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Contribution of small diameter non-peptidergic primary afferent neurons to central neuropathic pain in a new, more clinically relevant mouse model of multiple sclerosis
Nguyen KL, Lamerand SR, Deshpande RP, Taylor BK (2021) Contribution of small diameter non-peptidergic primary afferent neurons to central neuropathic pain in a new, more clinically relevant mouse model of multiple sclerosis. Neuroscience 2021 Abstracts P377/07. Society for Neuroscience, Virtual.
Summary: Over 50% of multiple sclerosis (MS) patients suffer from neuropathic pain (MSNP). Current treatments give inadequate relief due to incomplete understanding of underlying mechanisms. Recent electrophysiological recordings of primary afferent neurons (PAN) in the dorsal root ganglion (DRG) following experimental autoimmune encephalomyelitis (EAE), a mouse model of MS, revealed increased afterhyperpolarization in small-diameter fibers. These data form the premise of our goal to understand the contribution of small-diameter (peptidergic or non-peptidergic) PANs to MSNP. Arguably the most common method to induce EAE is administration of myelin oligodendrocyte glycoprotein (MOG) to generate an autoimmune response targeting the myelin sheath. A MOG fragment is typically given with two adjuvants: complete Freund’s adjuvant (CFA) to boost immunogenicity and pertussis toxin (PTX) to breakdown the blood-brain barrier and facilitate CNS immune cell infiltration. However, PTX can disrupt G-protein coupled receptors, cause pain, and alter autoimmune response gene expression. In 10-week-old C57BL/6 mice, we conducted the first rigorous comparison of a classic PTX EAE model with the novel non-PTX (nPTX) EAE model. We found that both PTX and nPTX EAE mouse models showed the same degree of: 1) motor deficits; 2) plantar hindpaw mechanical and cold hypersensitivity (except cold hypersensitivity resolved more quickly after PTX EAE than nPTX EAE); and 3) lumbar spinal cord demyelination. Unlike most rodent models of MS including PTX EAE, the nPTX EAE group exhibited somatosensory cortex demyelination, a core feature of MS in human patients and cold hypersensitivity. We suggest nPTX EAE to be the most clinically relevant rodent model available to study not only MSNP, but MS in general. To evaluate the contribution of peptidergic and non-peptidergic neurons to MSNP, we induced nPTX EAE. After 12 days we administered capsaicin (10µg/mouse, i.t.) or IB4-saporin (1.5µg/mouse, i.t.) to primarily ablate peptidergic or nonpeptidergic C-fibers, respectively. Ablation efficacy was successfully confirmed with dramatic loss in DRG of TRPV1/CGRP immunoreactivity (peptidergic C-fibers) following capsaicin, and IB4 immunoreactivity (nonpeptidergic C-fibers) following IB4-saporin. IB4-saporin, but not capsaicin, partially reduced mechanical hypersensitivity and reversed cold hypersensitivity within 9 days. These data suggest nonpeptidergic but not peptidergic C-fibers contribute to MSNP. Our next studies will use genetic knockout, chemogenetic, and optogenetic strategies using MrgprdCreER mice to modulate the activity of nonpeptidergic C-fibers.
Related Products: IB4-SAP (Cat. #IT-10)
The role of the patch compartment of striatum in reward-driven behaviors
Ahn J, Christy DJ, Horner K (2021) The role of the patch compartment of striatum in reward-driven behaviors. Neuroscience 2021 Abstracts P747/06. Society for Neuroscience, Virtual.
Summary: The striatum is a neural structure that plays a critical role in cognitive functions, behavioral decision-making, and reward generation. The striatum exhibits a heterogeneous composition, containing neurons belonging to the patch compartment—which is thought to be involved in habitual reward-related behaviors—surrounded by neurons belonging to the matrix compartment—which is thought to be involved in adaptive motor control. Additionally, the striatum is further subdivided into the dorsolateral striatum (DLS) and the dorsomedial striatum (DMS), each with their own patch and matrix compartments. The DMS has been associated with goal-oriented behavior seen during the initial stages of addiction. Conversely, the DLS has been associated with habitual behaviors seen during late-stage addictive behaviors that are inflexible. It is thought that drug addiction is initially mediated by the DMS before DLS activity becomes predominant. Previously, it has been shown that the patch compartment of the DLS is necessary for development of habitual behavior, but the role of the patch compartment of the DMS is less clear. Our study intends to demonstrate that selective ablation of DMS patch compartment neurons will result in a negative impact on the initial development of reward-driven behaviors during the early stages of drug addiction. Since patch compartment neurons express a high level of mu opioid receptors compared to the surrounding matrix, we used dermorphin-saporin, a toxin that selectively destroys mu opioid receptor-containing neurons to target patch compartment neurons in the DMS and DLS for ablation. Following infusion in the DMS or DLS with dermorphin-saporin (17 ng/μl) or vehicle, rats were trained to self-administer cocaine (0.4 mg/kg/infusion) on progressive ratio schedule of reinforcement, starting with fixed ratio of 1 and ending with a fixed ratio of 5. Ablation of the patch compartment altered the level of responding for cocaine as the schedule of reinforcement became progressively labor-intensive. These data suggest that the patch compartment contributes to reward-driven behaviors.
