targeted-toxins

Waite JJ, Chen AD (2001) Differential changes in rat cholinergic parameters subsequent to immunotoxic lesion of the basal forebrain nuclei. Brain Res 918:113-120. doi: 10.1016/s0006-8993(01)02968-7 PMID: 11684049

Summary: 192-Saporin (Cat. #IT-01) is used extensively to eliminate the cholinergic neurons of the basal forebrain in rats. Waite and Chen compare the degree of loss between 192-Saporin (6 or 8.2 µg in 10 µl into left lateral ventricle) and control (Saporin, 1.82 µg into left lateral ventricle; Cat. #PR-01) using three methods: Assay of post mortem choline acetyltransferase activity, in vivo microdialysis of extracellular acetylcholine (ACh), and in vivo assessment of the rate of ACh synthesis. The infusion of saporin alone had no effect. After fifteen weeks, the authors report compensation of cholinergic activity in lesioned animals occurs in the hippocampus, but not in the frontal cortex as determined by measurement of the rate of ACh synthesis.

Related Products: 192-IgG-SAP (Cat. #IT-01), Saporin Goat Polyclonal (Cat. #AB-15), Saporin Chicken Polyclonal, affinity-purified (Cat. #AB-17AP), Saporin (Cat. #PR-01)

Pang KCH, Nocera R, Secor AJ, Yoder RM (2001) GABAergic septohippocampal neurons are not necessary for spatial memory. Hippocampus 11:814-827. doi: 10.1002/hipo.1097

Summary: The medial septum and diagonal band of Broca (MSDB) are necessary for spatial memory. Both cholinergic and GABAergic neuronal populations are present in the MSDB. 192-Saporin (Cat. #IT-01) was used to eliminate cholinergic populations and kainic acid was used to reduce numbers of GABAergic neurons. Both agents were injected (independently or in combination) into the medial septum and each diagonal band of rats (192-Saporin 250 ng MS, 150 ng DB) to determine the importance of GABAergic neurons in the MSDB for spatial memory. The results showed elimination of GABAergic neurons has no impact on spatial memory, while elimination of cholinergic neurons has a mild impact.

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

Berger-Sweeney JE, Stearns NA, Murg SL, Floerke-Nashner LR, Lappi DA, Baxter MG (2001) Selective immunolesions of cholinergic neurons in mice: effects on neuroanatomy, neurochemistry, and behavior. J Neurosci 21(20):8164-8173. doi: 10.1523/JNEUROSCI.21-20-08164.2001

Summary: 192-Saporin (Cat. #IT-01) has long been an effective agent for elimination of cholinergic neurons in the basal forebrain of rats. Until the development of mu p75-SAP (Cat. #IT-16) there was no equivalent agent for use in mice. The authors tested mu p75-SAP in vitro and in vivo (1.8-3.6 µg in right lateral ventricle), using cytotoxic, histochemical, and behavioral assays. The data shows that mu p75-SAP is a highly selective and efficacious lesioning agent for cholinergic neurons in the mouse. The authors conclude that mu p75-SAP will be a powerful tool to use in combination with genetic modification to investigate cholinergic damage in mouse models of Alzheimer’s disease.

Related Products: mu p75-SAP (Cat. #IT-16), 192-IgG-SAP (Cat. #IT-01)

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: Details of the time course of early events have not been extensively studied. After ricin injections into the cervical vagus nerve, the proximal nerve becomes unresponsive to electrical stimulation between 36 and 48 hours. After septal injection of 192-Saporin (192-IgG-SAP, Cat. #IT-01), hippocampal theta rhythm begins to diminish on the third postoperative day and reaches a minimum by 7 days which is maintained indefinitely. Anatomical disintegration is complete within 10-14 days after injection of most toxins.

Q: Will this time course be the same regardless of the targeted toxin used or the method of administration?

A: Presumably, injection of toxin into the vicinity of target cell bodies and dendrites should produce effects somewhat sooner than toxin injections into axonal terminal fields where retrograde axonal transport must first deliver toxin to the perikarya. In the cervical vagus, based on transport times for ricin and inhibition of toxin transport by vincristine, we concluded that fast axonal transport is involved. Colchicine coinjected intraventricularly with 192-Saporin (192-IgG-SAP, Cat. #IT-01) prevents destruction of cholinergic basal forebrain neurons suggesting that fast axonal transport also is involved with i.c.v. toxin injections. Consequently, the delay introduced by injecting toxin into axon terminal fields is usually a few hours at most.

Q: What are some assays/methods to use to be able to graphically demonstrate cell death?

A: Toxin-induced cell death can be observed and documented with a variety of techniques. Often the easiest is simple Nissl staining because all of the RIP toxins (ricin, volkensin, saporin) produce profound chromatolysis that is readily apparent in Nissl stains (i.e. cresyl violet).

Electron microscopy can demonstrate details of neuron degeneration including loss of axon terminals at a distance from the cell body which can be useful in anatomic tracing studies.

Typically, target neurons express proteins that can be visualized with immunocytochemical techniques. Thus, immunofluorescence or peroxidase immunohistochemistry can be useful in detecting loss of staining for target molecules and co-expressed molecules in the neurons being targeted. The use of multiple markers is recommended to insure that cell loss occurred rather than down regulation of marker expression.

