Open annotations (there are currently
Altmetric provides a collated score for online attention across various platforms and media.
GPR30 in spinal cholecystokinin-positive neurons modulates neuropathic pain
https://doi.org/10.7554/eLife.102874.4
study investigates nerve-injury-induced allodynia by studying the role of a subpopulation of excitatory dorsal horn CCK+ neurons that express the estrogen receptor GPR30 and potentially modulate nociceptive sensitivity via direct inputs from primary somatosensory cortex. In this revised version, the authors addressed many of the critiques raised through added analyses that
support the notion that spinal GPR30 neurons are indeed an excitatory subpopulation of CCK+ neurons that contribute to neuropathic pain. While evidence of a direct functional corticospinal projection to CCK+/GPR30+ neurons is not fully demonstrated, this work will be of broad interest to researchers interested in the neural circuitry of pain.
https://doi.org/10.7554/eLife.102874.4.sa0
: Findings that have theoretical or practical implications beyond a single subfield
: Appropriate and validated methodology in line with current state-of-the-art
During the peer-review process the editor and reviewers write an eLife Assessment that summarises the significance of the findings reported in the article (on a scale ranging from landmark to useful) and the strength of the evidence (on a scale ranging from exceptional to inadequate).
Learn more about eLife Assessments
Neuropathic pain, a major health problem affecting 7–10% of the global population, lacks effective treatment due to its elusive mechanisms. Cholecystokinin-positive (CCK
) neurons in the spinal dorsal horn (SDH) are critical for neuropathic pain, yet the underlying molecular mechanisms remain unclear. Here, we show that the membrane estrogen receptor G-protein coupled estrogen receptor (GPER/GPR30) in spinal neurons was significantly upregulated in chronic constriction injury (CCI) mice and that inhibition of GPR30 in CCK
neurons reversed CCI-induced neuropathic pain. Furthermore, GPR30 in spinal CCK
neurons was essential for the enhancement of AMPA-mediated excitatory synaptic transmission in CCI mice. Moreover, GPR30 was expressed in spinal CCK
neurons that received direct projection from the primary sensory cortex (S1-SDH). Chemogenetic inhibition of S1-SDH post-synaptic neurons alleviated CCI-induced neuropathic pain. Conversely, chemogenetic activation of these neurons mimicked neuropathic pain symptoms, which were attenuated by spinal inhibition of GPR30. Finally, we confirmed that GPR30 in S1-SDH post-synaptic neurons was required for CCI-induced neuropathic pain. Taken together, our findings suggest that GPR30 in spinal CCK
neurons and S1-SDH post-synaptic neurons is pivotal for neuropathic pain, thereby representing a promising therapeutic target for neuropathic pain.
Neuropathic pain, a persistent and disabling condition affecting approximately 7–10% of the global population, arises from a lesion or dysfunction of the somatosensory nervous system (
). This disorder manifests as mechanical allodynia (pain triggered by innocuous stimuli) and thermal hyperalgesia (exaggerated pain responses to noxious heat) (
). However, the complex and elusive mechanisms of neuropathic pain still make it difficult to treat. Therefore, identifying precise mechanisms and discovering new therapeutic targets is urgently needed.
The spinal cord (SC) serves as a pivotal hub for processing peripheral sensory inputs and integrating descending modulatory signals. Neuropathic mechanical allodynia occurs via circuit-based transformation in this region (
). Superficial laminae of the SC primarily encode noxious stimuli, whereas deeper laminae process innocuous signals. Under neuropathic conditions, however, low-threshold mechanosensory inputs aberrantly activate nociceptive neurons in superficial laminae through disinhibition and sensitization mechanisms, driving mechanical allodynia. Excitatory interneurons, constituting ~75% of spinal dorsal horn (SDH) neurons, are central to this pathological process (
). Among these, cholecystokinin-expressing (CCK
) interneurons, enriched in SDH deep laminae, have recently been proposed as mediators of both mechanical and thermal hypersensitivity (
neurons receive direct corticospinal projections from the primary sensory cortex (S1), modulating neuropathic pain sensitivity (
); however, the molecular underpinnings of this regulation remain obscure.
Estrogen, beyond its classical nuclear receptors (ERα/ERβ), exerts non-genomic effects via the membrane receptor G protein-coupled estrogen receptor (GPR30), which is increasingly recognized as a key player in nociceptive modulation (
). Although GPR30’s role in pain modulation has been documented, its specific contribution to SDH circuitry in neuropathic pain remains unexplored.
In this study, we demonstrate that spinal GPR30 orchestrates neuropathic pain by modulating excitability of CCK
neurons and corticospinal descending facilitation. We discovered that GPR30 activation in spinal CCK
neurons was both required and sufficient for the development of neuropathic pain. Interestingly, we observed that GPR30 in spinal CCK
neurons was required for the enhancement of spontaneous excitatory post-synaptic currents (sEPSC) in CCI mice, in an AMPA-dependent manner. Importantly, we revealed that GPR30 was expressed in the spinal CCK
neurons receiving direct projections from S1 sensory cortex, and that GPR30 in S1-SDH post-synaptic neurons was critical for CCI-induced neuropathic pain. These findings establish GPR30 in spinal CCK
neurons as a compelling therapeutic target for neuropathic pain management.
To investigate the functional relevance of spinal GPR30 in neuropathic pain, we employed a chronic constriction injury (CCI) model to evaluate whether pharmacological blockade of spinal GPR30 alleviates neuropathic pain (
). Quantitative PCR (qPCR) analysis revealed a significant elevation of
(GPR30) mRNA levels in the lumbar SDH of CCI mice compared to sham (
mRNA levels in the DRG remained unchanged after CCI (
). Intrathecal application of the GPR30 antagonist, G-15, effectively attenuated CCI-induced mechanical allodynia and thermal hyperalgesia in both sexes of mice (
), whereas basal nociceptive thresholds remained unaltered in naïve mice (
Figure 1—figure supplement 1A and B
). Of note, the analgesic effects of G-15 lasted for up to 6 hours after intrathecal application in CCI mice (
). Immunochemical data demonstrated that innocuous tactile stimulation triggered pronounced c-Fos expression, a marker of neuronal activation, predominantly in GPR30
cells within the SDH of CCI mice (
). Critically, G-15 treatment substantially suppressed this c-Fos expression (
), indicating that spinal GPR30 inhibition normalizes both hypersensitivity and neuronal activation in neuropathic pain in both sexes.
Chronic constriction injury (CCI)-induced neuropathic pain and neuronal activation were reversed by spinal inhibition of GPR30.
) Schematic illustration of CCI surgery for induction of neuropathic pain (left) and diagram showing the timeline of CCI surgery, drug administration, and behavioral tests (right). (
mRNA in spinal dorsal horn (SDH) from sham and CCI mice (left, n=3 mice for each group) and
mRNA in DRG from sham and CCI mice (right, n=4 mice for each group). (
) Behavioral tests of basic nociception and 14 days after CCI or sham surgery along with intrathecal injection of GPR30 antagonist or vehicle in Von Frey tests (
) in mice of both sexes (n=6 mice for each group). (
) Immunochemical detection of c-Fos (green) and GPR30 (red). Scale bars: 100 μm. Boxed area of images is enlarged on the right. Scale bars: 10 μm. White arrows indicate double-positive cells. (G, H) Total number of c-Fos-positive neurons in the SDH per section in female mice (
) (n=3–4 mice for each group, 4–6 p