Evidence for preserved insulin responsiveness in the aging rat brain.

Insulin appears to exert salutary effects in the central nervous system (CNS). Thus, brain insulin resistance has been proposed to play a role in brain aging and dementia but is conceptually complex and unlikely to fit classic definitions established in peripheral tissues. Thus, we sought to characterize brain insulin responsiveness in young (4-5 months) and old (24 months) FBN male rats using a diverse set of assays to determine the extent to which insulin effects in the CNS are impaired with age.

Subarachnoid Hemorrhage Induces Sub-acute and Early Chronic Impairment in Learning and Memory in Mice.

Subarachnoid hemorrhage (SAH) leads to significant long-term cognitive deficits, so-called the post-SAH syndrome. Existing neurological scales used to assess outcomes of SAH are focused on sensory-motor functions. To better evaluate short-term and chronic consequences of SAH, we explored and validated a battery of neurobehavioral tests to gauge the functional outcomes in mice after the circle of Willis perforation-induced SAH.

Defective myelination in an RNA polymerase III mutant leukodystrophic mouse.

RNA polymerase (Pol) III synthesizes abundant short noncoding RNAs that have essential functions in protein synthesis, secretion, and other processes. Despite the ubiquitous functions of these RNAs, mutations in Pol III subunits cause Pol III-related leukodystrophy, an early-onset neurodegenerative disease. The basis of this neural sensitivity and the mechanisms of disease pathogenesis are unknown.

Microglial reduction of colony stimulating factor-1 receptor expression is sufficient to confer adult onset leukodystrophy.

Adult onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP) is a dementia resulting from dominantly inherited CSF1R inactivating mutations. The Csf1r mouse mimics ALSP symptoms and pathology. Csf1r is mainly expressed in microglia, but also in cortical layer V neurons that are gradually lost in Csf1r+/- mice with age.

Nociceptors protect sickle cell disease mice from vaso-occlusive episodes and chronic organ damage.

Sickle cell disease (SCD) is a common hereditary hematologic disorder. SCD patients suffer from acute vaso-occlusive episodes (VOEs), chronic organ damage, and premature death, with few therapeutic options. Although severe pain is a major clinical manifestation of SCD, it remains unknown whether nociception plays a role in SCD pathogenesis.

Microglial Homeostasis Requires Balanced CSF-1/CSF-2 Receptor Signaling.

CSF-1R haploinsufficiency causes adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP). Previous studies in the Csf1r mouse model of ALSP hypothesized a central role of elevated cerebral Csf2 expression. Here, we show that monoallelic deletion of Csf2 rescues most behavioral deficits and histopathological changes in Csf1r mice by preventing microgliosis and eliminating most microglial transcriptomic alterations, including those indicative of oxidative stress and demyelination.

Central IGF-1 protects against features of cognitive and sensorimotor decline with aging in male mice.

Disruptions in growth hormone/insulin-like growth factor-1 (GH/IGF-1) signaling have been linked to improved longevity in mice and humans. Nevertheless, while IGF-1 levels are associated with increased cancer risk, they have been paradoxically implicated with protection from other age-related conditions, particularly in the brain, suggesting that strategies aimed at selectively increasing central IGF-1 action may have favorable effects on aging. To test this hypothesis, we generated inducible, brain-specific (TRE-IGF-1 × Camk2a-tTA) IGF-1 (bIGF-1) overexpression mice and studied effects on healthspan.

Loss-of-Huntingtin in Medial and Lateral Ganglionic Lineages Differentially Disrupts Regional Interneuron and Projection Neuron Subtypes and Promotes Huntington's Disease-Associated Behavioral, Cellular, and Pathological Hallmarks.

Emerging studies are providing compelling evidence that the pathogenesis of Huntington's disease (HD), a neurodegenerative disorder with frequent midlife onset, encompasses developmental components. Moreover, our previous studies using a hypomorphic model targeting huntingtin during the neurodevelopmental period indicated that loss-of-function mechanisms account for this pathogenic developmental component (Arteaga-Bracho et al., 2016).

Neuropsychiatric Systemic Lupus Erythematosus Is Dependent on Sphingosine-1-Phosphate Signaling.

