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NF-kappaB mediated enhancement of potassium currents by the chemokine CXCL1/growth related oncogene in small diameter rat sensory neurons.

Yang RH, Strong JA, Zhang JM - Mol Pain (2009)

Bottom Line: We examined the direct effects of GRO/KC on small diameter DRG neurons, which are predominantly nociceptive.The amplitude of the fast inactivating component increased significantly with no large shifts in the voltage dependence of inactivation.The results suggest that GRO/KC has important effects in inflammatory processes via its direct actions on sensory neurons, and that activation of NF-kappaB is involved in the GRO/KC-induced enhancement of K currents.

View Article: PubMed Central - HTML - PubMed

Affiliation: Pain Research Center, Department of Anesthesiology, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267-0531, USA. Rui-Hua.Yang@uc.edu

ABSTRACT

Background: Inflammatory processes play important roles in both neuropathic and inflammatory pain states, but the effects of inflammation per se within the sensory ganglia are not well understood. The cytokine growth-related oncogene (GRO/KC; CXCL1) shows strong, rapid upregulation in dorsal root ganglion (DRG) in both nerve injury and inflammatory pain models. We examined the direct effects of GRO/KC on small diameter DRG neurons, which are predominantly nociceptive. Whole cell voltage clamp technique was used to measure voltage-activated potassium (K) currents in acutely cultured adult rat small diameter sensory neurons. Fluorescently labeled isolectin B4 (IB4) was used to classify cells as IB4-positive or IB4-negative.

Results: In IB4-negative neurons, voltage-activated K current densities of both transient and sustained components were increased after overnight incubation with GRO/KC (1.5 nM), without marked changes in voltage dependence or kinetics. The average values for the slow and fast decay time constants at 20 mV were unchanged by GRO/KC. The amplitude of the fast inactivating component increased significantly with no large shifts in the voltage dependence of inactivation. The increase in K currents was completely blocked by co-incubation with protein synthesis inhibitor cycloheximide (CHX) or NF-kappaB inhibitors pyrrolidine dithiocarbamate (PDTC) or quinazoline (6-Amino-4-(4-phenoxypheny lethylamino;QNZ). In contrast, the voltage-activated K current of IB4-positive neurons was unchanged by GRO/KC. GRO/KC incubation caused no significant changes in the expression level of eight selected voltage-gated K channel genes in quantitative PCR analysis.

Conclusion: The results suggest that GRO/KC has important effects in inflammatory processes via its direct actions on sensory neurons, and that activation of NF-kappaB is involved in the GRO/KC-induced enhancement of K currents.

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The NF-κB inhibitors pyrrolidine dithiocarbamate (PDTC) and quinazoline (6-Amino-4-(4-phenoxypheny lethylamino), QNZ) blocked the effects of GRO/KC on K currents. QNZ was dissolved in Ethanol. PDTC or QNZ was added 1 h before GRO/KC and was present throughout the incubation period. Neither PDTC nor QNZ had an effect on K currents in control cells (P = 0.867 and 0.999, respectively). *, significantly different from all other groups at this voltage. In PDTC experiments, GRO/KC (N = 18 cells), GRO/KC+PDTC (N = 18) were from 4 cultures, control (N = 13) and PDTC (N = 11) were from 4 cultures; in QNZ experiments, GRO/KC (N = 26), GRO/KC+QNZ (N = 26) were from 7 cultures, control (N = 6) and QNZ (N = 9) were from 2 cultures.
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Figure 7: The NF-κB inhibitors pyrrolidine dithiocarbamate (PDTC) and quinazoline (6-Amino-4-(4-phenoxypheny lethylamino), QNZ) blocked the effects of GRO/KC on K currents. QNZ was dissolved in Ethanol. PDTC or QNZ was added 1 h before GRO/KC and was present throughout the incubation period. Neither PDTC nor QNZ had an effect on K currents in control cells (P = 0.867 and 0.999, respectively). *, significantly different from all other groups at this voltage. In PDTC experiments, GRO/KC (N = 18 cells), GRO/KC+PDTC (N = 18) were from 4 cultures, control (N = 13) and PDTC (N = 11) were from 4 cultures; in QNZ experiments, GRO/KC (N = 26), GRO/KC+QNZ (N = 26) were from 7 cultures, control (N = 6) and QNZ (N = 9) were from 2 cultures.

Mentions: Two NF-κB inhibitors, pyrrolidine dithiocarbamate (PDTC) and quinazoline (6-Amino-4-(4-phenoxypheny lethylamino), QNZ) were used to explore the possible signaling pathway of GRO/KC effects on K currents. PDTC or QNZ was added 1 h before GRO/KC and was present throughout the incubation period. Both PDTC and QNZ blocked the effects of GRO/KC on K currents. Neither had effect on K currents in control cells (P = 0.867 and 0.999, respectively) (Figure 7).


