I am a
Home I AM A Search Login

Papers of the Week

Papers: 21 Dec 2019 - 27 Dec 2019

Animal Studies


2020 Jul

J Comp Neurol



Ablation of spinal cord estrogen receptor α-expressing interneurons reduces chemically-induced modalities of pain and itch.


Tran M, Braz J M, Hamel K, Kuhn J, Todd AJ, Basbaum AI
J Comp Neurol. 2020 Jul; 528(10):1629-1643.
PMID: 31872868.


Estrogens are presumed to underlie, at least in part, the greater pain sensitivity and chronic pain prevalence that women experience compared to men. Although previous studies revealed populations of estrogen receptor-expressing neurons in primary afferents and in superficial dorsal horn neurons, there is little to no information as to the contribution of these neurons to the generation of acute and chronic pain. Here we molecularly characterized neurons in the mouse superficial spinal cord dorsal horn that express estrogen receptor α (ERα) and explored the behavioral consequences of their ablation. We found that spinal ERα-positive neurons are largely excitatory interneurons and many co-express substance P, a marker for a discrete subset of nociceptive, excitatory interneurons. After viral, caspase-mediated ablation of spinal ERα-expressing cells, we observed a significant decrease in the first phase of the formalin test, but in male mice only. Decreased nocifensive behavior was also observed in the second phase but only after combining results from male and female mice. ERα-expressing neuron-ablation also reduced pruritogen-induced scratching in both male and female mice. There were no ablation-related changes in mechanical or heat withdrawal thresholds or in capsaicin-induced nocifensive behavior. In chronic pain models, we found no change in Complete Freund's adjuvant-induced thermal or mechanical hypersensitivity, or in partial sciatic nerve injury-induced mechanical allodynia. We conclude that ERα labels a subpopulation of excitatory interneurons that are specifically involved in chemically-evoked persistent pain and pruritogen-induced itch. This article is protected by copyright. All rights reserved.