Q: How long does it take to see the cell death occurring from the use of targeted toxins using saporin? Is there a time course of hours or days?
A: The figure below illustrates the time course of cell death very effectively. Internalization and cytotoxicity of SP-SAP in primary cultures of neonatal spinal cord neurons. Confocal image of neurons where the Substance P receptor; NK1R (SPR) immunofluorescence (A, C, D) appears red, areas of concentrated SPR immunofluorescence appear yellow. (A, C, and D) SPR immunofluorescence in neurons 2 hours, 1 day, and 4 days, respectively, after treatment with SP-SAP. (B) Confocal image showing SAP immunofluorescence (yellow) 2 hours after SP-SAP treatment.
These images were projected from 14 optical sections acquired at 0.8-mm intervals with a 603 lens. Bar, 25 mm.
It is recommended that you wait for two weeks to allow for all debris to be cleared and the animal to regain normal eating and sleeping habits.
Weisshaar CL, Winkelstein BA (2014) Ablating spinal NK1-bearing neurons eliminates the development of pain and reduces spinal neuronal hyperexcitability and inflammation from mechanical joint injury in the rat. J Pain 15(4):378-386. doi: 10.1016/j.jpain.2013.12.003
Summary: A high percentage of chronic neck pain involves the facet joint. Although the facet joint is innvervated by peptide-responsive nociceptive afferents, the role of these cells in the development and modulation of nociceptive signaling remains unclear. Using a previously developed rat model of facet joint injury, the authors examined the role of neurokinin-1 receptor-expressing spinal cells in this pathway. Rats received 100 ng SSP-SAP (Cat. #IT-11) via lumbar puncture. Blank-SAP (Cat. #IT-21) was used as a control. The results demonstrate that spinal NK1r-expressing cells are essential for nociception and inflammation due to a mechanical joint injury.
Takakura AC, Barna BF, Cruz JC, Colombari E, Moreira TS (2014) Phox2b-expressing retrotrapezoid neurons and the integration of central and peripheral chemosensory control of breathing in conscious rats. Exp Physiol 99(3):571-585. doi: 10.1113/expphysiol.2013.076752
Summary: Previous work has shown that lesions to the retrotrapezoid nucleus (RTN) have at least a modest effect on breathing, but it is unclear whether those lesions affected the entire nucleus or were incomplete. The authors used bilateral lesions of the RTN with 0.3 to 1.2 ng total of SSP-SAP (Cat. #IT-11) to eliminate neurokinin-1 receptor-expressing neurons; these are also Phox2b+TH- neurons. The results indicate that loss of Phox2b(+)TH(-) neurons may cause deficits seen after RTN lesion, and help define the ways in which these cells are involved in controlling central and peripheral chemoreflexes.
Freiria-Oliveira AH, Blanch GT, De Paula PM, Menani JV, Colombari DS (2013) Lesion of the commissural nucleus of the solitary tract/A2 noradrenergic neurons facilitates the activation of angiotensinergic mechanisms in response to hemorrhage. Neuroscience 254:196-204. doi: 10.1016/j.neuroscience.2013.09.017
Summary: Previous work has generated conflicting data on the role of catecholaminergic A2 neurons in the nucleus of the solitary tract (NTS) in control of arterial pressure lability. The authors used Anti-DBH-SAP (Cat. #IT-03) to lesion these neurons in a hypotensive hemorrhage model. Rats received two injections of 12.6 ng into the commissural NTS. Mouse IgG-SAP (Cat. #IT-18) was used as a control. The lesioned animals quickly recovered from hypotension, but were impaired by the icv administration of losartan.
Summary: Although mainly known for their involvement in the control of arterial pressure, C1 neurons are also suspected to participate in numerous other physiological processes such as neuroendocrine response, glucose homeostasis, food consumption, and others. This review discusses the role of these neurons as ’emergency medical technicians’ – cells that produce and modulate physiological survival responses to acute physical stress. The use of Anti-DBH-SAP (Cat. #IT-03) to delineate C1 neurons in the rostral ventrolateral aspect of the medulla oblongata is discussed.
