Purkinje cells adenosine

ADENOSINE, 5 -NUCLEOTIDASE AND ADENOSINE DESAMINASE Adenosine-like immunoreactivity was found in rat Purkinje cells, using polyclonal anti-... 

Steady state concentrations of adenosine are maintained through the activities of only three enzymes, 5 -nucleotidase (5 -N), adenosine kinase and adenosine deaminase. Adenosine kinase and adenosine deaminase were located mainly in the soluble fractions of rat cerebellar homogenates, whereas 5 -N was present in subcellular fractions (Philips and Newsholme, 1979), mainly in the synaptosomal fraction (Marani, 1977). Adenosine deaminase-immunoreactivity in rat cerebellum was present with one out of five polyclonal sera prepared by Nagy et ah (1988). Staining was present in most Purkinje cells with a variation in intensity. Staining was observed in the Purkinje cell axons and terminals in the cerebellar and vestibular nuclei. The localization of 5 -N will be discussed below. 

Adenosine blocks the parallel fiber-induced simple spike discharge in Purkinje cells (Kostopoulos et ah, 1975) but not the climbing fiber-mediated synaptic transmission (Kocsis et ah, 1984). The effect of adenosine is presynaptic and is mediated by Al-adenosine receptors that are located on parallel fibers. A1-adenosine receptors are coupled to pertussis toxin-sensitive G proteins and inhibit adenyl cyclase. Activation of A1-adenosine receptors decreases transmitter release from the terminals (Dolphin and Prestwich, 1985, see Fredholm and Dunwiddie, 1988, for a review). The presence of A1-adenosine receptors on parallel fibers was demonstrated autoradiographically by... 

Nagy JI, Yamamoto T, Dewar K, Geiger JD, Daddona PE (1988) Adenosine deaminase-Tike immunoreactivity in cerebellar Purkinje cells of rat. Brain Res.. 457, 21-28. 

Siggins GR, Hoffer BJ, Bloom FE (1971) Studies on norepinephrine-containing afferents to Purkinje cells of rat cerebellum. III. Evidence for mediation of norepinephrine effects by cyclic 3, 5 -adenosine monophosphate. Brain Res.. 25, 535-553. 

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