Sodium acamprosate and calcium exert additive effects on nucleus accumbens dopamine in the rat.

Acamprosate (Campral® - calcium-bis[N-acetylhomotaurinate]) is one of few available pharmacotherapies for individuals suffering from alcohol use disorder. Previously, we suggested that acamprosate reduces ethanol intake by increasing dopamine in the nucleus accumbens (nAc), thereby partly substituting for alcohol's dopamine releasing effect. An experimental study suggested the calcium moiety of acamprosate to be the active component of the drug and to mediate the relapse preventing effect. The aim of the present study was to, by means of reversed in vivo microdialysis, elucidate if the dopamine elevating properties of acamprosate are mediated by N-acetylhomotaurine or by the calcium moiety. Male rats were equipped with a microdialysis probe in the nAc and received acute local treatment with regular acamprosate (CaAcamp 0.5 mM), calcium chloride (CaCl2 0.5 mM), sodium acamprosate (NaAcamp 0.5-1 mM), the glycine receptor (GlyR) antagonist strychnine (Stry 20 µM), or vehicle. In all experiments, extracellular levels of dopamine and taurine were examined. We found that local perfusion with both CaAcamp and CaCl2 increased dopamine levels in a GlyR-dependent manner. NaAcamp did not influence dopamine levels, but concomitant administration with CaCl2 resulted in an additive dopamine output compared to the drugs administrated alone. We also found CaAcamp and the combination of CaCl2 and NaAcamp to increase accumbal taurine levels, suggesting that CaAcamp may act indirectly on GlyRs via taurine release. The present results indicate that both N-acetylhomotaurine and the calcium moiety of acamprosate have dopamine elevating properties within the nAc and that, in this respect, these substances are beneficial in combination.

The potential of 1H-MRS in CNS drug development.

RATIONALE: Proton magnetic resonance spectroscopy (1H-MRS) is a cross-species neuroimaging technique that can measure concentrations of several brain metabolites, including glutamate and GABA. This non-invasive method has promise in developing centrally acting drugs, as it can be performed repeatedly within-subjects and be used to translate findings from the preclinical to clinical laboratory using the same imaging biomarker. OBJECTIVES: This review focuses on the utility of single-voxel 1H-MRS in developing novel glutamatergic or GABAergic drugs for the treatment of psychiatric disorders and includes research performed in rodent models, healthy volunteers and patient cohorts. RESULTS: Overall, these studies indicate that 1H-MRS is able to detect the predicted pharmacological effects of glutamatergic or GABAergic drugs on voxel glutamate or GABA concentrations, although there is a shortage of studies examining dose-related effects. Clinical studies have applied 1H-MRS to better understand drug therapeutic mechanisms, including the glutamatergic effects of ketamine in depression and of acamprosate in alcohol dependence. There is an emerging interest in identifying patient subgroups with 'high' or 'low' brain regional 1H-MRS glutamate levels for more targeted drug development, which may require ancillary biomarkers to improve the accuracy of subgroup discrimination. CONCLUSIONS: Considerations for future research include the sensitivity of single-voxel 1H-MRS in detecting drug effects, inter-site measurement reliability and the interpretation of drug-induced changes in 1H-MRS metabolites relative to the known pharmacological molecular mechanisms. On-going technological development, in single-voxel 1H-MRS and in related complementary techniques, will further support applications within CNS drug discovery.

TSPAN5 influences serotonin and kynurenine: pharmacogenomic mechanisms related to alcohol use disorder and acamprosate treatment response.

We previously reported that SNPs near TSPAN5 were associated with plasma serotonin (5-HT) concentrations which were themselves associated with selective serotonin reuptake inhibitor treatment outcomes in patients with major depressive disorder (MDD). TSPAN5 SNPs were also associated with alcohol consumption and alcohol use disorder (AUD) risk. The present study was designed to explore the biological function of TSPAN5 with a focus on 5-HT and kynurenine concentrations in the tryptophan pathway. Ethanol treatment resulted in decreased 5-HT concentrations in human induced pluripotent stem cell (iPSC)-derived neuron culture media, and the downregulation of gene expression of TSPAN5, DDC, MAOA, MAOB, TPH1, and TPH2 in those cells. Strikingly, similar observations were made when the cells were treated with acamprosate-an FDA approved drug for AUD therapy. These results were replicated in iPSC-derived astrocytes. Furthermore, TSPAN5 interacted physically with proteins related to clathrin and other vesicle-related proteins, raising the possibility that TSPAN5 might play a role in vesicular function in addition to regulating expression of genes associated with 5-HT biosynthesis and metabolism. Downregulation of TSPAN5 expression by ethanol or acamprosate treatment was also associated with decreased concentrations of kynurenine, a major metabolite of tryptophan that plays a role in neuroinflammation. Knockdown of TSPAN5 also influenced the expression of genes associated with interferon signaling pathways. Finally, we determined that TSPAN5 SNPs were associated with acamprosate treatment outcomes in AUD patients. In conclusion, TSPAN5 can modulate the concentrations of 5-HT and kynurenine. Our data also highlight a potentially novel pharmacogenomic mechanism related to response to acamprosate.