See: Targeted Toxins

Sloviter R (2001) Featured Article: Immunolesioning hippocampal inhibitory interneurons. Targeting Trends 2(4)

Related Products: SSP-SAP (Cat. #IT-11), SP-SAP (Cat. #IT-07)

Read the featured article in Targeting Trends.

See Also:

• Martin JL et al. Focal inhibitory interneuron loss and principal cell hyperexcitability in the rat hippocampus after microinjection of a neurotoxic conjugate of saporin and a peptidase-resistant analog of substance P. J Comp Neurol 436:127-152, 2001.

Kanai T, Watanabe M, Okazawa A, Sato T, Yamazaki M, Okamoto S, Ishii H, Totsuka T, Iiyama R, Okamoto R, Ikeda M, Kurimoto M, Takeda K, Akira S, Hibi T (2001) Macrophage-derived IL-18-mediated intestinal inflammation in the murine model of Crohn’s disease. Gastroenterol 121:875-888. doi: 10.1053/gast.2001.28021

Summary: Crohn’s disease is an inflammatory bowel disease that is associated with several changes in the immune system, including an increased number of infiltrating macrophages. These macrophages release a variety of cytokines that are responsible for inflammation. The authors investigated the role of these macrophages in a mouse model by eliminating them with Mac-1-SAP (20 µg parenterally in tail vein; Cat. #IT-06). Seven days after treatment, mice showed no evidence of intestinal inflammation. These data demonstrate the role of macrophages in the development of inflammatory bowel conditions.

Related Products: Mac-1-SAP mouse/human (Cat. #IT-06), Mac-1-SAP rat (Cat. #IT-33)

Jasmin L, Ohara PT (2001) Long-term intrathecal catheterization in the rat. J Neurosci Methods 110:81-89. doi: 10.1016/s0165-0270(01)00420-4

Summary: The authors have developed a method that allows repeated administration of drugs with minimal stress to an experimental animal. To test the efficacy of this intrathecal catheter, they injected anti-DBH-SAP (5 µg; Cat. #IT-03,) and investigated the noradrenergic denervation of the spinal cord. All animals treated with anti-DBH-SAP showed extensive loss of spinal noradrenergic ennervation. Even three months after catheter implantation, the elimination of noradrenergic neurons in the spinal cord could be produced. This indicates the intrathecal catheter is an effective tool for the study of multiple-dose drug delivery.

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

Gerashchenko D, Kohls MD, Greco M, Waleh NS, Salin-Pascual R, Kilduff TS, Lappi DA, Shiromani PJ (2001) Hypocretin-2-saporin lesions of the lateral hypothalamus produce narcoleptic-like sleep behavior in the rat. J Neurosci 21(18):7273-7283. doi: 10.1523/JNEUROSCI.21-18-07273.2001 PMID: 11549737

Summary: Orexin (also knows as hypocretin) peptides are produced exclusively by neurons in the lateral hypothalamus, however non-specific lesioning in this region has not produced narcoleptic-like sleep. Gerashchenko et al. use orexin-SAP (490 ng/0.5 µl; Cat. #IT-20) to specifically eliminate orexin neurons in rats. The treated rats displayed several sleep disturbances found in narcolepsy, including increased slow-wave sleep, and sleep-onset REM sleep periods. The data suggest that orexin-SAP can be used to create a model for narcolepsy in rats.

Related Products: Orexin-B-SAP (Cat. #IT-20), Saporin Goat Polyclonal, affinity-purified FITC-labeled (Cat. #AB-15APFL), Saporin Chicken Polyclonal, affinity-purified (Cat. #AB-17AP)

Gerashchenko D, Salin-Pascual R, Shiromani PJ (2001) Effects of hypocretin-saporin injections into the medial septum on sleep and hippocampal theta. Brain Res 913:106-115. doi: 10.1016/s0006-8993(01)02792-5

Summary: Hypocretin, also known as orexin, neurons are located only in the lateral hypothalamus. Recently, the loss of these neurons was shown to be associated with narcolepsy. The authors used orexin-SAP (100 ng/0.5 µl; Cat. #IT-20) to eliminate parvalbumin and cholinergic neurons (orexin B receptor-expressing) in the rat medial septum. They used 192-Saporin (1 µg/ 1 µl; Cat. #IT-01) to contrast the effect and eliminate only cholinergic neurons (NGF/p75 receptor-expressing). Hippocampal theta activity was completely eliminated in orexin-SAP treated rats by day 12, suggesting that orexin neurons influence cognitive processes critical for survival.

Related Products: 192-IgG-SAP (Cat. #IT-01), Orexin-B-SAP (Cat. #IT-20)

Ferreira G, Meurisse M, Gervais R, Ravel N, Levy F (2001) Extensive immunolesions of basal forebrain cholinergic system impair offspring recognition in sheep. Neuroscience 106(1):103-116. doi: 10.1016/s0306-4522(01)00265-2

Summary: Through the use of 192-Saporin (Cat. #IT-01) the association of basal forebrain cholinergic neurons to learning instrumental tasks has been well established in the rat. The authors wished to examine whether these neurons were also associated with social learning tasks, such as offspring recognition in sheep. Using ME20.4-SAP (Cat. #IT-15) the basal forebrain cholinergic neurons of sheep were lesioned by intraventricular bilateral injections (150 µg). The results demonstrate that these neurons contribute to visual discrimination learning, and are involved in formation of lamb recognition memory.

Related Products: 192-IgG-SAP (Cat. #IT-01), ME20.4-SAP (Cat. #IT-15)