Development, neurochemical properties, and axonal projections of a population of last-order premotor interneurons in the white matter of the chick lumbosacral spinal cord

Antal, Miklós; Puskár, Zita; Birinyi, András; Storm‐Mathisen, Jon

doi:10.1002/(sici)1097-010x(20000201)286:2<157::aid-jez8>3.0.co;2-j

Cited by 5 publications

(1 citation statement)

References 71 publications

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“…Thus spinal interneurons exist that may form a network that is capable of coordinating motor and sympathetic activity. These interneurons may be GABAergic, as such neurons form a significant population within the spinal cord 35,39 and GABAergic terminals are maintained on SPN in spinalized animals 6 . Furthermore Deuchars et al 16 .…”

Section: Discussionmentioning

confidence: 99%

Control of Sympathetic, Respiratory and Somatomotor Outflow by an Intraspinal Pattern Generator

Goodchild¹,

Deurzen²,

Hildreth³

et al. 2008

Clin Exp Pharma Physio

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1. Sympathetic and somatic motor outflow results from the summation of excitatory and inhibitory inputs arising from intra- and supra-spinal origins. Here we determined the contribution of intra- and supra-spinal GABAergic inputs, utilizing GABA-A receptors, in producing sympathetic and somatic motor outflow. 2. Spinal GABA-A receptor blockade, with bicuculline or picrotoxin injected intrathecally at T9, increased the level and lability of arterial pressure, sympathetic (splanchnic and cervical sympathetic) and motor (phrenic) nerve activity. Bursts of activity occurring irregularly, at low frequency were seen in all nerves. 3. C1 spinal transection abolished phrenic nerve activity and reduced sympathetic nerve activities and arterial pressure. Intrathecal bicuculline-induced bursting in sympathetic and motor (phrenic, sciatic and brachial) nerves was similar to that seen prior to C1 transection. Thus supraspinal control of sympathetic and somatomotor outflow is not dependent on GABA-A receptors. 4. Bicuculline-induced effects on phrenic nerve activity were eliminated after C8 spinal cord transection and regular phrenic rhythm resumed indicating that bicuculline was not acting directly on phrenic motoneurons. 5. Bicuculline evoked similar bursting characteristics in both sympathetic and motor nerves attributable to increased excitability of spinal cord neurons. The bursting patterns evoked were often coincident in sympathetic and motor nerves suggesting a common site of origin. 6. These data suggest there is intraspinal coupling between multiple sympathetic and motor outflows in the adult rat spinal cord in vivo. Cervicothoracic spinal cord generator/s perhaps in the form of interneuronal networks, utilizing GABA-A and glutamate receptors, can simultaneously drive functionally independent nerves.

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Section: Discussionmentioning

confidence: 99%

Control of Sympathetic, Respiratory and Somatomotor Outflow by an Intraspinal Pattern Generator

Goodchild¹,

Deurzen²,

Hildreth³

et al. 2008

Clin Exp Pharma Physio

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Development of projection‐specific interneurons and projection neurons in the embryonic mouse and rat spinal cord

Nissen

Mochida

Glover

2005

J of Comparative Neurology

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Interneurons and projection neurons in the lumbar spinal cord of mouse and rat embryos were labeled retrogradely with fluorescent dextran amines from a distance of one segment from the segment of origin [lumbar segment (L) 2]. Six classes with specific axonal projections (ipsilateral ascending, descending, and bifurcating, and commissural ascending, descending, and bifurcating) were identified by differential labeling in both species and followed from embryonic day (E)12 to birth in the mouse. Neurons with shorter projections (intrasegmental interneurons) were not studied. We show that the four nonbifurcating neuron classes occupy characteristic, partially overlapping domains in the transverse plane, indicating a systematic pattern of migration and settlement related to axon trajectories. The number of neurons in each of the nonbifurcating classes increased steadily during development. Bifurcating neurons represented a minor fraction of the total throughout development and had relatively scattered positions within the ipsilateral and commissural neuron domains. Combination of retrograde tracing and immunohistochemistry for the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) showed that none of the spinal neurons in the six projection-specific classes was GABA positive, suggesting that all GABA-positive spinal neurons, including previously described GABA-positive commissural neurons, are unlikely to have projections exceeding one or two segments in either direction.

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Analysis of GABA-induced inhibition of spontaneous firing in chick accessory lobe neurons

et al. 2011

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It has been hypothesized that chick accessory lobes (ALs) contain functional neurons and act as a sensory organ of equilibrium. It was reported that neurons located in an outer layer of ALs showed γ-aminobutyric acid (GABA)- and glutamic acid decarboxylase (GAD)-like immunoreactivity more strongly than centrally located neurons, which were surrounded by the GAD-immunoreactive terminals. We investigated effects of GABA on the electrical activity of AL neurons. About 50% of embryonic AL neurons exhibited spontaneous firing. In the on-cell recording, GABA, muscimol, and GABA in combination with CGP35348 inhibited this firing. In whole-cell voltage clamp recordings, GABA and muscimol evoked a transient current. The mean reversal potential of GABA-evoked currents was close to the theoretical reversal potential of Cl⁻. These results indicate that GABA exerts the inhibitory effect on the firing through the activation of GABA(A) receptors. In addition, the intracellular concentration of Cl⁻ was estimated to be about 16 mM in measurements with the gramicidin-perforated configuration, indicating the physiological reversal potential of the GABA current was about -60 mV. In conclusion, AL neurons have an intrinsic mechanism to evoke the spontaneous firing, which can be arrested by the inhibitory mechanism through the activation of the GABA(A) receptors.

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Development, neurochemical properties, and axonal projections of a population of last-order premotor interneurons in the white matter of the chick lumbosacral spinal cord

Cited by 5 publications

References 71 publications

Control of Sympathetic, Respiratory and Somatomotor Outflow by an Intraspinal Pattern Generator

Control of Sympathetic, Respiratory and Somatomotor Outflow by an Intraspinal Pattern Generator

Development of projection‐specific interneurons and projection neurons in the embryonic mouse and rat spinal cord

Analysis of GABA-induced inhibition of spontaneous firing in chick accessory lobe neurons

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