Intranasal neuropeptide Y1 receptor antagonism improves motor deficits in symptomatic SOD1 ALS mice.

OBJECTIVE: Neuropeptide Y (NPY) is a 36 amino acid peptide widely considered to provide neuroprotection in a range of neurodegenerative diseases. In the fatal motor neuron disease amyotrophic lateral sclerosis (ALS), recent evidence supports a link between NPY and ALS disease processes. The goal of this study was to determine the therapeutic potential and role of NPY in ALS, harnessing the brain-targeted intranasal delivery of the peptide, previously utilised to correct motor and cognitive phenotypes in other neurological conditions. METHODS: To confirm the association with clinical disease characteristics, NPY expression was quantified in post-mortem motor cortex tissue of ALS patients and age-matched controls. The effect of NPY on ALS cortical pathophysiology was investigated using slice electrophysiology and multi-electrode array recordings of SOD1G93A cortical cultures in vitro. The impact of NPY on ALS disease trajectory was investigated by treating SOD1G93A mice intranasally with NPY and selective NPY receptor agonists and antagonists from pre-symptomatic and symptomatic phases of disease. RESULTS: In the human post-mortem ALS motor cortex, we observe a significant increase in NPY expression, which is not present in the somatosensory cortex. In vitro, we demonstrate that NPY can ameliorate ALS hyperexcitability, while brain-targeted nasal delivery of NPY and a selective NPY Y1 receptor antagonist modified survival and motor deficits specifically within the symptomatic phase of the disease in the ALS SOD1G93A mouse. INTERPRETATION: Taken together, these findings highlight the capacity for non-invasive brain-targeted interventions in ALS and support antagonism of NPY Y1Rs as a novel strategy to improve ALS motor function.

The influence of metallothionein treatment and treadmill running exercise on disease onset and survival in SOD1G93A amyotrophic lateral sclerosis mice.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease, characterised by the degeneration of motor neurons innervating skeletal muscle. The mechanisms underlying neurodegeneration in ALS are not yet fully elucidated, and with current therapeutics only able to extend lifespan by a matter of months there is a clear need for novel therapies to increase lifespan and patient quality of life. Here, we evaluated whether moderate-intensity treadmill exercise and/or treatment with metallothionein-2 (MT2), a neuroprotective protein, could improve survival, behavioural or neuropathological outcomes in SOD1G93A familial ALS mice. Six-week-old female SOD1G93A mice were allocated to one of four treatment groups: MT2 injection, i.m.; moderate treadmill exercise; neither MT2 nor exercise; or both MT2 and exercise. MT2-treated mice survived around 3% longer than vehicle-treated mice, with this mild effect reaching statistical significance in Cox proportional hazards analysis once adjusted for potential confounders. Mixed model body weight trajectories over time indicated that MT2-treated mice, with or without exercise, reached maximum body weight at a later age, suggesting a delay in disease onset of around 4% compared to saline-treated mice. Exercise alone did not significantly increase survival or delay disease onset, and neither exercise nor MT2 substantially ameliorated gait abnormalities or muscle strength loss. We conclude that neither exercise nor MT2 treatment was detrimental in female SOD1G93A mice, and further study could determine whether the mild effect of peripheral MT2 administration on disease onset and survival could be improved via direct administration of MT2 to the central nervous system.

Amyotrophic lateral sclerosis mutant TDP-43 may cause synaptic dysfunction through altered dendritic spine function.

Altered cortical excitability and synapse dysfunction are early pathogenic events in amyotrophic lateral sclerosis (ALS) patients and animal models. Recent studies propose an important role for TAR DNA-binding protein 43 (TDP-43), the mislocalization and aggregation of which are key pathological features of ALS. However, the relationship between ALS-linked TDP-43 mutations, excitability and synaptic function is not fully understood. Here, we investigate the role of ALS-linked mutant TDP-43 in synapse formation by examining the morphological, immunocytochemical and excitability profile of transgenic mouse primary cortical pyramidal neurons that over-express human TDP-43A315T In TDP-43A315T cortical neurons, dendritic spine density was significantly reduced compared to wild-type controls. TDP-43A315T over-expression increased the total levels of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropinionic acid (AMPA) glutamate receptor subunit GluR1, yet the localization of GluR1 to the dendritic spine was reduced. These postsynaptic changes were coupled with a decrease in the amount of the presynaptic marker synaptophysin that colocalized with dendritic spines. Interestingly, action potential generation was reduced in TDP-43A315T pyramidal neurons. This work reveals a crucial effect of the over-expression mutation TDP-43A315T on the formation of synaptic structures and the recruitment of GluR1 to the synaptic membrane. This pathogenic effect may be mediated by cytoplasmic mislocalization of TDP-43A315T Loss of synaptic GluR1, and reduced excitability within pyramidal neurons, implicates hypoexcitability and attenuated synaptic function in the pathogenic decline of neuronal function in TDP-43-associated ALS. Further studies into the mechanisms underlying AMPA receptor-mediated excitability changes within the ALS cortical circuitry may yield novel therapeutic targets for treatment of this devastating disease.