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Targeted toxins in pain.
Wiley RG, Lappi DA (2003) Targeted toxins in pain. Adv Drug Deliv Rev 55(8):1043-1054. doi: 10.1016/s0169-409x(03)00102-9
Summary: The authors discuss the use of ‘molecular neurosurgery’ in the study of nociception. Applications using targeted toxins, which include immunotoxins, protein-toxin conjugates, or peptide-toxin conjugates, are illustrated. The authors describe the use of these molecules as research tools, as well as their potential for therapeutics. A helpful table is included that lists neuronal surface markers and class of cells targeted for each targeted toxin. Reagents discussed: CTB-SAP (Cat. #IT-14), IB4-SAP (Cat. #IT-10), OX7-SAP (Cat. #IT-02), 192-Saporin (Cat. #IT-01), ME20.4-SAP (Cat. #IT-15), Anti-DBH-SAP (Cat. #IT-03), Anti-DAT-SAP (Cat. #IT-25), SP-SAP (Cat. #IT-07), Dermorphin-SAP (Cat. #IT-12), Orexin-SAP (Cat. #IT-20), CRF-SAP (Cat. #IT-13), and acetylated LDL-SAP (Cat. #IT-08).
Related Products: CTB-SAP (Cat. #IT-14), IB4-SAP (Cat. #IT-10), OX7-SAP (Cat. #IT-02), 192-IgG-SAP (Cat. #IT-01), ME20.4-SAP (Cat. #IT-15), Anti-DBH-SAP (Cat. #IT-03), Anti-DAT-SAP (Cat. #IT-25), SP-SAP (Cat. #IT-07), Dermorphin-SAP / MOR-SAP (Cat. #IT-12), Orexin-B-SAP (Cat. #IT-20), CRF-SAP (Cat. #IT-13), Acetylated LDL-SAP (Cat. #IT-08)
Long-term effects of decreased noradrenergic central nervous system innervation on pain behavior and opioid antinociception.
Jasmin L, Boudah A, Ohara PT (2003) Long-term effects of decreased noradrenergic central nervous system innervation on pain behavior and opioid antinociception. J Comp Neurol 460(1):38-55. doi: 10.1002/cne.10633
Summary: Noradrenaline (NA) is an essential element of the endogenous pain inhibitory system. The authors injected 5 µg of anti-DBH-SAP (Cat. #IT-03) into either the cerebral ventricles or lumbosacral cistern of rats to investigate whether a permanent reduction of noradrenergic innervation of the spinal cord leads to a chronic decreased nociceptive threshold. Although treated animals were less responsive to the antinociceptive effects of morphine, the results suggest that NA makes only a modest contribution to the nociceptive threshold.
Related Products: Anti-DBH-SAP (Cat. #IT-03)
Immunotoxin lesion of hypothalamically projecting norepinephrine and epinephrine neurons differentially affects circadian and stressor-stimulated corticosterone secretion.
Ritter S, Watts AG, Dinh TT, Sanchez-Watts G, Pedrow C (2003) Immunotoxin lesion of hypothalamically projecting norepinephrine and epinephrine neurons differentially affects circadian and stressor-stimulated corticosterone secretion. Endocrinology 144(4):1357-1367. doi: 10.1210/en.2002-221076
Summary: Hindbrain norepinephrine (NE) and epinephrine (E) neurons are important in the distribution of internal sensory signals. Injecting 42 ng of anti-DBH-SAP (Cat. #IT-03) into the paraventricular nucleus of rat hypothalamus, the authors were able to specifically destroy NE and E neurons. This study revealed the contribution of NE/E afferents to hypothalamo-pituitary-adrenal activation during stress and confirmed that NE and E neurons are required for specific stress responses.
Related Products: Anti-DBH-SAP (Cat. #IT-03)
Immunolesion of norepinephrine and epinephrine afferents to medial hypothalamus alters basal and 2-deoxy-D-glucose-induced neuropeptide Y and agouti gene-related protein messenger ribonucleic acid expression in the arcuate nucleus.