Grupe M, Paolone G, Jensen AA, Sandager-Nielsen K, Sarter M, Grunnet M (2013) Selective potentiation of (alpha4)3(beta2)2 nicotinic acetylcholine receptors augments amplitudes of prefrontal acetylcholine- and nicotine-evoked glutamatergic transients in rats. Biochem Pharmacol 86(10):1487-1496. doi: 10.1016/j.bcp.2013.09.005
Summary: Nicotinic acetylcholine receptors (nAChR) are involved in a wide range of processes in the central nervous system, many having to do with higher cognitive functions. In order to better understand how these receptors mediate attentional performance, the authors investigated glutamate release under varying conditions. In one series of experiments rats received a 160-ng injection of 192-IgG-SAP (Cat. #IT-01) into the right medial prefrontal cortex. The resulting decrease in glutamate release after the cholinergic lesion adds to the data indicating that positive modulation of nAChR may help alleviate attentional impairments caused by some brain disorders.
Romano A, Potes CS, Tempesta B, Cassano T, Cuomo V, Lutz T, Gaetani S (2013) Hindbrain noradrenergic input to the hypothalamic PVN mediates the activation of oxytocinergic neurons induced by the satiety factor oleoylethanolamide. Am J Physiol Endocrinol Metab 305(10):E1266-73. doi: 10.1152/ajpendo.00411.2013
Summary: Feeding behavior and energy balance are in part controlled by signals from the gut. Oleoylethanolamide (OEA) is an acylethanolamide that is thought to play a role in this network. Since peripheral administration of OEA has effects on the nucleus of the solitary tract (NTS) and paraventricular nucleus (PVN) the authors investigated the role of noradrenergic afferent input to these areas. Rats received bilateral 84-ng injections of Anti-DBH-SAP (Cat. #IT-03) into the PVN. Mouse IgG-SAP (Cat. #IT-18) was used as a control.
Khan D, Owens E, Zaben M, Dunnett SB, Gray WP (2013) CD4+ T lymphocytes interact with microglia to modulate hippocampal neurogenesis. Neuroscience 2013 Abstracts 699.04. Society for Neuroscience, San Diego, CA.
Summary: Hippocampal neurogenesis occurs within the subgranular zone of the dentate gyrus and is important for learning and memory. Neurogenesis is impaired in patients with chronic temporal lobe epilepsy, an observation that may account for the learning and memory deficits that these patients commonly have. Emerging literature demonstrates that CD4+ T lymphocytes increase neurogenesis and enhance cognition; however, the exact mechanisms remain undetermined. Vasoactive Intestinal Peptide (VIP) receptors are expressed on T lymphocytes, microglia and hippocampal progenitor cells, hence this study was designed to investigate VIP’s role in mediating neuro-immune modulation. Hippocampal cultures (P7-10 Sprague Dawley rats) were generated and maintained for 3 days in vitro (DIV) and treated with 5% supernatant generated from C57/Bl6 mouse spleen using a CD4+ T lymphocyte isolation kit. BrdU and experimental conditions were added for the terminal 6 hours before fixation and then processed for BrdU and nestin. For phenotype analysis, experimental conditions were added at 3DIV and fixed at 6DIV to be processed for nestin and TuJ1. To deplete microglia, Mac-1-SAP was added at 2DIV for 24 hours before experimental conditions were added. 5% T lymphocytes supernatant increased proliferation of hippocampal nestin-expressing cells; an effect that is further enhanced under VIP treatment via VPAC1 receptor subtype. Examining potential cytokine mediators of this effect, PCR analysis showed 6-fold increase in IL-4 mRNA expression, and IL-4 antagonist abolished VIP proliferative effects. Using Mac-1-SAP to account for microglial involvement by depleting microglia, VIP proliferative effects were abolished. Our phenotyping studies also demonstrated an additional neurogenic effect under VIP treated supernatant compared to standard control conditions. Taken together, these results show VPAC1 receptor subtype expressed by CD4+ T lymphocytes mediates VIP proliferative effects on hippocampal cells via IL-4 cytokine release. Microglia mediates VIP proliferative effects. While we demonstrated before that VPAC2 mediates hippocampal progenitor cell survival, the findings of this study strongly implicate VPAC1 receptor as a neuro-immune mediator of hippocampal neurogenesis, and from a therapeutic perspective, shows that the effect can be pharmacologically manipulated.
