targeted-toxins

Truitt WA, Sajdyk TJ, Dietrich AD, Oberlin B, McDougle CJ, Shekhar A (2007) From anxiety to autism: spectrum of abnormal social behaviors modeled by progressive disruption of inhibitory neuronal function in the basolateral amygdala in Wistar rats. Psychopharmacology (Berl) 191(1):107-118. doi: 10.1007/s00213-006-0674-y

Summary: The amygdala has been identified as being involved in social behaviors. Six 4 ng injections of SSP-SAP (Cat. #IT-11) were administered bilaterally into the basolateral nucleus (BLA) of the amygdala of rats. Blank-SAP (Cat. #IT-21) was used as a control. Results of a social interaction paradigm suggest that in normal animals social inhibition can be overcome by habituation. In lesioned animals, however, social inhibition is not reversed by habituation, indicating that NK-1 receptor-expressing GABAergic interneurons in the BLA are important in this system.

Related Products: SSP-SAP (Cat. #IT-11), Blank-SAP (Cat. #IT-21)

Furlong T, Carrive P (2007) Neurotoxic lesions centered on the perifornical hypothalamus abolish the cardiovascular and behavioral responses of conditioned fear to context but not of restraint. Brain Res 1128(1):107-119. doi: 10.1016/j.brainres.2006.10.058

Summary: This work examined the role of orexin-containing neurons in the perifornical hypothalamus (PeF) during stress response. Orexin-SAP (Cat. #IT-20) or the control conjugate blank-SAP (Cat. #IT-21) was injected into the PeF of pre-conditioned rats. Tests measuring restraint and conditioned fear to context were then performed on the lesioned animals. While the lesioning was not specific enough to connect results to orexin-containing neurons, the data indicate that the PeF is critical for some forms of stress, but not others.

Related Products: Orexin-B-SAP (Cat. #IT-20), Blank-SAP (Cat. #IT-21)

Dwyer TA, Servatius RJ, Pang KC (2007) Noncholinergic lesions of the medial septum impair sequential learning of different spatial locations. J Neurosci 27:299-303. doi: 10.1523/JNEUROSCI.4189-06.2007

Summary: The medial septum and the vertical limb of the diagonal band of Broca (MSDB) have extensive connections to the hippocampus. In general, impairments due to loss of cholinergic neurons in this area have been smaller than those due to the loss of noncholinergic neurons. The authors treated rats with either 192-IgG-SAP (Cat. #IT-01) or kainic acid into each hemisphere of the medial septum. Behavioral testing following surgery demonstrated that the animals with noncholinergic lesions had impaired performance, even when compared to the animals with cholinergic lesions.

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

Walker BR, Diefenbach KS, Parikh TN (2007) Inhibition within the nucleus tractus solitarius (NTS) ameliorates environmental exploration deficits due to cerebellum lesions in an animal model for autism. Behav Brain Res 176(1):109-120. doi: 10.1016/j.bbr.2006.08.008

Summary: In this work the authors use environmental exploration deficits in rats as a model for autism. Animals received 2 µg of either OX7-SAP (Cat. #IT-02) or 192-Saporin (Cat. #IT-01) into each ventricle. Only the OX7-SAP treated rats displayed a reduction in exploration behavior, and the anticonvulsant muscimol restored exploration behavior to control levels. This system may have use in controlling behavior deficits seen in autism.

Related Products: 192-IgG-SAP (Cat. #IT-01), OX7-SAP (Cat. #IT-02)

Q: Your targeted toxin kits come with different controls. I’m not sure of the best way to use them. For example, with the anti-SERT-SAP kit (Cat. # KIT-23) there is included unconjugated antibody, unconjugated saporin, and a control conjugate, mouse IgG-SAP. Should I use them all in the same experiment or for different purposes?

A: Yes, perhaps we do have a few too many options for controls; better too many than too few. For anti-SERT-SAP, the ideal control is mouse IgG-SAP (Cat. # IT-18). Anti-SERT-SAP is made from saporin conjugated to a mouse monoclonal IgG that has SERT as its antigen. So, mouse IgG-SAP – that is, saporin conjugated to mouse IgG that has no specific antigen for targeting – would be the best control, in my mind. For years, the unconjugated antibody and unconjugated saporin mixed together was the best control available (until we came out with the “irrelevant” control immunotoxins), and still might be considered a second good control, or useful in cases where down-regulation by the antibody is a concern.

Q: What about for the peptide toxins like orexin-SAP (Cat. # IT-20) or SP-SAP (Cat. #IT-07)— what controls are available for those?

