Modulation of Locomotor Activity by Multiple 5-HT and Dopaminergic Receptor Subtypes in the Neonatal Mouse Spinal Cord

Madriaga, M. A.; McPhee, Lisa C.; Chersa, Taha; Christie, Kimberly J.; Whelan, Patrick J.

doi:10.1152/jn.01181.2003

Cited by 114 publications

(167 citation statements)

References 47 publications

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“…Because our data could have DC drifts from time to time, we detrended the data. To analyze the stability and phase of the rhythms, we used time analyses techniques as previously described (Madriaga et al 2004;Pearson et al 2003). Cross-and autocorrelograms were calculated, and the quality of the rhythm was assessed by measuring the correlation coefficients for pairs of neurograms (C 5 , C 8 , L 2 , and L 5 ).…”

Section: Data Analysesmentioning

confidence: 99%

Interaction Between Developing Spinal Locomotor Networks in the Neonatal Mouse

Gordon¹,

Dunbar²,

Vanneste³

et al. 2008

Journal of Neurophysiology

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Gordon IT, Dunbar MJ, Vanneste KJ, Whelan PJ. Interaction between developing spinal locomotor networks in the neonatal mouse. J Neurophysiol 100: 117-128, 2008. First published April 24, 2008 doi:10.1152/jn.00829.2007. At birth, thoracosacral spinal cord networks in mouse can produce a coordinated locomotor-like pattern. In contrast, less is known about the cervicothoracic networks that generate forelimb locomotion. Here we show that cervical networks can produce coordinated rhythmic patterns in the brain stem-spinal cord preparation of the mouse. Segmentally the C 5 and C 8 neurograms were each found to be alternating left-right, and the ipsilateral C 5 and C 8 neurograms also alternated. Collectively these patterns were suggestive of locomotor-like activity. This pattern was not dependent on the presence of thoracosacral segments because they could be evoked following a complete transection of the spinal cord at T 5 . We next demonstrated that activation of thoracosacral networks either pharmacologically or by stimulation of sacrocaudal afferents could produce rhythmic activity within the C 5 and C 8 neurograms. On the other hand, pharmacological activation of cervical networks did not evoke alternating cervical rhythmic activity either in isolated cervicothoracic or -sacral preparations. Under these conditions, we found that activation of cervicothoracic networks could alter the timing of thoracosacral locomotor-like patterns. When thoracosacral networks were not activated pharmacologically but received rhythmic drive from cervicothoracic networks, a pattern of slow bursts with superimposed fast synchronous oscillations became the dominant lumbar neurogram pattern. Our data suggest that in neonatal mice the cervical CPG is capable of producing coordinated rhythmic patterns in the absence of input from lumbar segments, but caudorostral drive contributes to cervical patterns and rhythm stability.

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Section: Data Analysesmentioning

confidence: 99%

Interaction Between Developing Spinal Locomotor Networks in the Neonatal Mouse

Gordon¹,

Dunbar²,

Vanneste³

et al. 2008

Journal of Neurophysiology

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“…5-HT plays an important role in enabling the generation of the locomotor rhythm in rodents (MacLean et al, 1998;Madriaga et al, 2004;Christie and Whelan, 2005;Liu and Jordan, 2005;Pearlstein et al, 2005). Thus, we examined the effects of 5-HT on the firing properties of dCINs and adCINs in the spinal cord of neonatal mice.…”

Section: Effects Of 5-ht On the Membrane Potential Of Dcins And Adcinsmentioning

confidence: 99%

“…Serotonin also plays a central role in enabling the CPG for locomotion in the neonatal rodent (MacLean et al, 1998;Madriaga et al, 2004;Christie and Whelan, 2005;Liu and Jordan, 2005;Pearlstein et al, 2005). 5-HT receptor antagonists can abolish NMDA-evoked fictive locomotion in the rat (MacLean et al, 1998), and both ketanserin (a 5-HT 2 receptor antagonist) and SB 269970 [( R)-3-(2-(2-(4-methylpiperidin-1-yl)-ethyl)pyrrolidine-1-sulfonyl)phenol] (a 5-HT 7 receptor antagonist) disrupt the locomotor-like activity induced by electrical stimulation from brainstem in neonatal rodent spinal cord (Liu and Jordan, 2005;Pearlstein et al, 2005).…”

Section: Different Modulation Of Dcins and Adcins By Serotoninmentioning

confidence: 99%

“…CINs were monitored with whole-cell patch recordings from the L2 spinal segment, and their activity correlated to rhythmic flexor motor activity measured by extracellular recordings from the L2 ventral roots. 5-HT is thought to play an important role to organize the locomotor network for rhythmic activity (MacLean et al, 1998;Madriaga et al, 2004;Christie and Whelan, 2005;Liu and Jordan, 2005;Pearlstein et al, 2005), so we also studied the modulatory effects of 5-HT on the intrinsic membrane properties of dCINs and adCINs that were pharmacologically isolated from most fast synaptic inputs. Our results indicate that, in the mouse, a majority of dCINs fire rhythmically, whereas none of the adCINs show rhythmicity during fictive locomotion.…”

Section: Introductionmentioning

confidence: 99%

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Intrinsic and Functional Differences among Commissural Interneurons during Fictive Locomotion and Serotonergic Modulation in the Neonatal Mouse

Zhong

Díaz‐Ríos

Harris-Warrick

2006

Journal of Neuroscience

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Commissural interneurons (CINs) send their axons across the midline to innervate contralateral targets and have been implicated in the coordination of left-right limb movements during locomotion. In the neonatal mouse spinal cord, we studied the firing properties and responses to serotonin (5-HT) of two classes of CINs: those whose axons turn caudally after crossing the midline (dCINs) and those whose axons bifurcate after crossing the midline (adCINs). During NMDA and 5-HT-induced locomotor-like activity, a majority of lumbar (L2) dCINs fired rhythmically with ventral root-recorded motor activity, although their firing phase was widely distributed throughout the locomotor cycle. In contrast, none of the adCINs fired rhythmically during fictive locomotion. We studied the baseline firing and membrane properties, and responses to current injection, in dCINs and adCINs that had been partially isolated by blockade of rapid synaptic transmission (with antagonists to glutamate, GABA, and glycine). No significant baseline differences were found between the cell types. In contrast, 5-HT significantly increased the excitability of the isolated dCINs by depolarizing the membrane potential, reducing the postspike afterhyperpolarization amplitude and decreasing the action potential threshold. None of these parameters were affected by 5-HT in adCINs. These results, together with our recent study of a third class of CINs, the aCINs whose axons ascend after crossing the midline (Zhong et al., 2006), suggest that dCINs and aCINs, but not adCINs, are excited by 5-HT and are rhythmically active during fictive locomotion. Thus, they may play important roles in the coordination of left-right movements during fictive locomotion.

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“…Les dynamines sont des GTPases de haut poids moléculaire (environ 100 kDa) impliquées dans le trafic membranaire. Ces molécules hydrolysent le GTP et participent à la déformation des membranes biologiques nécessaire à la formation de vésicules [5]. Parmi les trois dynamines que compte cette famille chez l'homme, la dynamine 2 est une protéine ubiquitaire principalement impliquée dans l'endocytose et le trafic membranaire intracellulaire ainsi que dans la dynamique du réseau d'actine et la structure du centrosome.…”

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