Fraley GS, Ritter S (2003) Immunolesion of norepinephrine and epinephrine afferents to medial hypothalamus alters basal and 2-deoxy-D-glucose-induced neuropeptide Y and agouti gene-related protein messenger ribonucleic acid expression in the arcuate nucleus. Endocrinology 144(1):75-83. doi: 10.1210/en.2002-220659
Summary: Neuropeptide Y (NPY) and agouti gene-related protein (AGRP) are important peptides in the control of food intake. Prior studies have shown that mRNAs for both these peptides are increased in the arcuate nucleus of the hypothalamus (ARC) by glucoprivation. Using bilateral 42 ng intracranial injections of anti-DBH-SAP (Cat. #IT-03) in rats, the authors investigated the role of hindbrain catecholamine afferents in this increased ARC NPY and AGRP gene expression. The results indicate that these afferents contribute to basal NPY and AGRP gene expression as well as mediate the responsiveness of NPY and AGRP neurons to glucose deprivation.
Related Products: Anti-DBH-SAP (Cat. #IT-03)
Immunotoxic lesions of ascending catechoalminergic afferents abolish the CRH gene transcriptional response to 2-deoxyglucose in the rat paraventricular nucleus
Watts AG, Sanchez-Watts G, Dinh TT, Ritter S (2002) Immunotoxic lesions of ascending catechoalminergic afferents abolish the CRH gene transcriptional response to 2-deoxyglucose in the rat paraventricular nucleus. Neuroscience 2002 Abstracts 865.2. Society for Neuroscience, Orlando, FL.
Summary: CRH neurons in the medial parvicellular (mp) part of the paraventricular nucleus (PVH) are critical for the neural control of the hypothalamo-pituitary-adrenal axis. One of their most prominent afferents sets derives from hindbrain catecholaminergic neurons that are thought to help mediate viscerosensory influences on the PVHmp. Despite the prominence of this input, its precise role in controlling CRH neuronal function remains controversial. Here we report the effect on basal and stimulated CRH gene expression of an immunotoxin that selectively destroys catecholaminergic neurons. Rats were injected in the PVH with either a saporin-anti-dopamine B-hydroxylase (DBH) conjugate (DSAP), which leads to total loss of DBH immunoreactivity in the PVH, or saporin alone (SAP), which does not. Three weeks later, animals were injected either with 250mg/kg of 2-deoxy-D-glucose (2DG) or vehicle. Thirty mins later they were anesthetized and perfused with 4% buffered paraformaldehyde. Fifteen um frozen sections were cut through the hypothalamus and hybridized for CRH mRNA, CRH hnRNA, or c-fos mRNA. DSAP treatment had no effect on CRH mRNA levels in the PVH of vehicle- or 2DG-injected animals, but abolished the CRH hnRNA and c-fos mRNA responses to 2DG. We have reported elsewhere that DSAP lesions selectively abolish the corticosterone response to 2DG, but not to swim stress, or circadian corticosterone release. We now show that catecholaminergic afferents are required for 2DG-induced CRH gene expression, but not for basal expression.
Related Products: Anti-DBH-SAP (Cat. #IT-03)
Immunotoxic lesion of catecholamine afferents to paraventricular hypothalamus (PVH) impairs the corticosterone response to glucoprivation but not the basal secretory rhythm or response to swim stress
Ritter S, Dinh TT, Pedrow C, Roellich K (2002) Immunotoxic lesion of catecholamine afferents to paraventricular hypothalamus (PVH) impairs the corticosterone response to glucoprivation but not the basal secretory rhythm or response to swim stress. Neuroscience 2002 Abstracts 865.4. Society for Neuroscience, Orlando, FL.
Summary: Catecholamine afferents from the hindbrain densely innervate the medial parvicellular part of the PVH, which contains CRH neurons critical for control of corticosterone (CORT) secretion. However, the precise role of these afferents in control of CORT secretion is unclear. Here the immunotoxin, saporin conjugated to anti-dopamine B-hydroxylase(DSAP), which selectively lesions norepinephrine and epinephrine neurons, or unconjugated saporin (SAP) control solution, was microinjected into the PVH. After extensive habituation to testing conditions, DSAP and SAP rats were injected with 2-deoxy-D-glucose (2DG, 250mg/kg) or vehicle or subjected to a 5-min forced swim. Blood was sampled remotely between 0 and 240 min for radioimmunoassay of CORT. In a third test, blood was sampled every 4 hr for 24 hr to assess the basal secretory rhythm of CORT. Subsequently, loss of dopamine B-hydroxylase containing terminals without destruction of CRH neurons in the PVH of DSAP rats was confirmed by immunohistochemistry. In DSAP rats, the CORT response to 2DG was reduced dramatically to 29% of the response in SAP controls. In contrast, DSAP and SAP rats did not differ in their basal secretory rhythm or their CORT response to swim stress, indicating for the first time a stimulus-specific role of catecholamine afferents in control of CORT secretion. This finding is complemented by other work in which we (with A.G. Watts and G. Sanchez-Watts) show that these catecholamine afferents are required for 2DG-induced CRH gene expression, but not basal expression.
