Biology subjects

Allen, H. N.

Publications and source records attributed to Allen, H. N..

8 recordsLinked to original sources

bioRxiv2025

Amygdalar Calcitonin Gene-Related Peptide Driven Effects of Cold Sensitivity Induced by Peripheral Neuropathy in Mice

The central nucleus of the amygdala (CeA) is a critical regulator of nociception, and its role in pain modulation depends on factors such as hemispheric location, neuropeptide release, and experimental model. Calcitonin gene-related peptide (CGRP) is a potent neuropeptide modulator within the CeA. Previous research has demonstrated its CeA nociceptive role in migraine, visceral, arthritic, and inflammatory pain murine models. The contribution of CeA CGRP to neuropathic pain is unclear. This study examined the effects of CGRP and its receptor antagonist, CGRP 8-37, in the CeA on mechanical and cold sensitivity in two mouse models of neuropathic pain: chemotherapy-induced peripheral neuropathy (CIPN) mediated by paclitaxel (PTX) and injury-induced neuropathy through the spared nerve injury (SNI) model. Mechanical and cold sensitivity were measured using the hindpaw von Frey and topical acetone drop assays, respectively. Neither CGRP nor CGRP 8-37 in the CeA had any significant effect on mechanical sensitivity in either neuropathic pain model. In the SNI-treated mice, CGRP infusion into either the left or right CeA reduced cold sensitivity in the left and right SNI-treated hindpaw, while CGRP 8-37 infusion into the left or right CeA increased cold sensitivity in the right SNI-treated hindpaw only. In PTX-treated mice, CGRP infusion into the left or right CeA decreased cold sensitivity of the contralateral paw only. These results suggest that CGRP in the CeA influences pain modulation in a complex manner that depends not only on the hemisphere and injury site, but also on the underlying cause of the neuropathic condition. PERSPECTIVEThis article presents the anti-nociceptive properties of calcitonin gene-related peptide (CGRP) signaling within the central nucleus of the amygdala during neuropathic pain-like conditions in mice. This dataset can serve to guide novel drug development for treating chronic neuropathic pain conditions. HIGHLIGHTSO_LILateralization of the central nucleus of the amygdala (CeA) is pain-model dependent C_LIO_LICGRP signaling within the CeA is correlated with decreased cold sensitivity C_LIO_LIDifferent neuropathic etiologies yield differences in CGRP responsiveness C_LI

neuroscience↗

bioRxiv2025

Parabrachial bombesin receptor subtype 3 neurons facilitate heat pain in persistent inflammation

The parabrachial nucleus (PBN) is a critical hub for pain processing that acts as a switchboard for nociceptive signals, relaying sensory information to forebrain regions that integrate the sensory and affective dimensions of pain. Although the PBN is well established as a key regulator of pain, the remarkable heterogeneity of its neuronal populations has hindered efforts to identify specific cell types responsible for distinct aspects of pain processing. Here, we identify bombesin receptor subtype 3 (Brs3)-expressing neurons as a distinct glutamatergic PBN subpopulation involved in heat hypersensitivity associated with persistent pain. Using Fos expression analysis and in vivo calcium imaging, we demonstrate that Brs3 neurons exhibit heightened activity in response to heat stimulation following an inflammatory insult or neuropathic injury. Inhibition of Brs3 neurons effectively reduces heat, but not mechanical, hypersensitivity induced by both inflammatory and neuropathic pain, suggesting a specific role in processing heat hypersensitivity. Ablation of parabrachial Brs3 neurons prior to induction of pain also selectively prevents the development of heat hypersensitivity induced by persistent inflammation in mice. Brs3-expressing neurons encompass multiple previously identified pain-related PBN subpopulations, including those expressing the mu opioid receptor (Oprm1), tachykinin 1 receptor (Tacr1), and neuropeptide Y Y1 receptor (Npy1r), positioning Brs3 as a potential unifying marker of heat hypersensitivity circuits. These findings provide new insight into the organization of pain-processing networks in the PBN and highlight Brs3 neurons as a crucial population for heat pain.

neuroscience↗

bioRxiv2024

A synthetic potassium channel reduces oxidative stress 1 via cellular adaptronics

Aerobic metabolism is crucial for human life but reactive oxygen species (ROS) byproducts cause cellular toxicity. Although antioxidant defenses usually maintain ROS levels within a safe range, ROS production can exceed the buffering capacity of cells, causing oxidative stress and disease. Inspired by the principle of adaptronics, we created a synthetic potassium channel that senses cellular ROS levels and mitigates oxidative stress by modulating membrane potential. Engineered from TASK1 channel, ROSTASK1 is sensitive to supraphysiological ROS levels, imposing restorative membrane potential changes on cells or organelles under oxidative stress. We also engineered a blue-light sensitive ROSTASK1 to achieve optogenetic control. In proof-of-concept experiments, mitochondrially-delivered ROSTASK1 rescued ROS overproduction in myoblasts from a Leigh syndrome patient and ROSTASK1 abolished chronic pain-like behavior in mouse models of inflammation and nerve injury. Thus, by functioning as both a sensor and modulator of ROS levels, ROSTASK1 provides a self-healing system during oxidative stress.

biophysics↗

bioRxiv2024

Uncoupling the CRMP2-CaV2.2 interaction reduces pain-like behavior in a preclinical osteoarthritis model

