Microglial cannabinoid receptor type 1 mediates social memory deficits in mice produced by adolescent THC exposure and 16p11.2 duplication.

Adolescent cannabis use increases the risk for cognitive impairments and psychiatric disorders. Cannabinoid receptor type 1 (Cnr1) is expressed not only in neurons and astrocytes, but also in microglia, which shape synaptic connections during adolescence. However, the role of microglia in mediating the adverse cognitive effects of delta-9-tetrahydrocannabinol (THC), the principal psychoactive constituent of cannabis, is not fully understood. Here, we report that in mice, adolescent THC exposure produces microglial apoptosis in the medial prefrontal cortex (mPFC), which was exacerbated in a model of 16p11.2 duplication, a representative copy number variation (CNV) risk factor for psychiatric disorders. These effects are mediated by microglial Cnr1, leading to reduction in the excitability of mPFC pyramidal-tract neurons and deficits in social memory in adulthood. Our findings suggest the microglial Cnr1 may contribute to adverse effect of cannabis exposure in genetically vulnerable individuals.

Microglial cannabinoid receptor type 1 mediates social memory deficits produced by adolescent THC exposure and 16p11.2 duplication.

Adolescent cannabis use increases the risk for cognitive impairments and psychiatric disorders. Cannabinoid receptor type 1 (Cnr1) is expressed not only in neurons and astrocytes, but also in microglia, which shape synaptic connections during adolescence. Nonetheless, until now, the role of microglia in mediating the adverse cognitive effects of delta-9-tetrahydrocannabinol (THC), the principal psychoactive constituent of cannabis, has been unexplored. Here, we report that adolescent THC exposure produces microglial apoptosis in the medial prefrontal cortex (mPFC), which was exacerbated in the mouse model of 16p11.2 duplication, a representative copy number variation (CNV) risk factor for psychiatric disorders. These effects are mediated by microglial Cnr1, leading to reduction in the excitability of mPFC pyramidal-tract neurons and deficits in social memory in adulthood. Our findings highlight the importance of microglial Cnr1 to produce the adverse effect of cannabis exposure in genetically vulnerable individuals.

Loss of Astrocytic µ Opioid Receptors Exacerbates Aversion Associated with Morphine Withdrawal in Mice: Role of Mitochondrial Respiration.

Astrocytes express mu/µ opioid receptors, but the function of these receptors remains poorly understood. We evaluated the effects of astrocyte-restricted knockout of µ opioid receptors on reward- and aversion-associated behaviors in mice chronically exposed to morphine. Specifically, one of the floxed alleles of the Oprm1 gene encoding µ opioid receptor 1 was selectively deleted from brain astrocytes in Oprm1 inducible conditional knockout (icKO) mice. These mice did not exhibit changes in locomotor activity, anxiety, or novel object recognition, or in their responses to the acute analgesic effects of morphine. Oprm1 icKO mice displayed increased locomotor activity in response to acute morphine administration but unaltered locomotor sensitization. Oprm1 icKO mice showed normal morphine-induced conditioned place preference but exhibited stronger conditioned place aversion associated with naloxone-precipitated morphine withdrawal. Notably, elevated conditioned place aversion lasted up to 6 weeks in Oprm1 icKO mice. Astrocytes isolated from the brains of Oprm1 icKO mice had unchanged levels of glycolysis but had elevated oxidative phosphorylation. The basal augmentation of oxidative phosphorylation in Oprm1 icKO mice was further exacerbated by naloxone-precipitated withdrawal from morphine and, similar to that for conditioned place aversion, was still present 6 weeks later. Our findings suggest that µ opioid receptors in astrocytes are linked to oxidative phosphorylation and they contribute to long-term changes associated with opioid withdrawal.

Deficient mitochondrial respiration in astrocytes impairs trace fear conditioning and increases naloxone-precipitated aversion in morphine-dependent mice.