A: We have produced Blank-SAP as a control for the peptide ligand toxins. Blank-SAP (Cat. #IT-21) is a peptide that has the usual common amino acids that are found in peptide neurotransmitters, but arranged in a sequence that is random and not detected in homology searches. So, it’s like shooting blanks; it should never find an amenable receptor. This is quite an important control; the peptide ligand toxins are often delivered directly to tissue, and there are cases in which there will be no toxicity or non-specific toxicity. The best use we have seen for Blank-SAP has been in Bugarith et al. As any journal reviewer will tell you, it’s very important to document the specificity, and with Blank-SAP as a control, you can definitively show that toxicity is due to proper targeting, rather than non-specific cytotoxicity. This should provide the information needed so the reviewer doesn’t have to make you go back and document specificity with further experimental work!

See: Targeted Toxins, Control Conjugates

References

1. Bugarith K et al. Basomedial hypothalamic injections of neuropeptide Y conjugated to saporin selectively disrupt hypothalamic controls of food intake. Endocrinology 146(3):1179-1191, 2005.

Chauhan N (2007) Featured Article: Cholinergic immunolesioning produced tangle-like inclusions in TgCRND8 brain. Targeting Trends 8(1)

Related Products: mu p75-SAP (Cat. #IT-16)

Read the featured article in Targeting Trends.

See Also:

• Chauhan NB Cholinergic immunolesioning produced tangle-like inclusions in TgCRND8 brain. Neuroscience 2006 Abstracts 271.8, 2006. Society for Neuroscience, Atlanta, GA

Ma W, Eisenach JC (2007) Neuronal nitric oxide synthase is upregulated in a subset of primary sensory afferents after nerve injury which are necessary for analgesia from alpha2-adrenoceptor stimulation. Brain Res 1127(1):52-58. doi: 10.1016/j.brainres.2006.10.008

Summary: Peripheral nerve injury resulting in neuropathic pain often responds poorly to opioid treatment. alpha2-adrenoreceptor (AR) agonists, however, perform better after this type of injury. After a spinal nerve ligation, rats were treated with a 0.6 µg-intrathecal injection of 192-saporin (Cat. #IT-01). The increase of neuronal nitric oxide synthase (nNOS) caused by spinal ligation was abolished in the lesioned animals. The data indicate that AR agonists may reduce sensitization by activating nNOS fibers in the superficial dorsal horn.

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

Ohtori S, Inoue G, Koshi T, Ito T, Doya H, Moriya H, Takahashi K (2006) Substance P-saporin down-regulates substance P receptor immunoreactive sensory dorsal root ganglion neurons innervating the lumbar intervertebral discs in rats. Spine 31:2987-2991. doi: 10.1097/01.brs.0000250306.12996.fa

Summary: Neurokinin-1 (NK-1) receptor expressing neurons that innervate lumbar intervertebral discs may be involved in lower back pain. Here the authors investigate the basic effect of SP-SAP (Cat. #IT-07) on neurons innervating the L5/6 intervertebral disc. Rats were injected with 175 ng of SP-SAP. The number of NK-1 receptor expressing neurons was reduced by over 75% in the treated animals, demonstrating SP-SAP as a useful tool to investigate the mechanism of discogenic low back pain, particulary for investigating behavioral impacts.

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

Cabrera SM, Chavez CM, Corley SR, Kitto MR, Butt AE (2006) Selective lesions of the nucleus basalis magnocellularis impair cognitive flexibility. Behav Neurosci 120:298-306. doi: 10.1037/0735-7044.120.2.298

Summary: In humans, one aspect of cognitive flexibility is being able to shift attention under a variety of pressures. Here the authors suggest that lesions to the cholinergic nucleus basalis magnocellularis (NBM) will impair cognitive flexibility. The NBM of rats was lesioned with 0.08 µg of 192-IgG-SAP (Cat. #IT-01). Both lesioned and controlled animals displayed a similar ability to learn a discrimination task, but lesioned animals displayed perseveration – the uncontrollable repetition of a previously correct response – indicating a loss of cognitive flexibility.

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

Ritter S, Dinh TT, Li AJ (2006) Hindbrain catecholamine neurons control multiple glucoregulatory responses. Physiol Behav 89(4):490-500. doi: 10.1016/j.physbeh.2006.05.036

Summary: Glucose deficit evokes many responses in the brain. Recently these workers have been focusing on mechanisms eliciting glucoregulatory responses; the focus has settled on catecholaminergic neurons in the hindbrain. In a series of experiments rats received injections of anti-DBH-SAP (Cat. #IT-03) into epinephrine (E) and norepinephrine (NE) terminal areas of hypothalamus and spinal cord. The data suggest that E/NE neurons coordinate various components of the behavioral response to glucoprivation.

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