sfn2019

Grayson VS, Han Y, Guedea AL, Jovasevic V, Gao C, Apkarian A, Radulovic JM (2019) The role of subcortical hippocampal inputs in contextual memory formation. Neuroscience 2019 Abstracts 786.03. Society for Neuroscience, Chicago, IL.

Summary: The role of cortical efferents to the hippocampus in the formation of episodic-like memory is well established, however, less is known about the contribution of subcortical memory circuits to memory. In the present study, we studied the roles of several subcortical inputs into the dorsal hippocampus in mouse models of contextual fear conditioning, extinction, and reinstatement. Fear conditioning was induced by a single exposure of mice to a context followed by foot shock. Subsequently, mice were exposed to daily extinction trials. After significant reduction of freezing, indicating successful extinction, mice were exposed to a brief reminder shock and re-tested in the conditioning context. Circuit manipulations were performed by chemogenetic silencing with the inhibitory designer receptor exclusively activated by designer drugs (DREADD) hM4(Gi) or targeted cholinergic depletion induced by 192 IgG-saporin, at different stages of fear conditioning, extinction, and reinstatement. We identified projection- and neurotransmitter-specific roles of discrete circuits, indicating complex regulation of fear-inducing memories by subcortical afferents.

Related Products: 192-IgG-SAP (Cat. #IT-01)

Lee J, Seo Y, Shin J, Kong C, Na Y, Chang W, Chang J (2019) Increased transplantation efficacy of mesenchymal stem cell by focused ultrasound and improvement of the spatial memory in the 192 IgG-saporin rat model. Neuroscience 2019 Abstracts 048.01. Society for Neuroscience, Chicago, IL.

Summary: Introduction: Stem cell therapy has been found to have therapeutic effects in neurodegenerative disease, but traditional transplant methods, such as parenchymal or intravenous injection, possess limitations like secondary injuries, infection, and low survival rate of stem cells in the brain. Meanwhile, recently the focused ultrasound(FUS) was found to have promising results regarding transplantation of stem cells into the rat brain. However, the mechanism of stem cell transplantation with FUS and possibility of cognitive recovery remain elusive. Therefore, this study investigates a possibility for non-invasive focused ultrasound use in stem cell transplantation into the brain of dementia rat model. Materials & methods: We divided rats into five groups: Normal, Lesion, Cell only, FUS + Cell, and FUS only. We used 192 IgG-saporin for degeneration of basal forebrain cholinergic neuron and it was injected into all rats except for the normal group. After a week, 5p mesenchymal stem cells (MSC: 3*106/200ul) were injected in the tail vein of all rats of the cell only and FUS + Cell group, and the FUS + Cell group received the FUS three hours before cell transplantation. FUS was applied with parameters of 0.25Mpa, 300s (Targeted hippocampal region: AP -3.5, ML ±2). And last, FUS only group was received only FUS without any treatment. Five weeks after transplantation, rats performed the Morris water maze test. Results: MSC were detected in both cell only and FUS + Cell group of the hippocampus region. After comparing FUS+MSC & cell only rats, it was confirmed that FUS increases MSC homing in the sonicated rat’s brain. In addition, the most effective memory restoration occurred in the FUS + Cell group. Moreover, the FUS + Cell group exhibited better recall of the platform position than the other groups. And FUS only group did not recover. Conclusion: Noninvasive FUS can increase the efficacy of stem cell delivery. And memory impairment due to cholinergic denervation can be effectively improved by cell transplantation with FUS. The results of this study suggest possibility of stem cell homing and therapeutic effects of the FUS in dementia rat model. However, further study regarding the function of stem cells transplanted in the brain and a more detailed mechanism of stem cell homing by FUS is needed.

Related Products: 192-IgG-SAP (Cat. #IT-01)

Osterlund JR, BLackwell AA, Lipton M, Castillo V, Kartje GL, Tsai S-Y, Wallace DG (2019) Selective loss of septohippocampal cholinergic projections is associated with more circuitous homeward progressions. Neuroscience 2019 Abstracts 789.11. Society for Neuroscience, Chicago, IL.

