Intrathecal Delivery Research Articles

Intrathecal administration of nusinersen in adult and adolescent patients with spinal muscular atrophy and scoliosis: Transforaminal versus conventional approach

Spinal deformities and surgical correction of scoliosis can make intrathecal delivery of nusinersen very challenging. We aim to evaluate the feasibility and safety of intrathecal administration of nusinersen either via interlaminar or transforaminal approach in a cohort of adult and adolescent patients with spinal muscular atrophy (SMA). Twelve patients were treated with nusinersen in our center under CT-guidance; after a CT scan of the lumbar column, we identified a safe virtual trajectory for the needle and defined patients to address to the transforaminal approach (seven patients) or the interlaminar approach (five patients). Out of 47 procedures, all injections but one were successful. There was one adverse event (post-lumbar puncture syndrome) in the interlaminar approach group (out of 20 procedures) and four adverse events in TFA group (out of 27 procedures) including one serious adverse event, a subarachnoid hemorrhage that required hospitalization. Transforaminal approach can be considered an effective option for nusinersen administration but potentially associated with serious complications, therefore it should be recommended in very selected patients.

Intrathecal Riluzole for the Treatment of Patients With Amyotrophic Lateral Sclerosis

Abstract INTRODUCTION Oral riluzole is the only approved treatment known to improve survival in patients with amyotrophic lateral sclerosis (ALS), with modest efficacy and dosing limited by hepatic toxicity and asthenia. We postulated that a continuous intrathecal (IT) delivery of low daily doses of riluzole could elevate spinal cord (SC) concentrations well above those achievable with oral treatment alone, without increasing side-effects. METHODS A 6-wk and a 24-wk GLP study were conducted to evaluate the safety of IT riluzole in purpose-bred hound dogs. Oral riluzole, equivalent to 50 mg BID in humans, was administered in combination with one of 3 IT doses given through continuous infusion. Plasma, SC, and brain concentrations of riluzole were measured, along with assessments of safety and tolerability. RESULTS In the 6-wk study, when combining the oral and IT routes, IT infusion significantly increased SC concentrations well above those achieved with oral drug administration alone, without increasing brain concentrations. All IT doses in combination with oral administration were well tolerated by the animals. In the 6-mo study, the lowest dose used in the 6-wk study was dropped and a higher dose was added. This highest dose of IT riluzole was not tolerated by the dogs and yielded SC and brain concentrations significantly higher than achieved in any of our previous studies. CONCLUSION Continuous IT administration of riluzole when combined with oral administration can increase the SC concentration of riluzole above those achievable with oral therapy, without increasing the risk for adverse events associated with systemic drug exposure or off-target side-effects in the brain. Therefore, IT riluzole infusion when used in conjunction with oral therapy may safely enhance lower motor neuron neuroprotection and improve the survival benefit of the drug through enhanced SC delivery, and, with a careful selection of IT doses, it could be implemented in patients with ALS.

Gene replacement therapy after neuropathy onset provides therapeutic benefit in a model of CMT1X.

X-linked Charcot-Marie-Tooth disease (CMT1X), one of the commonest forms of inherited demyelinating neuropathy, results from GJB1 gene mutations causing loss of function of the gap junction protein connexin32 (Cx32). The aim of this study was to examine whether delayed gene replacement therapy after the onset of peripheral neuropathy can provide a therapeutic benefit in the Gjb1-null/Cx32 knockout model of CMT1X. After delivery of the LV-Mpz.GJB1 lentiviral vector by a single lumbar intrathecal injection into 6-month-old Gjb1-null mice, we confirmed expression of Cx32 in lumbar roots and sciatic nerves correctly localized at the paranodal myelin areas. Gjb1-null mice treated with LV-Mpz.GJB1 compared with LV-Mpz.Egfp (mock) vector at the age of 6months showed improved motor performance at 8 and 10months. Furthermore, treated mice showed increased sciatic nerve conduction velocities, improvement of myelination and reduced inflammation in lumbar roots and peripheral nerves at 10months of age, along with enhanced quadriceps muscle innervation. Plasma neurofilament light (NEFL) levels, a clinically relevant biomarker, were also ameliorated in fully treated mice. Intrathecal gene delivery after the onset of peripheral neuropathy offers a significant therapeutic benefit in this disease model, providing a proof of principle for treating patients with CMT1X at different ages.

In Vivo Intrathecal Tracer Dispersion in Cynomolgus Monkey Validates Wide Biodistribution Along Neuraxis.

