Central nervous system adenosine receptors

Virus, R. M., Ticho, S., Pilditch, M. Radulovacki, M. (1990). A comparison of the effects of caffeine, 8-cyclopentyltheophylline, and alloxazine on sleep in rats. Possible roles of central nervous system adenosine receptors. Neuropsychopharmacology 3 (4), 243-9. 

Matsuoka I, Ohkubo S (2004) ATP- and adenosine-mediated signaling in the central nervous system adenosine receptor activation by ATP through rapid and localized generation of adenosine by ecto-nucleotidases. J Pharmacol Sci 94 95-9... 

A1 adenosine receptors are inhibitory in the central nervous system. A receptors were originally characterized on the basis of their ability to inhibit adenylyl cyclase in adipose tissue. A number of other G-protein-mediated effectors of A receptors have subsequently been discovered these include activation of K+ channels, extensively characterized in striatal neurons [13], and inhibition of Ca2+ channels, extensively characterized in dorsal root ganglion cells [14]. Activation of A receptors has been shown to produce a species-dependent stimulation or inhibition of the phosphatidylinositol pathway in cerebral cortex. In other tissues, activation of A receptors results in synergistic activation of the phosphatidylinositol pathway in concert with Ca2+-mobilizing hormones or neurotransmitters [15]. The effectors of A adenosine receptors and other purinergic receptor subtypes are summarized in Table 17-2. 

Extracellular adenosine acts through a class of G protein-coupled receptors (GPCRs), defined across mammalian species as Ab A2a, A2B, and A3ARs (adenosine receptors). Adenosine has a cytoprotective role in the body, both in the periphery and in the central nervous system. Following binding of adenosine, or another naturally occurring agonist, the receptor... 

Three major mechanisms of action have dominated as possible explanations for the ergogenic potential of caffeine in the enhancement of exercise performance. These three mechanisms involve (1) the mobilization of intracellular calcium from the sarcoplasmic reticulum of skeletal muscle, (2) the increase of cyclic-3 ,5 -adenosine monophosphate (cAMP) by the inhibition of phosphodiesterases in muscles and adipocytes, and (3) the competitive antagonism of adenosine receptors, primarily in the central nervous system (CNS).8 9... 

Caffeine is also effective in the antagonism of peripheral adenosine (type I) receptors, which are known to inhibit lipolysis by subduing adenylate cyclase activity.28 The appeal of this mechanism of action is that the majority of the pharmacological effects of adenosine on the central nervous system can be inhibited by doses of caffeine that are well within physiologically non-toxic levels comparable to only a couple of cups of coffee.5... 

Fredholm, B. B. (1995). Adenosine receptors in the central nervous system. News Physiol. Sci. 10, 122-8. 

A[ adenosine receptors are inhibitory in the central nervous system 313... 

A2a adenosine receptors are highly expressed in the basal ganglia 314 A2b adenosine receptors regulate vascular permeability 314 A3 adenosine receptors are few in the central nervous system 314... 

The generic name of the cacao tree (Theobroma) means food of the Gods and gives its name to a caffeine-like stimulant, theobromine (a methylxanthine). It has been claimed that the theobromine in chocolate is responsible for its addictive characteristics. This is based on the fact that methylxanthines bind to adenosine receptors in the central nervous system and act as antagonists to this neurotransmitter (Chapter 14). However, another group of substances, the amides formed between ethanolamine and unsaturated fatty acids, are also possible candidates for the title of the chocolate drug . 

Substances with a neuromodulatory effect on brain neurotransmitters by direct actions of specific receptors that modify the actions of the transmitters listed include prostaglandins, adenosine, enkephalins, substance P, cholecystokinin, endorphins, endogenous benzodiazepine receptor ligands, and possibly histamine. CNS, central nervous system. NMDA, N-methyl-D-aspartate. Strych, strychnine. 

There are more than 10 billion neurons that make up the human nervous system, and they interact with one another through neurotransmitters. Acetylcholine, a number of biogenic amines (norepinephrine, dopamine, serotonin, and in all likelihood, histamine and norepinephrine), certain amino acids and peptides, and adenosine are neurotransmitters in the central nervous system. Amino acid neurotransmitters are glutamic and aspartic acids that excite postsynaptic membrane receptors of several neurons as well as y-aminobutyric acid (GABA) and glycine, which are inhibitory neurotransmitters. Endorphins, enkephalins, and substance P are considered peptidergic transmitters. There are many compounds that imitate the action of these neurotransmitters. 

Durieux ME. Muscarinic signalling in the central nervous system. Anesthesiology 1996 84 173-89. Lipkowski AW, Maszcz-Yuska I. Peptide, N-methyl-D-aspartate and adenosine receptors as analgesictargets. Curr Opin Anaesthesiol 1996 9 443-8. 

Adenosine receptors are widespread throughout the body and exert many different functions both in the central nervous system (CNS) and in the periphery. The A3 AR is expressed in CNS at low levels, mainly in hypothalamus and thalamus (Zhao et al. 2002). The highest levels of these receptors have been found in the lung and liver, in eosinophils, mast cells, kidney, heart spleen and other peripheral tissues (Fredholm et al. 2001 Young et al. 2004 Yaar et al. 2005). The A3 AR has been... 

Adenosine A3 Receptor Signaling in the Central Nervous System... 

Latini S, Pedata F (2001) Adenosine in the central nervous system release mechanisms and extracellular concentrations. J Neurochem 79(3) 463 184 Laudadio MA, Psarropoulou C (2004) The A3 adenosine receptor agonist 2-C1-IB-MECA facilitates epileptiform discharges in the CA3 area of immature rat hippocampal slices. Epilepsy Res 59(2—3) 83—94... 

The modes of action of different alkaloids are diverse. For example, nicotine binds to and affects nicotinic acetylcholine receptors and shows toxicity. A recent molecular 3D model suggests that both acetylcholine and nicotine bind to the same pocket formed in a nicotinic acetylcholine receptor.15 Morphine binds to and activates opioid receptors, transmembrane-spanning G protein-coupled receptors, in the central nervous system of humans.16 Caffeine, which is structurally similar to adenine, inhibits cyclic AMP phosphodiesterase activity and inhibits the degradation of cAMP, thus exerting a toxic effect on insects 17 in human beings, binding of caffeine to the adenosine A2A receptor induces wakefulness.18 Atropine binds to muscarinic acetylcholine receptors, competing with acetylcholine, and blocks neurotransmission.1... 

---