 'weight loss' in severity assessment schemes and humane endpoint criteria. A flexible implementation tailored to the experiment or intervention by scientists and authorities is therefore highly recommended. [ABSTRACT FROM AUTHOR]

Background: APPswe/PS1dE9 mice reproduce features of amyloid β (Aβ) pathology and neuronal dysfunction as reflected in electrophysiological recordings of neuronal hyperexcitability. This leads to changes in sleep‐wake‐rhythm, downstream affecting brain clearance functionality. Our objective is to investigate the effect of circadian rhythm and Aβ pathology on clearance efficacy in APPswe/PS1dE9 mice. Method: First, we examined the brain wide distribution of an intrahippocampal injected fluorescent dye. Dye was injected at 6 am (post wake period) or 6 pm (post sleep period) and sampled 1 or 3 h post injection for histological analysis (Figure 1A) in n = 3 transgenic mice and n = 3 non‐transgenic mice per group. Secondly, in an in vivo approach we analyzed the brain wide distribution of a gadolinium based contrast agent using a T2‐RARE sequence in a 7 Tesla small animal MRI scanner (Bruker BioSpin GmbH, Germany) (Figure 1B) in n = 4 transgenic mice and n = 4 non‐transgenic mice. We measured values for brightness in manually defined regions of interest with PMOD software (version 3.7; PMOD Technologies LLC, Switzerland). Result: In the first experiment, we were able to observe dye distribution in the brain parenchyma as surrogate for interstitial clearance net flux. Preliminary results point to an effect of circadian rhythm, as a trend of better dye distribution shortly after the sleep period was observed. Furthermore, a possible detrimental effect of the Aβ phenotype on clearance was observed in transgenic mice. In comparison to non‐transgenic mice they showed a trend of lesser dye distribution independent of day‐time. With the second approach, we were able to observe influx and efflux of applied contrast agent into cerebrospinal fluid. Preliminary data point to a trend of an increased slope of the influx as well as decreased slope of the efflux in transgenic mice. Conclusion: Histological analysis of a stereotactic injected dye is a feasible method for investigation of dye distribution outlining a possible effect of daytime and amyloid pathology. However, MR‐imaging is a promising tool as we will be able to observe the disease progression in mice longitudinally. Further experiments will be needed to ensure these preliminary results and maybe also point to underlying mechanistic basis. [ABSTRACT FROM AUTHOR]