Cuneothalamic relay neurons are postsynaptic to glycine-immunoreactive terminals in the rat cuneate nucleus

Lue, June‐Horng; Shieh, Jeng-Yi; Wen, Congcong; Chen, Seu Hwa

doi:10.1002/1098-2396(20000901)37:3<222::aid-syn6>3.0.co;2-b

Cited by 9 publications

(2 citation statements)

References 51 publications

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“…Inhibitory modulation in the rat DCN is provided by intrinsic inhibitory interneurons releasing GABA, glycine or both neurotransmitters (Popratiloff et al ., 1996). GABAergic interneurons synapse mainly on the proximal regions of CL cells (Lue et al ., 1994), whereas glycinergic interneurons appear to synapse in the distal dendrites in the same species (Popratiloff et al ., 1996; Lue et al ., 2000). It is unknown whether the above also applies to the cat.…”

Section: Discussionmentioning

confidence: 99%

Intracuneate mechanisms underlying primary afferent cutaneous processing in anaesthetized cats

Jorge-Soto

Aguilar

Martín-Cora

et al. 2004

Eur J of Neuroscience

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The cutaneous primary afferents from the upper trunk and forelimbs reach the medial cuneate nucleus in their way towards the cerebral cortex. The aim of this work was twofold: (i) to study the mechanisms used by the primary afferents to relay cutaneous information to cuneate cuneolemniscal (CL) and noncuneolemniscal (nCL) cells, and (ii) to determine the intracuneate mechanisms leading to the elaboration of the output signal by CL cells. Extracellular recordings combined with microiontophoresis demonstrated that the primary afferent cutaneous information is communicated to CL and nCL cells through AMPA, NMDA and kainate receptors. These receptors were sequentially activated: AMPA receptors participated mainly during the initial phase of the response, whereas kainate- and NMDA-mediated activity predominated during a later phase. The involvement of NMDA receptors was confirmed by in vivo intracellular recordings. The cutaneous-evoked activation of CL cells was decreased by GABA and increased by glycine acting at a strychnine-sensitive site, indicating that glycine indirectly affects CL cells. Two subgroups of nCL cells were distinguished based on their sensitivity to iontophoretic ejection of glycine and strychnine. Overall, the results support a model whereby the primary afferent cutaneous input induces a centre-surround antagonism in the cuneate nucleus by activating (via AMPA, NMDA and kainate receptors) and disinhibiting (via serial glycinergic-GABAergic interactions) a population of CL cells with overlapped receptive fields that at the same time inhibit (via GABAergic cells) other neighbouring CL cells with different receptive fields.

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Section: Discussionmentioning

confidence: 99%

Intracuneate mechanisms underlying primary afferent cutaneous processing in anaesthetized cats

Jorge-Soto

Aguilar

Martín-Cora

et al. 2004

Eur J of Neuroscience

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“…The suppression of the recurrent excitation by strychnine reinforces the suggestion that CL cells do not possess glycine receptors (Kelly & Renaud, 1973). Alternatively, while the GABAergic receptors might be mostly located in the soma and proximal dendrites (Lue et al ., 1994), the glycine receptors could be located in the distal dendrites (Popratiloff et al ., 1996; Lue et al ., 2000), unlikely to be affected by antagonist iontophoresed near the soma or, possibly, the modulatory effect of strychnine might not be detectable on spiking activity. A parsimonious view of our results suggests that glycinergic cells disinhibit CL neurons through interposed GABAergic cells (Fig.…”

Section: Discussionmentioning

confidence: 99%

The lemniscal–cuneate recurrent excitation is suppressed by strychnine and enhanced by GABA_A antagonists in the anaesthetized cat