Mitochondria are abundant in the fine processes of astrocytes, however, potential roles for astrocyte mitochondria remain poorly understood. In the present study, we performed a systematic examination of the effects of abnormal oxidative phosphorylation in astrocytes on several mouse behaviors. Impaired astrocyte oxidative phosphorylation was produced by astrocyte-specific deletion of the nuclear mitochondrial gene, Cox10, that encodes an accessory protein of complex IV, the protoheme:heme-O-farnesyl transferase. As expected, conditional deletion of the Cox10 gene in mice (cKO mice) significantly reduced expression of COX10 and Cytochrome c oxidase subunit I (MTCO1) of Complex IV, resulting in decreased oxidative phosphorylation without significantly affecting glycolysis. No effects of the deletion were observed on locomotor activity, anxiety-like behavior, nociception, or spontaneous alternation. Cox10 cKO female mice exhibited mildly impaired novel object recognition, while Cox10 cKO male mice were moderately deficient in trace fear conditioning. No group-related changes were observed in conditional place preference (CPP) that assessed effects of morphine on reward. In contrast to CPP, Cox10 cKO mice demonstrated significantly increased aversive behaviors produced by naloxone-precipitated withdrawal following chronic exposure to morphine, that is, jumping and avoidance behavior as assessed by conditional place aversion (CPA). Our study suggests that astrocyte oxidative phosphorylation may contribute to behaviors associated with greater cognitive load and/or aversive and stressful conditions.

Homeostatic regulation of neuronal excitability by probiotics in male germ-free mice.

Emerging evidence indicates that probiotics can influence the gut-brain axis to ameliorate somatic and behavioral symptoms associated with brain disorders. However, whether probiotics have effects on the electrophysiological activities of individual neurons in the brain has not been evaluated at a single-neuron resolution, and whether the neuronal effects of probiotics depend on the gut microbiome status have yet to be tested. Thus, we conducted whole-cell patch-clamp recording-assisted electrophysiological characterizations of the neuronal effects of probiotics in male germ-free (GF) mice with and without gut microbiome colonization. Two weeks of treatment with probiotics (Lactobacillus rhamnosus and Bifidobacterium animalis) significantly and selectively increased the intrinsic excitability of hippocampal CA1 pyramidal neurons, whereas reconstituting gut microbiota in GF mice reversed the effects of the probiotics leading to a decreased intrinsic excitability in hippocampal neurons. This bidirectional modulation of neuronal excitability by probiotics was observed in hippocampal neurons with corresponding basal membrane property and action potential waveform changes. However, unlike the hippocampus, the amygdala excitatory neurons did not show any electrophysiological changes to the probiotic treatment in either GF or conventionalized GF mice. Our findings demonstrate for the first time how probiotic treatment can have a significant influence on the electrophysiological properties of neurons, bidirectionally modulating their intrinsic excitability in a gut microbiota and brain area-specific manner.

MCT1 Deletion in Oligodendrocyte Lineage Cells Causes Late-Onset Hypomyelination and Axonal Degeneration.

Oligodendrocytes (OLs) are important for myelination and shuttling energy metabolites lactate and pyruvate toward axons through their expression of monocarboxylate transporter 1 (MCT1). Recent studies suggest that loss of OL MCT1 causes axonal degeneration. However, it is unknown how widespread and chronic loss of MCT1 in OLs specifically affects neuronal energy homeostasis with aging. To answer this, MCT1 conditional null mice were generated that allow for OL-specific MCT1 ablation. We observe that MCT1 loss from OL lineage cells is dispensable for normal myelination and axonal energy homeostasis early in life. By contrast, loss of OL lineage MCT1 expression with aging leads to significant axonal degeneration with concomitant hypomyelination. These data support the hypothesis that MCT1 is important for neuronal energy homeostasis in the aging central nervous system (CNS). The reduction in OL MCT1 that occurs with aging may enhance the risk for axonal degeneration and atrophy in neurodegenerative diseases.

Astrocyte DISC1 contributes to cognitive function in a brain region-dependent manner.

Our understanding of the contribution of genetic risk factors to neuropsychiatric diseases is limited to abnormal neurodevelopment and neuronal dysfunction. Much less is known about the mechanisms whereby risk variants could affect the physiology of glial cells. Our prior studies have shown that a mutant (dominant-negative) form of a rare but highly penetrant psychiatric risk factor, Disrupted-In-Schizophrenia-1 (DISC1), impairs metabolic functions of astrocytes and leads to cognitive dysfunction. In order to overcome the limitations of the mutant DISC1 model and understand the putative regional properties of astrocyte DISC1, we assessed whether knockdown of Disc1 (Disc1-KD) in mature mouse astrocytes of the prefrontal cortex (PFC) or the hippocampus would produce behavioral abnormalities that could be attributed to astrocyte bioenergetics. We found that Disc1-KD in the hippocampus but not PFC impaired trace fear conditioning in adult mice. Using the innovative deep learning approach and convolutional deep neural networks (cDNNs), ResNet50 or ResNet18, and single cell-based analysis, we found that Disc1-KD decreased the spatial density of astrocytes associated with abnormal levels and distribution of the mitochondrial markers and the glutamate transporter, GLAST. Disc1-KD in astrocytes also led to decreased expression of the glutamatergic and increased expression of the GABA-ergic synaptic markers, possibly via non-apoptotic activation of caspase 3 in neurons located within the individual territories of Disc1-KD astrocytes. Our results indicate that altered expression of DISC1 in astrocytes could impair astrocyte bioenergetics, leading to abnormalities in synaptic neurotransmission and cognitive function in a region-dependent fashion.