Summary: Rodents rely on self-movement cues as a source of information to maintain spatial orientation during exploration. The vestibular system provides a source of self-movement cues that are processed by the septohippocampal cholinergic system, and when damaged, disruptions in movement organization are observed. The current study examined the effects of medial septum infusion of 192 IgG-saporin on movement organization during a single exploratory session that limited rats to using only self-movement cues. Rats organize their exploratory behavior into stops and progression. Although stops occur throughout the environment, they tend to cluster within a restricted area indicative of home base establishment. In the current study, movement organization characteristics and home base stability were similar between the lesion and sham groups. However, the lesion group exhibited greater path circuity during progressions returning to the home base. Increases in path circuitry have been implicated in spatial disorientation, indicating a role for medial septum cholinergic projections in processing self-movement cues to maintain spatial orientation. These results provide a foundation for future work to investigate the efficacy of interventions that enhance neuroplasticity within the septohippocampal cholinergic system.

Related Products: 192-IgG-SAP (Cat. #IT-01)

Wang S, Kim M, Ong K, Pae E-K, Chung M-K (2019) Nociceptors expressing TRPV1 and trigeminal nucleus neurons expressing NK1 mediate orthodontic pain. Neuroscience 2019 Abstracts 052.10. Society for Neuroscience, Chicago, IL.

Summary: Orthodontic force produces mechanical irritation and inflammation in periodontium, which inevitably accompanies pain. Despite its high prevalence, treatment of orthodontic pain is not effective. Determining detailed neural mechanisms involving peripheral and central nervous system should be critical to improve the management of orthodontic pain. Periodontal ligament is projected by peptidergic nociceptors, which is enriched with transient receptor potential vanilloid 1 (TRPV1), a receptor for capsaicin. Trigeminal subnucleus caudalis (Vc), is critical for relaying orofacial nociceptive signal into brain. A group of second- order neurons in the superficial dorsal horn of Vc express neurokinin 1 receptor (NK1), a receptor for substance P, and receive inputs from peptidergic nociceptors. However, the contribution of these nociceptive neurons to orthodontic pain has not been determined. Orthodontic force of 10g produced reliable tooth movement in mice. Orthodontic pain was evaluated by measuring mouse grimace scale (MGS) and bite force (BF), which could represent spontaneous pain and chewing-evoked pain, respectively. Orthodontic force increased MGS and decreased BF, which peaked at 1d and returned near to sham level at 7d. Using targeted chemical ablation of specific subsets of neurons, we determined the contribution of TRPV1+ nociceptors and NK1+ Vc neurons to orthodontic pain behaviors in mice. Ablation of TRPV1+ nociceptors by injecting resiniferatoxin into trigeminal ganglia significantly attenuated orthodontic force assessed by MGS and BF. Chemical ablation of NK1+ Vc neurons by injecting saporin conjugated with substance P into Vc also significantly reduced the extent of changes in MGS and BF by orthodontic force. These results suggest that TRPV1+ trigeminal nociceptors and NK1+ Vc neurons constitute a major neural pathway for transmission of orthodontic pain, which is a fundamental neural mechanism of orthodontic pain transmission. The new mouse model of orthodontic pain will be useful for mechanistic study to develop novel approaches for painless orthodontics.

Related Products: SSP-SAP (Cat. #IT-11)

Galvan MA, Shramm PA, Bouajram R, Lappi DA, Ancheta LR (2019) A high efficacy selection method for transfected cells utilizing recombinant isolectin B4-saporin. Neuroscience 2019 Abstracts 794.10. Society for Neuroscience, Chicago, IL.