NF-kappaB mediated enhancement of potassium currents by the chemokine CXCL1/growth related oncogene in small diameter rat sensory neurons.

Yang RH, Strong JA, Zhang JM - Mol Pain (2009)

The NF-κB inhibitors pyrrolidine dithiocarbamate (PDTC) and quinazoline (6-Amino-4-(4-phenoxypheny lethylamino), QNZ) blocked the effects of GRO/KC on K currents. QNZ was dissolved in Ethanol. PDTC or QNZ was added 1 h before GRO/KC and was present throughout the incubation period. Neither PDTC nor QNZ had an effect on K currents in control cells (P = 0.867 and 0.999, respectively). *, significantly different from all other groups at this voltage. In PDTC experiments, GRO/KC (N = 18 cells), GRO/KC+PDTC (N = 18) were from 4 cultures, control (N = 13) and PDTC (N = 11) were from 4 cultures; in QNZ experiments, GRO/KC (N = 26), GRO/KC+QNZ (N = 26) were from 7 cultures, control (N = 6) and QNZ (N = 9) were from 2 cultures.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2698898&req=5

Figure 7: The NF-κB inhibitors pyrrolidine dithiocarbamate (PDTC) and quinazoline (6-Amino-4-(4-phenoxypheny lethylamino), QNZ) blocked the effects of GRO/KC on K currents. QNZ was dissolved in Ethanol. PDTC or QNZ was added 1 h before GRO/KC and was present throughout the incubation period. Neither PDTC nor QNZ had an effect on K currents in control cells (P = 0.867 and 0.999, respectively). *, significantly different from all other groups at this voltage. In PDTC experiments, GRO/KC (N = 18 cells), GRO/KC+PDTC (N = 18) were from 4 cultures, control (N = 13) and PDTC (N = 11) were from 4 cultures; in QNZ experiments, GRO/KC (N = 26), GRO/KC+QNZ (N = 26) were from 7 cultures, control (N = 6) and QNZ (N = 9) were from 2 cultures.
Mentions: Two NF-κB inhibitors, pyrrolidine dithiocarbamate (PDTC) and quinazoline (6-Amino-4-(4-phenoxypheny lethylamino), QNZ) were used to explore the possible signaling pathway of GRO/KC effects on K currents. PDTC or QNZ was added 1 h before GRO/KC and was present throughout the incubation period. Both PDTC and QNZ blocked the effects of GRO/KC on K currents. Neither had effect on K currents in control cells (P = 0.867 and 0.999, respectively) (Figure 7).

Bottom Line: We examined the direct effects of GRO/KC on small diameter DRG neurons, which are predominantly nociceptive.The amplitude of the fast inactivating component increased significantly with no large shifts in the voltage dependence of inactivation.The results suggest that GRO/KC has important effects in inflammatory processes via its direct actions on sensory neurons, and that activation of NF-kappaB is involved in the GRO/KC-induced enhancement of K currents.

View Article: PubMed Central - HTML - PubMed

Affiliation: Pain Research Center, Department of Anesthesiology, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267-0531, USA. Rui-Hua.Yang@uc.edu

ABSTRACT

Background: Inflammatory processes play important roles in both neuropathic and inflammatory pain states, but the effects of inflammation per se within the sensory ganglia are not well understood. The cytokine growth-related oncogene (GRO/KC; CXCL1) shows strong, rapid upregulation in dorsal root ganglion (DRG) in both nerve injury and inflammatory pain models. We examined the direct effects of GRO/KC on small diameter DRG neurons, which are predominantly nociceptive. Whole cell voltage clamp technique was used to measure voltage-activated potassium (K) currents in acutely cultured adult rat small diameter sensory neurons. Fluorescently labeled isolectin B4 (IB4) was used to classify cells as IB4-positive or IB4-negative.

Results: In IB4-negative neurons, voltage-activated K current densities of both transient and sustained components were increased after overnight incubation with GRO/KC (1.5 nM), without marked changes in voltage dependence or kinetics. The average values for the slow and fast decay time constants at 20 mV were unchanged by GRO/KC. The amplitude of the fast inactivating component increased significantly with no large shifts in the voltage dependence of inactivation. The increase in K currents was completely blocked by co-incubation with protein synthesis inhibitor cycloheximide (CHX) or NF-kappaB inhibitors pyrrolidine dithiocarbamate (PDTC) or quinazoline (6-Amino-4-(4-phenoxypheny lethylamino;QNZ). In contrast, the voltage-activated K current of IB4-positive neurons was unchanged by GRO/KC. GRO/KC incubation caused no significant changes in the expression level of eight selected voltage-gated K channel genes in quantitative PCR analysis.

Conclusion: The results suggest that GRO/KC has important effects in inflammatory processes via its direct actions on sensory neurons, and that activation of NF-kappaB is involved in the GRO/KC-induced enhancement of K currents.

Show MeSH
Related in: MedlinePlus