targeted-toxins

Ballmaier M, Casamenti F, Zoli M, Pepeu G, Spano P (2001) Selective immunolesioning of cholinergic neurons in nucleus basalis magnocellularis impairs prepulse inhibition of acoustic startle. Neuroscience 108(2):299-305. doi: 10.1016/s0306-4522(01)00413-4

Summary: One of the measures for schizophrenia is a deficit in sensorimotor gating (the ability of the brain to filter sensory input to focus on selective stimuli) measured by prepulse inhibition (PPI) of the startle reflex. The authors injected 300 nl of 400 ng/µl 192-Saporin (Cat. #IT-01) into each side of the nucleus basalis magnocellularis (NBM) in rats to examine the effect of NBM cholinergic neuron elimination on the startle reflex. The data show a significant, persistent disruption of the PPI independent of the amplitude of the startle reflex. This suggests the NBM may play an important role in information processing in schizophrenia.

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

Vogt LJ, Sim-Selley LJ, Childers SR, Wiley RG, Vogt BA (2001) Colocalization of mu-opioid receptors and activated G-proteins in rat cingulate cortex. J Pharmacol Exper Ther 299:840-848.

Summary: The anterior cingulate cortex (ACC) is a primary site of opiate drug action, and much of this activity is associated with the m-opioid receptor (MOR). The mechanisms by which MOR regulates pain in the ACC are not well understood. Using anti-DBH-SAP (7 µg into left lateral ventricle in rat; Cat. #IT-03) the authors mapped MOR activity in the ACC and evaluated the histochemical and behavioral relationships between MOR binding and mu-receptor-activated G-proteins after lesioning.

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

Himmelheber AM, Sarter M, Bruno JP (2001) The effects of manipulations of attentional demand on cortical acetylcholine release. Brain Res Cogn Brain Res 12(3):353-370. doi: 10.1016/s0926-6410(01)00064-7

Summary: Cortical cholinergic afferents from the basal forebrain are suspected to be involved in attentional tasks. Regulatory impairment of these afferents has been hypothesized to contribute to attentional deficits seen in conditions as diverse as Alzheimer’s disease and schizophrenia. The authors have previously shown that 192-Saporin (Cat. #IT-01) lesions result in severe impairments in tasks requiring sustained attentional processing. In these experiments the authors suggest that cell response is dependent on the level of demand. They demonstrate that removal of p75+ cells (0.5 µg/µl bilaterally infused into the nucleus basalis region in rat) impairs sustained attentional performance, but does not impact low-demand task performance.

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

Vulchanova L, Olson TH, Stone LS, Riedl MS, Elde R, Honda CN (2001) Cytotoxic targeting of isolectin IB4-binding sensory neurons. Neuroscience 108(1):143-155. doi: 10.1016/s0306-4522(01)00377-3 PMID: 11738138

Summary: Vulchanova et al. examine the role of IB4-binding neurons in nociception. IB4-SAP (Cat. #IT-10) was injected into rats (2 µg in left sciatic nerve). The resulting ablation of IB4-binding neurons provides evidence for their role in nociceptive processing and demonstrates a rapid compensatory response to signalling of acute pain.

Related Products: IB4-SAP (Cat. #IT-10), Saporin Goat Polyclonal (Cat. #AB-15), Saporin Goat Polyclonal, HRP-labeled (Cat. #AB-15HRP)

Wrenn CC, Wiley RG (2001) Lack of effect of moderate Purkinje cell loss on working memory. Neuroscience 107(3):433-445. doi: 10.1016/s0306-4522(01)00326-8

Summary: When 192-Saporin (Cat. #IT-01) is injected intracerebroventricularly, some p75-expressing cerebellar Purkinje cells are eliminated along with cholinergic neurons. To verify that the effects of basal forebrain lesions on working memory were not caused by loss of these Purkinje cells the authors compared doses of 1 µg OX7-SAP (Cat. #IT-02) and either 2 µg or 4 µg of 192-Saporin injected into the lateral ventricle. The data show that although similar amounts of Purkinje cells were eliminated by OX7-SAP and the lower dose of 192-Saporin, no working memory deficits resulted. Only the 4-µg dose of 192-Saporin produced working memory deficits, they conclude that this is not due to Purkinje cell loss, but the loss of cholinergic neurons.

