Phosphodiesterase type 2 and the homeostasis of cyclic GMP in living thalamic neurons.
The ubiquitous second messenger cyclic GMP (cGMP) is synthesized by soluble guanylate cyclases in response to nitric oxide (NO) and degraded by phosphodiesterases (PDE). We studied the homeostasis of cGMP in living thalamic neurons by using the genetically encoded fluorescence resonance energy transfer sensor Cygnet, expressed in brain slices through viral gene transfer. Natriuretic peptides had no effect on cGMP. Basal cGMP levels decreased upon inhibition of NO synthases or soluble guanylate cyclases and increased when PDEs were inhibited. Single cell RT-PCR analysis showed that thalamic neurons express PDE1, PDE2, PDE9, and PDE10. Basal cGMP levels were increased by the PDE2 inhibitors erythro-9-(2-hydroxy-3-nonyl) adenine (EHNA) and BAY60-7550 but were unaffected by PDE1 or PDE10 inhibitors. We conclude that PDE2 regulates the basal cGMP concentration in thalamic neurons. In addition, in the presence of 3-isobutyl-1-methylxanthine (IBMX), cGMP still decreased after application of a NO donor. Probenecid, a blocker of cGMP transporters, had no effect on this decrease, leaving PDE9 as a possible candidate for decreasing cGMP concentration. Basal cGMP level is poised at an intermediate level from which it can be up or down-regulated according to the cyclase and PDE activities.
Hepp
R
R
Université Pierre et Marie Curie-Paris6, CNRS, UMR 7102, Paris, France.
Tricoire
L
L
Université Pierre et Marie Curie-Paris6, CNRS, UMR 7102, Paris, France.
Hu
E
E
Université Pierre et Marie Curie-Paris6, CNRS, UMR 7102, Paris, France.
Gervasi
N
N
Université Pierre et Marie Curie-Paris6, CNRS, UMR 7102, Paris, France.
Paupardin-Tritsch
D
D
Université Pierre et Marie Curie-Paris6, CNRS, UMR 7102, Paris, France.
Lambolez
B
B
Université Pierre et Marie Curie-Paris6, CNRS, UMR 7102, Paris, France.
Vincent
P
P
Université Pierre et Marie Curie-Paris6, CNRS, UMR 7102, Paris, France.
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism*; D054678:Cyclic Nucleotide Phosphodiesterases, Type 2; D031541:Fluorescence Resonance Energy Transfer; D005456:Fluorescent Dyes; D006706:Homeostasis / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D009569:Nitric Oxide / Q000096:biosynthesis; D020030:Nitric Oxide Donors / Q000494:pharmacology; D052248:Nitric Oxide Synthase Type I / Q000037:antagonists & inhibitors / Q000378:metabolism; D009924:Organ Culture Techniques; D018408:Patch-Clamp Techniques; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013788:Thalamus / Q000378:metabolism*
D002352:Carrier Proteins; D005456:Fluorescent Dyes; D020030:Nitric Oxide Donors; D010726:Phosphodiesterase Inhibitors; D009569:Nitric Oxide; D052248:Nitric Oxide Synthase Type I; D010727:Phosphoric Diester Hydrolases; D054678:Cyclic Nucleotide Phosphodiesterases, Type 2; C517277:Pde2a protein, mouse; D006152:Cyclic GMP; D015056:1-Methyl-3-isobutylxanthine