targeted-toxins

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)

Dalley JW, Cardinal RN, Robbins TW (2004) Prefrontal executive and cognitive functions in rodents: neural and neurochemical substrates. Neurosci Biobehav Rev 28(7):771-784. doi: 10.1016/j.neubiorev.2004.09.006

Objective: To review current progress in our understanding of the rodent prefrontal cortex, especially evidence for functional divergence of the anatomically distinct sub-regions of the rat prefrontal cortex.

Summary: A greater understanding of the prefrontal cortex will come from using tasks that load specific cognitive and executive processes, in parallel with discovering new ways of manipulating the different sub-regions and neuromodulatory systems of the prefrontal cortex.

Usage: Lesions of the cortically projecting cholinergic neurons of the nucleus basalis magnocellularis made using excitotoxins, or the highly selective cholinergic immunotoxin 192 IgG-SAP, generally impair discriminative performance.

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

See Also:

• Heckers S et al. Complete and selective cholinergic denervation of rat neocortex and hippocampus but not amygdala by an immunotoxin against the p75 NGF receptor. J Neurosci 14:1271-1289, 1994.

Ma J, Shen B, Rajakumar N, Leung LS (2004) The medial septum mediates impairment of prepulse inhibition of acoustic startle induced by a hippocampal seizure or phencyclidine. Behav Brain Res 155(1):153-166. doi: 10.1016/j.bbr.2004.04.010

Summary: Deficits in sensorimotor gating, suppression of a motor response by a sensory stimulus are found in schizophrenic patients, as well as laboratory animals after administration of compounds such as phencyclidine (PCP). The authors lesioned the cholinergic system of the medial septum in rats with 0.14-0.21 µg injections of 192-Saporin (Cat. #IT-01) to examine the involvement of these neurons in sensorimotor gating. The authors suggest that GABAergic, but not cholinergic septohippocampal neurons mediate this deficit.

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

Estacio MA, Tsukamura H, Reyes BA, Uenoyama Y, I’anson H, Maeda K (2004) Involvement of brainstem catecholaminergic inputs to the hypothalamic paraventricular nucleus in estrogen receptor alpha expression in this nucleus during different stress conditions in female rats. Endocrinology 145(11):4917-4926. doi: 10.1210/en.2004-0469

Summary: Norepinephrine release in the paraventricular nucleus (PVN) is increased during periods of metabolic stress. The authors hypothesized that noradrenergic inputs to the PVN may also mediate estrogen receptor a (ERa) expression in the PVN during metabolic stress. 20 ng of Anti-DBH-SAP (Cat. #IT-03) was injected bilaterally into the PVN of rats, and ERa expression was examined in several stress models. Results indicate that during metabolic stress catecholaminergic inputs to the PVN play a major role in mediating the induction of ERa expression.

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

Wenninger JM, Pan LG, Klum L, Leekley T, Bastastic J, Hodges MR, Feroah TR, Davis S, Forster HV (2004) Large lesions in the pre-Botzinger complex area eliminate eupneic respiratory rhythm in awake goats. J Appl Physiol 97(5):1629-1636. doi: 10.1152/japplphysiol.00953.2003

Summary: Previously the authors demonstrated that lesioning the pre-Bötzinger Complex (pre-BötzC) with SP-SAP (Cat. #IT-07) resulted in transient disruptions of normal respiratory muscle activation in goats. The purpose of this study was to examine the effects of a more complete lesion of the pre-BötzC area. The authors treated SP-SAP-lesioned goats with ibotenic acid. The results suggest that the pre-BötzC is critical for generating a normal respiratory rhythm during the awake state.

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

Wenninger JM, Pan LG, Klum L, Leekley T, Bastastic J, Hodges MR, Feroah T, Davis S, Forster HV (2004) Small reduction of neurokinin-1 receptor-expressing neurons in the pre-Botzinger complex area induces abnormal breathing periods in awake goats. J Appl Physiol 97(5):1620-1628. doi: 10.1152/japplphysiol.00952.2003

Summary: Previous work has shown that lesion of the pre-Bötzinger Complex (pre-BötzC) of rats with SP-SAP (Cat. #IT-07) results in hypoventilation and an abnormal breathing pattern. The authors used 1 or 10 µl of 50 pM SP-SAP bilaterally injected into the pre-BötzC area to further investigate this system in goats. The results show transient changes in respiratory rhythm and respiratory muscle activation patterns, indicating that SP receptor-expressing neurons in the pre-BötzC are involved in the regulation of respiration.

