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Featured Article: Deletion of catecholaminergic neurons by anti-DBH-saporin disrupts hypothalamic MAP kinase and CREB activation
Khan AM, Rapp KL, Ponzio TA, Sanchez-Watts G, Watts AG (2009) Featured Article: Deletion of catecholaminergic neurons by anti-DBH-saporin disrupts hypothalamic MAP kinase and CREB activation. Targeting Trends 10(2)
Related Products: Anti-DBH-SAP (Cat. #IT-03), Mouse IgG-SAP (Cat. #IT-18)
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Methylphenidate-induced impulsivity: pharmacological antagonism by beta-adrenoreceptor blockade.
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)
Effect of noradrenergic denervation on cerebral cortex catecholamines in the rat
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)
Interactions between corticosterone and catecholaminergic afferents in the regulation of neuropeptide gene expression in neuroendocrine CRH neurons in the paraventricular nucleus of the hypothalamus
Rapp KL, Watts AG (2008) Interactions between corticosterone and catecholaminergic afferents in the regulation of neuropeptide gene expression in neuroendocrine CRH neurons in the paraventricular nucleus of the hypothalamus. Neuroscience 2008 Abstracts 782.2/RR7. Society for Neuroscience, Washington, DC.
Summary: Neurons in the medial parvicellular part of the paraventricular nucleus of the hypothalamus (PVH) are responsible for neuroendocrine activation of corticotropes in the anterior hypophysis. While corticotropin-releasing hormone (CRH) is the primary peptide responsible for synthesis and release of adrenocorticotropin hormone (ACTH), vasopressin (AVP) is also effective in stimulating ACTH, which stimulates synthesis & secretion of corticosterone (CORT) from the adrenal cortex. This descending pathway, the HPA axis, is part of the stress axis, as its output of CORT facilitates adaptation to changes in energy. While AVP is synthesized in both parvicellular and magnocellular populations of the PVH, it is the AVP in the parvicellular PVH that colocalizes with CRH and increases after adrenalectomy (ADX). The underlying mechanisms contributing to the CORT regulation of Crh and Avp expression still remain elusive, particularly with regard to the role of neural afferents. A major afferent projection system to the PVH originates from hindbrain catecholaminergic (CA) neuron subpopulations. Using saporin-anti-dopamine beta hydroxylase (DSAP) immunotoxin conjugate, to specifically eliminate CA afferents has revealed the importance of CA projections to PVH for both increased Crh expression, and elevated levels of circulating ACTH & CORT following glycemic challenges. We utilized DSAP-mediated deafferentation, followed by ADX and CORT replacement, to determine the role of CA afferents in mediating effects of circulating CORT on Crh and Avp regulation. Male Sprague Dawley rats (~315g) received acute bilateral microinjections of DSAP stereotaxically delivered into the PVH. A control group received bilateral microinjections of saporin conjugated to a non-targeting mouse IgG (SAP). One week later, rats received ADX and timed-release CORT pellet implants (25, 50 or 100 mg). Seven days post-ADX, rats were killed, and radioimmunoassay of plasma from terminal blood samples revealed significantly higher CORT levels in DSAP- vs. SAP-treated rats in CORT replaced groups: 25 mg (p < 0.001), 50 mg (p < 0.01). In contrast, in situ hybridization revealed significantly increased CRH mRNA levels (p < 0.001) and AVP hnRNA levels (p < 0.02) in DSAP- vs. SAP-treated rats with comparable plasma CORT levels. These results suggest that loss of hindbrain CA afferents contributes to the ability of circulating CORT to regulate Crh and Avp expression. The data implicate synergistic interactions between CORT & PVH neural afferents that provide critical metabolic information from the periphery in the regulation of CRH neuroendocrine neurons. Supported by NINDS. (NS029728)
Related Products: Anti-DBH-SAP (Cat. #IT-03)
Stimulus-, circuit- and intracellular-level determinants of MAP kinase and CREB activation in parvicellular hypothalamic paraventricular neurons
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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Analysis of inhibitory phase of formalin test: Effects of specific neural lesions
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)
Renal sympathoinhibition induced by hypernatremia: Involvement of A1 noradrenergic neurons.
