Biology subjects

Carrasquillo, Y.

Publications and source records attributed to Carrasquillo, Y..

11 recordsLinked to original sources

bioRxiv2026

Differential utilization of PACAP and glutamate in parabrachial neurons shapes pain and stress

The external parabrachial nucleus (elPBN) contributes to diverse behaviors, including pain and stress. Neurons in this region use glutamatergic and neuropeptidergic signaling, with pituitary adenylate cyclase-activating polypeptide (PACAP) expressed in a subset of glutamatergic neurons. Deletion of PACAP in elPBN neurons attenuates behavioral responses to stress, but the contribution of PACAP to pain sensitization and of glutamatergic neurotransmission to pain- and stress-related responses remain poorly understood. Here, we show that constitutive loss of PACAP markedly attenuated nerve injury-induced hypersensitivity across heat, pressure, cold and tactile modalities without altering baseline nociception, while also reducing inflammation-induced spontaneous pain-related behavior. Notably, selective deletion of PACAP within elPBN neurons phenocopied the suppression of injury-induced hypersensitivity, but left inflammation- induced pain-related behavior unaffected. Ex vivo optogenetic-assisted circuit mapping showed that activation of PACAP-expressing elPBN terminals elicited glutamatergic transmission onto central amygdala (CeA) PKC{delta}-expressing neurons. Selective deletion of VGluT2 in elPBN neurons reduced nerve injury-induced hypersensitivity but, unlike PACAP deletion, also reduced inflammation-induced pain-related behavior, while leaving stress-induced hypophagia intact. Together, these findings reveal differential requirements for PACAP and glutamatergic neurotransmission within the elPBN across pain- and stress-related behaviors.

neuroscience↗

bioRxiv2026

Predicting Pain Using a Data-Driven Agent-Based Model of the Bilateral Central Amygdala

Sensory processing in the amygdala is a complex, dynamic process. Decades of surgical, electrical, pharmacological, optogenetic, and chemogenetic in vivo manipulations have revealed the nociceptive functions of anatomically- and genetically-restricted neuronal populations. In parallel, molecular and electrophysiological approaches have allowed for high-resolution, temporal examination of nociceptive-induced alterations in amygdala plasticity. Computational integration of this data is critical for future therapeutic development; in practice, these models would allow for in silico prediction of amygdala activity following injury, and in a reciprocal fashion, changes in pain-like behaviors following manipulation of discrete amygdala neuronal populations. To this end, we developed a three-dimensional computer model of the bilateral central nucleus of the amygdala (CeA). We employed agent-based modelling to integrate wet-lab data from two CeA cell populations: Calcitonin Gene-Related Peptide Receptor (CGRPR; Calcrl) expressing cells and Protein Kinase C delta (PKC{delta}; Prkcd) expressing cells. We integrated the spatial location, connectivity, neuronal activity, and electrophysiological properties of these neurons in our realistic bilateral model architecture. Our model captures properties of the amygdala that drive pain modulation, including hemisphere-specific physiological differences, and generates predictions of nociception related to bladder injury. Predictions from the model were compared retrospectively to pain outcomes during manipulation of CGRPR-expressing neurons in whole mice. These comparisons show strong alignment between our model and in vivo outcomes. Significance StatementNociceptive processing in the amygdala emerges from interactions among cell types. No framework has been developed that recapitulates this complexity. Here, we generated a 3-D agent-based computational model of the bilateral central amygdala (CeA) using data that accounts for pain-associated changes in neuronal physiology, cellular identity, anatomical positioning, and temporal specificity. The model revealed that hemispheric differences in intrinsic CeA neuronal excitability are dominant drivers of nociceptive output. Furthermore, when manipulated to mimic injury-associated plasticity, the model accurately predicted behavioral outcomes. This model is a publicly available computational tool that predicts hemisphere-targeted pain therapy efficacy. Moreover, the flexibility of this framework will allow future adaptations to other brain areas and disease contexts.

neuroscience↗

bioRxiv2026

CGRP receptor-expressing neurons in the central amygdala contributes to injury-induced pain hypersensitivity