Aguilar

Jorge-Soto

Rivadulla

et al. 2002

Eur J of Neuroscience

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In the somatosensory system, cuneolemniscal (CL) cells fire high frequency doublets of spikes facilitating the transmission of sensory information to diencephalic target cells. We studied how lemniscal feedback affects ascending transmission of cutaneous neurons of the middle cuneate nucleus. Electrical stimulation of the contralateral medial lemniscus and of the skin at sites evoking responses with minimal threshold induced recurrent activation of CL cells at a latency of 1-3.5 ms. The lemniscal feedback activation was suppressed by increasing the stimulating intensity at the same sites, suggesting recurrent-mediated lateral inhibition. The glycine antagonist strychnine blocked the recurrent excitatory responses while GABAA antagonists uncovered those obscured by stronger stimulation. CL cells sharing a common receptive field (RF) potentiate one another by recurrent activation and disinhibition, the disinhibition being produced by serial interactions between glycinergic and GABAergic interneurons. Conversely, CL cells with different RFs inhibit each other through recurrent GABA-mediated inhibition. The lemniscal feedback would thus enhance the surround antagonism of a centre response by increasing the spatial resolution and the transmission of weak signals.

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Quantitative stereological evaluation of the gracile and cuneate nuclei and their projection neurons in the rat

Bermejo

Jiménez

Torres

et al. 2003

J of Comparative Neurology

102

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Stereological methods were employed to estimate the volume and neuron numbers of the rat dorsal column nuclei (DCN). These methods were applied to Nissl-stained sections from control animals and cases that received injections of horseradish peroxidase in the thalamus, the cerebellum, or the spinal cord. Additional cases received combinations of fluorescent tracers in the same structures, to examine whether some of the retrogradely labeled neurons sent collaterals to different targets. The mean volume of the DCN is 0.81 mm(3) (range 0.65-1.10 mm(3)), of which 3%, 39%, and 59% correspond, respectively, to the nucleus of Bischoff (Bi), the gracile (Gr), and the cuneate (Cu) nuclei. Within Cu, the middle division (CuM) is the largest (42%), followed by the rostral (CuR; 36%) and caudal (CuC; 22%) divisions. The mean total number of neurons in the DCN is 16,000 (range 12,400-19,500), of which 2.4%, 34.0% and 63.6% correspond, respectively, to Bi, Gr, and Cu. Within Cu, CuM contains 48% of all neurons, and 27% correspond to CuR and 25% to CuC. Interanimal variability is moderate for the whole DCN and Cu but increases when individual nuclei are considered. About 80% of DCN neurons project to the thalamus, 3% to the spinal cord, and 7% to the cerebellum. Thalamic-projecting cells are more numerous in CuM and Gr (83%), and relatively less common in Bi and CuC (72-74%). Most of the DCN neurons projecting to the spinal cord appear in CuC and CuM. Two-thirds of the neurons projecting to the cerebellum are located in CuR, 20% in CuM, and 15% in Gr. A small fraction of neurons projects simultaneously to spinal cord and thalamus.

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Cuneothalamic relay neurons are postsynaptic to glycine-immunoreactive terminals in the rat cuneate nucleus

Cited by 9 publications

References 51 publications

Intracuneate mechanisms underlying primary afferent cutaneous processing in anaesthetized cats

Intracuneate mechanisms underlying primary afferent cutaneous processing in anaesthetized cats

The lemniscal–cuneate recurrent excitation is suppressed by strychnine and enhanced by GABA_A antagonists in the anaesthetized cat

Quantitative stereological evaluation of the gracile and cuneate nuclei and their projection neurons in the rat

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Cuneothalamic relay neurons are postsynaptic to glycine-immunoreactive terminals in the rat cuneate nucleus

Cited by 9 publications

References 51 publications

Intracuneate mechanisms underlying primary afferent cutaneous processing in anaesthetized cats

Intracuneate mechanisms underlying primary afferent cutaneous processing in anaesthetized cats

The lemniscal–cuneate recurrent excitation is suppressed by strychnine and enhanced by GABAA antagonists in the anaesthetized cat

Quantitative stereological evaluation of the gracile and cuneate nuclei and their projection neurons in the rat

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The lemniscal–cuneate recurrent excitation is suppressed by strychnine and enhanced by GABA_A antagonists in the anaesthetized cat