saporin

Rygh LJ, Suzuki R, Rahman W, Wong Y, Vonsy JL, Sandhu H, Webber M, Hunt S, Dickenson AH (2006) Local and descending circuits regulate long-term potentiation and zif268 expression in spinal neurons. Eur J Neurosci 24(3):761-772. doi: 10.1111/j.1460-9568.2006.04968.x

Summary: Long-term potentiation (LTP) has been shown to occur in sensory areas of the spinal cord. This modification of synaptic strength may be one of the mechanisms by which acute pain is transformed into chronic pain. 10 µl of 1-µM SP-SAP (Cat. #IT-07) or control saporin (Cat. #PR-01) was injected into the subarachnoid space (L4-L5) of rats. Using electrophysiological recording, immunohistochemistry, behavioral assessment, and antisense experiments, the authors demonstrate that dorsal horn neuron generation of LTP may transform acute pain into chronic pain.

Related Products: SP-SAP (Cat. #IT-07), Saporin (Cat. #PR-01)

Zhu JP, Xu W, Angulo JA (2006) Distinct mechanisms mediating methamphetamine-induced neuronal apoptosis and dopamine terminal damage share the neuropeptide substance p in the striatum of mice. Ann N Y Acad Sci 1074:135-148. doi: 10.1196/annals.1369.013 PMID: 17105911

Objective: To investigate the mechanism by which substance P mediates METH-induced damage.

Summary: The authors propose that substance P mediates the apoptosis of some striatal neurons via the intrastriatal activation of nitric oxide synthesis. Substance P may also mediate damage of the dopamine terminals via an extrastriatal mechanism involving the substantia nigra and cortical glutamate release.

Usage: Mice were given intrastriatal injections of SSP-SAP (4ng/mcl). Saporin was used as control.

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

Vera-Portocarrero LP, Zhang ET, Ossipov MH, Xie JY, King T, Lai J, Porreca F (2006) Descending facilitation from the rostral ventromedial medulla maintains nerve injury-induced central sensitization. Neuroscience 140(4):1311-1320. doi: 10.1016/j.neuroscience.2006.03.016

Summary: Rats were treated with 1.5 pmol of dermorphin-SAP (Cat. #IT-12) or saporin (Cat. #PR-01) into each side of the rostral ventromedila medulla, followed by spinal nerve ligation. The data indicate that mu opioid-expresing neurons are necessary to maintain nerve injury-induced central sensitization.

Related Products: Dermorphin-SAP / MOR-SAP (Cat. #IT-12), Saporin (Cat. #PR-01)

Allen JW (2006) Featured Article: Safety and efficacy of Substance P-SAP. Targeting Trends 7(3)

Related Products: SP-SAP (Cat. #IT-07), Saporin (Cat. #PR-01)

Read the featured article in Targeting Trends.

See Also:

• Allen JW et al. Safety evaluation of Intrathecal Substance P-Saporin, a targeted neurotoxin, in dogs. Toxicol Sci 91(1):286-298, 2006.

Li AJ, Wang Q, Ritter S (2006) Differential responsiveness of dopamine-beta-hydroxylase gene expression to glucoprivation in different catecholamine cell groups. Endocrinology 147(7):3428-3434. doi: 10.1210/en.2006-0235

Summary: This work examines how subpopulations of hindbrain catecholaminergic neurons participate in systemic glucoregulation. Rats were treated with bilateral 42 ng infusions of anti-DBH-SAP (Cat. #IT-03) into the paraventricular nucleus of the hypothalamus. Dopamine-beta-hydroxylase (DBH) expression in glucoprivic animals was then analyzed by in situ hybridization and immunohistochemistry. The data demonstrate that the ventrolateral medulla contains most of the catecholamine neurons responsive to glucoprivation.

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

Emgard M, Paradisi M, Pirondi S, Fernandez M, Giardino L, Calza L (2007) Prenatal glucocorticoid exposure affects learning and vulnerability of cholinergic neurons. Neurobiol Aging 28(1):112-121. doi: 10.1016/j.neurobiolaging.2005.11.015

Summary: Women at risk of preterm delivery are commonly treated with synthetic glucocorticoids such as dexamethasone and betamethasone. Here the authors examined adult rats that were prenatally exposed to glucocorticoids. After 2.5 µg intracerebroventricular injections of 192-IgG-SAP (Cat. #IT-01) or 0.44 µg of saporin (Cat. #PR-01), the rats were tested in a water maze pool. The evidence suggests that not only do prenatal glucocorticoids affect adult cognitive function, they also make cholinergic neurons more susceptible to challenges later in life.