It is commonly believed that in intrathecal (IT) drug delivery, agent distribution is confined to a narrow region close to the injection site, thereby undermining the efficacy of the method. To test the claim, multimodal in vivo imaging was used to experimentally observe the effects of IT infusion in cynomolgus monkey, looking at cerebrospinal fluid flow, anatomy, and dispersion of a radiolabeled tracer. At high infusion rates, the tracer reached the cervical region after only 2 h, demonstrating rapid and wide distribution. The same in vivo nonhuman primate imaging data also provided evidence in support of a computational fluid dynamic model for the prediction of drug distribution following IT injection. Tracer dispersion was predicted in two specimens matching the distribution acquired with positron emission tomography (PET). For the third specimen, tracer dispersion simulations were conducted as a blind study: predictions were made before in vivo biodistribution data was known. In all cases, the computational fluid dynamics (CFD) predictions of drug dispersion after IT administration showed close spatio-temporal agreement with tracer biodistribution in vivo. Validation by in vivo nonhuman primate data confirms our ability to predict the biodistribution of intrathecally administered agents in subject-specific models of the central nervous system from first principles. The experiments reinstate IT delivery as a viable administration method when targeting molecules to the whole spine or the brain. The proposed computational methodology enables rational design of novel therapies for neurological diseases that require reliable, efficient, and safe delivery of therapeutic agents to specific target sites in the central nervous system.

Increased ER–mitochondria tethering promotes axon regeneration

Translocation of the endoplasmic reticulum (ER) and mitochondria to the site of axon injury has been shown to facilitate axonal regeneration; however, the existence and physiological importance of ER-mitochondria tethering in the injured axons are unknown. Here, we show that a protein linking ER to mitochondria, the glucose regulated protein 75 (Grp75), is locally translated at axon injury site following axotomy, and that overexpression of Grp75 in primary neurons increases ER-mitochondria tethering to promote regrowth of injured axons. We find that increased ER-mitochondria tethering elevates mitochondrial Ca2+ and enhances ATP generation, thereby promoting regrowth of injured axons. Furthermore, intrathecal delivery of lentiviral vector encoding Grp75 to an animal with sciatic nerve crush injury enhances axonal regeneration and functional recovery. Together, our findings suggest that increased ER-mitochondria tethering at axonal injury sites may provide a therapeutic strategy for axon regeneration.

Gene Therapy Corrects Brain and Behavioral Pathologies in CLN6-Batten Disease.

CLN6-Batten disease, a form of neuronal ceroid lipofuscinosis is a rare lysosomal storage disorder presenting with gradual declines in motor, visual, and cognitive abilities and early death by 12–15 years of age. We developed a self-complementary adeno-associated virus serotype 9 (scAAV9) vector expressing the human CLN6 gene under the control of a chicken β-actin (CB) hybrid promoter. Intrathecal delivery of scAAV9.CB.hCLN6 into the cerebrospinal fluid (CSF) of the lumbar spinal cord of 4-year-old non-human primates was safe, well tolerated, and led to efficient targeting throughout the brain and spinal cord. A single intracerebroventricular (i.c.v.) injection at post-natal day 1 in Cln6 mutant mice delivered scAAV9.CB.CLN6 directly into the CSF, and it prevented or drastically reduced all of the pathological hallmarks of Batten disease. Moreover, there were significant improvements in motor performance, learning and memory deficits, and survival in treated Cln6 mutant mice, extending survival from 15 months of age (untreated) to beyond 21 months of age (treated). Additionally, many parameters were similar to wild-type counterparts throughout the lifespan of the treated mice.

Managing Chronic Non-Malignant Pain in the Elderly: Intrathecal Therapy

Intrathecal drug delivery (IDD) was first described in 1981 by Onofrio, who used a pump for continuous and intrathecal delivery of morphine to treat cancer pain. Over the following four decades, many reports supported this treatment method with implanted pumps for cancer and non-cancer pain. To date, more than 300,000 pumps for pain therapy and spasticity have been implanted worldwide. This article reviews current knowledge regarding intrathecal opioid therapy, focusing particularly on the use of IDD in elderly patients. Current literature is presented, and the arguments in favor of and against this therapy in elderly patients are discussed.

