targeted-toxins

Yegla B, Francesconi JA, Forde JC, Parikh V (2015) Cholinergic contributions to PASA and functional compensation in rats. Neuroscience 2015 Abstracts 253.11/V29. Society for Neuroscience, Chicago IL.

Summary: Neuroimaging studies have indicated increased recruitment of prefrontal regions coupled to reduced activation of posterior regions in task-performing older adults. This shift of activity in cortical networks is described as posterior-anterior shift in aging (PASA). What cellular mechanisms contribute to PASA and how it provides functional compensation for age-related decline in cognitive capacities remains unknown? Cortically-projecting forebrain cholinergic neurons modulate cortical networks and facilitate attentional processes. Here we examined whether cortical cholinergic inputs contribute to PASA expression and maintenance of attentional capacities in aging. Young (3 months) and aged (24 months) Wistar rats were trained in a sustained attention task (SAT) that requires them to distinguish between signal and non-signal events. After attaining criterion performance (_70% correct responses for 3 consecutive sessions), rats received bilateral infusions of cholinoselective immunotoxin 192-IgG SAP either into the prefrontal cortex (PFC) or posterior parietal cortex (PPC) to produce partial cholinergic deafferentation. Control animals were infused with saline. Following behavioral testing 4 weeks post-surgery, animals were perfused 45-min after the last session to examine changes in neuronal activity in the PFC and PPC using c-fos immunohistochemistry. Partial prefrontal cholinergic deafferentation in aged rats produced robust deficits in response accuracy on signal trials as compared to aged sham (p=0.04) and young lesion (p=0.03) rats. In general, c-fos expressing neurons were higher in the PFC of aged rats as compared to young rats. Although prefrontal neuronal activity did not differ between the aged sham and PFC lesion group, there was a trend for a higher neuronal activity in the PPC of the latter. Surprisingly, attentional performance displayed a negative correlation with the prefrontal activity. Neuronal activity in the PPC did not correlate with performance. PPC-infused aged rats displayed no lesion effect on SAT and performed better than aged rats infused with 192 IgG-SAP into the PFC (p=0.04). Moreover, partial loss of cholinergic inputs into the PPC reduced PFC recruitment as compared to PFC lesioned aged rats. Collectively, these data suggest that reduced cortical activity in young rats compared to aged rats may represent better neural capacity, or the efficient utilization of normal brain regions, for task performance. Moreover, PASA is not triggered by prefrontal cholinergic inputs, but these inputs may regulate the reciprocal interactions between the PFC and PPC networks to maintain optimal performance in aging.

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

Nair DV, Al-Badri MM, Peng H, Pachego-Quinto J, Eckman CB, Iacono D, Eckman EA (2015) Preliminary investigation on the antidepressive effect of chronic oxotremorine treatment in a rodent model of Alzheimer’s disease. Neuroscience 2015 Abstracts 40.29/C34. Society for Neuroscience, Chicago IL.