Adolescent Δ9-Tetrahydrocannabinol Exposure and Astrocyte-Specific Genetic Vulnerability Converge on Nuclear Factor-κB-Cyclooxygenase-2 Signaling to Impair Memory in Adulthood.

BACKGROUND: Although several studies have linked adolescent cannabis use to long-term cognitive dysfunction, there are negative reports as well. The fact that not all users develop cognitive impairment suggests a genetic vulnerability to adverse effects of cannabis, which are attributed to action of Δ9-tetrahydrocannabinol (Δ9-THC), a cannabis constituent and partial agonist of brain cannabinoid receptor 1. As both neurons and glial cells express cannabinoid receptor 1, genetic vulnerability could influence Δ9-THC-induced signaling in a cell type-specific manner. METHODS: Here we use an animal model of inducible expression of dominant-negative disrupted in schizophrenia 1 (DN-DISC1) selectively in astrocytes to evaluate the molecular mechanisms, whereby an astrocyte genetic vulnerability could interact with adolescent Δ9-THC exposure to impair recognition memory in adulthood. RESULTS: Selective expression of DN-DISC1 in astrocytes and adolescent treatment with Δ9-THC synergistically affected recognition memory in adult mice. Similar deficits in recognition memory were observed following knockdown of endogenous Disc1 in hippocampal astrocytes in mice treated with Δ9-THC during adolescence. At the molecular level, DN-DISC1 and Δ9-THC synergistically activated the nuclear factor-κB-cyclooxygenase-2 pathway in astrocytes and decreased immunoreactivity of parvalbumin-positive presynaptic inhibitory boutons around pyramidal neurons of the hippocampal CA3 area. The cognitive abnormalities were prevented in DN-DISC1 mice exposed to Δ9-THC by simultaneous adolescent treatment with the cyclooxygenase-2 inhibitor, NS398. CONCLUSIONS: Our data demonstrate that individual vulnerability to cannabis can be exclusively mediated by astrocytes. Results of this work suggest that genetic predisposition within astrocytes can exaggerate Δ9-THC-produced cognitive impairments via convergent inflammatory signaling, suggesting possible targets for preventing adverse effects of cannabis within susceptible individuals.

DISC1 regulates lactate metabolism in astrocytes: implications for psychiatric disorders.

Our knowledge of how genetic risk variants contribute to psychiatric disease is mainly limited to neurons. However, the mechanisms whereby the same genetic risk factors could affect the physiology of glial cells remain poorly understood. We studied the role of a psychiatric genetic risk factor, Disrupted-In-Schizophrenia-1 (DISC1), in metabolic functions of astrocytes. We evaluated the effects of knockdown of mouse endogenous DISC1 (DISC1-KD) and expression of a dominant-negative, C-terminus truncated human DISC1 (DN-DISC1) on the markers of energy metabolism, including glucose uptake and lactate production, in primary astrocytes and in mice with selective expression of DN-DISC1 in astrocytes. We also assessed the effects of lactate treatment on altered affective behaviors and impaired spatial memory in DN-DISC1 mice. Both DISC1-KD and DN-DISC1 comparably decreased mRNA and protein levels of glucose transporter 4 and glucose uptake by primary astrocytes. Decreased glucose uptake was associated with reduced oxidative phosphorylation and glycolysis as well as diminished lactate production in vitro and in vivo. No significant effects of DISC1 manipulations in astrocytes were observed on expression of the subunits of the electron transport chain complexes or mitofilin, a neuronal DISC1 partner. Lactate treatment rescued the abnormal behaviors in DN-DISC1 male and female mice. Our results suggest that DISC1 may be involved in the regulation of lactate production in astrocytes to support neuronal activity and associated behaviors. Abnormal expression of DISC1 in astrocytes and resulting abnormalities in energy supply may be responsible for aspects of mood and cognitive disorders observed in patients with major psychiatric illnesses.