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

Vago R, Marsden CJ, Lord JM, Ippoliti R, Flavell DJ, Flavell SU, Ceriotti A, Fabbrini MS (2005) Saporin and ricin A chain follow different intracellular routes to enter the cytosol of intoxicated cells. FEBS J 272(19):4983-4995. doi: 10.1111/j.1742-4658.2005.04908.x

Summary: Some bacterial toxins such as Pseudomonas aeruginosa exotoxin A carry a KDEL-like C-terminal peptide sequence, which targets the protein to the endoplasmic reticulum. Saporin (Cat. #PR-01) is a plant ribosome-inactivating protein, which does not contain a KDEL-like sequence. Here the authors examined the intracellular pathways utilized by saporin. Although ricin, another plant ribosome-inactivating protein, could be visualized in the Golgi complex, saporin was not. The data suggest that saporin may utilize endosomes during its journey through the cell.

Related Products: Saporin (Cat. #PR-01)

Q: You have stated previously that it was unlikely that saporin compounds or constituents would be excreted in urine or feces. However, you acknowledge that experimental data is lacking. Have there been any tests of animal urine or feces for saporin content? My animal care staff are concerned.

A: One of the reasons that no studies have been done on excretion of saporin is that there isn’t much on the theoretical side to cause concern. The primary issue is that the quantity used in mice (and even rabbits) is so small that when looked at in human terms (i.e., an animal 10 to 100-times larger), the dosage becomes insignificant. The LD50 for saporin in mice is 4-8 mg/kg;[1] that would translate in humans to more than you’ll ever use! The immunotoxins, which contain only about 20% saporin by weight, really do not contain all that much saporin.

Looking at it another way, you need a concentration of about 100 nM to see even a vague hint of toxicity of saporin to cells. In human blood, that would correspond to 24 mg injected systemically into a person. It would be really expensive for anyone to get close to that number.

As far as urine and feces go, the same calculations are appropriate, but there will be considerable degradation – the protein content in urine and feces is quite low and the probability is that you will be dealing with only saporin. Remember, saporin is a plant protein that is related to proteins in foods that we eat (cucumbers, for example).

Q: Are there any studies which indicate what doses of saporin (by itself or compounded with an antibody) would be hazardous if ingested or injected (i.e. systemic dose level resulting in death or organ dysfunction).

A: When there is an antibody that does recognize a human epitope (the human p75-saporin immunotoxin that is used in rabbits, for example), at about 1 pM one sees the slightest bit of toxicity to cells. That translates, if injected by error into a human blood supply, to about 170 micrograms. That also is a gigantic dose. I am using very conservative numbers here, and the bottom line is that you cannot accidentally reach such dangerous levels under normal handling situations.

Having said all this, we still recommend that our customers take excellent care of themselves and we state clearly that precautions should be taken by people handling these materials, just as they should use precautions with all laboratory chemicals. Please refer to the data sheets provided with our products for safety instructions.

See: Saporin (Cat. #PR-01)

References

1. Stirpe F et al. Hepatotoxicity of immunotoxins made with saporin, a ribosome-inactivating protein from Saponaria officinalis. Virchows Arch B Cell Pathol Incl Mol Pathol 53(5):259-271, 1987.

Hodges MR, Opansky C, Qian B, Davis S, Bonis J, Bastasic J, Leekley T, Pan LG, Forster HV (2004) Transient attenuation of CO2 sensitivity after neurotoxic lesions in the medullary raphe-area in awake goats. J Appl Physiol 97(6):2236-2247. doi: 10.1152/japplphysiol.00584.2004

Summary: The authors wished to investigate the influence medullary raphe-area neurons have on breathing. This control may be through CO2/H+ chemoreceptors and/or through non-chemoreceptor modulation. 1 or 10 µl of 50 pM SP-SAP (Cat. #IT-07) or Saporin (Cat. #PR-01) was injected into the raphe of goats. Breathing and CO2 sensitivity were evaluated during different physiologic conditions. The data suggest that SP receptor- and glutamate receptor-expressing neurons in the medullary raphe both influence CO2 sensitivity, but not altered breathing periods.

Related Products: SP-SAP (Cat. #IT-07), Saporin (Cat. #PR-01)

Stirpe F (2004) Featured Article: The discovery of saporin. Targeting Trends 5(3)

Related Products: Saporin (Cat. #PR-01)

Read the featured article in Targeting Trends.