Intrathecal delivery of recombinant AAV1 encoding hepatocyte growth factor improves motor functions and protects neuromuscular system in the nerve crush and SOD1-G93A transgenic mouse models

Amyotrophic lateral sclerosis (ALS) is a fatal neuromuscular disease resulting from motor neuron degeneration that causes muscle weakness, paralysis, and eventually respiratory failure. We investigated whether recombinant adeno-associated virus encoding human hepatocyte growth factor (rAAV-HGF) could generate beneficial effects in two mouse models with neuromuscular problems when intrathecally delivered to the subarachnoid space. We chose AAV serotype 1 (rAAV1) based on the expression levels and distribution of HGF protein in the lumbar spinal cord (LSC). After a single intrathecal (IT) injection of rAAV1-HGF, the protein level of HGF in the LSC peaked on day 14 and thereafter gradually decreased over the next 14 weeks. rAAV1-HGF was initially tested in the mouse nerve crush model. IT injection of rAAV1-HGF improved mouse hindlimb strength and rotarod performance, while histological analyses showed that the length of regenerated axons was increased and the structure of the neuromuscular junction (NMJ) was restored. rAAV1-HGF was also evaluated in the SOD1-G93A transgenic (TG) mouse model. Again, rAAV1-HGF not only improved motor performance but also increased the survival rate. Moreover, the number and diameter of spinal motor neurons (SMNs) were increased, and the shape of the NMJs restored. Data from in vitro motor cortical culture experiments indicated that treatment with recombinant HGF protein (rHGF) increased the axon length of corticospinal motor neurons (CSMNs). When cultures were treated with an ERK inhibitor, the effects of HGF on axon elongation, protein aggregation, and oxidative stress were suppressed, indicating that ERK phosphorylation played an important role(s). Taken together, our results suggested that HGF might play an important role(s) in delaying disease progression in the SOD1-G93A TG mouse model by reducing oxidative stress through the control of ERK phosphorylation.

CDK5 inhibits the clathrin-dependent internalization of TRPV1 by phosphorylating the clathrin adaptor protein AP2μ2.

Transient receptor potential vanilloid 1 (TRPV1), a nonselective, ligand-gated cation channel, responds to multiple noxious stimuli and is targeted by many kinases that influence its trafficking and activity. Studies on the internalization of TRPV1 have mainly focused on that induced by capsaicin or other agonists. Here, we report that constitutive internalization of TRPV1 occurred in a manner dependent on clathrin, dynamin, and adaptor protein complex 2 (AP2). The μ2 subunit of AP2 (AP2μ2) interacted directly with TRPV1 and was required for its constitutive internalization. Cyclin-dependent kinase 5 (CDK5) phosphorylated AP2μ2 at Ser45, which reduced the interaction between TRPV1 and AP2μ2, leading to decreased TRPV1 internalization. Intrathecal delivery of a cell-penetrating fusion peptide corresponding to the Cdk5 phosphorylation site in AP2μ2, which competed with AP2μ2 for phosphorylation by Cdk5, increased the abundance of TRPV1 on the surface of dorsal root ganglion neurons and reduced complete Freund's adjuvant (CFA)-induced inflammatory thermal hyperalgesia in rats. In addition to describing a mechanism of TRPV1 constitutive internalization and its inhibition by CDK5, these findings demonstrate that CDK5 promotes inflammatory thermal hyperalgesia by reducing TRPV1 internalization, providing previously unidentified insights into the search for drug targets to treat pain.

Mir-17∼92 Confers Motor Neuron Subtype Differential Resistance to ALS-Associated Degeneration.

Progressive degeneration of motor neurons (MNs) is the hallmark of amyotrophic lateral sclerosis (ALS). Limb-innervating lateral motor column MNs (LMC-MNs) seem to be particularly vulnerable and are among the first MNs affected in ALS. Here, we report association of this differential susceptibility with reduced expression of the mir-17∼92 cluster in LMC-MNs prior to disease onset. Reduced mir-17∼92 is accompanied by elevated nuclear PTEN in spinal MNs of presymptomatic SOD1G93A mice. Selective dysregulation of the mir-17∼92/nuclear PTEN axis in degenerating SOD1G93A LMC-MNs was confirmed in a double-transgenic embryonic stem cell system and recapitulated in human SOD1+/L144F-induced pluripotent stem cell (iPSC)-derived MNs. We further show that overexpression of mir-17∼92 significantly rescues human SOD1+/L144F MNs, and intrathecal delivery of adeno-associated virus (AAV)9-mir-17∼92 improves motor deficits and survival in SOD1G93A mice. Thus, mir-17∼92 may have value as a prognostic marker of MN degeneration and is a candidate therapeutic target in SOD1-linked ALS. VIDEO ABSTRACT.