AAH2 gene is not required for dopamine-dependent neurochemical and behavioral abnormalities produced by Toxoplasma infection in mouse.

Infection with the protozoan parasite, Toxoplasma gondii (T. gondii), has been associated with the increased risk for several psychiatric disorders. The exact mechanisms of a hypothesized contribution of T. gondii infection are poorly understood. The T. gondii genome contains two aromatic amino acid hydroxylase genes (AAH1 and AAH2) that encode proteins that can produce L-DOPA. One popular hypothesis posits that these encoded enzymes might influence dopamine (DA) production and hence DA synaptic transmission, leading to neurobehavioral abnormalities in the infected host. Prior studies have shown that deletion of these genes does not alter DA levels in the brain or exploratory activity in infected mice. However, possible effects of AAH gene deficiency on infection-induced brain and behavior alterations that are directly linked to DA synaptic transmission have not been evaluated. We found that chronic T. gondii infection of BALB/c mice leads to blunted response to amphetamine or cocaine and decreased expression of Dopamine Transporter (DAT) and Vesicular Monoamine Transporter 2 (VMAT2). Deletion of AAH2 had no effects on these changes in infected mice. Both wild type and Δaah2 strains produced comparable levels of neuroinflammation. Our findings demonstrate that AAH2 is not required for T. gondii infection-produced DA-dependent neurobehavioral abnormalities.

Overexpression of Truncated Human DISC1 Induces Appearance of Hindbrain Oligodendroglia in the Forebrain During Development.

Genetic, neuroimaging, and gene expression studies suggest a role for oligodendrocyte (OLG) dysfunction in schizophrenia (SZ). Disrupted-in-schizophrenia 1 (DISC1) is a risk gene for major psychiatric disorders, including SZ. Overexpression of mutant truncated (hDISC1), but not full-length sequence of human DISC1 in forebrain influenced OLG differentiation and proliferation of glial progenitors in the developing cerebral cortex concurrently with reduction of OLG progenitor markers in the hindbrain. We examined gene and protein expression of the molecular determinants of hindbrain OLG development and their interactions with DISC1 in mutant hDISC1 mice. We found ectopic upregulation of hindbrain glial progenitor markers (early growth response 2 [Egr2] and NK2 homeobox 2 [Nkx2-2]) in the forebrain of hDISC1 (E15) embryos. DISC1 and Nkx2-2 were coexpressed and interacted in progenitor cells. Overexpression of truncated hDISC1 impaired interactions between DISC1 and Nkx2-2, which was associated with increased differentiation of OLG and upregulation of hindbrain mature OLG markers (laminin alpha-1 [LAMA1] and myelin protein zero [MPZ]) suggesting a suppressive function of endogenous DISC1 in OLG specialization of hindbrain glial progenitors during embryogenesis. Consistent with findings in hDISC1 mice, several hindbrain OLG markers (PRX, LAMA1, and MPZ) were significantly upregulated in the superior temporal cortex of persons with SZ. These findings show a significant effect of truncated hDISC1 on glial identity cells along the rostrocaudal axis and their OLG specification. Appearance of hindbrain OLG lineage cells and their premature differentiation may affect cerebrocortical organization and contribute to the pathophysiology of SZ.

DISC1 in Astrocytes Influences Adult Neurogenesis and Hippocampus-Dependent Behaviors in Mice.

The functional role of genetic variants in glia in the pathogenesis of psychiatric disorders remains poorly studied. Disrupted-In-Schizophrenia 1 (DISC1), a genetic risk factor implicated in major mental disorders, has been implicated in regulation of astrocyte functions. As both astrocytes and DISC1 influence adult neurogenesis in the dentate gyrus (DG) of the hippocampus, we hypothesized that selective expression of dominant-negative C-terminus-truncated human DISC1 (mutant DISC1) in astrocytes would affect adult hippocampal neurogenesis and hippocampus-dependent behaviors. A series of behavioral tests were performed in mice with or without expression of mutant DISC1 in astrocytes during late postnatal development. In conjunction with behavioral tests, we evaluated adult neurogenesis, including neural progenitor proliferation and dendrite development of newborn neurons in the DG. The ameliorative effects of D-serine on mutant DISC1-associated behaviors and abnormal adult neurogenesis were also examined. Expression of mutant DISC1 in astrocytes decreased neural progenitor proliferation and dendrite growth of newborn neurons, and produced elevated anxiety, attenuated social behaviors, and impaired hippocampus-dependent learning and memory. Chronic treatment with D-serine ameliorated the behavioral alterations and rescued abnormal adult neurogenesis in mutant DISC1 mice. Our findings suggest that psychiatric genetic risk factors expressed in astrocytes could affect adult hippocampal neurogenesis and contribute to aspects of psychiatric disease through abnormal production of D-serine.

