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Nitric oxide-mediated modulation of the murine locomotor network.

Foster JD, Dunford C, Sillar KT, Miles GB - J. Neurophysiol. (2013)

Bottom Line: The effects of DEA/NO were mimicked by the cGMP analog 8-bromo-cGMP.The number of NOS-positive cells was also found to increase during postnatal development.In summary, we have shown that NO, derived from sources within the mammalian spinal cord, modulates the output of spinal motor networks and is therefore likely to contribute to the fine-tuning of locomotor behavior.

View Article: PubMed Central - PubMed

Affiliation: School of Psychology and Neuroscience, University of St Andrews, St Andrews, Fife, United Kingdom.

ABSTRACT
Spinal motor control networks are regulated by neuromodulatory systems to allow adaptability of movements. The present study aimed to elucidate the role of nitric oxide (NO) in the modulation of mammalian spinal locomotor networks. This was investigated with isolated spinal cord preparations from neonatal mice in which rhythmic locomotor-related activity was induced pharmacologically. Bath application of the NO donor diethylamine NONOate (DEA/NO) decreased the frequency and modulated the amplitude of locomotor-related activity recorded from ventral roots. Removal of endogenous NO with coapplication of a NO scavenger (PTIO) and a nitric oxide synthase (NOS) blocker [nitro-l-arginine methyl ester (l-NAME)] increased the frequency and decreased the amplitude of locomotor-related activity. This demonstrates that endogenously derived NO can modulate both the timing and intensity of locomotor-related activity. The effects of DEA/NO were mimicked by the cGMP analog 8-bromo-cGMP. In addition, the soluble guanylyl cyclase (sGC) inhibitor ODQ blocked the effects of DEA/NO on burst amplitude and frequency, although the frequency effect was only blocked at low concentrations of DEA/NO. This suggests that NO-mediated modulation involves cGMP-dependent pathways. Sources of NO were studied within the lumbar spinal cord during postnatal development (postnatal days 1-12) with NADPH-diaphorase staining. NOS-positive cells in the ventral horn exhibited a rostrocaudal gradient, with more cells in rostral segments. The number of NOS-positive cells was also found to increase during postnatal development. In summary, we have shown that NO, derived from sources within the mammalian spinal cord, modulates the output of spinal motor networks and is therefore likely to contribute to the fine-tuning of locomotor behavior.

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Inhibition of NO-sensitive soluble guanylyl cyclase (sGC) with ODQ blocks the effect of DEA/NO on the amplitude but not frequency of locomotor-related activity. A: raw (top) and rectified/integrated (bottom) traces recorded from left and right L2 ventral roots showing the effect of DEA/NO (200 μM) in the presence of ODQ (100 μM). B: time course plots of normalized data aggregated into 1-min bins show no change in amplitude (top) but a decrease in frequency (bottom) when DEA/NO is applied in the presence of ODQ. C: locomotor burst amplitude (Ci) and frequency (Cii) during a 5-min period in control with ODQ, DEA/NO application in the presence of ODQ (25 min into DEA/NO application), and washout with ODQ (25 min from start of washout). Individual data points are shown in gray, and mean is represented by black line. Statistically significant differences in pairwise comparisons: *P < 0.05; n = 12.
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Figure 4: Inhibition of NO-sensitive soluble guanylyl cyclase (sGC) with ODQ blocks the effect of DEA/NO on the amplitude but not frequency of locomotor-related activity. A: raw (top) and rectified/integrated (bottom) traces recorded from left and right L2 ventral roots showing the effect of DEA/NO (200 μM) in the presence of ODQ (100 μM). B: time course plots of normalized data aggregated into 1-min bins show no change in amplitude (top) but a decrease in frequency (bottom) when DEA/NO is applied in the presence of ODQ. C: locomotor burst amplitude (Ci) and frequency (Cii) during a 5-min period in control with ODQ, DEA/NO application in the presence of ODQ (25 min into DEA/NO application), and washout with ODQ (25 min from start of washout). Individual data points are shown in gray, and mean is represented by black line. Statistically significant differences in pairwise comparisons: *P < 0.05; n = 12.

Mentions: To further elucidate the role of the sGC/cGMP pathway we next applied DEA/NO (50 or 200 μM) in the presence of the sGC blocker ODQ (100 μM). The effects of both 50 and 200 μM DEA/NO on the amplitude of locomotor-related activity were blocked by ODQ (100 μM; DEA/NO 50 μM: F[2,12] = 1.8, P > 0.05, n = 7, data not shown; DEA/NO 200 μM: F[2,22] = 2.3, P > 0.05, n = 12, Fig. 4, B and Ci). ODQ also blocked the reduction in frequency induced by 50 μM (F[2,12] = 1.8, P > 0.05, n = 7; data not shown) but not 200 μM (Fig. 4, A, B, and Cii; F[2,22] = 7.9, P < 0.05, n = 12) DEA/NO. Comparison of the percent change in frequency induced by DEA/NO (200 μM) with and without ODQ (100 μM) showed no difference in the magnitude of this effect (Student's t-test, P > 0.05). At higher concentrations of ODQ (200 μM, n = 6; data not shown) the locomotor rhythm became unstable or ceased, so we could not test the possibility that 100 μM ODQ was an insufficient concentration to block the effects of 200 μM DEA/NO on locomotor frequency. Together these findings further support the idea that NO-mediated modulation of the intensity of locomotor output generated by spinal CPG circuitry involves the sGC/cGMP pathway.