The Configuration of the Perivascular System Transporting Macromolecules in the CNS.

Large blood vessels entering the CNS are surrounded by perivascular spaces that communicate with the cerebrospinal fluid and, at their termini, with the interstitial space. Solutes and particles can translocate along these perivascular conduits, reportedly in both directions. Recently, this prompted a renewed interest in the intrathecal therapy delivery route for CNS-targeted therapeutics. However, the extent of the CNS coverage by the perivascular system is unknown, making the outcome of drug administration to the CSF uncertain. We traced the translocation of model macromolecules from the CSF into the CNS of rats and non-human primates. Conduits transporting macromolecules were found to extend throughout the parenchyma from both external and internal (fissures) CNS boundaries, excluding ventricles, in large numbers, on average ca. 40 channels per mm2 in rats and non-human primates. The high density and depth of extension of the perivascular channels suggest that the perivascular route can be suitable for delivery of therapeutics to parenchymal targets throughout the CNS.

Antibodies binding the head domain of P2X4 inhibit channel function and reverse neuropathic pain.

P2X4 is a ligand-gated ion channel implicated in neuropathic pain. Drug discovery efforts targeting P2X4 have been unsuccessful largely because of the difficulty in engineering specificity and selectivity. Here, we describe for the first time the generation of a panel of diverse monoclonal antibodies (mAbs) to human and mouse P2X4, capable of both positive and negative modulation of channel function. The affinity-optimised anti-P2X4 mAb IgG#151-LO showed exquisite selectivity for human P2X4 and induced potent and complete block of P2X4 currents. Site-directed mutagenesis of P2X4 revealed the head domain as a key interaction site for inhibitory mAbs. Inhibition of spinal P2X4 either by intrathecal delivery of an anti-P2X4 mAb or by systemic delivery of an anti-P2X4 bispecific mAb with enhanced blood-spinal cord barrier permeability produced long-lasting (>7 days) analgesia in a mouse model of neuropathic pain. We therefore propose that inhibitory mAbs binding the head domain of P2X4 have therapeutic potential for the treatment of neuropathic pain.

Intrathecal delivery of ALS cerebrospinal fluid induces motor deficits and motor neuron death in mice (P1.4-013)

Intrathecal delivery of ALS cerebrospinal fluid induces motor deficits and motor neuron death in mice (P1.4-013)

A2A and 5‐HT Receptors are Differentially Required for Respiratory Plasticity Over the Course of Motor Neuron Loss in Intrapleurally CTB‐SAP Treated Rats

Loss of respiratory (e.g., phrenic) motor neurons leads to ventilatory failure in patients with neuromuscular diseases, but there are currently no treatments to maintain ventilation or to significantly and consistently preserve/restore ventilatory capacity in these patients. Genetic models have been used to study the impact of motor neuron loss; however, the rate and amount of motor neuron death cannot be controlled in these models, and degeneration is not limited to only respiratory motor neurons making it difficult to study treatment modalities to improve ventilation. Thus, we have developed a novel model of controlled respiratory motor neuron death using intrapleural injection of cholera toxin B conjugated to saporin (CTB‐SAP), in which we find that eupneic ventilation is maintained despite deficits in maximal ventilatory capacity. Our previous results demonstrated that respiratory plasticity is not only observed 7 days (d) after CTB‐SAP delivery, but that it is actually enhanced compared to control treatments. At 28d, however, respiratory plasticity is comparable to control levels, suggesting that the underlying mechanisms of plasticity at both time points may differ. Further, we suggest that neuroplasticity mechanisms contribute to maintain ventilation in the face of respiratory motor neuron loss. Although multiple cellular pathways give rise to respiratory plasticity, this study will focus on serotonin (5‐HT) and adenosine 2A (A2A) receptors based on our preliminary receptor expression data. Our preliminary data indicate that A2A receptor expression is increased in 7d, not 28d, CTB‐SAP treated rats, whereas 5‐HT receptor expression decreases at 7d and recovers to control levels in 28d CTB‐SAP treated rats. Thus, we hypothesize that distinct mechanisms (A2A receptor‐dependent at 7d, 5‐HT receptor‐dependent at 28d) enable respiratory plasticity and maintain eupneic ventilation in CTB‐SAP‐induced neuropathology. Using anesthetized, paralyzed and ventilated CTB‐SAP treated adult Sprague Dawley rats, we studied acute intermittent hypoxia (AIH; 3, 5 min bouts of 10.5% O2) induced phrenic long‐term facilitation (pLTF) following intrathecal C4 delivery of either the A2A receptor antagonist (10 μM MSX‐3) or the 5‐HT receptor antagonist (20 mM methysergide) to rats that received bilateral, intrapleural injections of: 1) CTB‐SAP (25μg), or 2) un‐conjugated CTB and SAP (control) in rats treated 7d or 28d prior. Our preliminary results indicate that pLTF is abolished after MSX‐3 at 7d and methysergide at 28d vs. controls and vehicle treated CTB‐SAP rats. These observations suggest that A2A receptors are necessary for respiratory plasticity early (7d), but 5‐HT receptors are required late (28d). Studies are underway to assess whether these receptors are required to maintain eupneic ventilation using whole‐body plethysmography. Results from this project will increase our understanding of how respiratory plasticity is initiated and how eupneic ventilation is maintained over the course of neuropathology, and will have broad implications for potential therapies to preserve/restore ventilatory function in disorders in which respiratory motor neuron death is associated.Support or Funding InformationNIH R00 HL119606 and SCIDRPThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Implantable Pumps Require Specific Medications To Prevent Pump Failure And Risks To Patient Safety.

