targeted-toxins

Burk JA, Lowder MW, Altemose KE (2008) Attentional demands for demonstrating deficits following intrabasalis infusions of 192 IgG-saporin. Behav Brain Res 195:231-238. doi: 10.1016/j.bbr.2008.09.006

Summary: Attentional processing has been shown to be dependent on basal forebrain cholinergic inputs to the cerebral cortex. In this work the authors wished to specify which components should be used to demonstrate deficits following the loss of these neurons. Rats received 200 ng intrabasalis infusions of 192-IgG-SAP (Cat. #IT-01). Testing of lesioned animals indicated that attentional deficits are due to increase of overall attentional task demands as opposed to any single task parameter.

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

Fitz NF, Gibbs RB, Johnson DA (2008) Selective lesion of septal cholinergic neurons in rats impairs acquisition of a delayed matching to position T-maze task by delaying the shift from a response to a place strategy. Brain Res Bull 77:356-360. doi: 10.1016/j.brainresbull.2008.08.016

Summary: It has been theorized that the effect of cholinergic lesions of the medial septum on learning depend on the stressful nature of the task being learned. The authors injected 0.2 µg of 192-IgG-SAP (Cat. #IT-01) into the medial septum of rats then examined the strategies used by these animals to learn a delayed matching to position T-maze task. Lesioned animals were less able to switch from one strategy to another, indicating that this mechanism is the primary one affected by septal cholinergic lesions.

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

Milstein JA, Dalley JW, Robbins TW (2010) Methylphenidate-induced impulsivity: pharmacological antagonism by beta-adrenoreceptor blockade. J Psychopharmacol 24:309-321. doi: 10.1177/0269881108098146

Summary: In this work bilateral 20 ng intracortical injections of anti-DBH-SAP (Cat. #IT-03) were used to examine the role of noradrenergic neurons in the control of psychostimulant-induced impulsivity. Although β-adrenoreceptor blockade abolished this impulsivity, lesioning noradrenergic neurons in the cortex had no effect. The data indicate that modulation of impulsive responding in this model is controlled by β-adrenoreceptors.

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

Zhang W, Gardell S, Zhang D, Xie JY, Agnes RS, Badghisi H, Hruby VJ, Rance N, Ossipov MH, Vanderah TW, Porreca F, Lai J (2009) Neuropathic pain is maintained by brainstem neurons co-expressing opioid and cholecystokinin receptors. Brain 132:778-787. doi: 10.1093/brain/awn330

Summary: It has been hypothesized that a subset of rostral ventromedial medulla (RVM) neurons co-expressing the cholecystokinin type 2 receptor and the mu-opioid receptor are responsible for the maintenance of neuropathic pain. Rats were treated with 50-ng bilateral RVM injections of Dermorphin-SAP (Cat. #IT-12), CCK-SAP (Cat. #IT-31), or saporin (Cat. #PR-01) as a control. Lesion of the RVM neurons prevented hyperalgesia in response to CCK treatment, and shortened abnormal pain states caused by sciatic nerve injury.

Related Products: Dermorphin-SAP / MOR-SAP (Cat. #IT-12), CCK-SAP (Cat. #IT-31), Saporin (Cat. #PR-01)

Khan AM, Rapp KL, Ponzio TA, Sanchez-Watts G, Watts AG (2008) Stimulus-, circuit- and intracellular-level determinants of MAP kinase and CREB activation in parvicellular hypothalamic paraventricular neurons. Neuroscience 2008 Abstracts 865.23/MM24. Society for Neuroscience, Washington, DC.

Summary: Systemic insulin or 2-deoxyglucose (2-DG) rapidly elevate phosphorylated MAP kinases (phospho-ERK1/2) and/or CRH hnRNA in PVHp neurons, and increase circulating ACTH and corticosterone. These neuroendocrine responses are likely driven by hindbrain-originating catecholaminergic (CA) neuron subpopulations, which richly innervate the PVHp and are activated by glycemic challenges. Supporting this, acute in vivo or in vitro PVH delivery of the prototypical catecholamine, norepinephrine (NE), recapitulates these responses (J Neurosci, 2007, 27:7344-7360). Here, we determined whether PVHp ERK/CREB phosphorylation responses require: 1) intact CA afferents, when triggered by three distinct in vivo challenges; and 2) upstream MEK kinase activity, when triggered by NE application in acute hypothalamic slices maintained in vitro. Methods. Rats given PVH microinjections of anti-dopamine-b-hydroxylase (DBH)-saporin antibody-toxin conjugate (DSAP) or mIgG-saporin control conjugate received either normal 0.9% saline vehicle or one of three systemic challenges: insulin (2 U/kg, i.v.); 2-DG (250 mg/kg, i.v.); or hypertonic saline (1.5 M, i.p.) and sacrificed 30 min later. Brains were processed for CRH mRNA/hnRNA hybridization, or DBH, phospho-ERK or phospho-CREB immunocytochemistry. Plasma was collected for hormone determinations at 0 and 30 min. In separate in vitro studies, acute hypothalamic slices received either no treatment (controls), or received bath-applied NE (100 mM) in the presence or absence of the MEK inhibitor, U0126 (10 mM), or the inactive MEK inhibitor analogue, U0124 (10 mM). Ten min later, slices were placed in fixative. Results. 1. Sham-lesioned animals: Relative to vehicle, all challenges elevated phospho-ERK1/2, phospho-CREB, and ACTH/corticosterone levels; and, except for insulin, also increased CRH hnRNA. 2. Lesioned animals: DSAP treatment selectively destroyed hindbrain-originating CA afferents. In insulin- and, to a lesser extent, 2-DG-treated animals, this loss was accompanied by markedly reduced PVH phospho-ERK1/2 and circulating ACTH/corticosterone. In contrast, these responses remained robust in CA-deafferented hypertonic saline-treated rats. Phospho-CREB levels were differentially reduced relative to phospho-ERK in lesioned rats. 3. Slices: NE-induced PVH elevations of phosphorylated ERK1/2 and CREB were reduced markedly by U0126, but not U0124, pre-treatment. Conclusions. PVHp phospho-ERK selectively couples to CA afferents during glycemic challenges and ERK/CREB recruitment appears to require MEK activity.