NeuroHeal Improves Muscle Regeneration after Injury.

Musculoskeletal injuries represent a challenging medical problem. Although the skeletal muscle is able to regenerate and recover after injury, the process engaged with conservative therapy can be inefficient, leading to a high re-injury rate. In addition, the formation of scar tissue implies an alteration of mechanical properties in muscle. There is still a need for new treatments of the injured muscle. NeuroHeal may be one option. Published studies demonstrated that it reduces muscle atrophy due to denervation and disuse. The main objective of the present work was to assess the potential of NeuroHeal to improve muscle regeneration after traumatic injury. Secondary objectives included characterizing the effect of NeuroHeal treatment on satellite cell biology. We used a rat model of sport-induced injury in the gastrocnemius and analyzed the effects of NeuroHeal on functional recovery by means of electrophysiology and tetanic force analysis. These studies were accompanied by immunohistochemistry of the injured muscle to analyze fibrosis, satellite cell state, and fiber type. In addition, we used an in vitro model to determine the effect of NeuroHeal on myoblast biology and partially decipher its mechanism of action. The results showed that NeuroHeal treatment advanced muscle fiber recovery after injury in a preclinical model of muscle injury, and significantly reduced the formation of scar tissue. In vitro, we observed that NeuroHeal accelerated the formation of myotubes. The results pave the way for novel therapeutic avenues for muscle/tendinous disorders.

NeuroHeal Treatment Alleviates Neuropathic Pain and Enhances Sensory Axon Regeneration.

Peripheral nerve injury (PNI) leads to the loss of motor, sensory, and autonomic functions, and often triggers neuropathic pain. During the last years, many efforts have focused on finding new therapies to increase axonal regeneration or to alleviate painful conditions. Still only a few of them have targeted both phenomena. Incipient or aberrant sensory axon regeneration is related to abnormal unpleasant sensations, such as hyperalgesia or allodynia. We recently have discovered NeuroHeal, a combination of two repurposed drugs; Acamprosate and Ribavirin. NeuroHeal is a neuroprotective agent that also enhances motor axon regeneration after PNI. In this work, we investigated its effect on sensory fiber regeneration and PNI-induced painful sensations in a rat model of spare nerve injury and nerve crush. The follow up of the animals showed that NeuroHeal treatment reduced the signs of neuropathic pain in both models. Besides, the treatment favored sensory axon regeneration, as observed in dorsal root ganglion explants. Mechanistically, the effects observed in vivo may improve the resolution of cell-protective autophagy. Additionally, NeuroHeal treatment modulated the P2X4-BDNF-KCC2 axis, which is an essential driver of neuropathic pain. These data open a new therapeutic avenue based on autophagic modulation to foster endogenous regenerative mechanisms and reduce the appearance of neuropathic pain in PNI.

Novel neuroprotective therapy with NeuroHeal by autophagy induction for damaged neonatal motoneurons.

Rationale: Protective mechanisms allow healthy neurons to cope with diverse stresses. Excessive damage as well as aging can lead to defective functioning of these mechanisms. We recently designed NeuroHeal using artificial intelligence with the goal of bolstering endogenous neuroprotective mechanisms. Understanding the key nodes involved in neuroprotection will allow us to identify even more effective strategies for treatment of neurodegenerative diseases. Methods: We used a model of peripheral nerve axotomy in rat pups, that induces retrograde apoptotic death of motoneurons. Nourishing mothers received treatment with vehicle, NeuroHeal or NeuroHeal plus nicotinamide, an inhibitor of sirtuins, and analysis of the pups were performed by immunohistochemistry, electron microscopy, and immunoblotting. In vitro, the post-translational status of proteins of interest was detailed using organotypic spinal cord cultures and genetic modifications in cell lines to unravel the neuroprotective mechanisms involved. Results: We found that the concomitant activation of the NAD+-dependent deacetylase SIRT1 and the PI3K/AKT signaling pathway converge to increase the presence of deacetylated and phosphorylated FOXO3a, a transcription factor, in the nucleus. This favors the activation of autophagy, a pro-survival process, and prevents pro-apoptotic PARP1/2 cleavage. Major conclusion: NeuroHeal is a neuroprotective agent for neonatal motoneurons that fine-tunes autophagy on by converging SIRT1/AKT/FOXO3a axis. NeuroHeal is a combo of repurposed drugs that allow its readiness for prospective pediatric use.