Tiwari D, Warden H, Haynes JM, Nicolazzo JA, Pouton CW, Short JL (2013) Investigating the potential of stem cell based therapy in an immunotoxin mouse model of Alzheimer’s disease. Neuroscience 2013 Abstracts 712.19. Society for Neuroscience, San Diego, CA.
Summary: Purpose: Alzheimer’s disease (AD) is a neurodegenerative disorder characterized by reduced cognitive function. Stem cell based therapeutic approaches are a potential therapeutic option. In order to investigate this possibility the study focuses on the characterization of a dual reporter embryonic stem (ES) cell line and validation of an immunotoxin mouse model of AD for future transplantation experiments. Methods: A dual (mcherry and Lhx8+) reporter ES cell line was derived from the E14Tg2a mouse ES cell line. The ES cells were assessed for their differentiation capability and characterized using mmunocytochemistry. For the immunotoxin model, 6-8 week old C57BL/6 male mice (n = 12) were treated with bilateral intracerebroventricular injections of saline (control) or mu-p75-saporin toxin (0.4µg/µl/mouse) to cause cholinergic neuronal lesions. Mice were cognitively assessed using a novel three day water maze (WM) protocol and the novel object recognition (NOR) paradigm. Immunohistochemistry was done to detect the toxin dependent loss of cholinergic neurons. Results and conclusions: A significant difference in learning the WM task was observed during cued and spatial trials, with toxin-treated mice taking longer to reach the platform than control mice (two way ANOVA; p<0.01). Performance in the WM during the probe trial was also significantly reduced in toxin-treated mice, compared to control mice (t-test; p<0.05), indicating memory loss in toxin-injected mice and better learning in the saline-treated controls. However, no memory impairment was detected using the NOR test. Immunohistochemistry for choline acetyltransferase (ChAT) confirmed a significant loss (p<0.0001; t test) of cholinergic neurons in the medial septum. These data indicate that the toxin model is appropriate for use in subsequent transplantation studies. FACS analysis of the reporter cell line showed the presence of a small population of Lhx8+ cells at day 6 and 10 of differentiation. Immunocytochemistry for ChAT on day 18 cells revealed the presence of a few cholinergic positives neurons as compared to wild type controls. Literature suggests a possible role of Lhx8 in cholinergic development and these cells will be investigated further in order to select cholinergic progenitors for transplantation.
Lee S-Y, Kim M-S, Han J-S (2013) Activation of NF-κB signaling in the hippocampus without cholinergic input was aggravated by chronic stress. Neuroscience 2013 Abstracts 717.18. Society for Neuroscience, San Diego, CA.
Summary: Previous studies have demonstrated that loss of cholinergic input to hippocampus contributes dysfunction of HPA axis and alters GR-PKA-NF-κB signaling in hippocampus. In the hippocampus without cholinergic input, interactions of GR and PKA are decreased, whereas interactions of PKA and NF-κB are increased and phosphorylations on Ser276 of NF-κB p65 are increased. On the other hand, activation of NF-κB p65 is associated with behavioral action of stress and depression. The present research was conducted to examine whether NF-κB activation induced by cholinergic lesions is aggravated in response to chronic stress. Young adult rats received immunotoxic lesions of basal forebrain cholinergic neurons by intracranial injections of 192 IgG-saporin into the medial septum/vertical limb of the diagonal band and substantia innominata/nucleus basalis. After 2 weeks recovery from surgery, rats with cholinergic lesions and vehicle-injected control rats were subjected to 1 hr restraint stress per day for 2 weeks. We examined that cholinergic deafferentation induced alterations in GR and NF-κB p65 expression in hippocampus and prefrontal cortex. Rats with cholinergic deafferentation and chronic stress showed more activation of NF-κB p65 signaling in the hippocampus compared with rats with cholinergic deafferentation only. Thus the loss of cholinergic integrity during aging and in AD might increase proneness to chronic stress.