The central nucleus of amygdala (CeA) comprises diverse populations of neurons, forming a complex network responsible for regulating various behavioral responses. Among these, neurons expressing calcitonin gene-related peptide receptors (CGRPR) have emerged as key players in CGRP neuropeptide-mediated pain modulation. While previous studies emphasize CGRPs key role in synaptic plasticity and its connection with pain behavior in the CeA, the precise functional attributes and contributions of CeA-CGRPR-expressing neurons in pain processing remain elusive. This study reveals the co-localization of CGRPR-expressing neurons in the CeA with phosphorylated extracellular signal-regulated kinase (pERK), a marker indicating pain plasticity, in a neuropathic pain model. Electrophysiological assessments of these neurons in slice preparations unveiled heightened intrinsic excitability after sciatic nerve cuff implantation, contingent upon their rostro-caudal positioning within the CeA. Furthermore, our behavioral experiments using chemogenetic inhibition of CeA-CGRPR neurons demonstrated the ability to reverse nerve injury-induced hypersensitivity. Conversely, activating these neurons induced pain-related hypersensitivity even in the absence of injury. Our findings also highlight a sex-specific role of CeA-CGRPR neurons in formalin-induced spontaneous pain response. Collectively, these data reinforce the involvement of CeA-CGRPR neurons in pain processing, contributing to a better understanding of how neural circuits are affected in persistent pain conditions. Significance StatementOur study shows the role of CGRPR-expressing neurons within the CeA during pain processing. Using a cuff-implanted neuropathic mouse model, we discovered that CGRPR-expressing neurons co-localize with phosphorylated extracellular signal-regulated kinase (pERK), a hallmark of pain plasticity, in both male and female mice. Furthermore, our electrophysiological investigations reveal that posterior CeA-CGRPR neurons exhibit increased excitability following sciatic nerve cuff implantation. Importantly, we demonstrate that CeA-CGRPR neurons exert bidirectional effects on pain behavior in mice, irrespective of sex differences in nerve injury-induced pain responses while showing sex-specific spontaneous pain responses in the formalin-induced model. These findings show the role of CeA-CGRPR neurons in pain modulation, underscoring their potential significance in understanding and addressing persistent pain conditions.

neuroscience↗

bioRxiv2024

Loss of Intracellular Fibroblast Growth Factor 14 (iFGF14) Increases the Excitability of Mature Hippocampal and Cortical Pyramidal Neurons

Mutations in FGF14, which encodes intracellular fibroblast growth factor 14 (iFGF14), have been linked to spinocerebellar ataxia type 27 (SCA27), a multisystem disorder associated with progressive deficits in motor coordination and cognitive function. Mice (Fgf14-/-) lacking iFGF14 display similar phenotypes, and we have previously shown that the deficits in motor coordination reflect reduced excitability of cerebellar Purkinje neurons, owing to the loss of iFGF14-mediated regulation of the voltage-dependence of inactivation of the fast transient component of the voltage-gated Na+ (Nav) current, INaT. Here, we present the results of experiments designed to test the hypothesis that loss of iFGF14 also attenuates the intrinsic excitability of mature hippocampal and cortical pyramidal neurons. Current-clamp recordings from adult mouse hippocampal CA1 pyramidal neurons in acute in vitro slices, however, revealed that repetitive firing rates were higher in Fgf14-/-, than in wild type (WT), cells. In addition, the waveforms of individual action potentials were altered in Fgf14-/- hippocampal CA1 pyramidal neurons, and the loss of iFGF14 reduced the time delay between the initiation of axonal and somal action potentials. Voltage-clamp recordings revealed that the loss of iFGF14 altered the voltage-dependence of activation, but not inactivation, of INaT in CA1 pyramidal neurons. Similar effects of the loss of iFGF14 on firing properties were evident in current-clamp recordings from layer 5 visual cortical pyramidal neurons. Additional experiments demonstrated that the loss of iFGF14 does not alter the distribution of anti-Nav1.6 or anti-ankyrin G immunofluorescence labeling intensity along the axon initial segments (AIS) of mature hippocampal CA1 or layer 5 visual cortical pyramidal neurons in situ. Taken together, the results demonstrate that, in contrast with results reported for neonatal (rat) hippocampal pyramidal neurons in dissociated cell culture, the loss of iFGF14 does not disrupt AIS architecture or Nav1.6 localization/distribution along the AIS of mature hippocampal (or cortical) pyramidal neurons in situ.

