Calcium/calmodulin-dependent kinase II mediates NO-elicited PKG activation to participate in spinal reflex potentiation in anesthetized rats.
Calcium/calmodulin protein kinase (CaMK)-dependent nitric oxide (NO) and the downstream intracellular messenger cGMP, which is activated by soluble guanylate cyclase (sGC), are believed to induce long-term changes in efficacy of synapses through the activation of protein kinase G (PKG). The aim of this study was to examine the involvement of the CaMKII-dependent NO/sGC/PKG pathway in a novel form of repetitive stimulation-induced spinal reflex potentiation (SRP). A single-pulse test stimulation (TS; 1/30 Hz) on the afferent nerve evoked a single action potential, while repetitive stimulation (RS; 1 Hz) induced a long-lasting SRP that was abolished by a selective Ca(2+)/CaMKII inhibitor, autocamtide 2-related inhibitory peptide (AIP). Such an inhibitory effect was reversed by a relative excess of nitric oxide synthase (NOS) substrate, L-arginine. In addition, the RS-induced SRP was abolished by pretreatment with the NOS inhibitor, N(G)-nitro-L-arginine-methyl ester (L-NAME). The sGC activator, protoporphyrin IX (PPIX), reversed the blocking effect caused by L-NAME. On the other hand, a sGC blocker, 1H-[1, 2, 4]oxadiazolo[4, 3-alpha]quinoxalin-1-one (ODQ), abolished the RS-induced SRP. Intrathecal applications of the membrane-permeable cGMP analog, 8-bromoguanosine 3',5'-cyclic monophosphate sodium salt monohydrate (8-Br-cGMP), reversed the blocking effect on the RS-induced SRP elicited by the ODQ. Our findings suggest that a CaMKII-dependent NO/sGC/PKG pathway is involved in the RS-induced SRP, which has pathological relevance to hyperalgesia and allodynia.
Chen
Gin-Den
GD
Department of Physiology, College of Medicine, Chung-Shan Medical University, No. 110 Chang-Kuo North Road Section 1, Taichung, Taiwan.
Peng
Mei-Lin
ML
Wang
Pei-Yi
PY
Lee
Shin-Da
SD
Chang
Hung-Ming
HM
Pan
Shwu-Fen
SF
Chen
Mei-Jung
MJ
Tung
Kwong-Chung
KC
Lai
Cheng-Yuan
CY
Lin
Tzer-Bin
TB
D000200:Action Potentials / Q000502:physiology; D000758:Anesthesia; D000818:Animals; D002118:Calcium / Q000378:metabolism; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D017869:Cyclic GMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004576:Electromyography; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006930:Hyperalgesia / Q000378:metabolism*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009473:Neuronal Plasticity / Q000502:physiology; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism; D010069:Oxadiazoles / Q000494:pharmacology; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012018:Reflex / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013116:Spinal Cord / Q000201:enzymology*
C095284:1H-(1,2,4)oxadiazolo(4,3-a)quinoxalin-1-one; D004791:Enzyme Inhibitors; D010069:Oxadiazoles; D011810:Quinoxalines; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D017869:Cyclic GMP-Dependent Protein Kinases; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D002118:Calcium; D019331:NG-Nitroarginine Methyl Ester