Summary: Alzheimer’s disease (AD) is a progressive neurodegenerative disease and the rate of progression varies from individual to individual. A great deal of evidence supports the idea that depression and other neuropsychiatric conditions co-exist with cognitive decline. However, the neurobiological basis of these symptoms and their influence on the clinical course of AD remain unclear. Our lab has shown previously that the 192-IgG saporin rat model of AD-like basal forebrain cholinergic cell loss exhibits a depression-like phenotype that develops months after the well-described impairment in spatial working memory. Furthermore, we have shown that chronic intracerebroventricular administration of the muscarinic agonist oxotremorine reverses both spatial working memory deficits and the depression-like behavior triggered by cholinergic denervation, and induces hippocampal neurogenesis. Current experiments are focused on determining additional pathological correlates of depression in this model and how they may be modulated by muscarinic agonists. To induce AD-like basal forebrain cholinergic cell loss, adult female Sprague Dawley rats were injected intracerebroventricularly (icv) with the immunotoxin 192-IgG-saporin (SAP) or saline as control (SHAM). After a 5 week recovery period, the rats received either 2 or 6 weeks of icv infusion of either oxotremorine or vehicle (saline) via osmotic minipump. Behavioral testing to assess the depressive phenotype was carried out using the sucrose consumption test every 2 weeks during oxotremorine treatment. The phenotype was further confirmed by forced swim test. The levels of ChAT, tryptophan hydroxylase (TPH), muscarinic receptors and FosB and ΔFosB were assessed in the hippocampus, basal forebrain, and orbitofrontal cortex by western blot and immunohistochemistry. Our preliminary results show increases in TPH, M1 receptors and FosB in the hippocampus, basal forebrain, and orbitofrontal cortex of a subset of treated animals, but no changes ChAT or ΔFosB. Further experiments are in progress to determine if there are changes in the expression of these and additional proteins in other brain regions including the nucleus accumbens, an area involved in activational aspects of motivation which also contributes to behavioral disorders such as to depression. The results of these studies may provide new insight in understanding the molecular basis of depression and antidepressant action of oxotremorine thereby defining new targets for possible therapeutic intervention for depressive symptoms in AD.

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

Pittenger CJ (2015) Modeling Tourette syndrome pathophysiology through targeted manipulation of striatal interneurons. Neuroscience 2015 Abstracts 6.07. Society for Neuroscience, Chicago IL.

Summary: Postmortem studies of Tourette syndrome patients has revealed a reduction in the number of specific striatal interneurons. The authors explored the hypothesis that this neuronal deficit is enough to produce the symptoms of Tourette syndrome in mice. Animals received 90-ng injections of Anti-ChAT-SAP (Cat. #IT-42) into the striatum. Rabbit IgG-SAP (Cat. #IT-35) was used as a control. The data suggest that loss of the striatal interneurons is enough to produce some, but not all, of the symptoms caused by Tourette syndrome.

Related Products: Anti-ChAT-SAP (Cat. #IT-42), Rabbit IgG-SAP (Cat. #IT-35)

See Also:

• Xu M et al. Targeted ablation of cholinergic interneurons in the dorsolateral striatum produces behavioral manifestations of Tourette syndrome. Proc Natl Acad Sci U S A 112:893-898, 2015.

Q: I’m trying to find out if enough Anti-DBH-SAP will be retrogradely transported and taken up by non targeted sympathetic neurons by bulk fluid-phase endocytosis. Does saporin become degraded after it kills the neuron or does it enter the extracellular matrix?

A: It is very unlikely that a targeted toxin such as Anti-DBH-SAP is freed from the targeted neuron in a meaningful condition. There has never been a reported identification of a targeted toxin, functionally or not, after it has eliminated its targeted neuron. Current evidence indicates that effective suicide transport agents undergo endocytosis at nerve terminals followed by retrograde axonal transport of the endocytic vesicles containing the toxin. Experiments using vincristine have shown that the retrograde axonal transport of suicide transport toxins utilizes the fast transport system (microtubules). However, it is not known what determines whether or not a specific toxin-ligand undergoes axonal transport after internalization.

Related Products: Anti-DBH-SAP (Cat. #IT-03)

Aoki S, Wickens JR (2015) Featured Article: A specific immunotoxin elucidates a causal role of striatal cholinergic system in behavioral flexibility. Targeting Trends 16(4)

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

Read the featured article in Targeting Trends.

See Also:

• Aoki S et al. Role of Striatal Cholinergic Interneurons in Set-Shifting in the Rat. J Neurosci 35:9424-9431, 2015.

Aicher S, Hermes S, Hegarty D (2015) Denervation of the lacrimal gland leads to corneal hypoalgesia in a novel rat model of aqueous dry eye disease. Invest Ophthalmol Vis Sci 56:6981-6989. doi: 10.1167/iovs.15-17497

Summary: 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.

