Ageing brains attend a symphony with asynchronous transmitter release

Neurotransmitter release progressively desynchronizes in induced human neurons during synapse maturation and aging

Rapid release of neurotransmitters in synchrony with action potentials is considered a key hardwired property of synapses. Here, in glutamatergic synapses formed between induced human neurons, we show that action potential-dependent neurotransmitter release becomes progressively desynchronized as synapses mature and age. In this solely excitatory network, the emergence of NMDAR-mediated transmission elicits endoplasmic reticulum (ER) stress leading to downregulation of key presynaptic molecules, synaptotagmin-1 and cysteine string protein α, that synchronize neurotransmitter release. The emergence of asynchronous release with neuronal maturity and subsequent aging is maintained by the high-affinity Ca2+ sensor synaptotagmin-7 and suppressed by the introduction of GABAergic transmission into the network, inhibition of NMDARs, and ER stress. These results suggest that long-term disruption of excitation-inhibition balance affects the synchrony of excitatory neurotransmission in human synapses.

Effects of Naodesheng tablets on amyloid beta-induced dysfunction: A traditional Chinese herbal formula with novel therapeutic potential in Alzheimer's disease revealed by systems pharmacology

Naodesheng (NDS) tablets have been widely used to treat ischemic stroke clinically. NDS relieves neurological function impairment and improve learning and memory in rats with focal cerebral ischemia, suggesting that NDS has potential for Alzheimer's disease (AD) treatment. However, there are no studies about its effective material basis and possible mechanisms. In this study, a systems pharmacology method was applied to reveal the potential molecular mechanism of NDS in the treatment of AD. First, we obtained 360 NDS candidate constituents through ADMET filter analysis. Then, 115 AD-related targets were uncovered by pharmacophore model prediction via mapping the predicted targets against AD-related proteins. In addition, compound-target and target-function networks were established to suggest potential synergistic effects among the candidate constituents. Furthermore, potential targets regulated by NDS were integrated into AD-related pathways to demonstrate the therapeutic mechanism of NDS in AD treatment. Subsequently, a validation experiment proved the therapeutic effect of NDS on cognitive dysfunction in rats with intracerebroventricular injection of Aβ. We found that administration of NDS tablets regulates β-amyloid metabolism, improves synaptic plasticity, inhibits neuroinflammation and improves learning and memory function. In conclusion, this is the first study to provide a comprehensive systems pharmacology approach to elucidate the potential therapeutic mechanism of NDS tablets for AD treatment. We suggest that the protective effects of NDS in neurodegenerative conditions could be partly attributed to its role in improving synaptic plasticity and inhibiting neuroinflammation via NF-κB signaling pathway inhibition and cAMP/PKA/CREB signaling pathway activation.