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bioRxiv2023

Divergent changes in PBN excitability in a mouse model of neuropathic pain

The transition from acute to chronic pain involves maladaptive plasticity in central nociceptive pathways. Growing evidence suggests that changes within the parabrachial nucleus (PBN), an important component of the spino-parabrachio-amygdaloid pain pathway, are key contributors to the development and maintenance of chronic pain. In animal models of chronic pain, PBN neurons become sensitive to normally innocuous stimuli and responses to noxious stimuli become amplified and more often produce after-discharges that outlast the stimulus. Using ex vivo slice electrophysiology and two mouse models of neuropathic pain, sciatic cuff and chronic constriction of the infraorbital nerve (CCI-ION), we find that changes in the firing properties of PBN neurons and a shift in inhibitory synaptic transmission may underlie this phenomenon. Compared to PBN neurons from shams, a larger proportion of PBN neurons from mice with a sciatic cuff were spontaneously active at rest, and these same neurons showed increased excitability relative to shams. In contrast, quiescent PBN neurons from cuff mice were less excitable than those from shams. Despite an increase in excitability in a subset of PBN neurons, the presence of after-discharges frequently observed in vivo were largely absent ex vivo in both injury models. However, GABAB-mediated presynaptic inhibition of GABAergic terminals is enhanced in PBN neurons after CCI-ION. These data suggest that the amplified activity of PBN neurons observed in rodent models of chronic pain arise through a combination of changes in firing properties and network excitability. Significance StatementHyperactivity of neurons in the parabrachial nucleus (PBN) is causally linked to exaggerated pain behaviors in rodent models of chronic pain but the underlying mechanisms remain unknown. Using two mouse models of neuropathic pain, we show the intrinsic properties of PBN neurons are largely unaltered following injury. However, subsets of PBN neurons become more excitable and GABAB receptor mediated suppression of inhibitory terminals is enhanced after injury. Thus, shifts in network excitability may be a leading factor in injury induced potentiation of PBN activity.

neuroscience↗

bioRxiv2023

The parabrachial to central amygdala circuit is a key mediator of injury-induced pain sensitization

The spino-ponto-amygdaloid pathway is a major ascending circuit relaying nociceptive information from the spinal cord to the brain. Potentiation of excitatory synaptic transmission in the parabrachial nucleus (PbN) to central amygdala (CeA) pathway has been reported in rodent models of persistent pain. At the behavioral level, the PbN[->]CeA pathway has been proposed to serve as a general alarm system to potential threats that modulates pain-related escape behaviors, threat memory, aversion, and affective-motivational (but not somatosensory) responses to painful stimuli. Increased sensitivity to previously innocuous somatosensory stimulation is a hallmark of chronic pain. Whether the PbN[->]CeA circuit contributes to heightened peripheral sensitivity following an injury, however, remains unknown. Here, we demonstrate that activation of CeA-projecting PbN neurons contributes to injury-induced behavioral hypersensitivity but not baseline nociception in male and female mice. Using optogenetic assisted circuit mapping, we confirmed a functional excitatory projection from PbN[->]CeA that is independent of the genetic or firing identity of CeA cells. We then showed that peripheral noxious stimulation increases the expression of the neuronal activity marker c-Fos in CeA-projecting PbN neurons and chemogenetic inactivation of these cells reduces behavioral hypersensitivity in models of neuropathic and inflammatory pain without affecting baseline nociception. Lastly, we show that chemogenetic activation of CeA-projecting PbN neurons is sufficient to induce bilateral hypersensitivity without injury. Together, our results demonstrate that the PbN[->]CeA pathway is a key modulator of pain-related behaviors that can amplify responses to somatosensory stimulation in pathological states without affecting nociception under normal physiological conditions. Significance StatementEarly studies identified the spino-ponto-amygdaloid pathway as a major ascending circuit conveying nociceptive inputs from the spinal cord to the brain. The functional significance of this circuit to injury-induced hypersensitivity, however, remains unknown. Here, we addressed this gap in knowledge using viral-mediated anatomical tracers, ex-vivo electrophysiology and chemogenetic intersectional approaches in rodent models of persistent pain. We found that activation of this pathway contributes to injury-induced hypersensitivity, directly demonstrating a critical function of the PbN[->]CeA circuit in pain modulation.

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

4R-Tobacco-Cembranoid is a Positive Allosteric Modulator of the Alpha7 Nicotinic Acetylcholine Receptor that modulates inflammation-induced thermal hypersensitivity in mice