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

Devoto P, Flore G, Saba P, Frau R, Gessa G (2015) Selective inhibition of dopamine-beta-hydroxylase enhances dopamine release from noradrenergic terminals in the medial prefrontal cortex. Brain Behav 5:e00393. doi: 10.1002/brb3.393

Summary: 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 of Anti-DBH-SAP treatement. The data demonstrate a mechanism for the synergistic effect of cocaine on nepicastat-induced dopamine release.

Related Products: Anti-DBH-SAP (Cat. #IT-03), Mouse IgG-SAP (Cat. #IT-18), Saporin (Cat. #PR-01)

Cao Q, Lu J, Li Q, Wang C, Wang X, Lee V, Wang C, Nguyen H, Zheng G, Zhao Y, Alexander S, Wang Y, Harris D (2016) CD103+ dendritic cells elicit CD8+ t cell responses to accelerate kidney injury in adriamycin nephropathy. J Am Soc Nephrol 27:1344-1360. doi: 10.1681/ASN.2015030229

Summary: Although it is known that dendritic cells (DCs) are involved in chronic kidney disease, it is not well understood how they either resolve or aggravate the condition. CD103+ dendritic cells in particular, are known to maintain tolerance through interaction with regulatory T cells, as well as protect against infection through interactions with CD8+ T cells. In this work the authors depleted CD103+ DCs by administering 1 mg/kg of anti-CD103-SAP (Cat. #IT-50) to the intraperitoneal space of mice subject to adriamycin nephropathy. Rat IgG-SAP (Cat. #IT-17) was used as a control. Elimination of the CD103+ DCs attenuated the kidney injury, indicating that in murine chronic kidney disease CD103+ DCs are pathogenic rather than therapeutic.

Related Products: Anti-CD103-SAP (Cat. #IT-50), Rat IgG-SAP (Cat. #IT-17)

Kras J, Weisshaar C, Pall P, Winkelstein B (2015) Pain from intra-articular NGF or joint injury in the rat requires contributions from peptidergic joint afferents. Neurosci Lett 604:193-198. doi: 10.1016/j.neulet.2015.07.043

Summary: Both peptidergic and non-peptidergic neurons innervate the facet joint, which is the source of pain in a majority of neck trauma. In this work the authors examined these subpopulations of neurons to determine the contribution of each in facet joint pain. 100 ng of SSP-SAP (Cat. #IT-11) was injected into bilateral C6/C7 facet joints of rats. Alternatively, rats received 5 μg of rIB4-SAP (Cat. #IT-10) via the same method. Saporin (Cat. #PR-01) was used as control. SSP-SAP, but not rIB4-SAP was able to prevent NGF-induced mechanical and thermal hypersensitivity. SSP-SAP administration also prevented behavioral hypersensitivity and NGF upregulation in the dorsal root ganglion after facet joint distraction. The data indicate that interference with peptidergic signaling within the facet joint may be a treatment for pain originating in that location.

Related Products: SSP-SAP (Cat. #IT-11), IB4-SAP (Cat. #IT-10), Saporin (Cat. #PR-01)

Saeed A, Pawlowski S, Ribeiro-da-Silva A (2015) Limited changes in spinal lamina I dorsal horn neurons following the cytotoxic ablation of non-peptidergic C-fibers. Mol Pain 11:54. doi: 10.1186/s12990-015-0060-z

Summary: For the most part nociceptive information is moved from the periphery to the spinal cord through small diameter primary afferents. One subclass of these afferents is further divided into peptidergic and non-peptidergic populations. The authors examined the role of the non-peptidergic afferents in normal nociception and pain, especially the aspect that in rat neuropathic and inflammatory pain models there is novel expression of neurokinin-1 receptors in some neurons normally devoid of this protein. Rats received 4.8-μg injections of rIB4-SAP (Cat. #IT-10) into the left sciatic nerve, over three injection sites. While the number of non-peptidergic neurons was significantly reduced, de novo expression of the neurokinin-1 receptor was not increased in lamina I pyramidal projection neurons.

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