Expression of mutant DISC1 in Purkinje cells increases their spontaneous activity and impairs cognitive and social behaviors in mice.

In addition to motor function, the cerebellum has been implicated in cognitive and social behaviors. Various structural and functional abnormalities of Purkinje cells (PCs) have been observed in schizophrenia and autism. As PCs express the gene Disrupted-In-Schizophrenia-1 (DISC1), and DISC1 variants have been associated with neurodevelopmental disorders, we evaluated the role of DISC1 in cerebellar physiology and associated behaviors using a mouse model of inducible and selective expression of a dominant-negative, C-terminus truncated human DISC1 (mutant DISC1) in PCs. Mutant DISC1 male mice demonstrated impaired social and novel placement recognition. No group differences were found in novelty-induced hyperactivity, elevated plus maze test, spontaneous alternation, spatial recognition in Y maze, sociability or accelerated rotarod. Expression of mutant DISC1 was associated with a decreased number of large somata PCs (volume: 3000-5000µm3) and an increased number of smaller somata PCs (volume: 750-1000µm3) without affecting the total number of PCs or the volume of the cerebellum. Compared to control mice, attached loose patch recordings of PCs in mutant DISC1 mice revealed increased spontaneous firing of PCs; and whole cell recordings showed increased amplitude and frequency of mEPSCs without significant changes in either Rinput or parallel fiber EPSC paired-pulse ratio. Our findings indicate that mutant DISC1 alters the physiology of PCs, possibly leading to abnormal recognition memory in mice.

Cell Type-Specific Effects of Mutant DISC1: A Proteomics Study.

Despite the recent progress in psychiatric genetics, very few studies have focused on genetic risk factors in glial cells that, compared to neurons, can manifest different molecular pathologies underlying psychiatric disorders. In order to address this issue, we studied the effects of mutant disrupted in schizophrenia 1 (DISC1), a genetic risk factor for schizophrenia, in cultured primary neurons and astrocytes using an unbiased mass spectrometry-based proteomic approach. We found that selective expression of mutant DISC1 in neurons affects a wide variety of proteins predominantly involved in neuronal development (e.g., SOX1) and vesicular transport (Rab proteins), whereas selective expression of mutant DISC1 in astrocytes produces changes in the levels of mitochondrial (GDPM), nuclear (TMM43) and cell adhesion (ECM2) proteins. The present study demonstrates that DISC1 variants can perturb distinct molecular pathways in a cell type-specific fashion to contribute to psychiatric disorders through heterogenic effects in diverse brain cells.

Behavioral sequelae of astrocyte dysfunction: focus on animal models of schizophrenia.

Astrocytes regulate multiple processes in the brain ranging from trophic support of developing neurons to modulation of synaptic neurotransmission and neuroinflammation in adulthood. It is, therefore, understandable that pathogenesis and pathophysiology of major psychiatric disorders involve astrocyte dysfunctions. Until recently, there has been the paucity of experimental approaches to studying the roles of astrocytes in behavioral disease. A new generation of in vivo models allows us to advance our understanding of the roles of astrocytes in psychiatric disorders. This review will evaluate the recent studies that focus on the contribution of astrocyte dysfunction to behavioral alterations pertinent to schizophrenia and will propose the possible solutions of the limitations of the existing approaches.

DISC1 signaling in cocaine addiction: Towards molecular mechanisms of co-morbidity.

Substance abuse and other psychiatric diseases may share molecular pathology. In order to test this hypothesis, we examined the role of Disrupted In Schizophrenia 1 (DISC1), a psychiatric risk factor, in cocaine self-administration (SA). Cocaine SA significantly increased expression of DISC1 in the nucleus accumbens (NAc); while knockdown of DISC1 in NAc significantly increased cocaine SA and decreased phosphorylation of GSK-3ß at Ser9 compared to scrambled shRNA. Our study provides the first mechanistic evidence of a critical role of DISC1 in drug-induced behavioral neuroadaptations and sheds more light at the shared molecular pathology of drug abuse and other major psychiatric disorders.