Alcohol dependence treating agent, acamprosate, prevents traumatic brain injury-induced neuron death through vesicular zinc depletion.

Acamprosate, also known as N-acetyl homotaurine, is an N-methyl-d-aspartate receptor antagonist that is used for treating alcohol dependence. Although the exact mechanism of acamprosate has not been clearly established, it appears to work by promoting a balance between the excitatory and inhibitory neurotransmitters, glutamate, and gamma-aminobutyric acid, respectively. Several studies have demonstrated that acamprosate provides neuroprotection against ischemia-induced brain injury. However, no studies have been performed evaluating the effect of acamprosate on traumatic brain injury (TBI). In the present study, we sought to evaluate the therapeutic potential of acamprosate to protect against neuronal death following TBI. Rats were given oral acamprosate (200 mg/kg/d for 2weeks) and then subjected to a controlled cortical impact injury localized over the parietal cortex. Histologic analysis was performed at 3hours, 24hours, and 7days after TBI. We found that acamprosate treatment reduced the concentration of vesicular glutamate and zinc in the hippocampus. Consequently, this reduced vesicular glutamate and zinc level resulted in a reduction of reactive oxygen species production after TBI. When evaluated 24hours after TBI, acamprosate administration reduced the number of degenerating neurons, zinc accumulation, blood-brain barrier disruption, neutrophil infiltration, and dendritic loss. Acamprosate also reduced glial activation and neuronal loss at 7days after TBI. In addition, acamprosate rescued TBI-induced neurologic and cognitive dysfunction. The present study demonstrates that acamprosate attenuates TBI-induced brain damage by depletion of vesicular glutamate and zinc levels. Therefore, this study suggests that acamprosate may have high therapeutic potential for prevention of TBI-induced neuronal death.

Acamprosate's ethanol intake-reducing effect is associated with its ability to increase dopamine.

Previous studies indicate that the anti-craving substance acamprosate modulates nucleus accumbens (nAc) dopamine levels via a dopamine-controlling nAc-VTA-nAc neurocircuitry. It was demonstrated that glycine receptors in the nAc are involved both in the dopamine-elevating effect and the ethanol intake-reducing effect of the drug. Here we wanted to explore the interaction of ethanol and acamprosate on nAc dopamine and investigate whether dopaminergic transmission may be related to the ethanol intake-reducing effects. In three separate studies we investigated nAc extracellular dopamine levels by means of in vivo microdialysis after administration of acamprosate and ethanol in 1) naïve rats, 2) rats pre-treated with acamprosate for two days or 3) ethanol medium- and high-preferring rats receiving ten days of acamprosate pre-treatment. In the first two studies, acamprosate elevated dopamine and simultaneously prevented ethanol from further increasing dopamine output. In the third study, long-term acamprosate pre-treatment produced a loss of the ethanol intake-reducing as well as the dopamine-elevating effects of acamprosate, and the dopamine elevating property of ethanol was restored. We suggest that acamprosate may partly substitute for the dopamine-elevating effect of ethanol but once tolerance develops to this effect, the ability to decrease ethanol intake is lost.

Generation of silent synapses in dentate gyrus correlates with development of alcohol addiction.

The brain circuits and synaptic processes that underlie alcohol addiction are currently the subject of intensive research. Here we focus on hippocampal circuitry and show that chemogenetic inhibition of dentate gyrus (DG) during presentation of alcohol-associated cues has long-lasting effects on mice behavior. DG inhibition enhances alcohol seeking and drinking, suggesting that DG regulates addiction-related behaviors. To test this hypothesis, we perform whole-cell patch-clamp recordings from the granule cells of DG and look for electrophysiological correlates of alcohol addiction. We observe that presentation of alcohol-associated cue light that induces relapse to alcohol-seeking results in generation of silent synapses, that lack functional AMPA receptors. Furthermore, using human criteria of addiction, we differentiate mice controlling their alcohol consumption from those that undergo transition to addiction to discover that the levels of silent synapses induced by alcohol cues are specifically increased in the addicted mice. As the total level of dendritic spines that harbor synapses is constant at this time point, our data indicate that synapses of perforant path to DG are weakened during cue relapse. Finally we demonstrate that, acamprosate, a drug that limits alcohol drinking and seeking in addicts, prevents generation of silent synapses in DG upon presentation of alcohol-associated cues. Altogether, our data suggest that weakening of DG synapses upon cue relapse contributes to persistent alcohol addiction-related behaviors.

