Targeting Topics 16q1

Endogenous opioid activity in the anterior cingulate cortex is required for relief of pain.

Navratilova E, Xie JY, Meske D, Qu C, Morimura K, Okun A, Arakawa N, Ossipov M, Fields HL, Porreca F.

J Neurosci 35(18):7264-7271, 2015.

There are a number of neuronal circuits involved in the processing of pain, including those that control somatosensory, affective, and cognitive aspects of pain perception. Opioid signaling in the anterior cingulate cortex (ACC) plays a part in pain modulation – this area has also been implicated in the encoding of pain aversiveness. In order to examine the neuronal mechanisms of pain relief and the following reward, the authors of this paper administered 48 ng of Dermorphin-SAP (Cat. #IT-12) into the rostral ACC of rats. Saporin (Cat. #PR-01) was used as a control. The results illuminate the opioid pathway during pain treatment, and the dependence of nucleus accumbens dopaminergic transmission on upstream ACC opioid circuits during pain processing.

proBDNF and p75NTR Control Excitability and Persistent Firing of Cortical Pyramidal Neurons.

Gibon J, Buckley SM, Unsain N, Kaartinen V, Seguela P, Barker PA.

J Neurosci 35(26):9741-9753, 2015.

Principal neurons in the entorhinal cortex (EC) display persistent firing (PF) during working-memory tasks. Much of the communication between the hippocampus and the neocortex passes through the EC, and the EC also receives some cholinergic input from the medial septum and diagonal band of Broca. In this work the authors investigated the role of pro-brain-derived neurotrophic factor (proBDNF) and the p75 receptor in excitability and PF in the EC. The authors propose the proBDNF/p75 system as a regulator for pyramidal neuron excitability and PF in the EC, preventing runaway activity. Some of the western blot and current-clamp data was generated using Anti-p75 (Cat. #AB-N01; no concentration information provided).

Repeated Mu-Opioid Exposure Induces a Novel Form of the Hyperalgesic Priming Model for Transition to Chronic Pain.

Araldi D, Ferrari LF, Levine JD.

J Neurosci 35(36):12502-12517, 2015.

Repeated administration of mu-opioid receptor agonists can lead to persistent mechanical hyperalgesia. One current hypothesis is that a form of hyperalgesic priming is triggered by the repeated activation of these receptors. Classic hyperalgesic priming is associated with signaling via protein kinase Cε (PKε), which is mediated by isolectin-B4+ (IB4) nociceptors. In this work the authors eliminated the IB4+ nociceptors with a 3.2 μg intrathecal injection of recombinant IB4-SAP (Cat. #IT-10). The authors found that hyperalgesic priming induced through the use of DAMGO was dependent on protein kinase A activation rather than activation of PKε. This work demonstrates a novel model for hyperalgesic priming transitioning to chronic pain.

Roles of isolectin B4-binding afferents in colorectal mechanical nociception.

La JH, Feng B, Kaji K, Schwartz ES, Gebhart GF.

Pain 157(2):348-354, 2016.

Primary afferent neurons are often classified as peptidergic or non-peptidergic. One characteristic of the non-peptidergic neurons is that they bind isolectin-B4. In the spinal cord these neurons terminate mainly in inner lamina II. Non-peptidergic neurons in the spinal cord have been found to be involved in various aspects of pain response. In this work the authors examined the role of non-peptidergic neurons in the viscerosensory system. Rats received 1.5 μg of intrathecal recombinant IB4-SAP (Cat. #IT-10) between the L5 and L6 vertebrae. Saporin (Cat. #PR-01) was used as a control. While IHC demonstrated that a majority of viscerosensory L6 colon DRG neurons are IB4+, they do not play a significant role in colorectal mechano-nociception.

Phenotypic and functional characterization of Bst+/- mouse retina.

Riazifar H, Sun G, Wang X, Rupp A, Vemaraju S, Ross-Cisneros FN, Lang RA, Sadun AA, Hattar S, Guan MX, Huang T.

Dis Model Mech 8(8):969-976, 2015.

The belly spot and tail mutant mouse strain was first reported on in 1976. Among other phenotypic changes, it carries ocular mutations including retinal colobomas, reduced retinal ganglion cells (RGCs), and axon misrouting. In order to assess the use of this strain as a murine model for stem cell therapies of retinal degenerative diseases the authors performed a number of characterization experiments including electron microscopy, immunohistochemistry, testing of circadian rhythms, and morphological studies. Some of the immunohistochemistry was done using Anti-Melanopsin (Cat. #AB-N38) at a 1:5000 dilution.

Disruption of Spinal Noradrenergic Activation Delays Recovery of Acute Incision-Induced Hypersensitivity and Increases Spinal Glial Activation in the Rat.

Arora V, Morado-Urbina CE, Aschenbrenner CA, Hayashida KI, Wang F, Martin TJ, Eisenach JC, Peters CM.

Pain 17(2):190-202, 2016.

A significant percentage of patients who undergo surgery experience prolonged clinically impactful pain, reducing the quality of life and physical function. Disruption of the descending noradrenergic input has been hypothesized to be important to the generation of this type of pain state. Using an acute incision model, the authors administered 5 μg ofAnti-DBH-SAP (Cat. #IT-03) to the L5-L6 interspace of rats. Mouse IgG-SAP (Cat. #IT-18) was used as a control. Lesioned animals demonstrated a significant increase in mechanical hypersensitivity, and a smaller increase in thermal hypersensitivity. This and other results suggest that spinally projecting noradrenergic pathways are necessary for normal recovery from surgical incision, and possibly other types of pain.

Denervation of the Lacrimal Gland Leads to Corneal Hypoalgesia in a Novel Rat Model of Aqueous Dry Eye Disease.

Aicher SA, Hermes SM, Hegarty DM.

Invest Ophthalmol Vis Sci 56(11):6981-6989, 2015.

One result of functional disruption of the tear gland is dry eye disease (DED), which represents a group of disorders rather than a singular one. DED manifests itself in altered responses to noxious corneal stimulation, but many of these patients do not actually have dry eyes or tear gland dysfunction. In order to investigate what circuits are involved in DED the authors created two models, one of which used the ablation of p75 receptor-expressing neurons innervating the extraorbital lacrimal gland. Rats received 2.5 μg of 192-IgG-SAP (Cat. #IT-01) directly into the left extraorbital lacrimal gland. Tear production in the lesioned animals was normal, and responses to noxious cold stimuli were impaired. This accompanied by unchanged fiber density indicates that the nociceptive signaling was affected on a molecular level.

Cholinergic deafferentation of the hippocampus causes non-temporally graded retrograde amnesia in an odor discrimination task.

Koppen JR, Stuebing SL, Sieg ML, Blackwell AA, Blankenship PA, Cheatwood JL, Wallace DG.

Behav Brain Res 299:97-104, 2016.

The memory impairments experienced in neurodegenerative disorders such as Alzheimer’s disease have been well documented. One theory attributes these impairments to the loss of cholinergic basal forebrain neurons, a hallmark of Alzheimer’s disease. Some patients experience a retrograde amnesia, in which older memories are relatively stable and more recent memories are frequently lost. The temporal relationship of memories to disease onset has not been definitively established. In this work the authors administered either 150 ng or 200 ng of 192-IgG-SAP (Cat. #IT-01) into the medial septum of rats. Using a string-pulling task, a model for temporal learning was established. The results indicate that cholinergic projections originating in the medial septum are involved in long-term memory retrieval, and that loss of these neurons does not create a temporal type of amnesia.

Selective inhibition of dopamine-beta-hydroxylase enhances dopamine release from noradrenergic terminals in the medial prefrontal cortex.

Devoto P, Flore G, Saba P, Frau R, Gessa GL.

Brain Behav 5(10):e00393, 2015.

Dopamine-beta-hydroxylase (DBH) is a neuronal enzyme that is a potential target for the treatment of cocaine abuse, alcohol dependence, and eating disorders. Here the authors administered 5 μg of icv Anti-DBH-SAP (Cat. #IT-03) to rats, and assessed the effect of the dopaminergic lesion on levels of extracellular dopamine. Mouse IgG-SAP (Cat. #IT-18) and saporin (Cat. #PR-01) were used as controls. Extracellular levels of dopamine were significantly increased in both lesioned animals and those treated with the DBH inhibitor nepicastat. Clonadine could reverse the nepicastat effect, but not the effect ofAnti-DBH-SAP treatement. The data demonstrate a mechanism for the synergistic effect of cocaine on nepicastat-induced dopamine release.

Treatment Efficacy of NGF Nanoparticles Combining Neural Stem Cell Transplantation on Alzheimer’s Disease Model Rats.

Chen Y, Pan C, Xuan A, Xu L, Bao G, Liu F, Fang J, Long D.

Med Sci Monit 21:3608-3615, 2015.

NSC (neural stem cell) transplants into animals have been shown to compensate for the loss of cholinergic cells in the basal forebrain, a hallmark of Alzheimer’s disease. One hurdle to overcome is the actuation of NSC differentiation into the specific replacement cells needed. NGF has been shown to induce this differentiation, but it has a very short half-life and does not permeate tissue very effectively. In this work the authors administered 5 mL of icv 192-IgG-SAP (Cat. #IT-01) to rats, followed by a graft of NCSs in the presence of NGF nanoparticles with a polymer coating. Rats receiving both NCSs and NGF nanoparticles showed significantly improved memory and learning functions as compared to control animals.

Basal Forebrain Cholinergic Deficits Reduce Glucose Metabolism and Function of Cholinergic and GABAergic Systems in the Cingulate Cortex.

Jeong da U, Oh JH, Lee JE, Lee J, Cho ZH, Chang JW, Chang WS.

Yonsei Med J 57(1):165-172, 2016.

A common result of cholinergic neuron loss in the hippocampus and cortical regions due to Alzheimer’s disease is a reduction in glucose metabolism. The authors examine the interaction between the cell loss and metabolic changes. Rats received 5-μg bilateral cortical injections of 192-IgG-SAP (Cat. #IT-01), were subject to water maze testing, and analyzed by 18F-2-fluoro-2-deoxyglucose positron emission tomography. Lesioned animals displayed decreased learning performance and reduced metabolic activity in the cingulate cortex.

Method for Confirming Cytoplasmic Delivery of RNA Aptamers.

Dickey DD, Thomas GS, Dassie JP, Giangrande PH.

Methods Mol Biol 1364:209-217, 2016.

Single-stranded RNA aptamers have the potential to be utilized as therapeutics in numerous diseases, and can be used for the delivery of RNA interference modulators. One roadblock encountered has been the lack of a method to confirm delivery of a payload by the aptamers to the cytoplasm of cells. In this work the authors describe a protocol involving combining biotinylated aptamers and Streptavidin-ZAP (Cat. #IT-27) at a 4:1 molar ratio, then testing the conjugates in an in vitro cytotoxicity assay. FGF-SAP (Cat. #IT-38) was used as a control.