Potassium Permanganate Can Mark the Site of Microdialysis in Brain Sections

Sun, Man-Hua; Hildebrandt, Laurie; Curran, Aidan K.; Darnall, Robert A.; Chen, Gengxin; Filiano, James J.

doi:10.1179/his.2000.23.2.151

Cited by 16 publications

(4 citation statements)

References 8 publications

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“…Confirmation of the probe placement was accomplished using KMnO 4 to mark the location of the center of the microdialysis probe membrane[20]. Following the termination of the experiment, the dialysis probes were removed from the guide cannulae.…”

Section: 0 Materials and Methodsmentioning

confidence: 99%

Dichlorvos-induced central apnea: Effects of selective brainstem exposure in the rat

Gaspari

Paydarfar

2011

NeuroToxicology

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IntroductionOrganophosphate (OP) agents are used globally as insecticides and related compounds have been weaponized as nerve agents. Intentional exposures are responsible for a tremendous burden to the health care system in many developing countries [1][2][3][4]. OP agents exert their clinical effects largely by binding to peripheral and central acetylcholinesterase, resulting in a rise in the level of post-synaptic acetylcholine (ACh). The increased levels of postsynaptic ACh induce a range of central effects including seizure, apnea and long-term cognitive deficits [5][6][7].OP-induced central apnea is well documented in animal models of OP-toxicity and is postulated to be an important cause of fatality following human exposure [5]. The neural substrate underlying normal automatic respiratory rhythm generation (i.e, the central respiratory oscillator or CRO) is a topic of investigation and debate [8,9]. There is substantial evidence pointing to the importance of specific neuronal groups within the ventral medulla. The pre-Bötzinger complex (preBötC) contains cholinergic neurons [10] and is integral to normal respiratory function [11]. Other sites in the ventral region of the medulla are involved in respiratory control and contain cholinergic synapses, including the ventral surface of the medulla [12], the nucleus ambiguus [13] and the retrotrapezoid nucleus [14]. These and other brainstem sites may be involved in OP-induced central apnea, for example by affecting chemo-responsive or rhythm generating respiratory neurons or by inhibiting inspiratory drive through pontine cholinergic circuits [15].The hypothesized role of the brainstem in OP-induced central apnea has not been tested directly using validated models of OP poisoning, but the idea is supported indirectly by observations that perturbations of synaptic ACh in circuits involved in breathing cause changes in the pattern of respiratory activity. Some regions of the brainstem demonstrate increased respiratory activity when exposed to elevated ACh levels [10,16], while others demonstrate respiratory depression but not apnea [17]. However, it is unclear how these findings relate to OP poisoning as they stem from studies designed to mimic the cholinergic perturbations that occur during normal circuit function. Toxic levels of synaptic ACh Corresponding Author: Romolo J Gaspari, MD, Department of Emergency Medicine, 55 Lake Ave North, Worcester, MA 01655, Romolo.gaspari@umassmemorial.org, Office -508-334-7943, Fax -508-421-1410. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. NIH Public Access Author ManuscriptNeuroto...

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Section: 0 Materials and Methodsmentioning

confidence: 99%

Dichlorvos-induced central apnea: Effects of selective brainstem exposure in the rat

Gaspari

Paydarfar

2011

NeuroToxicology

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“…At the conclusion of the experiments, each piglet was killed with a lethal injection of pentobarbital sodium followed by an intra-cardiac injection of 5-10 ml of saturated potassium chloride. Microinjections of 20 -50 l of 1% potassium permanganate were made through a broken microdialysis probe to mark the location of the tip of the microdialysis probe in reference to external landmarks (63). The brain stem was removed and frozen in cryoembedding medium (Tissue-Tek OCT; Sakura Finetek, Torrance, CA).…”

Section: Methodsmentioning

confidence: 99%

Activation of 5-HT_1Areceptors in the paragigantocellularis lateralis decreases shivering during cooling in the conscious piglet

