IDOL regulates systemic energy balance through control of neuronal VLDLR expression.

Liver X receptors limit cellular lipid uptake by stimulating the transcription of Inducible Degrader of the LDL Receptor (IDOL), an E3 ubiquitin ligase that targets lipoprotein receptors for degradation. The function of IDOL in systemic metabolism is incompletely understood. Here we show that loss of IDOL in mice protects against the development of diet-induced obesity and metabolic dysfunction by altering food intake and thermogenesis. Unexpectedly, analysis of tissue-specific knockout mice revealed that IDOL affects energy balance, not through its actions in peripheral metabolic tissues (liver, adipose, endothelium, intestine, skeletal muscle), but by controlling lipoprotein receptor abundance in neurons. Single-cell RNA sequencing of the hypothalamus demonstrated that IDOL deletion altered gene expression linked to control of metabolism. Finally, we identify VLDLR rather than LDLR as the primary mediator of IDOL effects on energy balance. These studies identify a role for the neuronal IDOL-VLDLR pathway in metabolic homeostasis and diet-induced obesity

Can Animal Models of Disease Reliably Inform Human Studies?

H. Bart van der Worp and colleagues discuss the controversies and possibilities of translating the results of animal experiments into human clinical trials

Different strokes for different folks: the rich diversity of animal models of focal cerebral ischemia

No single animal model is able to encompass all of the variables known to affect human ischemic stroke. This review highlights the major strengths and weaknesses of the most commonly used animal models of acute ischemic stroke in the context of matching model and experimental aim. Particular emphasis is placed on the relationships between outcome and underlying vascular variability, physiologic control, and use of models of comorbidity. The aim is to provide, for novice and expert alike, an overview of the key controllable determinants of experimental stroke outcome to help ensure the most effective application of animal models to translational research

Photothrombosis-induced infarction of the mouse cerebral cortex is not affected by the Nrf2-activator sulforaphane.

Sulforaphane-induced activation of the transcription factor NF-E2 related factor 2 (Nrf2 or the gene Nfe2l2) and subsequent induction of the phase II antioxidant system has previously been shown to exert neuroprotective action in a transient model of focal cerebral ischemia. However, its ability to attenuate functional and cellular deficits after permanent focal cerebral ischemia is not clear. We assessed the neuroprotective effects of sulforaphane in the photothrombotic model of permanent focal cerebral ischemia. Sulforaphane was administered (5 or 50 mg/kg, i.p.) after ischemic onset either as a single dose or as daily doses for 3 days. Sulforaphane increased transcription of Nrf2, Hmox1, GCLC and GSTA4 mRNA in the brain confirming activation of the Nrf2 system. Single or repeated administration of sulforaphane had no effect on the infarct volume, nor did it reduce the number of activated glial cells or proliferating cells when analyzed 24 and 72 h after stroke. Motor-function as assessed by beam-walking, cylinder-test, and adhesive test, did not improve after sulforaphane treatment. The results show that sulforaphane treatment initiated after photothrombosis-induced permanent cerebral ischemia does not interfere with key cellular mechanisms underlying tissue damage

ACE inhibition reduces infarction in normotensive but not hypertensive rats: correlation with cortical ACE activity

Angiotensin-converting enzyme (ACE) inhibition can reduce stroke risk by up to 43% in humans and reduce the associated disability, and hence understanding the mechanism of improvement is important. In animals and humans, these effects may be independent of the blood pressure-lowering effects of ACE inhibition. Normotensive (Wistar–Kyoto (WKY)) and hypertensive (spontaneously hypertensive rat (SHR)) animals were treated with the ACE inhibitors ramipril or lisinopril for 7 or 42 days before 2 hours of transient middle cerebral artery occlusion (MCAo). Blood pressure, serum ACE, and blood glucose levels were measured and stroke infarct volume was recorded 24 hours after stroke. Despite greater reductions in blood pressure, infarct size was not improved by ACE inhibition in hypertensive animals. Short-term ACE inhibition produced only a modest reduction in blood pressure, but WKY rats showed marked reductions in infarct volume. Long-term ACE inhibition had additional reductions in blood pressure; however, infarct volumes in WKY rats did not improve further but worsened. WKY rats differed from SHR in having marked cortical ACE activity that was highly sensitive to ACE inhibition. The beneficial effects of ACE inhibition on infarct volume in normotensive rats do not correlate with changes in blood pressure. However, WKY rats have ACE inhibitor-sensitive cortical ACE activity that is lacking in the SHR

The motor function of the mice was examined prior to, 24 and 72 h after ischemic onset.