Osteoarthritis (OA) represents a significant pain challenge globally, as current treatments are limited and come with substantial and adverse side effects. Voltage-gated calcium channels have proved to be pharmacologically effective targets, with multiple FDA-approved CaV2.2 modulators available for the treatment of pain. Although effective, drugs targeting CaV2.2 are complicated by the same obstacles facing other pain therapeutics-invasive routes of administration, narrow therapeutic windows, side effects, and addiction potential. We have identified a key regulator of CaV2.2 channels, collapsing response mediator protein 2 (CRMP2), that allows us to indirectly regulate CaV2.2 expression and function. We developed a peptidomimetic modulator of CRMP2, CBD3063, that effectively reverses neuropathic and inflammatory pain without negative side effects by reducing membrane expression of CaV2.2. Using a rodent model of OA, we demonstrate the intraperitoneal administration of CBD3063 alleviates both evoked and non-evoked behavioral hallmarks of OA pain. Further, we reveal that CBD3063 reduces OA-induced increased neural activity in the parabrachial nucleus, a key supraspinal site modulating the pain experience. Together, these studies suggest CBD3063 is an effective analgesic for OA pain.

neuroscience↗

bioRxiv2024

A parabrachial hub for the prioritization of survival behavior

Long-term sustained pain in the absence of acute physical injury is a prominent feature of chronic pain conditions. While neurons responding to noxious stimuli have been identified, understanding the signals that persist without ongoing painful stimuli remains a challenge. Using an ethological approach based on the prioritization of adaptive survival behaviors, we determined that neuropeptide Y (NPY) signaling from multiple sources converges on parabrachial neurons expressing the NPY Y1 receptor to reduce sustained pain responses. Neural activity recordings and computational modeling demonstrate that activity in Y1R parabrachial neurons is elevated following injury, predicts functional coping behavior, and is inhibited by competing survival needs. Taken together, our findings suggest that parabrachial Y1 receptor-expressing neurons are a critical hub for endogenous analgesic pathways that suppress sustained pain states.

neuroscience↗

bioRxiv2023

Intranasal CRMP2-Ubc9 Inhibitor Regulates NaV1.7 to Alleviate Trigeminal Neuropathic Pain

Dysregulation of voltage-gated sodium NaV1.7 channels in sensory neurons contributes to chronic pain conditions, including trigeminal neuropathic pain. We previously reported that chronic pain results in part from increased SUMOylation of collapsin response mediator protein 2 (CRMP2), leading to an increased CRMP2/NaV1.7 interaction and increased functional activity of NaV1.7. Targeting this feed-forward regulation, we developed compound 194, which inhibits CRMP2 SUMOylation mediated by the SUMO-conjugating enzyme Ubc9. We further demonstrated that 194 effectively reduces the functional activity of NaV1.7 channels in dorsal root ganglia neurons and alleviated inflammatory and neuropathic pain. Here, we employed a comprehensive array of investigative approaches, encompassing biochemical, pharmacological, genetic, electrophysiological, and behavioral analyses, to assess the functional implications of NaV1.7 regulation by CRMP2 in trigeminal ganglia (TG) neurons. We confirmed the expression of Scn9a, Dpysl2, and UBE2I within TG neurons. Furthermore, we found an interaction between CRMP2 and NaV1.7, with CRMP2 being SUMOylated in these sensory ganglia. Disrupting CRMP2 SUMOylation with compound 194 uncoupled the CRMP2/NaV1.7 interaction, impeded NaV1.7 diffusion on the plasma membrane, and subsequently diminished NaV1.7 activity. Compound 194 also led to a reduction in TG neuron excitability. Finally, when intranasally administered to rats with chronic constriction injury of the infraorbital nerve (CCI-ION), 194 significantly decreased nociceptive behaviors. Collectively, our findings underscore the critical role of CRMP2 in regulating NaV1.7 within TG neurons, emphasizing the importance of this indirect modulation in trigeminal neuropathic pain.

neuroscience↗

bioRxiv2022

A parabrachial-to-amygdala circuit that determines hemispheric lateralization of somatosensory processing

BackgroundThe central amygdala (CeA) is a bilateral hub of pain and emotional processing with well-established functional lateralization. We reported that optogenetic manipulation of neural activity in the left and right CeA has opposing effects on bladder pain. MethodsTo determine the influence of calcitonin gene-related peptide (CGRP) signaling from the parabrachial nucleus (PBN) on this diametrically opposed lateralization, we administered CGRP and evaluated the activity of CeA neurons in acute brain slices as well as the behavioral signs of bladder pain in the mouse. ResultsWe found that CGRP increased firing in both the right and left CeA neurons. Furthermore, we found that CGRP administration in the right CeA increased behavioral signs of bladder pain and decreased bladder pain-like behavior when administered in the left CeA. ConclusionsThese studies reveal a parabrachial-to-amygdala circuit driven by opposing actions of CGRP that determines hemispheric lateralization of visceral pain.

neuroscience↗

bioRxiv2022

Endogenous μ-opioid - neuropeptide Y Y1 receptor synergy silences chronic postoperative pain

Tissue injury creates a delicate balance between latent pain sensitization (LS) and compensatory endogenous analgesia. Inhibitory G protein-coupled receptor (GPCR) interactions that oppose LS, including -opioid receptor (MOR) and neuropeptide Y Y1 receptor (Y1R) activity, persist in the spinal cord dorsal horn (DH) for months, even after the resolution of normal pain thresholds. Here, we demonstrate that following recovery from surgical incision, a potent endogenous analgesic synergy between MOR and Y1R activity persists within DH interneurons to reduce the intensity and duration of latent postoperative hyperalgesia and ongoing pain. Failure of such endogenous GPCR signaling to maintain LS in remission may underlie the transition from acute to chronic pain states.

neuroscience↗