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

Pokala VN, Fitz NF, Witt-Enderby PA, Johnson DA (2004) Septohippocampal cholinergic lesion and hippocampal alpha-secretase activity in rat. Neuroscience 2004 Abstracts 846.14. Society for Neuroscience, San Diego, CA.

Summary: Previously we have shown that selective cholinergic lesion of the septohippocampal pathway in the rat resulted in a significant decrease in hippocampal extracellular acetylcholine (ACh) concentration, a compensatory increase in muscarinic receptor binding, but a decrease in muscarinic receptor-coupled G protein activation. The intent of this study was to investigate the effect of selective cholinergic lesion of the septohippocampal pathway on hippocampal alpha-secretase activity and expression. Alpha-secretase is an enzyme responsible for the proteolytic cleavage of amyloid protein precursor (APP) to release a neuroprotective soluble amyloid protein precursor (sAPP). Sprague-Dawley rats were infused into the medial septum with either the selective cholinergic immunotoxin 192 IgG-saporin (0.22 mg in 1ml aCSF) or vehicle. After 6 weeks the rats were euthanized and the hippocampus dissected from the brain and quickly frozen. Hippocampal homogenate was analyzed for alpha-secretase activity and expression. The results demonstrated an 80% decrease in alpha-secretase activity in SAP treated animals compared to control.

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

Pearson MS, Woods M, Whiteside GT, Garrison AE, Pomonis JD, Walker K (2004) IB4-SAP reduces IB4 staining in the spinal cord and prevents axotomy induced sprouting of Aβ fibers. Neuroscience 2004 Abstracts 858.6. Society for Neuroscience, San Diego, CA.

Summary: Peripheral nerve injury results in hyperalgesia and allodynia. It has been proposed that sprouting of myelinated touch responsive Aß-fibers into the innervation territory of pain sensitive C-fibers in the spinal cord contributes to these abnormal behaviors. The extent of sprouting has recently been challenged and it has been proposed that C-fibers rather than Aß-fibers are involved. We have investigated whether selectively ablating a population of small diameter nociceptors using isolectin B4 conjugated to saporin (IB4-SAP), reduces axotomy-induced sprouting. Male Sprague-Dawley rats received intraneural injections of either IB4-SAP or PBS (3 µl, 0.66 µg/µl) and two weeks later the sciatic nerve was axotomized at the mid-thigh level. Two weeks later, the sciatic nerve was injected with the retrograde tracer, cholera toxin-ß subunit (CTB) (2 µl, 2%) that selectively traces Aß-fibers. Three days post CTB the animals were perfused, the spinal cord harvested, sectioned and stained immunohistochemically for IB4 and CTB. IB4-SAP treatment resulted in a substantial reduction of IB4 staining in the spinal cord versus PBS injected controls. As previously described, axotomy resulted in considerable CTB immunostaining in laminae I, II and III compared to non-axotomized controls in which it was present only in laminae I and III. IB4-SAP treatment followed by axotomy resulted in a substantial reduction of CTB immunostaining in lamina II compared to PBS injected controls. These results suggest that intraneural IB4-SAP ablates a population of small diameter nociceptors and that axotomy induced CTB staining in lamina II is due to uptake of CTB by C-fibers.

Related Products: IB4-SAP (Cat. #IT-10)

ATS Poster of the Year Winner. Read the featured article in Targeting Trends.

Chance WT, Dayal R, Friend L, Sheriff S (2004) Intraventricular injection of CRF receptor 2 antisense oligonucleotide reduces burn-induced hypermetabolism. Neuroscience 2004 Abstracts 890.22. Society for Neuroscience, San Diego, CA.

