Limits...
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.

Show MeSH

Related in: MedlinePlus

Removal of endogenous NO leads to a decrease in the amplitude and increase in the frequency of the locomotor-related activity. A: raw (top) and rectified/integrated (bottom) traces recorded from left and right L2 ventral roots showing the effect of coapplication of NOS inhibitor nitro-l-arginine methyl ester (l-NAME; 200 μM) and NO scavenger PTIO (400 μM). B: time course plots of normalized data aggregated into 1-min bins show a decrease in amplitude (top) and an increase in frequency (bottom) during coapplication of l-NAME and PTIO. C: locomotor burst amplitude (Ci) and frequency (Cii) during a 5-min period in control, l-NAME and PTIO application, and washout (25 and 45 min from start of drug application or washout). Individual data points are shown in gray, and mean is represented by black line. Statistically significant differences in pairwise comparisons: *P < 0.05, **P < 0.01, ***P < 0.001; n = 8. a.u., Arbitrary unit.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3921400&req=5

Figure 2: Removal of endogenous NO leads to a decrease in the amplitude and increase in the frequency of the locomotor-related activity. A: raw (top) and rectified/integrated (bottom) traces recorded from left and right L2 ventral roots showing the effect of coapplication of NOS inhibitor nitro-l-arginine methyl ester (l-NAME; 200 μM) and NO scavenger PTIO (400 μM). B: time course plots of normalized data aggregated into 1-min bins show a decrease in amplitude (top) and an increase in frequency (bottom) during coapplication of l-NAME and PTIO. C: locomotor burst amplitude (Ci) and frequency (Cii) during a 5-min period in control, l-NAME and PTIO application, and washout (25 and 45 min from start of drug application or washout). Individual data points are shown in gray, and mean is represented by black line. Statistically significant differences in pairwise comparisons: *P < 0.05, **P < 0.01, ***P < 0.001; n = 8. a.u., Arbitrary unit.

Mentions: Next we investigated whether NO-mediated modulation represents an endogenous mechanism utilized by spinal cord circuitry to control locomotor output. To investigate the potential role of endogenous NO in the modulation of the murine locomotor network, we coapplied the NO scavenger PTIO (400 μM) and the NOS inhibitor l-NAME (200 μM) while recording fictive locomotion from isolated spinal cord preparations. When l-NAME and PTIO were coapplied to reduce the amount of endogenous NO available, we observed a decrease in the amplitude of locomotor-related ventral root bursts (7.7 ± 2.2%; Fig. 2, A, B, and Ci; F[3,18] = 11.8, P < 0.001, n = 8). Interestingly, the washout of l-NAME and PTIO was associated with an increase in amplitude during an extended washout period (18.7 ± 4.8% increase compared with control, n = 7). The similarity between this increase and the long-term effects of 50 μM DEA/NO application suggest that it may relate to a rebound in endogenous NO levels following the washout of blockers/scavengers. The coapplication of l-NAME and PTIO also led to an increase in the frequency (20.4 ± 2.4%; Fig. 2, A, B, and Cii; F[3,18] = 3.2, P < 0.05, n = 8) of locomotor-related activity. There was again no relationship between control frequency and the magnitude of frequency effects induced by l-NAME and PTIO. These findings demonstrate that NO is produced by the spinal cord during locomotor network activity. Furthermore, this endogenous NO modulates locomotor control circuitry to regulate the frequency and intensity of locomotor-related output.


Nitric oxide-mediated modulation of the murine locomotor network.

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

Removal of endogenous NO leads to a decrease in the amplitude and increase in the frequency of the locomotor-related activity. A: raw (top) and rectified/integrated (bottom) traces recorded from left and right L2 ventral roots showing the effect of coapplication of NOS inhibitor nitro-l-arginine methyl ester (l-NAME; 200 μM) and NO scavenger PTIO (400 μM). B: time course plots of normalized data aggregated into 1-min bins show a decrease in amplitude (top) and an increase in frequency (bottom) during coapplication of l-NAME and PTIO. C: locomotor burst amplitude (Ci) and frequency (Cii) during a 5-min period in control, l-NAME and PTIO application, and washout (25 and 45 min from start of drug application or washout). Individual data points are shown in gray, and mean is represented by black line. Statistically significant differences in pairwise comparisons: *P < 0.05, **P < 0.01, ***P < 0.001; n = 8. a.u., Arbitrary unit.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 2: Removal of endogenous NO leads to a decrease in the amplitude and increase in the frequency of the locomotor-related activity. A: raw (top) and rectified/integrated (bottom) traces recorded from left and right L2 ventral roots showing the effect of coapplication of NOS inhibitor nitro-l-arginine methyl ester (l-NAME; 200 μM) and NO scavenger PTIO (400 μM). B: time course plots of normalized data aggregated into 1-min bins show a decrease in amplitude (top) and an increase in frequency (bottom) during coapplication of l-NAME and PTIO. C: locomotor burst amplitude (Ci) and frequency (Cii) during a 5-min period in control, l-NAME and PTIO application, and washout (25 and 45 min from start of drug application or washout). Individual data points are shown in gray, and mean is represented by black line. Statistically significant differences in pairwise comparisons: *P < 0.05, **P < 0.01, ***P < 0.001; n = 8. a.u., Arbitrary unit.
Mentions: Next we investigated whether NO-mediated modulation represents an endogenous mechanism utilized by spinal cord circuitry to control locomotor output. To investigate the potential role of endogenous NO in the modulation of the murine locomotor network, we coapplied the NO scavenger PTIO (400 μM) and the NOS inhibitor l-NAME (200 μM) while recording fictive locomotion from isolated spinal cord preparations. When l-NAME and PTIO were coapplied to reduce the amount of endogenous NO available, we observed a decrease in the amplitude of locomotor-related ventral root bursts (7.7 ± 2.2%; Fig. 2, A, B, and Ci; F[3,18] = 11.8, P < 0.001, n = 8). Interestingly, the washout of l-NAME and PTIO was associated with an increase in amplitude during an extended washout period (18.7 ± 4.8% increase compared with control, n = 7). The similarity between this increase and the long-term effects of 50 μM DEA/NO application suggest that it may relate to a rebound in endogenous NO levels following the washout of blockers/scavengers. The coapplication of l-NAME and PTIO also led to an increase in the frequency (20.4 ± 2.4%; Fig. 2, A, B, and Cii; F[3,18] = 3.2, P < 0.05, n = 8) of locomotor-related activity. There was again no relationship between control frequency and the magnitude of frequency effects induced by l-NAME and PTIO. These findings demonstrate that NO is produced by the spinal cord during locomotor network activity. Furthermore, this endogenous NO modulates locomotor control circuitry to regulate the frequency and intensity of locomotor-related output.

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