[Protein kinase a mediated excitatory adrenergic effect on chronically compressed dorsal root ganglion neurons in rats].
With a model of chronically compressed dorsal root ganglion (CCD), the present study was undertaken to test how the plasticity of sympathetic-sensory coupling is and whether the coupling is mediated by intracellular messenger PKA by analysing extracellularly recorded spontaneous activity of single A-fibers originating from the CCD neurons in vitro. Eighty-five out of 95 neurons from injured DRGs during application of norepinephrine (NE) were adrenosensitive. Among the 85 neurons, 44 exhibited excitation, 21 showing excitation followed by suppression, 6 displaying alternated excitation and suppression, and 14 suppression. In addition, adrenosensitivity was observed in 15 silent injured DRGs. The excitatory effect of NE was blocked by alpha 1 and alpha 2 adrenoceptor antagonists yohimbine (10 mumol/L) or prazosin (5 mumol/L). Rp-cAMPS (50-250 mumol/L, n = 6), a specific inhibitor of PKA, and H-89 (10 mumol/L, n = 6), an inhibitor of PKA catalytic subunit, obviously suppressed the NE-evoked excitation. Furthermore, the excitatory effect of NE was attenuated by SQ 22, 536 (1 mmol/L), an adenylate cyclase inhibitor (n = 6). The above results demonstrate that injury to DRG neuron body triggered the adrenosensitivity, which was mediated by alpha 1, alpha 2 adrenoceptors and PKA.
Xu
H
H
Department of Physiology, Fourth Military Medical University, Xi'an 710033.
Hu
S J
SJ
Han
Y
Y
Long
K P
KP
D000320:Adrenergic Fibers / Q000502:physiology; D000344:Afferent Pathways; D000818:Animals; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000494:pharmacology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D004594:Electrophysiology; D005260:Female; D005727:Ganglia, Spinal / Q000293:injuries / Q000503:physiopathology*; D066298:In Vitro Techniques; D007546:Isoquinolines / Q000494:pharmacology; D008297:Male; D009474:Neurons / Q000502:physiology; D011843:Radiculopathy / Q000503:physiopathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013449:Sulfonamides; D013873:Thionucleotides / Q000494:pharmacology*
D007546:Isoquinolines; D013449:Sulfonamides; D013873:Thionucleotides; C016957:adenosine-3',5'-cyclic phosphorothioate; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide