Biology subjects

Cooper, A. H.

Publications and source records attributed to Cooper, A. H..

8 recordsLinked to original sources

bioRxiv2026

Precision cell-state silencing of injured afferents alleviates spontaneous neuropathic pain

Excessive primary afferent activity sustains neuropathic pain, but safe and effective therapeutic inhibition has proved elusive. Realising the promise of gene therapies to meet this challenge requires strategies to identify and selectively target the neuronal populations responsible. Here, we use chemo- and optogenetic approaches to demonstrate that activity in injured afferents drives spontaneous pain but is dispensable for normal sensory function, thereby creating a therapeutic opportunity. Guided by chromatin accessibility profiling, we create an injury-responsive viral vector that confers >95% specificity for injured sensory neurons. Combined with the translationally relevant chemogenetic PSAM4-GlyR, this targeting module effectively silences hyperexcitable human sensory neurons and alleviates spontaneous neuropathic pain in mice. These findings establish precision cell-state targeting of sensory neurons as a promising therapeutic strategy for chronic pain.

neuroscience↗

bioRxiv2025

Characterisation of cold-selective lamina I spinal projection neurons

Skin cooling is detected by primary afferents that express the Trpm8 channel, but how this information is conveyed to the brain remains poorly understood. We have previously identified a population of lamina I projection neurons belonging to the anterolateral system (ALS) that receive numerous contacts from Trpm8-expressing primary afferents. Here, using a semi-intact somatosensory preparation, we provide evidence that these cells correspond to the cold-selective ALS neurons identified in previous physiological studies. We also confirm the presence of synapses from Trpm8 afferents onto these cells at the ultrastructural level and with optogenetics. Based on our previous transcriptomic findings, we identify calbindin as a molecular marker, and show that this can be used to target the cold-selective ALS neurons for anterograde tracing studies. We provide evidence that they project to brain regions that have been implicated in thermosensation: the rostralmost part of the lateral parabrachial area, the caudal part of the periaqueductal grey matter, and the posterior triangular and ventral posterolateral nuclei of the thalamus. Our findings provide important insights into the organisation of neuronal circuits that underlie thermoregulation and the perception of cold stimuli applied to the skin.

neuroscience↗

bioRxiv2025

De novo expression of neuropeptide Y in sensory neurons does not contribute to peripheral neuropathic pain

Nerve damage induces a robust de novo expression of the pain-modulatory peptide neuropeptide Y (NPY) in large-diameter primary afferent neurons that innervate the dorsal horn of the spinal cord and the dorsal column nuclei. To determine whether this functions to modulate peripheral neuropathic pain, we selectively deleted the Npy gene in neurons of the dorsal root ganglion (DRG), without disruption of its expression in brain or dorsal horn neurons. We then subjected sensory neuron-specific NPY deletion mutant mice (Pirt-NPY) and their wild-type controls to either sham surgery, spared sural nerve injury (SNI) or spared tibial nerve injury (tSNI). Conditional Npy deletion did not change the severity or duration of static mechanical, dynamic mechanical, or cold allodynia in SNI or tSNI models, nor ongoing neuropathic pain as assessed with conditioned place preference to gabapentin. When injected after the resolution of tSNI-induced mechanical hypersensitivity (a latent pain sensitization model of chronic neuropathic pain), the NPY Y1 receptor-specific antagonist BIBO3304 equally reinstated mechanical hypersensitivity in Pirt-NPY mice and their wildtype controls. We conclude that nerve injury-induced upregulation of NPY in sensory neurons does not cause mechanical or cold hypersensitivity or ongoing pain, and that tonic inhibitory control of neuropathic pain by NPY in the spinal cord is mediated by release from dorsal horn interneurons rather than sensory neurons.

neuroscience↗

bioRxiv2024

The effect of laboratory diet and feeding on growth parameters in zebrafish

Despite being one of the most used laboratory species in biomedical, behavioural and physiological research, the nutritional requirements of zebrafish (Danio rerio) are poorly understood, and no standardised laboratory diet exists. Diet and feeding regimen can significantly impact the welfare of the fish and in turn experimental reproducibility. Consequently, the establishment of a standardised diet and feeding protocol for laboratory zebrafish is imperative to enhance animal welfare, guarantee research reproducibility and advance the economic and environmental sustainability of laboratory dietary practices. The aim of this systematic review was to determine the optimal feed for juvenile zebrafish growth and development. A comprehensive search was conducted in PubMed, Scopus and Google Scholar to identify relevant studies published up to August 2023 and the studies were selected based on the predefined inclusion/exclusion criteria. A total of 1065 articles were identified in the databases, of which 14 were included in this review. We conducted data extraction and risk-of-bias analysis in the included studies. Statistical comparisons for specific growth rate, weight gain (%) and length gain (%) parameters were performed to determine the optimal feed for enhanced juvenile growth. We identify an insect-based diet as optimal for juvenile growth for all three growth parameters. We also identify areas of potential heterogeneity and conclude by encouraging a standardised laboratory diet to ensure reproducible data and encourage zebrafish welfare.

developmental biology↗

bioRxiv2023

Peripheral nerve injury results in a biased loss of sensory neuron sub-populations