Summary: Transfection protocols often rely on the use of antibiotics for the selection of transfected cells and has become the accepted approach for in vitro research and therapeutic applications. Antibiotics have several shortcomings such as cost, continuous use, and harmful effects — even on the transfected cell population. In addition, selection pressures are often inefficient and fail to provide a population of cells that express the gene of interest (GOI) at high levels. We have used three separate GOI’s to select for solely high-expressing transfectants using targeted toxin selection pressure. Normal Rat Kidney Cells (KNRK) were individually transfected to express green fluorescent protein (GFP), melanopsin or the low-affinity nerve growth factor receptor (p75) using an innovative new transfection delivery vector called pGEI. The results from various assays were utilized to visually determine the expression rate and pattern of the targeted toxin selection method. Melanopsin and p75 — a photopigment and nerve growth factor, respectively — were of great interest to express in our transfected cells as a means to study their role in the development and function of neurons. The delivery vector, pGEI, removes resident Galalpha(1-3)Gal epitopes from non- human mammalian cell surfaces. This residue is the target of recombinant Isolectin B4 – Saporin (IB4-SAP), a selective targeted toxin. IB4-SAP is extremely potent, with an EC50 in the low picomolar range for alpha-D-galactopyranoside expressing cells in vitro. The cells with the highest expression of the inserted vector, and therefore the GOI, will have these residues removed. Those that fail to express the vector or do not express the vector in high enough amounts, will not have all the residues removed, and will be targeted and eliminated via IB4-SAP. This method of selection provides a means of purifying the highest- expressing transfected populations using a more cost-effective and time-saving approach.

Related Products: IB4-SAP (Cat. #IT-10)

Andrén A, Adermark L, Söderpalm B, Ericson M (2019) An acetylcholine-dopamine interaction in the rat nucleus accumbens and its tentative involvement in ethanol’s dopamine-liberating effect. Neuroscience 2019 Abstracts 079.08. Society for Neuroscience, Chicago, IL.

Summary: Alcohol use disorder is a chronic, relapsing brain disorder associated with serious medical consequences leading to preterm death. Although few in number, cholinergic interneurons (CIN) have arisen as an important cell population within the nucleus accumbens (nAc) that may exert a regulatory impact on dopamine (DA) neurotransmission locally. A defect in CIN have been suggested to be involved in psychiatric diseases such as alcohol addiction. The mechanisms through which endogenous cholinergic activity modulates DA release in response to ethanol administration and its role in development of addiction is not known. In this project, the aim was to study if acetylcholine (ACh) can influence DA release locally in the nAc and if so, through which receptor population(s) this effect is mediated. Further, we wanted to determine the role of ACh in ethanol-induced DA elevation.Using reversed in vivo microdialysis, the acetylcholinesterase inhibitor physostigmine was administered locally in the nAc of male Wistar rats followed by addition of either the muscarinic ACh receptor inhibitor scopolamine or the nicotinergic ACh receptor inhibitor mecamylamine. Subsequently, ethanol was perfused following local pretreatment with scopolamine or mecamylamine, using the same methodology. An immunotoxin, anti-ChAT-saporine, was infused locally into the nAc of a subset of male Wistar rats to selectively lesion CIN, followed by local ethanol administration via reversed in vivo microdialysis. Local administration of physostigmine induced a DA elevation within the nAc, an effect blocked by scopolamine but not by mecamylamine. Local administration of ethanol increased DA levels. Scopolamine pretreatment non-significantly attenuated the ethanol-induced DA elevation, whereas pretreatment with mecamylamine had no effect. Preliminary results indicate a minor attenuation of the DA elevation observed after local administration of ethanol in toxin-treated animals, as compared to sham-treated controls. Taken together, these results suggest that ACh increases extracellular DA levels in nAc in vivo, an effect mediated by muscarinic ACh-receptors and not by nicotinic ACh-receptors. Considering that scopolamine moderately attenuated ethanol-induced DA output and that lesioning of CIN appeared to hamper DA release in response to ethanol, ACh release from CIN within the nAc may be partially involved in ethanol-induced DA release in nAc.

Related Products: Anti-ChAT-SAP (Cat. #IT-42)

Chew C, Sengelaub DR (2019) Exercise is neuroprotective following partial motoneuron depletion via androgen action at the target muscle. Neuroscience 2019 Abstracts 134.13. Society for Neuroscience, Chicago, IL.