SIRT1 activation with neuroheal is neuroprotective but SIRT2 inhibition with AK7 is detrimental for disconnected motoneurons.

Sirtuin 1 (SIRT1) activity is neuroprotective, and we have recently demonstrated its role in the retrograde degenerative process in motoneurons (MNs) in the spinal cord of rats after peripheral nerve root avulsion (RA) injury. SIRT2 has been suggested to exert effects opposite those of SIRT1; however, its roles in neurodegeneration and neuron response after nerve injury remain unclear. Here we compared the neuroprotective potentials of SIRT1 activation and SIRT2 inhibition in a mouse model of hypoglossal nerve axotomy. This injury induced a reduction of around half MN population within the hypoglossal nucleus by a non-apoptotic neurodegenerative process triggered by endoplasmic reticulum (ER) stress that resulted in activation of the unfolded protein response mediated by IRE1α and XBP1 by 21 days post injury. Both SIRT1 activation with NeuroHeal and SIRT2 inhibition with AK7 protected NSC-34 motor neuron-like cells against ER stress in vitro. In agreement with the in vitro results, NeuroHeal treatment or SIRT1 overexpression was neuroprotective of axotomized hypoglossal MNs in a transgenic mouse model. In contrast, AK7 treatment or SIRT2 genetic depletion in mice inhibited damaged MN survival. To resolve the in vitro/in vivo discrepancies, we used an organotypic spinal cord culture system that preserves glial cells. In this system, AK7 treatment of ER-stressed organotypic cultures was detrimental for MNs and increased microglial nuclear factor-κB and the consequent transcription of cytotoxic pro-inflammatory factors similarly. The results highlight the importance of glial cells in determining the neuroprotective impact of any treatment.

Calcium chloride mimics the effects of acamprosate on cognitive deficits in chronic alcohol-exposed mice.

RATIONALE: Acamprosate (calcium-bis N-acetylhomotaurinate) is the leading medication approved for the maintenance of abstinence, shown to reduce craving and relapse in animal models and human alcoholics. Acamprosate can improve executive functions that are impaired by chronic intermittent ethanol (CIE) exposure. Recent work has suggested that acamprosate's effects on relapse prevention are due to its calcium component, which raises the question whether its pro-cognitive effects are similarly mediated by calcium. OBJECTIVES: This study examined the effects of acamprosate on alcohol-induced behavioral deficits and compared them with the effects of the sodium salt version of N-acetylhomotaurinate or calcium chloride, respectively. METHODS: We exposed mice to alcohol via three cycles of CIE and measured changes in alcohol consumption in a limited-access paradigm. We then compared the effects of acamprosate and calcium chloride (applied subchronically for 3 days during withdrawal) in a battery of cognitive tasks that have been shown to be affected by chronic alcohol exposure. RESULTS: CIE-treated animals showed deficits in attentional set-shifting and deficits in novel object recognition. Alcohol-treated animals showed no impairments in social novelty detection and interaction, or delayed spontaneous alternation. Both acamprosate and calcium chloride ameliorated alcohol-induced cognitive deficits to comparable extents. In contrast, the sodium salt version of N-acetylhomotaurinate did not reverse the cognitive deficits. CONCLUSIONS: These results add evidence to the notion that acamprosate produces its anti-relapse effects through its calcium moiety. Our results also suggest that improved regulation of drug intake by acamprosate after withdrawal might at least in part be related to improved cognitive function.

Boosted Regeneration and Reduced Denervated Muscle Atrophy by NeuroHeal in a Pre-clinical Model of Lumbar Root Avulsion with Delayed Reimplantation.

The "gold standard" treatment of patients with spinal root injuries consists of delayed surgical reconnection of nerves. The sooner, the better, but problems such as injury-induced motor neuronal death and muscle atrophy due to long-term denervation mean that normal movement is not restored. Herein we describe a preclinical model of root avulsion with delayed reimplantation of lumbar roots that was used to establish a new adjuvant pharmacological treatment. Chronic treatment (up to 6 months) with NeuroHeal, a new combination drug therapy identified using a systems biology approach, exerted long-lasting neuroprotection, reduced gliosis and matrix proteoglycan content, accelerated nerve regeneration by activating the AKT pathway, promoted the formation of functional neuromuscular junctions, and reduced denervation-induced muscular atrophy. Thus, NeuroHeal is a promising treatment for spinal nerve root injuries and axonal regeneration after trauma.