The Food and Drug Administration has issued a Safety Communication regarding implantable pumps used for drug administration and the risks of using medications not approved for use with the pumps to treat or manage pain.Nurses who work with patients receiving intrathecal delivery of pain medication via an implantable pump are urged to carefully read the pump's labeling to identify which medications are approved for use with the pump.

MRNA: A Novel Avenue to Antibody Therapy?

First attempts to use exogenous mRNA for protein expression invivo were made more than 25 years ago. However, widespread appreciation of invitro transcribed mRNA as a powerful technology for supplying therapeutic proteins to the body has evolved only during the past few years. Various approaches to turning mRNA into a potent therapeutic have been developed. All of them share utilization of specifically designed, rather than endogenous, sequences and thorough purification protocols. Apart from this, there are two fundamental philosophies, one promoting the use of chemically modified nucleotides, the other advocating restriction to unmodified building blocks. Meanwhile, both strategies have received broad support by successful mRNA-based protein treatments in animal models. For such invivo use, specifically optimized mRNA had to be combined with potent formulations to enable efficient invivo delivery. The present review analyzes the applicability of mRNA technology to antibody therapy in all main fields: antitoxins, infectious diseases, and oncology.

<p>Near-resolution of persistent idiopathic facial pain with low-dose lumbar intrathecal ziconotide: a case report</p>

PurposePersistent idiopathic facial pain (PIFP) is a poorly defined and debilitating chronic pain state with a challenging and often inadequate treatment course. This is the first case report identifying the novel use of low-dose lumbar intrathecal ziconotide to successfully treat PIFP with nearly complete resolution of pain and minimal to no side effects.MethodsThe patient was a 37 year-old female whose PIFP was refractory to multimodal medication management and multiple neurovascular surgical interventions. A single-shot lumbar intrathecal trial of ziconotide (2.5 mL, equivalent 2.5 μg) was injected when she was at her baseline pain level — VAS 7/10. She received complete resolution of her pain for about 9 hours, concordant with ziconotide’s half-life. She was subsequently implanted with a lumbar intrathecal delivery system.ResultsThe patient experienced complete resolution of her facial pain with a single-shot intrathecal trial of ziconotide. The intrathecal pump system has provided nearly complete (VAS 1/10) pain relief. Two flares of pain occurred 10 and 18 months after pump placement, which subsequently resolved after increasing the ziconotide dose by 0.5 μg/day on each occasion. The patient is currently maintained on a dose of 2.0 μg/day and is pain-free.ConclusionThis is the first case report describing the use of a single-shot lumbar intrathecal trial of ziconotide and subsequent placement of lumbar (as opposed to thoracic) intrathecal ziconotide pump for PIFP. A single-injection intrathecal trial is a low-risk, viable option for patients with this debilitating and frustrating pain condition. Successful trials and subsequent intrathecal pump placement with ziconotide may supplant multimodal medication management and/or invasive orofacial surgical intervention for PIFP.