Related Products: Anti-DBH-SAP (Cat. #IT-03)
Role of hindbrain catecholaminergic afferents to the medial hypothalamus in the regulation of penile reflexes in the rat
Fraley GS (2002) Role of hindbrain catecholaminergic afferents to the medial hypothalamus in the regulation of penile reflexes in the rat. Neuroscience 2002 Abstracts 681.4. Society for Neuroscience, Orlando, FL.
Summary: The use of ex copula erections, or reflexive erections, has been used for decades in the study of the central pathways and neuroendocrinology of penile erections. However, the exact neuroendocrine pathways involved in developing penile erections are not known. This study utilized molecular neurosurgical techniques combined with behavioral, histological, and molecular analyses to determine a central link between metabolic state and penis erectile function. Utilizing saporin-conugate immunolesion techniques (DSAP), hindbrain catecholaminergic afferents to the hypothalamus that are reported to be glucoresponsive were eliminated. DSAP-lesioned rats had a significantly attenuated glucoprivic feeding response and significantly attenuated penile reflexes compared to controls. Analysis of Nissl-stained spinal cord sections demonstrated a significant reduction in the size of sexually dimorphic motoneurons. Furthermore, qualitative analysis of calcitonin gene-related immunoreactivity (CGRPir) in alternate spinal sections revealed a decrease in CGRPir in sexually dimorphic motor pools. Analysis of hypothalamic mRNA levels showed a significant increase in both oxytocin and neuropeptide Y mRNA, but not b-actin mRNA. No significant differences were seen, however, in the weight of the perineal muscles, seminal vessicles, or in plasma testosterone levels. These data indicate a novel hindbrain-hypothalamic-spinal cord pathway by which potential glucoresponsive neurons effect the ability to achieve penile erection based upon availability of metabolic fuel.
Related Products: Anti-DBH-SAP (Cat. #IT-03)
Simultaneous neurotoxic lesions of noradrenergic LC, histaminergic TMN and cholinergic BF neurons do not elicit hypersomnia whereas lesions of the hypocretin-containing LH neurons do.
Blanco-Centurion CA, Gerashchenko D, Murillo-Rodriguez E, Shiromani PJ (2002) Simultaneous neurotoxic lesions of noradrenergic LC, histaminergic TMN and cholinergic BF neurons do not elicit hypersomnia whereas lesions of the hypocretin-containing LH neurons do. Neuroscience 2002 Abstracts 577.16. Society for Neuroscience, Orlando, FL.
Summary: Wakefulness is believed to be due to activation of neurons in the locus coeruleus (LC), tuberomammillary nucleus (TMN) and the basal forebrain (BF). These neurons receive a heavy projection from hypocretin (HCRT) neurons. It has been proposed that the HCRT neurons maintain wakefulness via their innervation of these three groups of neurons. Here we test this hypothesis by lesioning the LC, TMN and the BF. Sprague-Dawley rats implanted with sleep recording electrodes were given microinjections of the following saporin neurotoxins to lesion specific neurons: α-DBH-saporin (vol=0.4 μL; 1 μg/μL, LC lesion) , HCRT2-saporin (vol=0.4 μL; 0.20 μg/μL, TMN lesion) and 192IgG-saporin (vol=0.5 μL; 0.4 μg/μL, BF lesion). Six rats given saline injections served as controls. Immediately after surgery sleep recordings were made continuously for three weeks. In rats that had double lesions (n=7)(combinations of LC, TMN or BF) sleep was not increased. In two rats the LC, TMN and BF were destroyed (>95%) but there was no hypersomnia either. However, one rat that had a triple lesion and also had 30% loss of HCRT neurons showed significant and persistent hypersomnia. Previously, lesion of a single wake-active neuronal population has not been found to increase sleep. We have now found that double or triple lesions also do not produce hypersomnia. Only when the HCRT neurons are lesioned, sleep is affected. This suggests that HCRT neurons play a primary role in waking and the LC, TMN or BF neurons do not mediate this function.