Hoffman

Brown²,

Sirlin³

et al. 2007

American Journal of Physiology-Regulatory, Integrative and Comp

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Activation of 5-HT(1A) receptors in the medullary raphé decreases sympathetic outflow to thermoregulatory mechanisms, including brown adipose tissue (BAT), thermogenesis, and peripheral vasoconstriction when these mechanisms are previously activated with leptin, prostaglandins, or cooling. These same mechanisms are also inhibited during rapid eye movement (REM) sleep. It is not known whether shivering is also modulated by medullary raphé neurons. We previously showed in the conscious piglet that activation of 5-HT(1A) receptors with 8-OH-DPAT (DPAT) in the paragigantocellularis lateralis (PGCL), a medullary region lateral to the midline raphé that contains 5-HT neurons, decreases heart rate, body temperature and muscle activity during non-rapid eye movement (NREM) sleep. We therefore hypothesized that activation of 5-HT(1A) receptors in the PGCL would also attenuate shivering and peripheral vasoconstriction during cooling. During REM sleep in a cool environment, shivering, carbon dioxide production, and body temperature decreased, and ear capillary blood flow and ear skin temperature increased. Shivering associated with rapid cooling was attenuated after dialysis of DPAT into the PGCL. In animals maintained in a continuously cool environment, dialysis of DPAT into the PGCL attenuated shivering and decreased body temperature, but there were no significant increases in ear capillary blood flow or ear skin temperature. We conclude that both naturally occurring REM sleep and exogenous activation of 5-HT(1A) receptors in the PGCL are associated with a suspension of shivering during cooling. Our data are consistent with the hypothesis that 5-HT neurons in the PGCL facilitate oscillating spinal motor circuits involved in shivering but are less involved in modulating sympathetically mediated thermoregulatory mechanisms.

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“…Microinjections of 20–50 μl of 1% potassium permanganate were made into the medulla through a broken microdialysis probe passed through the guide tube. Manganese oxide, which is formed by oxidation of the permanganate, stains the tissue brown and indelibly marks the location of the tip of the probe and site of microinjection (Sun et al, 2000). The brainstem was removed from the animal, placed in cryo-embedding medium (Tissue-Tek O.C.T.…”

Section: Methodsmentioning

confidence: 99%

An adenosine A2A antagonist injected in the NTS reverses thermal prolongation of the LCR in decerebrate piglets

Xia

Bartlett

Leiter

2008

Respiratory Physiology & Neurobiology

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Hyperthermia prolongs the laryngeal chemoreflex (LCR). Under normothermic conditions, adenosine antagonists shorten and adenosine A 2A (Ad-A 2A ) agonists prolong the LCR. Therefore, we tested the hypothesis that SCH-58261, an Ad-A 2A receptor antagonist, would prevent thermal prolongation of the LCR when injected unilaterally within the nucleus of the solitary tract (NTS). We studied decerebrate piglets aged 4-13 days. We elicited the LCR by injecting 0.1 ml of water into the larynx and recorded integrated phrenic nerve activity. The laryngeal chemoreflex was prolonged when the body temperature of each piglet was raised ~ 2 degrees C, and SCH-58261 reversed the thermal prolongation of the LCR when injected into the NTS (n = 13), but not when injected in the nucleus ambiguus (n=9). Injections of vehicle alone into the NTS did not alter the thermal prolongation of the LCR (n=9). We conclude that activation of adenosine receptors, perhaps located on GABAergic neurons in the NTS, contributes to thermal prolongation of the LCR.

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Potassium Permanganate Can Mark the Site of Microdialysis in Brain Sections

Cited by 16 publications

References 8 publications

Dichlorvos-induced central apnea: Effects of selective brainstem exposure in the rat

Dichlorvos-induced central apnea: Effects of selective brainstem exposure in the rat

Activation of 5-HT_1Areceptors in the paragigantocellularis lateralis decreases shivering during cooling in the conscious piglet

An adenosine A2A antagonist injected in the NTS reverses thermal prolongation of the LCR in decerebrate piglets

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Potassium Permanganate Can Mark the Site of Microdialysis in Brain Sections

Cited by 16 publications

References 8 publications

Dichlorvos-induced central apnea: Effects of selective brainstem exposure in the rat

Dichlorvos-induced central apnea: Effects of selective brainstem exposure in the rat

Activation of 5-HT1Areceptors in the paragigantocellularis lateralis decreases shivering during cooling in the conscious piglet

An adenosine A2A antagonist injected in the NTS reverses thermal prolongation of the LCR in decerebrate piglets

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Activation of 5-HT_1Areceptors in the paragigantocellularis lateralis decreases shivering during cooling in the conscious piglet