About 40% of patients with systemic lupus erythematosus experience diffuse neuropsychiatric manifestations, including impaired cognition and depression. Although the pathogenesis of diffuse neuropsychiatric SLE (NPSLE) is not fully understood, loss of brain barrier integrity, autoreactive antibodies, and pro-inflammatory cytokines are major contributors to disease development. Fingolimod, a sphingosine-1-phosphate (S1P) receptor modulator, prevents lymphocyte egress from lymphoid organs through functional antagonism of S1P receptors.

Lipocalin-2 is a pathogenic determinant and biomarker of neuropsychiatric lupus.

Neuropsychiatric manifestations in lupus (NPSLE) affect ∼20-40% of patients. In the central nervous system, lipocalin-2 (LCN2) can promote injury through mechanisms directly linked to NPSLE, including brain barrier disruption, neurotoxicity, and glial activation. Since LCN2 is elevated in lupus and has been implicated in neuroinflammation, we investigated whether LCN2 is required for the pathogenesis of NPSLE.

Methotrexate causes persistent deficits in memory and executive function in a juvenile animal model.

Methotrexate is a dihydrofolate reductase inhibitor widely employed in curative treatment for children with acute lymphoblastic leukemia (ALL). However, methotrexate administration is also associated with persistent cognitive deficits among long-term childhood cancer survivors. Animal models of methotrexate-induced cognitive deficits have primarily utilized adult animals.

Pathobiology of Christianson syndrome: Linking disrupted endosomal-lysosomal function with intellectual disability and sensory impairments.

Christianson syndrome (CS) is a recently described rare neurogenetic disorder presenting early in life with a broad range of neurological symptoms, including severe intellectual disability with nonverbal status, hyperactivity, epilepsy, and progressive ataxia due to cerebellar atrophy. CS is due to loss-of-function mutations in SLC9A6, encoding NHE6, a sodium-hydrogen exchanger involved in the regulation of early endosomal pH. Here we review what is currently known about the neuropathogenesis of CS, based on insights from experimental models, which to date have focused on mechanisms that affect the CNS, specifically the brain.

Rigor and reproducibility in rodent behavioral research.

Behavioral neuroscience research incorporates the identical high level of meticulous methodologies and exacting attention to detail as all other scientific disciplines. To achieve maximal rigor and reproducibility of findings, well-trained investigators employ a variety of established best practices. Here we explicate some of the requirements for rigorous experimental design and accurate data analysis in conducting mouse and rat behavioral tests.

Loss of Gas6 and Axl signaling results in extensive axonal damage, motor deficits, prolonged neuroinflammation, and less remyelination following cuprizone exposure.

The TAM (Tyro3, Axl, and MerTK) family of receptor tyrosine kinases (RTKs) and their ligands, Gas6 and ProS1, are important for innate immune responses and central nervous system (CNS) homeostasis. While only Gas6 directly activates Axl, ProS1 activation of Tyro3/MerTK can indirectly activate Axl through receptor heterodimerization. Therefore, we generated Gas6 Axl double knockout (DKO) mice to specifically examine the contribution of this signaling axis while retaining ProS1 signaling through Tyro3 and MerTK.

Liposomal Cytarabine Induces Less Neurocognitive Dysfunction Than Intrathecal Methotrexate in an Animal Model.

Liposomal cytarabine is currently being tested clinically as an alternative to intrathecal (IT) methotrexate (MTX) for preventing relapse within the central nervous system among patients with acute lymphoblastic leukemia. To compare the toxicity and cognitive deficits caused by IT MTX versus liposomal cytarabine, juvenile Long Evans rats were treated with IT injections of MTX 1 mg/kg×4 doses over 8 days, or liposomal cytarabine 0.8 mg once.

A study of time- and sex-dependent effects of vortioxetine on rat sexual behavior: Possible roles of direct receptor modulation.

Treatment-related sexual dysfunction is a common side effect of antidepressants and contributes to patient non-compliance or treatment cessation. However, the multimodal antidepressant, vortioxetine, demonstrates low sexual side effects in depressed patients. To investigate the mechanisms involved, sexual behavior was assessed in male and female rats after acute, and repeated (7 and 14 days) treatment with vortioxetine, flesinoxan (a 5-HT receptor agonist), CP-94253 (a 5-HT receptor agonist), or ondansetron (a 5-HT receptor antagonist).

Drugs with antidepressant properties affect tryptophan metabolites differently in rodent models with depression-like behavior.