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

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Wiley RG, Moore SA, Kline IV RH (2008) Analysis of inhibitory phase of formalin test: Effects of specific neural lesions. Neuroscience 2008 Abstracts 772.4/MM19. Society for Neuroscience, Washington, DC.

Summary: The formalin test has been widely used as a model of persistent pain. The 90 mins of formalin-induced nocifensive responding can be divided into two phases (phase 1, first ~10 mins; phase 2, last ~60 mins) separated by a period of reduced responding (interphase, IP), that has received relatively little attention. Behavioral inhibition during the IP of the formalin test has been associated with electrophysiological evidence of inhibition of dorsal horn nociceptive neurons (Henry et al, Pain, 82:57, 1999), probably due, at least in part, to local spinal mechanisms. Behavioral inhibition during IP has been shown to be enhanced by morphine and suppressed by naloxone. In the present study, we sought to determine the effect of selective depletion of specific dorsal horn interneurons known to be involved in nociception, i.e. neurons expressing NPY1R, GalR1 or MOR, or selective destruction of cerebral noradrenergic neurons or spinal cord projecting 5-HT neurons on formalin-induced nociceptive behavior, with particular attention to IP. Type-selective lesions were produced by lumbar intrathecal injection of NPY-saporin, galanin-saporin or dermorphin-saporin, respectively. Cerebral noradrenergic neurons and spinally projecting 5-HT neurons were destroyed using the immunotoxins, anti-DBH-saporin (intracerebroventricular) or anti-SERT-saporin (lumbar intrathecal), respectively. Partial loss of dorsal horn interneurons expressing NPY1R or GalR1 decreased nocifensive responding during IP and phase 2 of the formalin test, while partial loss of MOR-expressing dorsal horn interneurons increased nocifensive responding during IP and during phase 2. Both antiDBH-sap and antiSERT-sap decreased responding during IP, without effects on either phase 1 or 2. These results suggest that the apparent anti-nociception during IP and phase 2 produced by loss of NPY1R- and GalR1-expressing dorsal horn neurons is due to increased inhibition over excitation/facilitation of nociceptive projection neurons, whereas depletion of MOR-expressing interneurons produces the opposite effect. The apparent enhanced nociception during IP, but not phase I and II, produced by anti-DBH-sap and anti-SERT-sap suggests that these neural systems serve to enhance the excitability of nociceptive projection neurons during the formalin IP. Electrophysiologic and pharmacologic studies of formalin IP in selectively lesioned animals combined with the above behavioral findings may reveal new insights into endogenous modulation of nocifensive motor responses and/or nociception.

Related Products: NPY-SAP (Cat. #IT-28), Anti-SERT-SAP (Cat. #IT-23), Galanin-SAP (Cat. #IT-34), Anti-DBH-SAP (Cat. #IT-03), Dermorphin-SAP / MOR-SAP (Cat. #IT-12)

Lecourtier L (2008) Involvement of the habenula in cognition through its regulatory role upon monoamine and acetylcholine transmissions. Neuroscience 2008 Abstracts 698.4. Society for Neuroscience, Washington, DC.

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

Martin MM, Winter SS, Cheatwood JL, Carter LA, Jones JL, Weathered SL, Wagner SJ, Wallace DG (2008) Organization of food protection behavior is differentially influenced by 192 IgG-saporin lesions of either the medial septum or the nucleus basalis magnocellularis. Brain Res 1241:122-135. doi: 10.1016/j.brainres.2008.09.018

Summary: In this work the authors used a food-protection model to investigate the role of cholinergic neurons in the processing of information from internal and external sources. Rats received the following amounts of 192-IgG-SAP (Cat. #IT-01): 15 ng or 20 ng into the medial septum (MS), or 20 ng into the nucleus basalis magnocellularis (NB). While the NB lesions reduced the number of successful food protection behaviors, lesions in the MS disrupted the temporal organization of this behavior.

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

Flore G, Saba P, Paba S, Gessa G, Pistis M, Devoto P (2008) Effect of noradrenergic denervation on cerebral cortex catecholamines in the rat. Neuroscience 2008 Abstracts 726.3/D6. Society for Neuroscience, Washington, DC.

Summary: Previous studies in rats have indicated that extracellular dopamine (DA) content in cortical areas with scarce or undetectable dopaminergic innervation, such as the occipital (Occ) or parietal cortex, is modestly lower than that present in areas densely innervated such as the medial prefrontal (mPF) cortex, suggesting that extracellular DA may originate, other than from dopaminergic, also from the homogeneously and densely distributed noradrenergic terminals. To further verify such hypothesis cortical noradrenergic neurons were lesioned with the intraventricular injection of the immunotoxin anti-DA-beta-hydroxylase saporin. Extracellular DA and noradrenaline (NA) were measured in the mPF and Occ cortices by microdialysis 15 to 18 days after the lesion when tissue NA content had been reduced by about 95%, with respect to control rats injected with PBS. The lesion reduced extracellular NA in both cortices, but increased extracellular DA in the mPF and Occ cortices. To verify if such increase was due to the impairment of DA uptake into NA terminals, the NA transporter was inhibited with nisoxetine (NIS). While in control rats NIS increased both extracellular NA and DA, in denervated rats it failed to modify extracellular NA and DA in either cortex, confirming that the NA transporter had been inactivated by the lesion. To verify if the lesion modified the output capacity of dopaminergic and noradrenergic neurons, the effect of the alpha2-adrenoreceptor blocker RS 79948 (RS), given alone or in combination with NIS, in control and denervated rats was compared. In control rats, RS increased extracellular NA and DA in both cortices; in combination with nisoxetine RS produced a striking more than tenfold increase in extracellular NA and DA. In lesioned rats RS increased DA levels, failed to modify extracellular NA, while its co-administration with NIS slightly increased NA output. However, after RS plus NIS, extracellular DA was increased by the same extent as after RS alone, indicating that denervation had severely impaired the capacity of neurons to increase DA output after alpha2-adrenoceptor block. The possibility that such neurons might correspond to NA neurons surviving the lesion is discussed.

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

Laplante FP, Dufresne M, Lappi DA, Sullivan RM (2008) Depletion of cholinergic neurons in the nucleus accumbens and its possible involvement in schizophrenic symptomatology. Neuroscience 2008 Abstracts 761.18/FF34. Society for Neuroscience, Washington, DC.

Summary: Schizophrenia is a mental disorder characterized by dysfunctions in several neurotransmitter systems including the central cholinergic system. While alterations in cholinergic neurotransmission have been demonstrated in schizophrenic brains, their biological significance remains to be established. Post-mortem studies of schizophrenic patients have shown a reduction in the density of cholinergic interneurons in the striatum, most prominently in the ventral striatum or nucleus accumbens (N. Acc). Intra-accumbens acetylcholine interacts functionally with the mesolimbic dopaminergic system and is believed to dampen the effects of excessive dopamine (DA) release. Therefore, we hypothesize that a reduction in the density of cholinergic neurons in the N. Acc will be behaviorally relevant, if not causal, to the enhanced (ventral) striatal dopaminergic neurotransmission described in schizophrenia and may contribute substantially to the emergence of schizophrenic symptomatology. In this study we aimed to reproduce in rats a selective reduction in N.Acc. cholinergic cell density, and study the neurophysiological and behavioural consequences of these lesions, relevant to the neuropsychopathology of schizophrenia. A novel saporin immunotoxin coupled with an antibody targeting choline acetyltransferase (ChAT) has been developed. We microinjected this immunotoxin bilaterally (0.5 μg/μl; 0.5 μl) into the N. Acc (core and shell) of adult male Srpague-Dawley rats. Using immunohistochemistry to quantify ChAT staining, we have confirmed that this toxin caused a 40-50 % loss in the number of cholinergic neurons in this region within two weeks post-injection. Lesioned rats exhibited significantly higher spontaneous locomotor activity than control rats and were shown to be hypersensitive to the locomotor activating effects of amphetamine and quinpirole. Furthermore, in separate groups of animals, we have observed in lesioned rats, a reduction in the prepulse inhibition of the acoustic startle response. Taken together, it is proposed that reduction of cholinergic neurons in the N. Acc triggers an enhanced DA responsivity in the N.Acc which may prove highly effective in reproducing behavioral abnormalities analogous to those found in schizophrenia. The neurophysiological consequences of these lesions on DA neurotransmission will be further addressed by measuring both pre- and postsynaptic indices of DA function in this region.

Related Products: Anti-ChAT-SAP (Cat. #IT-42)