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

Bugarith K, Ritter S, Dinh T (2001) Hyperphagia and obesity results from the injection of the immunotoxin neuropeptide Y (NPY)-saporin (NPY-sap) into the paraventricular hypothalamus (PVH) of rats. Neuroscience 2001 Abstracts 948.2. Society for Neuroscience, San Diego, CA.

Summary: NPY is a peptide implicated in the control of numerous physiological processes. A variety of G-protein coupled receptors, Y1, Y2, Y4, and Y5, mediate the actions of NPY. Recently a new immunotoxin, NPY-SAP, has been developed that is potentially of great importance for the study of NPY function. NPY-SAP is a conjugate of the peptide NPY and saporin, a plant toxin that inactivates ribosomes. The proposed mechanism of toxicity involves immunotoxin binding NPY receptors and destruction of neurons containing these receptors. In this study we injected different doses of NPY-sap or unconjugated saporin (SAP) into the PVH to test the effects of this new toxin. We found that at low doses, there was no effect of NPY-SAP on cytoarchitecture or immunoreactivity of select peptides in the PVH. There was also no difference in body weight between the groups. At high doses, there was histologically-detectable damage in the hypothalamus of NPY-SAP animals. We also found a major difference in body weight between the NPY-SAP rats and SAP controls. Ten weeks after the injections, the NPY-SAP rats (654.3g ± 39.04g) were much heavier than the SAP rats (410.6g ± 15.29g). Further, daytime (0800 – 1700H) food intake was about twice as much in NPY-SAP (9.53g ± 0.996g) as in SAP (5.74g ± 0.476g) rats, with no difference in overnight (1700 – 0800H) feeding. Work is ongoing to determine the specificity of the lesion and the mechanism of action of NPY-SAP.

Related Products: NPY-SAP (Cat. #IT-28)

Demas GE, Bartness TJ (2001) Novel method for localized, functional sympathetic nervous system denervation of peripheral tissue using guanethidine. J Neurosci Methods 112:21-28. doi: 10.1016/s0165-0270(01)00452-6

Summary: Sympathectomy, or surgical interruption of sympathetic nerve pathways, is an important technique in the analysis of the sympathetic nervous system. The authors investigate and compare several different methods of performing a sympathectomy in hamsters, including surgery, chemical, and immunotoxic lesions using anti-DBH-SAP (ten 2-µl injections, at either 0.65 µg/µl or 0.325 µg/µl, into inguinal white adipose tissue; Cat. #IT-03).

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

Truitt WA, Stanton LA, Coolen LM (2001) Targeted lesions of Substance P receptor cells in L3-4 lumbar spinal cord severely impair male ejaculatory behavior. Neuroscience 2001 Abstracts 958.18. Society for Neuroscience, San Diego, CA.

Summary: Previously we demonstrated the existence of a spinothalamic pathway in the male rat where neural activation is specifically induced by ejaculation. This pathway consists of the parvocellular subparafascicular thalamic nucleus (SPFp) and the neurons projecting to the SPFp that are located in the lumbar spinal cord, specifically in laminae 10 and 7 of segments L3-L4. This neuron population coexpresses galanin (Gal) and substance P receptors (SPR). To test the hypothesis that these cells relay sensory information related to ejaculation, these neurons were lesioned by targeting the SPR with the neurotoxin SSP-saporin, a high affinity analogue of substance P conjugated to the ribosome inhibitor saporin. SSP-saporin (4 ng/µl) or an equal concentration of unconjugated saporin was injected bilaterally into L3-L4 region in either sexually experienced or naïve male Sprague Dawley rats (n=5 each). Sexual behavior was tested weekly, starting ten days following surgery. Following the sixth behavioral test, rats were sacrificed and spinal cord tissue was immunostained for GAL, SPR, or NeuN to assess specific and nonspecific tissue damage. In rats injected with unconjugated saporin, the Gal/SPR cell population was intact and sexual behavior was not altered. In contrast, in rats receiving SSP-saporin, Gal/SPR cell population was significantly decreased (77%) or absent. Moreover, SSP-saporin lesions severely disrupted ejaculatory behavior. Interestingly, display of mounts and intromissions remained intact. These results suggest that Gal/SPR cells in laminae 10 and 7 of L3-4 lumbar spinal cord may be essential for male ejaculatory behavior.