<p><b>A</b>) 24 h after ischemia, all mice demonstrated significant functional deficits that were not affected by sulforaphane treatment. (mean±SD, <i>n</i> = 8–12, t-test or one way ANOVA *<i>p</i>≤0.05, **<i>p</i>≤0.001, ***<i>p</i>≤0.0001; solid black circle vehicle, solid grey circle 5 mg/kg sulforaphane, open box 50 mg/kg sulforaphane). <b>B</b>) 72 h after ischemia, mice treated with sulforaphane were able to complete the round beam task compared to vehicle. All other behavioural outcome measurements had returned to pre stroke baseline levels. (mean±SD, <i>n</i> = 8–12, solid black line vehicle, solid grey line 5 mg/kg sulforaphane, dashed grey line 50 mg/kg sulforaphane, *** F(2,48) = 53.21, <i>p</i>≤0.0001).</p

Infarct volume presented as scattergrams and as their distribution across in anterior and posterior plane at A) 24 h and B) 72 h after ischemia.

<p>Infarct volume and distribution did not change with time. Single or repeated doses of sulforaphane did not protect as infarct volume did not differ in comparison to vehicle treated animals (mean±SD; <i>n</i> = 8–13, one way ANOVA 24 h p = 0.38, 72 h p = 0.93; solid black vehicle, solid gre 5 mg/kg sulforaphane, open box 50 mg/kg sulforaphane). Coronal images of representative cortical infarcts at 0.5 mm from Bregma 72 h after onset in C) vehicle, D) 5 mg/kg sulforaphane and E) 50 mg/kg sulforaphane treated animals.</p

Messenger RNA levels of Nrf2 related gene products.

<p><b>A</b>) Nqo1 and Nrf2 (Nfe2l2) expression in brain of naïve mice 24 h after treatment with sulforaphane or vehicle. Nrf2 is significantly increased by 5 mg/kg sulforaphane (mean±SD; <i>n</i> = 3, *<i>p</i>≤0.05; solid black box vehicle, solid grey box 5 mg/kg sulforaphane, open box 50 mg/kg sulforaphane). <b>B</b>) There was no additive effect of sulforaphane on stimulation of the Nrf2 system. Hmox1 and Gsta4 expression was significantly greater in animals 12 h after ischemia and 5 mg/kg sulforaphane treatment. GCLC treatment was increased by ischemia alone. (mean±SD; <i>n</i> = 3, ***<i>p</i>≤0.0001; solid black box sham and vehicle, solid grey box ischemia alone, open box grey diagonal stripes ischemia and 5 mg/kg sulforaphane).</p

Cell proliferation and glial cell distribution determined by immunostaining 72 h after infarction.

<p>The bar graphs (mean±SD) represent the cell distribution in the peri-infarct, transition and core regions <b>A</b>) the percentage of total cell number per region and <b>B-D</b>) the number of cells/µm², <b>B’</b>) activated microglia (Iba1), <b>C’</b>) proliferating cells (BrdU) and <b>D’</b>) reactive astrocytes (GFAP). No GFAP positive cells were observed in the core region. Sulforaphane treatment only altered the microglial cell number in the peri-infarct region compared to vehicle treatment (F(2,15) = 4.76, <i>p</i>≤0.025) (<i>n</i> = 5–9 in each group, solid black box GFAP astrocytes, solid grey box Iba1 microglia, open box BrdU proliferating cells).</p