Molecular neuroimaging of post-injury plasticity.

Nerve injury induces long-term changes in neuronal activity in the primary somatosensory cortex (S1), which has often been implicated as the origin of sensory dysfunction. However, the cellular mechanisms underlying this phenomenon remain unclear. C-fos is an immediate early gene, which has been shown to play an instrumental role in plasticity. By developing a new platform to image real-time changes in gene expression in vivo, we investigated whether injury modulates the levels of c-fos in layer V of S1, since previous studies have suggested that these neurons are particularly susceptible to injury. The yellow fluorescent protein, ZsYellow1, under the regulation of the c-fos promoter, was expressed throughout the rat brain. A fiber-based confocal microscope that enabled deep brain imaging was utilized, and local field potentials were collected simultaneously. In the weeks following limb denervation in adult rats (n=10), sensory stimulation of the intact limb induced significant increases in c-fos gene expression in cells located in S1, both contralateral (affected, 27.6±3 cells) and ipsilateral (8.6±3 cells) to the injury, compared to controls (n=10, 13.4±3 and 1.0±1, respectively, p value<0.05). Thus, we demonstrated that injury activates cellular mechanisms that are involved in reshaping neuronal connections, and this may translate to neurorehabilitative potential.

NAP (davunetide) modifies disease progression in a mouse model of severe neurodegeneration: protection against impairments in axonal transport.

NAP (davunetide) is a novel neuroprotective compound with mechanism of action that appears to involve microtubule (MT) stabilization and repair. To evaluate, for the first time, the impact of NAP on axonal transport in vivo and to translate it to neuroprotection in a severe neurodegeneration, the SOD1-G93A mouse model for amyotrophic lateral sclerosis (ALS) was used. Manganese-enhanced magnetic resonance imaging (MRI), estimating axonal transport rates, revealed a significant reduction of the anterograde axonal transport in the ALS mice compared to healthy control mice. Acute NAP treatment normalized axonal transport rates in these ALS mice. Tau hyperphosphorylation, associated with MT dysfunction and defective axonal transport, was discovered in the brains of the ALS mice and was significantly reduced by chronic NAP treatment. Furthermore, in healthy wild type (WT) mice, NAP reversed axonal transport disruption by colchicine, suggesting drug-dependent protection against axonal transport impairment through stabilization of the neuronal MT network. Histochemical analysis showed that chronic NAP treatment significantly protected spinal cord motor neurons against ALS-like pathology. Sequential MRI measurements, correlating brain structure with ALS disease progression, revealed a significant damage to the ventral tegmental area (VTA), indicative of impairments to the dopaminergic pathways relative to healthy controls. Chronic daily NAP treatment of the SOD1-G93A mice, initiated close to disease onset, delayed degeneration of the trigeminal, facial and hypoglossal motor nuclei as was significantly apparent at days 90-100 and further protected the VTA throughout life. Importantly, protection of the VTA was significantly correlated with longevity and overall, NAP treatment significantly prolonged life span in the ALS mice.

D-NAP prophylactic treatment in the SOD mutant mouse model of amyotrophic lateral sclerosis: review of discovery and treatment of tauopathy.

Davunetide (NAP) is a leading drug candidate being tested against tauopathy. Davunetide is an eight-amino-acid peptide fragment derived by structure-activity studies from activity-dependent neuroprotective protein, activity-dependent neuroprotective protein (ADNP). ADNP is essential for brain formation. ADNP haploinsufficiency in mice results in tauopathy and cognitive deficits ameliorated by davunetide treatment. This article summarizes in brief recent reviews about NAP protection against tauopathy including the all D-amino acid analogue-D-NAP (AL-408). D-NAP was discovered to have similar neuroprotective functions to NAP in vitro. Here, D-NAP was tested as prophylactic as well as therapeutic treatment for amytrophic lateral sclerosis (ALS) in the widely used TgN(SOD1-G93A)1Gur transgenic mouse model. Results showed D-NAP-associated prophylactic protection, thus daily treatment starting from day 2 of age resulted in a prolonged life course in the D-NAP-treated mice, which was coupled to a significant decrease in tau hyperphosphorylation. These studies correlate protection against tau hyperphosphorylation and longevity in a severe model of ALS-like motor impairment and early mortality. NAP is a first-in-class drug candidate/investigation compound providing neuroprotection coupled to inhibition of tau pathology. D-NAP (AL-408) is a pipeline product.