Noradrenaline microdialysis

Figure 4,7 The effect of perfusion of the microdialysis probe with a medium containing a depolarising (80 mM) concentration of K" ", or Ca +-free medium, for the periods indicated by the bars. The graph shows efflux of noradrenaline in the frontal cortex of anaesthetised rats. Increasing the concentration of K" " in the medium infused via the probe increases noradrenaline efflux whereas removing Ca reduces it...

Figure 4.8 Noradrenaline concentration in dialysis samples from probes implanted in the rat frontal cortex. Spontaneous efflux of noradrenaline is stable throughout a 4h sampling period ( extended basals ) but is increased markedly when either the noradrenaline reuptake inhibitor, desipramine (5 pM), or the a2-adrenoceptor antagonist, atipamezole (0.5 pM), is infused into the extracellular fluid via the microdialysis probe ( retrodialysis )...

Even if this turns out to be the case, it is likely that noradrenergic neurons in different brain regions make different contributions to this process. This complication is suggested by the results of a recent microdialysis study in which release of noradrenaline in response to the sound of a buzzer alone was provoked after repeated... 

Figure 8.11 Noradrenaline efflux, measured by microdialysis, in the rat frontal cortex and hypothalamus, (a) Repeated exposure to a tone, alone, has no effect on noradrenaline efflux in either brain region, (b) After repeated pairing of the tone with transfer of the rat to a brightly lit (aversive) arena, the sound of the tone alone triggers a significant ( P<0.05, cf last basal sample) increase in noradrenaline efflux in the frontal cortex, but not the hypothalamus. (Based on a figure from McQuade and Stanford 2000)...

Measurements of noradrenaline release in animals have not helped to resolve this confusion. Microdialysis studies in vivo have confirmed that anxiogenic doses of... 

Kehr J, Yoshitake T, Wang FH, Wynick D, Holmberg K, et al. 2001. Microdialysis in freely moving mice Determination of acetylcholine, serotonin and noradrenaline release in galanin transgenic mice. J Neuro Sci Method 109 71-80. 

Kawahara H, Kawahara Y, Westerink BHC (2000) The role of afferents to the locus coeruleus in the handling stress-induced increase in the release of noradrenaline in the medial prefrontal cortex a dual probe microdialysis study in the rat brain. Eur J Pharmacol 387 279-86 Kerr DIB, Ong J (1995) GABAB receptors. Pharmacol Ther 67 187-246... 

Yokoo, H., Tanaka, M., Tanaka, T. Tsuda, A. (1990a). Stress-induced increase in noradrenaline release in the rat hypothalamus assessed by intracranial microdialysis. Experientia, 46, 290-292. 

Cenci MA, Kalen P, Mandel RJ, Bjorklund A (1992) Regional differences in the regulation of dopamine and noradrenaline release in medial frontal cortex, nucleus accumbens and caudate-putamen a microdialysis study in the rat. Brain Res 557(2) 217-228. 

Cutaneous microdialysis has also been used to examine the role of vasoconstriction on transport of drugs through hmnan skin (Boutsiouki et al., 2001 Morgan et al., 2003). The organophosphorus insecticide malathion is observed following topical application to human volunteers in microdialysate after 30 min, with a steady state reached after 2 h (Boutsiouki et al., 2001). Adding the vasoconstrictor noradrenaline... 

This chapter describes two microbore LC-based methods for measurement of monoamine neurotransmitters in rat brain dialysates a method for the determination of the catecholamines (CA) noradrenaline (NAD), adrenaline (AD), and dopamine (DA) and a method for the determination of the indoleamine serotonin (5HT) and its major metabolite 5-hydroxyindoleacetic acid (SHIAA) (3). For all compounds, a limit of detection of 1 pmol or less (in an injected volume of 10 pL) can be achieved. Basal serotonin can be measured in microdialysates without including a reuptake inhibitor in the microdialysis perfusion fluid. Both of these systems are routinely used in the authors laboratory for the analysis of dialysates from striatum, hippocampus, and substantia nigra. Both methods are selective, robust, and can be automated. 

Yoshitake T, Kehr J, Yoshitake S, Fujino K, Nohta H, Yamaguchi M. Determination of serotonin, noradrenaline, dopamine and their metabolites in rat brain extracts and microdialysis samples by column liquid chromatography with fluorescence detection following derivatization with benzylamine and 1,2-diphenylethylenediamine. J Chromatogr B Anal Tech Biomed Life Sci 2004 807 177—83. 

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