Nature Neuroscience 2017, Vol 20, p1122-1132

By Guang Yang at the Neuroscience Institute part of New York University School of Medicine

Funding by the Ralph French Charitable Foundation Trust, and the NIH

Abstract: Neuropathic pain involves long-lasting modifications of pain pathways that result in abnormal cortical activity. How cortical circuits are altered and contribute to the intense sensation associated with allodynia is unclear. Here we report a persistent elevation of layer V pyramidal neuron activity in the somatosensory cortex of a mouse model of neuropathic pain. This enhanced pyramidal neuron activity was caused in part by increases of synaptic activity and NMDA-receptor-dependent calcium spikes in apical tuft dendrites. Furthermore, local inhibitory interneuron networks shifted their activity in favor of pyramidal neuron hyperactivity somatostatin-expressing and parvalbumin-expressing inhibitory neurons reduced their activity, whereas vasoactive intestinal polypeptide–expressing interneurons increased their activity. Pharmacogenetic activation of somatostatin-expressing cells reduced pyramidal neuron hyperactivity and reversed mechanical allodynia. These findings reveal cortical circuit changes that arise during the development of neuropathic pain and identify the activation of specific cortical interneurons as therapeutic targets for chronic pain treatment.

My takeaways:

1. These researchers conducted deep mechanistic studies into how chronic pain is occurring in a spared nerve injury mouse model. They then demonstrated using numerous interesting techniques how the nerves adapted to this damage. Finally, they identify potential nerve targets to reduce or even eliminate chronic pain. This could be life-changing for individuals with epilepsy, schizophrenia, general pain, and depression.

2. The biggest roadblocks ahead will not be identifying a small molecule inhibitor to block this chronic pain, but proving efficacy on in larger animal models (and humans) quantitatively.