Summary: We have previously demonstrated that partial depletion of motoneurons innervating the quadriceps muscles induces dendritic atrophy in remaining motoneurons. Furthermore, systemic treatment with supplemental androgens is neuroprotective, and dendritic atrophy following partial motoneuron depletion is attenuated. Blockade of the androgen receptor at the target muscle prevents the neuroprotective effects on motoneuron dendrites in rats treated with supplemental androgens. We have recently shown that exercise is also neuroprotective on motoneuron dendrites following partial motoneuron depletion, and circulating levels of androgens have previously been shown to increase following exercise. Together, these results suggest that exercise may be neuroprotective via androgen action at the muscle. In the present study, we examine whether blockade of androgen receptors at the target musculature would prevent the neuroprotective effects of exercise on dendrites following partial motoneuron depletion. Motoneurons innervating the vastus medialis muscle in adult male rats were selectively killed by intramuscular injection of cholera toxin-conjugated saporin. Simultaneously, some saporin-injected rats were given implants of the androgen receptor antagonist hydroxyflutamide, either directly at the quadriceps musculature or interscapularly as a systemic control. Following saporin injections, some animals were allowed free access to running wheels attached to their home cages. Four weeks later, motoneurons innervating the ipsilateral vastus lateralis muscle were labeled with cholera toxin-conjugated horseradish peroxidase, and dendritic arbors were reconstructed in three dimensions. Compared with untreated males, partial motoneuron depletion resulted in decreased dendritic length in remaining quadriceps motoneurons. Early data suggests that following partial motoneuron depletion, exercised males with androgen receptor blockade at the quadriceps show dendritic lengths that are significantly shorter than those of exercised males with no treatment, while dendritic lengths in exercised males with interscapular implants do not differ from those of exercised animals without implants. These findings suggest that exercise may be protective against dendritic atrophy via androgens binding at the target musculature.

Related Products: CTB-SAP (Cat. #IT-14)

Truckenbrod LM, Bumanglag AV, Chun E, Hernandez A, Federico QP, Maurer AP, Sloviter RS, Burke SN (2019) Targeted hippocampal GABA neuron ablation produces hippocampal sclerosis, epilepsy, and dissociable effects on the Morris water maze and object-place paired association tasks. Neuroscience 2019 Abstracts 158.03. Society for Neuroscience, Chicago, IL.

Summary: An epileptogenic role for hippocampal GABAergic dysfunction has recently been reported (Chun et al. 2019). Specifically, selective ablation of hippocampal GABA neurons by Stable Substance P-saporin (SSP-saporin) conjugate caused dorsal hippocampal sclerosis and chronic epilepsy, without involving convulsive status epilepticus or widespread brain injury. The current study assessed cognitive function in chronically epileptic SSP-saporin-treated rats and their vehicle-injected controls ~8 months following injection. First, rats completed the Morris Water Maze test of spatial learning and memory (Morris et al., 1982). Animals then underwent testing with the object-place paired association (OPPA) task, which requires the hippocampus as well as functional connectivity between the hippocampus and cortical areas (Jo and Lee, 2010; Hernandez et al., 2017), and then a simple object discrimination task. Interestingly, both controls and rats with dorsal hippocampal sclerosis and chronic epilepsy were able to learn the location of the hidden platform in the Morris Water Maze task and could also acquire a simple pair-wise object discrimination. However, epileptic rats with dorsal hippocampal sclerosis were significantly impaired on the OPPA task, which requires animals to integrate spatial location memory with a correct object choice and is a more sensitive measure of cognitive dysfunction (Hernandez et al., 2015). These data indicate that, similar to humans with medial temporal lobe epilepsy, selective hippocampal sclerosis and epilepsy in this model do not result in global cognitive decline. Rather, cognitive functions that require functional connectivity between the hippocampus and cortical areas are selectively affected.

Related Products: SSP-SAP (Cat. #IT-11)

ATS Poster of the Year Winner. Read the featured article in Targeting Trends.

See Also:

• Chun E et al. Targeted hippocampal GABA neuron ablation by stable substance P-saporin causes hippocampal sclerosis and chronic epilepsy in rats. Epilepsia 60(5):e52-e57, 2019.