Intrathecal Delivery of Folate Conjugated near-Infrared Quantum Dots for Targeted in Vivo Imaging of Gliomas in Mice Brains.

Folate acid receptors (FR) are overexpressed in various tumor types, and this makes them excellent targets for tumor localization. From the literature, folate-modified quantum dots (QDs) have the potential to effectively target and monitor brain tumors in vivo. Here we report the high tumor targeting efficacy of folate acid (FA) labeled near-infrared (NIR) QDs with their maximum emission at 800 nm. After coupling QD800-PEG (CdSeTe/ZnS) with FA, we used the orthotopic transplantation mouse model with folate-rich U87MG to test targeted fluorescence imaging of the tumor after intrathecal delivery. The results show that the tumor uptake of QD800-FA is much higher than that of QD800. The semiquantitative analysis of the region of interest (ROI) showed a higher tumor uptake of 90.9 ± 0.6%ID/g of QD800-FA as compared to 24.8 ± 1.6%ID/g of QD800. At the end point of our study, 6 weeks after injection, we could still observe fluorescence signals from the mouse brain.

Visualization of intrathecal delivery by PET-imaging

BackgroundIntrathecal (IT) delivery is useful in both basic research and clinical treatments. Here we aim to test a new minimally invasive distribution route to the subarachnoid space (SAS) and the flow of IT administrations. We placed a radioligand into SAS during positron emission tomography (PET) scanning as a proof of concept. New methodWe injected a 11C-labeled PET-tracer using a surgically placed catheter in the cisterna magna of anesthetized female pigs. The pigs were scanned for 1.5–2 hours in a PET/CT-scanner. The pressure from continuous infusion of artificial CSF (aCSF) promoted distribution of the tracer. The procedure was done under continuous intracranial pressure (ICP) monitoring. The catheter was made accessible both by externalization through the skin and through a subcutaneously placed sterile titanium port connected to the catheter. After image reconstruction, we used PMOD software to assess the tracer distribution throughout SAS. Internalisation of the catheter to a port enables survival studies. Previous studies performing ventriculography have placed a catheter trough brain cortex and parenchyma; such procedures may affect any behavioural or neurological evaluation, and have an increased risk of bleeding per- and post-operatively (Kaiser & Frühauf, 2007). ResultsThe PET-CT visualized tracer was evenly distributed in the SAS. Furthermore, the ICP measurement made it possible to adjust infusion speed within acceptable pressure levels. ConclusionThis new method can be useful for testing distribution of PET-tracers, antibiotics, chemotherapeutics and a wide range of other pharmaceuticals targeting the CNS and spinal cord in large animal models, and potentially later in human.

Development of Cardiovascular Dysfunction in a Rat Spinal Cord Crush Model and Responses to Serotonergic Interventions.

Selection of a proper spinal cord injury (SCI) rat model to study therapeutic effects of cell transplantation is imperative for research in cardiovascular functional recovery, due to the local harsh milieu inhibiting cell growth. We recently found that a crushed spinal cord lesion can minimize fibrotic scarring and grafted cell death compared with open-dura injuries. To determine if this SCI model is applicable for studying cardiovascular recovery, we examined hemodynamic consequences following crushed SCI and tested cardiovascular responses to serotonin (5-HT) or dopamine (DA) receptor agonists. Using a radio-telemetric system, multiple cardiovascular parameters were recorded prior to, 2, and 4 weeks after SCI, including resting mean arterial pressure (MAP) and heart rate (HR), as well as spontaneous or colorectal distension (CRD)-induced autonomic dysreflexia (AD). The results showed that this injury caused tachycardia at rest as well as the occurrence of spontaneous or artificially induced dysreflexic events. Four weeks post-injury, specific activation of 5-HT2A receptors by subcutaneous (s.c.) or intrathecal (i.t.) delivery of Dimethoxy-4-iodoamphetamine (DOI) remarkably increased resting MAP levels in a dose-dependent fashion. During CRD-induced autonomic dysreflexia, systemic administration of DOI alleviated the severity of bradycardia responsive to episodic hypertension. In contrast, selective stimulation of 5-HT1A receptors with 8-OH-DPAT or non-selective activation of DA receptors with apomorphine did not affect cardiovascular performance. Thus, crush injuries induce cardiovascular abnormalities in rats that are sensitive to 5-HT2A receptor stimulation, indicating a reliable SCI model to study how cell-based approaches impact the severity of autonomic dysreflexia and identify a possible target for pharmacological interventions.