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

Dinh TT, Sanders NM, Pedrow C, Ritter S (2001) Selective immunotoxin lesion of spinally projecting norepineprhine and epinephrine (NE/E) neurons impairs the glucagon response to 2-deoxy-d-glucose (2DG). Neuroscience 2001 Abstracts 947.1. Society for Neuroscience, San Diego, CA.

Summary: Previous work has shown that the targeted immunotoxin, anti-dopamine ß-hydroxylase conjugated to saporin (DSAP), can be used to selectively destroy subpopulations of hindbrain NE/E neurons projecting to or through a particular DSAP injection site. Using this approach, we have shown that NE/E neurons projecting to the hypothalamus are required for feeding and glucocorticoid responses to 2DG-induced glucoprivation and those projecting spinally are required for the adrenal medullary response. In this study, we injected DSAP or unconjugated saporin (SAP) control solution into the spinal cord at T2-T4 to investigate the role of the spinally projecting NE/E neurons in glucagon secretion induced by 2DG (250 mg/kg). Controls injected spinally with unconjugated saporin (SAP) had a glucagon response that peaked at 308% of pre-2DG levels, while DSAP-injected rats had a significantly blunted response to 2DG, peaking at 197% of pre-2DG levels. 2DG-induced hyperglycemia also was impaired in the DSAP rats, but not in the SAP rats. Both SAP and DSAP rats had normal feeding and glucocorticoid responses to 2DG. Results suggest that spinally-projecting NE/E neurons participate in the neural control of glucagon secretion under conditions of glucose deficit. In combination with other findings, these results indicate that hindbrain NE/E neurons contribute to four major glucoregulatory responses (increased feeding, and increased secretion of glucagon, glucocorticoids and adrenal medullary epinephrine) through their projections to hypothalamic or spinal cord effector sites.

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

Fraley GS, Dinh TT, Ritter S (2001) Immunotoxin lesion of catecholaminergic neurons innervating the medial hypothalamus elevates basal expression of and attenuates glucoprivaation-induced increases in agouti gene related protein (AGRP) mRNA. Neuroscience 2001 Abstracts 947.2. Society for Neuroscience, San Diego, CA.

Summary: Catecholaminergic (CA) innervation of medial hypothalamic structures is necessary for glucoprivation-induced feeding, glucocorticoid secretion and Fos expression in the paraventricular (PVH) and arcuate nuclei of the hypothalamus. In this experiment, we tested the hypothesis that the 2-deoxy-D-glucose (2DG)-induced an increase in AGRP mRNA expression (reported recently by Sergeyev et al., 2000) also requires NE/E neurons. CA neurons innervating the medial hypothalamus were lesioned using the toxin, saporin, targeted for selective entry into NE/E neurons by conjugation with a monoclonal antibody against dopamine beta hydroxylase. This toxin (DSAP), or unconjugated saporin (SAP) control solution, was bilaterally microinjected into the PVH. DSAP rats with confirmed 2DG-induced feeding deficits (DSAP 1.7 +/- 0.29 g; SAP 5.1 +/- 0.31 g; p < 0.05) and controls were injected with 2DG (250 mg/kg), or saline and maintained for 2 hrs without food. Hypothalami were harvested and subjected to Northern blot analysis of AGRP mRNA. Blot analysis revealed that 2DG increased mRNA expression in SAP controls (2DG: 1.0 +/- 0.05 RDU; saline: 0.7 +/- 0.02, p< .05), but not in DSAP lesioned rats (2DG: 1.1 +/- 0.04; saline: 1.0 +/- 0.03). In addition, basal AGRP mRNA expression was significantly elevated in DSAP-lesioned rats compared to SAP controls (p < .05). These data suggest that basal AGRP gene expression is controlled by hindbrain CA neurons and that increased AGRP gene expression induced by glucoprivation also requires these neurons.

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