Pedrino GR, Rosa DA, Korim WS, Cravo SL (2008) Renal sympathoinhibition induced by hypernatremia: Involvement of A1 noradrenergic neurons. Auton Neurosci 142(1-2):55-63. doi: 10.1016/j.autneu.2008.06.006
Summary: A1 noradrenergic neurons in the caudal ventrolateral medulla (CVLM) are thought to contribute to body fluid homeostasis and cardiovascular regulation. In order to examine the role these neurons play on inhibition of renal sympathetic nerve activity (RSNA) induced by hypertonic saline infusion, rats received 6.3 ng of anti-DBH-SAP (Cat. #IT-03) into the CVLM. Saporin (Cat. #PR-01) was used as a control. Animals treated with anti-DBH-SAP displayed lengthened duration of the pressor response and sustained RSNA.
Related Products: Anti-DBH-SAP (Cat. #IT-03), Saporin (Cat. #PR-01)
Noradrenergic inputs to the paraventricular hypothalamus contribute to hypothalamic-pituitary-adrenal axis and central Fos activation in rats after acute systemic endotoxin exposure.
Bienkowski MS, Rinaman L (2008) Noradrenergic inputs to the paraventricular hypothalamus contribute to hypothalamic-pituitary-adrenal axis and central Fos activation in rats after acute systemic endotoxin exposure. Neuroscience 156(4):1093-1102. doi: 10.1016/j.neuroscience.2008.08.011
Summary: Noradrenergic (NA) neurons in the central nervous system are activated during the immune response to systemic lipopolysaccharide (LPS). The authors tested whether these neurons with axonal inputs to the paraventricular nucleus (PVN) were necessary for LPS-directed Fos expression and increase of plasma corticosterone. Rats received 44-ng bilateral injections of anti-DBH-SAP (Cat. #IT-03) into the medial PVN then were challenged with i.p. LPS. Lesioned animals had attenuated Fos activation and smaller than normal increases in plasma corticosterone.
Related Products: Anti-DBH-SAP (Cat. #IT-03)
Lesions of medullary catecholaminergic neurons increase salt intake in rats.
Colombari DS, Pedrino GR, Freiria-Oliveira AH, Korim WS, Maurino IC, Cravo SL (2008) Lesions of medullary catecholaminergic neurons increase salt intake in rats. Brain Res Bull 76:572-578. doi: 10.1016/j.brainresbull.2008.04.001
Summary: Catecholaminergic neurons in the caudal ventrolateral medulla (CVLM) are thought to contribute to cardiovascular regulation and body fluid homeostasis. Bilateral 6.3-ng injections of anti-DBH-SAP (Cat. #IT-03) were administered to the CVLM of rats. Saporin (Cat. #PR-01) was used as a control. After lesioning and challenge with either furosemide/captopril or water deprivation, intake of 0.3 M NaCl and water were observed. The data indicate medullary catecholaminergic neurons play an inhibitory role in sodium appetite.
Related Products: Anti-DBH-SAP (Cat. #IT-03), Saporin (Cat. #PR-01)
An early sympathetic nervous system influence exacerbates collagen-induced arthritis via CD4+CD25+ cells.
Harle P, Pongratz G, Albrecht J, Tarner IH, Straub RH (2008) An early sympathetic nervous system influence exacerbates collagen-induced arthritis via CD4+CD25+ cells. Arthritis Rheum 58:2347-2355. doi: 10.1002/art.23628
Summary: The sympathetic nervous system can play conflicting roles in collagen-induced arthritis (CIA). CD4+CD25+ T cells can play an immunoregulatory effect in this system depending on the expression of the FoxP3 transcription factor. Mice received 5 µg intraperitoneal injections of anti-DBH-SAP (Cat. #IT-03) to induce an early sympathectomy. The results indicate that the sympathetic nervous system increases disease severity in CIA by stimulating some of the proinflammatory aspects of CD4+CD25+ T cells.
Related Products: Anti-DBH-SAP (Cat. #IT-03)