Alpha7 nicotinic acetylcholine receptors (7nAChRs) are activated in response to inflammation and modulate pain in humans and rodent models. The use of 7nAChRs agonists as a therapeutic option for inflammation and pain is challenged by unwanted effects resulting from constant activation and/or desensitization of 7nAChRs. Positive allosteric modulators (PAMs) represent a compelling alternative as they increase endogenous nicotinic transmission but do not result in progressive desensitization or loss of receptor function. In the present study, we evaluated the function of the 4R tobacco cembranoid (4R) as a PAM of 7nAChR that reduces inflammation and pain-related behaviors in mouse models of inflammatory pain. Our electrophysiological experiments show that 4R potentiates choline-evoked currents in SH-SY5Y cells overexpressing 7nAChRs in a dose-dependent manner. At the behavioral level, we show that subcutaneous administration of 4R decreases inflammation-induced thermal but not tactile hypersensitivity or formalin-induced spontaneous nociceptive responses in both male and female mice. We further show reduced inflammation-induced paw edema in 4R-treated males, with no measurable effect observed in female mice. Altogether, the results from the experiments in this study identify 4R as a PAM of 7nAChRs that reduces thermal hypersensitivity in male and female mice and inflammation in a sex-specific manner. These findings highlight the use of 4R as a potential novel treatment strategy for pain and inflammation.

neuroscience↗

bioRxiv2022

Sex differences in pain-related behaviors and clinical progression of disease in mouse models of visceral pain

Previous studies have reported sex differences in irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD) patients, including differences in visceral pain perception. Despite this, sex differences in behavioral manifestations of visceral pain and underlying pathology of the gastrointestinal tract have been largely understudied in preclinical research. In this study, we evaluated potential sex differences in spontaneous visceral nociceptive responses, referred abdominal hypersensitivity, disease progression and bowel pathology in mouse models of acute and persistent colon inflammation. Our experiments show that females exhibit more visceral nociceptive responses and referred abdominal hypersensitivity than males in the context of acute but not persistent colon inflammation. We further demonstrate that, following acute and persistent colon inflammation, visceral pain-related behavioral responses in females and males are distinct, with increases in licking of the abdomen only observed in females and increases in abdominal contractions only seen in males. During persistent colon inflammation, males exhibit worse disease progression than females, which is manifested as worse physical appearance and higher weight loss. However, no measurable sex differences were observed in persistent inflammation-induced bowel pathology, stool consistency or fecal blood. Overall, our findings demonstrate that visceral pain-related behaviors and disease progression in the context of acute and persistent colon inflammation are sex-dependent, highlighting the importance of considering sex as a biological variable in future mechanistic studies of visceral pain as well as in the development of diagnostics and therapeutic options for chronic gastrointestinal diseases.

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bioRxiv2021

Bidirectional modulation of pain-related behaviors in the zona incerta

Central amygdala neurons expressing protein kinase C-delta (CeA-PKC{delta}) are sensitized following nerve injury and promote pain-related responses in mice. The neural circuits underlying modulation of pain-related behaviors by CeA-PKC{delta} neurons, however, remain unknown. In this study, we identified a functional monosynaptic inhibitory neural circuit that originates in CeA-PKC{delta} neurons and terminates in the ventral region of the zona incerta (ZI), a subthalamic structure previously linked to pain processing. Behavioral experiments further show that chemogenetic inhibition of GABAergic ZI neurons is sufficient to induce bilateral hypersensitivity in uninjured mice as well as contralateral hypersensitivity after nerve injury. In contrast, chemogenetic activation of GABAergic ZI neurons reverses nerve injury-induced hypersensitivity, demonstrating that silencing of the ZI is required for injury-induced behavioral hypersensitivity. Our results identify a previously unrecognized inhibitory efferent pathway from CeA-PKC{delta} neurons to the ZI and demonstrate that ZI-GABAergic neurons can bidirectionally modulate pain-related behaviors in mice.

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bioRxiv2019

Cell-type specificity of neuronal excitability and morphology in the central amygdala

Central amygdala (CeA) neurons expressing protein kinase C delta (PKC{delta}+) or Somatostatin (Som+) differentially modulate diverse behaviors. The underlying features supporting cell-type-specific function in the CeA, however, remain unknown. Using whole-cell patch-clamp electrophysiology in acute mouse brain slices and biocytin-based neuronal reconstructions, we demonstrate that neuronal morphology and relative excitability are two distinguishing features between Som+ and PKC{delta}+ CeLC neurons. Som+ neurons, for example, are more excitable, compact and with more complex dendritic arborizations than PKC{delta}+ neurons. Cell size, intrinsic membrane properties, and anatomical localization were further shown to correlate with cell-type-specific differences in excitability. Lastly, in the context of neuropathic pain, we show a shift in the excitability equilibrium between PKC{delta}+ and Som+ neurons, suggesting that imbalances in the relative output of these cells underlie maladaptive changes in behaviors. Together, our results identify fundamentally important distinguishing features of PKC{delta}+ and Som+ cells that support cell-type-specific function in the CeA.

neuroscience↗