The metabolism of tryptophan through kynurenine and serotonin pathways is linked to depression. Here, effects of different drugs with antidepressant properties (vortioxetine, fluoxetine, and ketamine) on various tryptophan metabolites in different brain regions and plasma were examined using tandem mass spectrometry (LC-MS/MS), in Flinders Sensitive Line rats, a genetic rat model of depression, and its controls: Flinders Sensitive Line and Sprague-Dawley rats. Protein levels of kynurenine pathway enzymes were measured in the brains and livers of these rat strains.

BXD recombinant inbred strains participate in social preference, anxiety and depression behaviors along sex-differences in cytokines and tactile allodynia.

Depression and anxiety are the most common psychiatric disorders, representing a major public health concern. Dysregulation of oxidative and inflammatory systems may be associated with psychiatric disorders, such as depression and anxiety. Due to the need to find appropriate animal models to the understanding of such disorders, we queried whether 2 BXD recombinant inbred (RI) mice strains (BXD21/TyJ RI and BXD84/RwwJ RI mice) and C57BL/6 wild-type mice show differential performance in depression and anxiety related behaviors and biomarkers.

Quantitation of plasmatic lysosphingomyelin and lysosphingomyelin-509 for differential screening of Niemann-Pick A/B and C diseases.

Acid sphingomyelinase deficiency (ASMd, Niemann-Pick disease A/B) and Niemann-Pick type C disease (NPC) share core clinical symptoms. Initial diagnostic discrimination of these two rare lysosomal storage diseases is thus difficult. As sphingomyelin accumulates in ASMd as well as NPC, lysosphingomyelin (sphingosylphosphorylcholine) and its m/z 509 analog were suggested as biomarkers for both diseases.

Distinct Antidepressant-Like and Cognitive Effects of Antidepressants with Different Mechanisms of Action in Middle-Aged Female Mice.

Background: Cognitive dysfunction is among the key symptoms of major depressive disorder and can be affected by antidepressants. Cognitive decline also occurs in normal aging. The effects of different antidepressants on affective and cognitive domains in older subjects are seldom assessed simultaneously.

Postnatal and adult consequences of loss of huntingtin during development: Implications for Huntington's disease.

The mutation in huntingtin (mHtt) leads to a spectrum of impairments in the developing forebrain of Huntington's disease (HD) mouse models. Whether these developmental alterations are due to loss- or gain-of-function mechanisms and contribute to HD pathogenesis is unknown. We examined the role of selective loss of huntingtin (Htt) function during development on postnatal vulnerability to cell death.

In vivo and in vitro effects of vortioxetine on molecules associated with neuroplasticity.

Neuroplasticity is fundamental for brain functions, abnormal changes of which are associated with mood disorders and cognitive impairment. Neuroplasticity can be affected by neuroactive medications and by aging. Vortioxetine, a multimodal antidepressant, has shown positive effects on cognitive functions in both pre-clinical and clinical studies.

Selective expression of mutant huntingtin during development recapitulates characteristic features of Huntington's disease.

Recent studies have identified impairments in neural induction and in striatal and cortical neurogenesis in Huntington's disease (HD) knock-in mouse models and associated embryonic stem cell lines. However, the potential role of these developmental alterations for HD pathogenesis and progression is currently unknown. To address this issue, we used BACHD:CAG-Cre(ERT2) mice, which carry mutant huntingtin (mHtt) modified to harbor a floxed exon 1 containing the pathogenic polyglutamine expansion (Q97).

Sleep duration, depression, and oxytocinergic genotype influence prepulse inhibition of the startle reflex in postpartum women.

The postpartum period is characterized by a post-withdrawal hormonal status, sleep deprivation, and susceptibility to affective disorders. Postpartum mothering involves automatic and attentional processes to screen out new external as well as internal stimuli. The present study investigated sensorimotor gating in relation to sleep duration, depression, as well as catecholaminergic and oxytocinergic genotypes in postpartum women.

Intracerebroventricular administration of TNF-like weak inducer of apoptosis induces depression-like behavior and cognitive dysfunction in non-autoimmune mice.

Fn14, the sole known signaling receptor for the TNF family member TWEAK, is inducibly expressed in the central nervous system (CNS) in endothelial cells, astrocytes, microglia, and neurons. There is increasing recognition of the importance of the TWEAK/Fn14 pathway in autoimmune neurologic conditions, including experimental autoimmune encephalomyelitis and neuropsychiatric lupus. Previously, we had found that Fn14 knockout lupus-prone MRL/lpr mice display significantly attenuated neuropsychiatric manifestations.