There is a rich literature describing loss of dorsal root ganglion (DRG) neurons following peripheral axotomy, but the vulnerability of discrete subpopulations has not yet been characterised. Furthermore, the extent and even presence of neuron loss following injury has recently been challenged. In this study, we have used a range of transgenic recombinase driver mouse lines to genetically label molecularly defined subpopulations of DRG neurons and track their survival following traumatic nerve injury. We find that spared nerve injury (SNI) leads to a marked loss of cell containing DRG-volume and a concomitant loss of small diameter DRG neurons. Neuron loss occurs unequally across subpopulations and is particularly prevalent in non-peptidergic nociceptors, marked by expression of Mrgprd. We show that this subpopulation is almost entirely lost following SNI and severely depleted (by roughly 50%) following sciatic nerve crush. Finally, we used an in vitro model of DRG neuron survival to demonstrate that non-peptidergic nociceptor loss is likely dependent on the absence of neurotrophic support. Together, these results profile the extent to which DRG neuron subpopulations can survive axotomy, with implications for our understanding of nerve injury-induced plasticity and pain.

neuroscience↗

bioRxiv2023

Deep sequencing of Phox2a nuclei reveals five classes of anterolateral system neurons

The anterolateral system (ALS) is a major ascending pathway from the spinal cord that projects to multiple brain areas and underlies the perception of pain, itch and skin temperature. Despite its importance, our understanding of this system has been hampered by the considerable functional and molecular diversity of its constituent cells. Here we use fluorescence-activated cell sorting to isolate ALS neurons belonging to the Phox2a-lineage for single-nucleus RNA sequencing. We reveal five distinct clusters of ALS neurons (ALS1-5) and document their laminar distribution in the spinal cord using in situ hybridization. We identify 3 clusters of neurons located predominantly in laminae I-III of the dorsal horn (ALS1-3) and two clusters with cell bodies located in deeper laminae (ALS4 & ALS5). Our findings reveal the transcriptional logic that underlies ALS neuronal diversity in the adult mouse and uncover the molecular identity of two previously identified classes of projection neurons. We also show that these molecular signatures can be used to target groups of ALS neurons using retrograde viral tracing. Overall, our findings provide a valuable resource for studying somatosensory biology and targeting subclasses of ALS neurons. Significance StatementThe anterolateral system (ALS) is a major ascending pathway from the spinal cord that underlies perception of pain, itch and skin temperature. It is therefore an important target for the development of new treatments for chronic pain. Our understanding of this system has been hampered by the considerable diversity of its constituent cells. Here we dissect the complex heterogeneity of these cells by using high-resolution RNA sequencing. We reveal five distinct types of ALS neurons, which are differentially distributed within the spinal cord, and probably represent functional populations. Our data provide novel insights into the molecular architecture of the ALS, and will be important for future studies to define the roles of different ALS cell types in sensory processing.

neuroscience↗

bioRxiv2023

Neuropeptide Y-expressing dorsal horn inhibitory interneurons gate spinal pain and itch signalling

Somatosensory information is processed by a complex network of interneurons in the spinal dorsal horn. It has been reported that inhibitory interneurons that express neuropeptide Y (NPY), either permanently or during development, suppress mechanical itch, with no effect on pain. Here we investigate the role of interneurons that continue to express NPY (NPY-INs) in adulthood. We find that chemogenetic activation of NPY-INs reduces behaviours associated with acute pain and pruritogen-evoked itch, whereas silencing them causes exaggerated itch responses that depend on cells expressing the gastrin-releasing peptide receptor. As predicted by our previous studies, silencing of another population of inhibitory interneurons (those expressing dynorphin) also increases itch, but to a lesser extent. Importantly, NPY- IN activation also reduces behavioural signs of inflammatory and neuropathic pain. These results demonstrate that NPY-INs gate pain and itch transmission at the spinal level, and therefore represent a potential treatment target for pathological pain and itch.

neuroscience↗

bioRxiv2022

Microphysiological vascular malformation model reveals a role of dysregulated Rac1 and mTORC1/2 in lesion formation.

Somatic activating mutations of PIK3CA are associated with the development of vascular malformations (VMs). Here, we describe a microfluidic model of PIK3CA-driven VMs consisting of human umbilical vein endothelial cells (HUVECs) expressing PIK3CA activating mutations embedded in 3D hydrogels. We observed enlarged and irregular vessel phenotypes, consistent with clinical signatures and concomitant with PI3K-driven upregulation of Rac1/PAK, MEK/ERK, and mTORC1/2 signaling. We observed differential effects between Alpelisib, a PIK3CA inhibitor, and Rapamycin, an mTORC1 inhibitor, in mitigating matrix degradation and vascular network topology. While both drugs are effective in preventing vessel enlargement, Alpelisib suppressed mTORC2-dependent AKT1 phosphorylation and MEK/ERK signaling. Rapamycin failed to reduce MEK/ERK and mTORC2 activity and resulted in vascular hyperbranching, while inhibiting PAK, MEK1/2, and mTORC1/2 signaling mitigates abnormal growth and vascular dilation. Collectively, these findings establish an in vitro platform for modeling VMs and confirm a role of dysregulated Rac1/PAK and mTORC1/2 signaling in PIK3CA-driven VMs.

bioengineering↗