Related Products: Dermorphin-SAP / MOR-SAP (Cat. #IT-12)
A brief history of saporin and its contributions to neuroscience
Shramm PA, Ancheta LR, Bouajram R, Lappi DA (2021) A brief history of saporin and its contributions to neuroscience. Neuroscience 2021 Abstracts J002.11. Society for Neuroscience, Virtual.
Summary: When investigating the origins of targeted toxins (a drug, therapy, or scientific tool directed to a unique extracellular target), an appropriate place to begin is with the Nobel Prize-winning work of Paul Ehrlich and his concept of the “magic bullet.” Over 100 years later, the use of targeted toxins to perform molecular neurosurgery has become a vital practice that allows researchers to observe changes in organisms after eliminating a neuronal population. A prime example of this practice is the specific targeting of cholinergic neurons in the basal forebrain to mimic Alzheimer’s disease (AD). The research tool designed for this purpose is 192-IgG-Saporin, an antibody conjugated to the ribosome-inactivating protein (RIP) Saporin. Researchers have used this targeted toxin for over 30 years. A 2019 publication by Verkhratsky et al. reviews AD models and states this is the only lesion model that specifically targets cholinergic neurons. In 1983, during a quest to find the optimal payload for a targeted toxin, Fiorenzo Stirpe and colleagues discovered Saporin, a plant protein isolated from the common soapwort plant Saponaria officinalis. Unlike ricin and abrin, Saporin does not have a binding chain and cannot enter a cell on its own. Scientists have devised new ways to use Saporin to advance their research and drug development activities. Just a few examples include: 1. A novel suicide gene therapy approach that uses a vector encoding a double-stranded DNA aptamer to deliver the gene encoding Saporin, 2. Delivery of Saporin encapsulated in a nanotechnology system for development of cancer treatments, 3. A deeper understanding of the difference between pain and itch and the relevant pathways, and 4. Development of a stable epilepsy animal model that is used for screening specific treatments that will lead to micro-methods to eliminate the disease. This review will focus on Saporin as the payload delivered to cells. Targeted toxins (typically targeted by an antibody or peptide chemically linked or genetically fused) provide robust tools for neuroscience where ablation of specific neuronal populations is used to study behavior and function. Saporin is an ideal molecule because of its extreme resistance to high temperatures and denaturation, retention of catalytic activity after conjugation, and lack of a binding chain to allow entrance to the cytoplasm of cells on its own. As a result, it is one of the most studied RIPs used for its vigorousness, potency, safety, and ease of use in the laboratory. The information presented will shed light on the history of Saporin, current applications, and what the future holds for this protein in the neuroscience field.
Related Products: Saporin (Cat. #PR-01)
Effects of age on sexually dimorphic food protection behavior associated with hippocampal cholinergic deafferentation.
Osterlund Oltmanns JR, Schaeffer EA, Blackwell AA, Pietrucha SA, Yang H, Tasi S, Kartje GL, Wallace D (2021) Effects of age on sexually dimorphic food protection behavior associated with hippocampal cholinergic deafferentation. Neuroscience 2021 Abstracts P210.07. Society for Neuroscience, Virtual.
Summary: Loss of hippocampal cholinergic projection originating from basal forebrain structures has been associated with the progression of Dementia of the Alzheimer’s Type. The role of these fibers in information processing deficits has been debated; however, spontaneous behaviors such as food protection have been observed to dissociate the contributions of hippocampal and cortical cholinergic function. Sexual dimorphism and age are critical factors in the progression of neurodegenerative disorders, yet these factors have not been evaluated in food protection behavior. The current study infused the immunotoxin 192-IgG-Saporin bilaterally into the medial septum to produce selective cholinergic deafferentation of the hippocampal formation. Female and male rats received infusion of the immunotoxin at either three or 18 months of age. Testing in the in the food protection paradigm began six weeks after the surgery. During the five days of testing, rats received two food protection sessions. Each of these sessions involved the rat (dodger) being placed in a transparent cylinder with a same sex conspecific (robber). The dodger was given a one-gram food item to consume, while the robber made multiple attempts to obtain the food item. The number, success rate, and type of food protection behaviors were recorded across all food protection sessions. Rats also received a third session each day in which the latency to consume the food item was recorded in the absence of the conspecific. Preliminary results indicate that sex and age interact with cholinergic hippocampal deafferentation to influence the organization of food protection behaviors. These observations establish a foundation for future work investigating novel therapeutic interventions that target neuroplasticity within spared cholinergic systems.
Related Products: 192-IgG-SAP (Cat. #IT-01)
Nociception impedes grasping recovery in the spinal cord injured rat.