Nitric oxide-mediated modulation of the murine locomotor network.

Foster JD, Dunford C, Sillar KT, Miles GB - J. Neurophysiol. (2013)

Inhibition of NO-sensitive soluble guanylyl cyclase (sGC) with ODQ blocks the effect of DEA/NO on the amplitude but not frequency of locomotor-related activity. A: raw (top) and rectified/integrated (bottom) traces recorded from left and right L2 ventral roots showing the effect of DEA/NO (200 μM) in the presence of ODQ (100 μM). B: time course plots of normalized data aggregated into 1-min bins show no change in amplitude (top) but a decrease in frequency (bottom) when DEA/NO is applied in the presence of ODQ. C: locomotor burst amplitude (Ci) and frequency (Cii) during a 5-min period in control with ODQ, DEA/NO application in the presence of ODQ (25 min into DEA/NO application), and washout with ODQ (25 min from start of washout). Individual data points are shown in gray, and mean is represented by black line. Statistically significant differences in pairwise comparisons: *P < 0.05; n = 12.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3921400&req=5

Figure 4: Inhibition of NO-sensitive soluble guanylyl cyclase (sGC) with ODQ blocks the effect of DEA/NO on the amplitude but not frequency of locomotor-related activity. A: raw (top) and rectified/integrated (bottom) traces recorded from left and right L2 ventral roots showing the effect of DEA/NO (200 μM) in the presence of ODQ (100 μM). B: time course plots of normalized data aggregated into 1-min bins show no change in amplitude (top) but a decrease in frequency (bottom) when DEA/NO is applied in the presence of ODQ. C: locomotor burst amplitude (Ci) and frequency (Cii) during a 5-min period in control with ODQ, DEA/NO application in the presence of ODQ (25 min into DEA/NO application), and washout with ODQ (25 min from start of washout). Individual data points are shown in gray, and mean is represented by black line. Statistically significant differences in pairwise comparisons: *P < 0.05; n = 12.
Mentions: To further elucidate the role of the sGC/cGMP pathway we next applied DEA/NO (50 or 200 μM) in the presence of the sGC blocker ODQ (100 μM). The effects of both 50 and 200 μM DEA/NO on the amplitude of locomotor-related activity were blocked by ODQ (100 μM; DEA/NO 50 μM: F[2,12] = 1.8, P > 0.05, n = 7, data not shown; DEA/NO 200 μM: F[2,22] = 2.3, P > 0.05, n = 12, Fig. 4, B and Ci). ODQ also blocked the reduction in frequency induced by 50 μM (F[2,12] = 1.8, P > 0.05, n = 7; data not shown) but not 200 μM (Fig. 4, A, B, and Cii; F[2,22] = 7.9, P < 0.05, n = 12) DEA/NO. Comparison of the percent change in frequency induced by DEA/NO (200 μM) with and without ODQ (100 μM) showed no difference in the magnitude of this effect (Student's t-test, P > 0.05). At higher concentrations of ODQ (200 μM, n = 6; data not shown) the locomotor rhythm became unstable or ceased, so we could not test the possibility that 100 μM ODQ was an insufficient concentration to block the effects of 200 μM DEA/NO on locomotor frequency. Together these findings further support the idea that NO-mediated modulation of the intensity of locomotor output generated by spinal CPG circuitry involves the sGC/cGMP pathway.

Bottom Line: The effects of DEA/NO were mimicked by the cGMP analog 8-bromo-cGMP.The number of NOS-positive cells was also found to increase during postnatal development.In summary, we have shown that NO, derived from sources within the mammalian spinal cord, modulates the output of spinal motor networks and is therefore likely to contribute to the fine-tuning of locomotor behavior.

View Article: PubMed Central - PubMed

Affiliation: School of Psychology and Neuroscience, University of St Andrews, St Andrews, Fife, United Kingdom.

ABSTRACT
Spinal motor control networks are regulated by neuromodulatory systems to allow adaptability of movements. The present study aimed to elucidate the role of nitric oxide (NO) in the modulation of mammalian spinal locomotor networks. This was investigated with isolated spinal cord preparations from neonatal mice in which rhythmic locomotor-related activity was induced pharmacologically. Bath application of the NO donor diethylamine NONOate (DEA/NO) decreased the frequency and modulated the amplitude of locomotor-related activity recorded from ventral roots. Removal of endogenous NO with coapplication of a NO scavenger (PTIO) and a nitric oxide synthase (NOS) blocker [nitro-l-arginine methyl ester (l-NAME)] increased the frequency and decreased the amplitude of locomotor-related activity. This demonstrates that endogenously derived NO can modulate both the timing and intensity of locomotor-related activity. The effects of DEA/NO were mimicked by the cGMP analog 8-bromo-cGMP. In addition, the soluble guanylyl cyclase (sGC) inhibitor ODQ blocked the effects of DEA/NO on burst amplitude and frequency, although the frequency effect was only blocked at low concentrations of DEA/NO. This suggests that NO-mediated modulation involves cGMP-dependent pathways. Sources of NO were studied within the lumbar spinal cord during postnatal development (postnatal days 1-12) with NADPH-diaphorase staining. NOS-positive cells in the ventral horn exhibited a rostrocaudal gradient, with more cells in rostral segments. The number of NOS-positive cells was also found to increase during postnatal development. In summary, we have shown that NO, derived from sources within the mammalian spinal cord, modulates the output of spinal motor networks and is therefore likely to contribute to the fine-tuning of locomotor behavior.

Show MeSH
Related in: MedlinePlus