Purines as transmitter molecules : : electrophysiological studies on purinergic signalling in different cell systems / / Elisabetta Coppi.

• Superior document: Premio FUP. Tesi di dottorato ; 1
• VerfasserIn: Coppi, Elisabetta,
• Place / Publishing House: Firenze : : Firenze University Press,, [2008]; ©2008
• Year of Publication: 2008
• Language: English
• Series: Premio FUP. Tesi di dottorato ; 1.
• Physical Description: 1 online resource (192 pages) :; illustrations; digital, PDF file(s).

Purinergic nucleotides and nucleosides (ATP, ADP, AMP and adenosine) are essential intracellular metabolites involved in a number of cellular processes, from energy supply to protein phosphorylation. However, in the last years, several studies demonstrated their involvement in cell signalling by the activation of specific membrane receptors (P1 and P2) and their role as neurotransmitters began to be investigated. The present work was aimed to clarify the effects of purinergic neurotransmission in different cell systems by using electrophysiological techniques. Relevant results of this research include the observation that P1 and P2 receptors play a deleterious role during "in vitro" ischemia in the rat brain, and the first demonstration of P2 receptor expression and function in a line of adult human mesenchymal stem cells.

Table of Contents

Abbreviations -- Introduction -- 1. Historical overview -- 2. Synthesis, release and catabolism of ATP -- 2.1 Vesicular release of ATP -- 2.2 Anion channel-mediated release of ATP -- 2.3 Connexin hemichannel-mediated ATP release -- 3. Synthesis, release and catabolism of adenosine -- 3.1 Adenosine release -- 3.2 Synthesis of adenosine at extracellular level -- Purinergic receptors -- 1. P1 receptors -- 2. Pharmacology of P1 receptors -- 3. Distribution of P1 receptors -- 3.1 Central Nervous System (CNS) -- 4. P2 receptors -- 5. P2X receptors -- 6. Pharmacology of P2X receptors -- 6.1 Agonists -- 6.2 Antagonists -- 7. P2Y receptors -- 8. Pharmacology of P2Y receptors -- 8.1 Agonists -- 8.2 Antagonists -- 9. Distribution of P2 receptors -- 9.1 Neuronal localization of P2X receptors -- 9.2 Neuronal localization of P2Y receptors -- Effects of extracellular purines -- 1. Role of P1 receptors -- 1.1 P1 receptors and neurotransmission -- 1.1 P1 receptors and cerebral ischemia -- 2. Anoxic depolarization -- 3. Role of P2 receptors -- 3.1 P2 receptors and neurotransmission -- 3.2 P2 receptors and cerebral ischemia -- 3.3 P2 receptors and trophic effects -- Aim of the study -- Materials and methods -- 1. Extracellular recordings -- 1.1 Acute rat hippocampal slices preparation -- 1.2 Experimental procedure -- 1.3 Protocols used -- 1.4 OGD conditions -- 2. Patch clamp recordings -- 3. Cell cultures -- 4. Solutions -- 5. Patch pipettes fabrication -- 6. Experimental procedures -- 7. Voltage clamp protocols -- 8. Current clamp experiments -- 9. Measurement of ATP release from hMSCs -- 10. Chemicals -- 11. Statistical analysis -- RESULTS. Section 1 ROLE OF PURINES IN CA1 HIPPOCAMPAL NEUROTRANSMISSION UNDER NORMOXIC CONDITIONS AND DURING OGD. EXTRACELLULAR RECORDINGS FROM RAT HIPPOCAMPAL SLICES -- Chapter 1 Role of A3 adenosine receptors during OGD -- 1. Historical background -- 2. Results -- 2.1 Experiments were performed on a total of 219 slices taken from 133 rats -- 3. Discussion -- 3.1 Role of adenosine receptor antagonists in depression and disruption of CA1 hippocampal excitatory synaptic transmission during in vitro ischemia -- 3.2 Therapeutic implications for the protective role of adenosine A3 receptor antagonists during prolonged ischemic conditions -- 3.3 Role of adenosine receptor agonists in depression and disruption of CA1 hippocampal excitatory synaptic transmission during in vitro ischemia -- 3.5 Conclusions -- Chapter 2 Role of P2 purinergic receptors on hippocampal CA1 neurotransmission under normoxic conditions and during OGD -- 1. Historical background -- 2. Results -- 2.1 Effects of ATP on CA1 hippocampal neurotransmission -- 2.2 Effects of ATP?S on CA1 hippocampal neurotransmission -- 2.3 Effects of ATP and ATP?S on PPF in the CA1 region of rat hippocampus -- 2.4 Effects of different purinergic antagonists on OGD-evoked disruption of neurotransmission in the CA1 region of rat hippocampal slices -- 3. Discussion -- 3.1 Role of P2 receptors in hippocampal neurotransmission under normoxic conditions -- 3.2 Role of P2 receptors in hippocampal neurotransmission during OGD -- 3.3 Conclusions -- RESULTS. Section 2 -- STUDIES ON P2 RECEPTOR MODULATION OF MEMBRANE IONIC CURRENTS BY PATCH CLAMP RECORDINGS -- Chapter 3 Role of P2Y1 receptor stimulation in medium spiny neurons of rat striatal slices -- 1. Historical background -- 2. Results -- 2.1 P2Y1 receptor activation increases the outward currents elicited by a voltage ramp depolarization in striatal medium spiny neurons -- 2.2 Characterization of the P2Y1 -activated conductance in striatal medium spiny neurones -- 2.3 Single channel recordings show SK potassium channel opening following P2Y1 receptor activation -- 2.4 2MeS-ADP decreases the firing rate of medium spiny neurons recorded under the current-clamp mode in striatal slices -- 2.5 Spontaneous miniature synaptic currents are increased in amplitude during the application of 2meS-ADP -- 3. Discussion -- Chapter 4 Role of purine nucleotides in cultured hMSCs: release of ATP and activation of P2 receptors -- 1. Historical background -- 2. Results -- 2.1 Electrophysiological experiments -- 2.2 Effects of exogenous ATP in potassium-free conditions -- 2.3 Effects of ATP in hMSCs in the perforated patch-clamp configuration -- 3. Discussion -- 3.1 Conclusion -- Chapter 5 Pharmacological characterization of the recently deorphanized GPR17 receptor transfected in 1321N1 astrocytoma cells -- 1. Historical background -- 2. Results -- 2.1 Exogenously applied UDP-glucose and UDP-galactose activate outward potassium currents in 1321N1 astrocytoma cell stably transfected with GPR17 -- 2.2 GPR17 receptor, stably transfected1321N1 astrocytoma cells, is also sensitive to leukotriene-related compounds -- 3. Discussion -- Final remarks -- References.