Walker J, Kim T, Giszter S, Detloff MR (2021) Nociception impedes grasping recovery in the spinal cord injured rat. Neuroscience 2021 Abstracts P372.04. Society for Neuroscience, Virtual.
Related Products: IB4-SAP (Cat. #IT-10)
Revisiting the sigma-1 receptor as a biological target to treat affective and cognitive disorders
Sałaciak K, Pytka K (2022) Revisiting the sigma-1 receptor as a biological target to treat affective and cognitive disorders. Neurosci Biobehav Rev 132:1114-1136. doi: 10.1016/j.neubiorev.2021.10.037
Objective: This review focuses on the sigma-1 receptor as a target for treatment of depression and cognitive disorders.
Summary: Sigma-1 receptor ligands, and predominantly agonists, might be the next generation of psychotherapeutic agents.
Usage: 192-IgG-SAP is listed as a neurotoxin that induced a memory impairment in rats based on the Morris water maze.
Related Products: 192-IgG-SAP (Cat. #IT-01)
See Also:
A neuropeptide code for itch
Chen ZF (2021) A neuropeptide code for itch. Nat Rev Neurosci 22(12):758-776. doi: 10.1038/s41583-021-00526-9
Related Products: Bombesin-SAP (Cat. #IT-40)
Role of microglia and astrocytes in spinal cord injury induced neuropathic pain
Miranpuri GS, Bali P, Nguyen J, Kim JJ, Modgil S, Mehra P, Buttar S, Brown G, Yutuc N, Singh H, Wood A, Singh J, Anand A (2021) Role of microglia and astrocytes in spinal cord injury induced neuropathic pain. Ann Neurosci 28(3-4):219-228. doi: 10.1177/09727531211046367
Summary: Given the severity and incapacitating effects of spinal cord injury neuropathic pain (SCINP), it is imperative to study the pathways involved and find new therapeutic targets in coordination with stem cell research, and to develop a new gold-standard in SCINP treatment. Chronic inflammation by microglia, when targeted with Mac-1-SAP, helps in pain reversal.
Related Products: Mac-1-SAP rat (Cat. #IT-33)
Evaluation of the activity of choline acetyltransferase from different synaptosomal fractions at the distinct stages of spatial learning in the morris water maze
Storozheva ZI, Zakharova EI, Proshin AT (2021) Evaluation of the activity of choline acetyltransferase from different synaptosomal fractions at the distinct stages of spatial learning in the morris water maze. Front Behav Neurosci 15:755373. doi: 10.3389/fnbeh.2021.755373
Objective: To examine the role of hippocampal and cortical ACh in the acquisition, consolidation, storage, retention and adaptive flexibility of new, recent and remote memory traces in spatial learning models.
Summary: The application of functional ablation or stimulation techniques is necessary. The approach used can be regarded as one of the possible ways of delineating temporal stages of spatial learning and could be applied in the studies of other signalling pathways.
Usage: Selective loss of septohippocampal and/or corticopetal cholinergic projections has been shown to cause attention deficit.
Related Products: 192-IgG-SAP (Cat. #IT-01)
See Also:
- McGaughy J et al. Behavioral vigilance following infusions of 192 IgG-saporin into the basal forebrain: selectivity of the behavioral impairment and relation to cortical AChE-positive fiber density. Behav Neurosci 110:247-265, 1996.
- Lehmann O et al. A double dissociation between serial reaction time and radial maze performance in rats subjected to 192 IgG-saporin lesions of the nucleus basalis and/or the septal region. Eur J Neurosci 18(3):651-666, 2003.
Heart failure impairs mood and memory in male rats and down-regulates the expression of numerous genes important for synaptic plasticity in related brain regions
Parent MB, Ferreira-Neto HC, Kruemmel AR, Althammer F, Patel AA, Keo S, Whitley KE, Cox DN, Stern JE (2021) Heart failure impairs mood and memory in male rats and down-regulates the expression of numerous genes important for synaptic plasticity in related brain regions. Behav Brain Res 414:113452. doi: 10.1016/j.bbr.2021.113452
Objective: To assess the effects of heart failure (HF) on genetic markers of synaptic plasticity in brain areas critical for memory and mood, and to assess the effects of severely reduced ejection fraction (≤40 %) on cognition regulation.
Summary: Collectively, the present findings provide support for the growing consensus that HF is not only a neurohumoral cardiovascular problem but is also a disorder of mood and memory.
Related Products: 192-IgG-SAP (Cat. #IT-01)
See Also:
- Dobryakova YV et al. Intracerebroventricular administration of 192IgG-saporin alters expression of microglia-associated genes in the dorsal but not ventral hippocampus. Front Mol Neurosci 10:429, 2018.
- Dobryakova YV et al. Cholinergic deficit induced by central administration of 192IgG-Saporin is associated with activation of microglia and cell loss in the dorsal hippocampus of rats. Front Neurosci 13:146, 2019.