Summary: Following major burn trauma, mammals exhibit a prolonged hypermetabolic response proportional to the size of the burn. The ability to control metabolic rate would likely result in better clinical management of burn patients. Our research employing a saporin-CRF conjugate to lesion CRF receptors suggested that activity at CRF receptor(R)-2 mediated increased resting energy expenditure (REE) in burned rats. In the present study we assessed whether treatment of burned rats with antisense oligonucleotides (ON) to CRF or CRF R-2 would reduce REE. Following anesthetization (ketamine/xylazine:80/15 mg/kg,), cannulae (24 ga) were implanted into the 3rd ventricle of 52 adult, male, SD rats. Two weeks later, these rats were anesthetized and subjected to a 25 sec, 30% body surface area, open flame burn (n = 30) or sham burn procedures (n = 22). Following (2-6 days) the burn trauma, either sense or antisense ONs to CRF (15 ug) or CRF R-2 (20 ug) was injected, ivt. REE (kcal/kg/24 hrs) was determined in these rats 7 and 14 days after burn by indirect calorimetry. Treatment with CRF antisense ON did not reduce REE in any groups. Burned rats given the CRF R-2 sense ON exhibited significant hypermetabolism both 7 (188±5 vs 156± 9) and 14 (201±8 vs 151±14) days post-burn, as compared to sham-burned rats. Burned rats treated with the CRF R-2 antisense ON were not significantly different from sham burned rats 7 (169±8) or 14 (167±5) days post-burn. Since the antisense treatment should decrease translation of message into protein at the receptor, these results suggest that activity at the CRF-2 receptor is necessary for expression of burn-induced hypermetabolism. Therefore, it is possible that CRF-2 receptor antagonists could be useful in treating burn-induced hypermetabolism.

Related Products: CRF-SAP (Cat. #IT-13)

Zhou D, Levin BE (2004) PVN anti-SERT-SAP injections reduce body weight gain, normal and glucoprivic feeding, and hypoglycemia- and stress-induced corticosterone responses. Neuroscience 2004 Abstracts 893.14. Society for Neuroscience, San Diego, CA.

Summary: Hindbrain serotonin (5HT) neurons are highly ramified with single neurons innervating several forebrain and hypothalamic areas such as the paraventricular nucleus (PVN). To assess their importance in the regulation of energy homeostasis and hypothalamo-pituitary-adrenal activation, anti-SERT-SAP (SS), an antibody to the 5HT re-uptake transporter (SERT) conjugated to a ribosomal toxin saporin (SAP), was injected bilaterally into the PVN of rats to selectively destroy hypothalamically-projecting 5HT neurons. Unconjugated SAP injections served as controls. SS injections significantly destroyed rostral dorsal (DRa) and medial raphe (MRa) 5HT neurons. Compared to SAP rats, SS rats had 13% lower food intake (SAP 71.2+3.2g vs. SS 61.7+2.8g, P=0.037) and 44% lower body weight gain (SAP 26.9+2.9g vs. SS 15.3+.31g, P=0.003) over 8d. Food intake over 24h (but not 3h) after insulin-induced hypoglycemia was 22% lower in SS (25.1±1.2g) than SAP rats (32.2±0.9g, P<0.01) and their blood glucose levels dropped more during 120min of hypoglycemia (AUC, -3945+77mg/dl) than SAP controls (-3675+108; P=0.01) suggesting a counterregulatory defect. This was supported by a 39% lower 30min corticosterone (Cort) response to hypoglycemia in SS (126±25µg/ml) vs. SAP controls (208±21 μg/ml, P<0.05). On the other hand, the glucagon response to hypoglycemia did not differ between SS (81.3±10.1pg/ml) and SAP-injected rats (65.8±7.6pg/ml; P=0.72). Finally, SS injections reduced the Cort response to 30min immobilization stress (SS 389±21 vs. SAP 460±25 µg/mg; P<0.05) by 15% without significantly affecting basal levels (SS 18.0±3.9 vs. SAP 10.1±2.2 µg/ml, P=0.09). Thus, DRa and MRa 5HT projections to the forebrain play a significant role in energy homeostasis, hypoglycemia-induced feeding and the Cort responses to both hypoglycemia and stress.

Related Products: Anti-SERT-SAP (Cat. #IT-23)