Related Products: Anti-DBH-SAP (Cat. #IT-03)
The dyssynaptic pathway from the caudal ventrolateral medulla to the spinal cord is relevant for pain modulation
Tavares I, Cobos AR, Almeida A, Lima D (2002) The dyssynaptic pathway from the caudal ventrolateral medulla to the spinal cord is relevant for pain modulation. Neuroscience 2002 Abstracts 351.21. Society for Neuroscience, Orlando, FL.
Summary: The caudal ventrolateral medulla (VLM) exerts α2-adrenoreceptor mediated inhibition of pain transmission at the spinal cord. Anatomical studies described a dysynaptic pathway, connecting the VLM with the spinal cord through the A5 noradrenergic cell group, in which the spinally-projecting A5 noradrenergic neurons give collaterals to the VLM. In order to evaluate the role of the VLM-A5-spinal pathway in pain modulation, retrograde transport of the neurotoxin saporin-anti-dopamine-β-hydroxylase (SAP-anti-DBH) from the VLM was used. The VLM of Wistar rats was injected with 0.5μl of a 1% SAP-anti-DBH solution or saline (control group). Four days later, all animals were injected with 50 μl of 5% formalin in the ipsilateral hindpaw, and pain behavior and noxious-evoked spinal c-fos expression, were evaluated. In the SAP-anti-DBH group, a 27% decrease in DBH-immunoreactive neuronal population at the A5 noradrenergic cell group was detected and neuronal death was confirmed by Fluojade staining. Hyperalgesia was detected in the second phase of the formalin test. The numbers of Fos-immunoreacted neurons in the spinal dorsal horn increased. The data suggest that the VLM-A5-spinal pathway participates in pain modulation. It remains to be ascertained whether the lack of effect at the first-phase of the formalin test is due to an insufficient destruction of the A5 noradrenergic cell group or whether it points to a differential effect of this pathway in the two phases of the formalin test.
Related Products: Anti-DBH-SAP (Cat. #IT-03)
Long-term effects on pain behavior of decreased spinal noradrenaline in neuropathic rats
Ohara PT, Boudah A, Jasmin L (2002) Long-term effects on pain behavior of decreased spinal noradrenaline in neuropathic rats. Neuroscience 2002 Abstracts 351.22. Society for Neuroscience, Orlando, FL.
Summary: We sought to determine if a permanent reduction in the noradrenergic (NA) input to the spinal cord in adult rats would alter the pain behavior associated with nerve injury. Selective NA denervation of the lumbo-sacral cord was achieved by intrathecal injection of anti-dopamine beta-hydroxylase antibodies conjugated to the toxin saporin in 12 female rats. Spinal NA denervation was confirmed histologically in all animals. Saline injected rats served as controls. Two weeks after toxin or saline treatment, a unilateral peripheral neuropathy was induced by tight ligation of the left L5 spinal nerve in both groups. Unexpectedly, the same degree of mechanical hyperalgesia was present in the neuropathic paw of rats in both the toxin and saline treated groups. Rats lacking NA spinal afferents, however, were less responsive to the antinoiceptive effects of morphine administered systemically or intracerebroventricularly. Also, toxin treated rats did not display opioid dependant stress analgesia. Finally, toxin treated rats were more responsive to the antinociceptive effect of the NK1 antagonist CP 96,345 but not to its enantiomer CP 96,344. From these results we conclude that the permanent loss of spinal NA does not alter neuropathic pain behavior, possibly because of compensatory changes in the CNS. The decreased response to opioids is consistent with the previous suggestions of an interaction between noradrenergic and opioidergic systems in producing analgesia. The increased response to NK1 antagonists shows that NA tonically inhibits substance.
Related Products: Anti-DBH-SAP (Cat. #IT-03)