The spinothalamic system of the rat: Structural types of retrogradely labelled neurons in the marginal zone (lamina I)

Lima, Deolinda; Coimbra, Antonio

doi:10.1016/0306-4522(88)90232-1

Cited by 123 publications

(73 citation statements)

References 34 publications

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“…Our present observations in the monkey and our prior observations in the cat, however, are not consistent with the report in the rat by Lima and Coimbra (1988) that most retrogradely HRP-or CTb-labeled lamina I STT cells were pyramidal in shape, with others belonging to their flattened (or multipolar) type. This could suggest a species difference.…”

Section: Discussioncontrasting

confidence: 57%

“…First, previous retrograde labeling studies in cat and rat have produced conflicting results. Even though Golgi studies in cat (Gobel, 1978) and rat (Lima and Coimbra, 1986) both described similar cell types in lamina I (fusiform, pyramidal, and multipolar), a retrograde labeling study of lamina I STT cells in the rat reported that they were mostly pyramidal cells (Lima and Coimbra, 1988), whereas a comparable study in the cat found fusiform, pyramidal, and multipolar lamina I STT cells . Both studies utilized cholera toxin subunit b (CTb), which provides excellent retrograde morphological definition (Ericson and Blomqvist, 1988).…”

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confidence: 96%

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Morphology and Distribution of Spinothalamic Lamina I Neurons in the Monkey

Zhang

Craig

1997

J. Neurosci.

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Lamina I spinothalamic tract (STT) neurons were identified by retrograde labeling with cholera toxin subunit b (CTb) in monkeys. On the basis of the criteria of somatal shape and dendritic orientation in horizontal sections used in prior work in the cat, three distinct morphological types were recognized: fusiform (F) cells with spindle-shaped somata and two main longitudinal dendritic arbors; pyramidal (P) cells with triangular somata and three main dendrites oriented primarily longitudinally; and multipolar (M) cells with polygonal somata and four or more dendrites directed longitudinally and mediolaterally. Some cells had transitional shapes, but cells with indeterminate shapes and a few with small round, unipolar, or eccentric somata were grouped as unclassified (U). Greater variation appeared in the monkey than had been seen in the cat, and more subtypes were noted. The overall proportions of these cell types were: 47% F, 27% P, 22% M, and 5% U. Differential longitudinal distributions were found over the length of the spinal cord (from the second cervical through the first coccygeal segments). Pyramidal and multipolar cells together predominated in the enlargements, whereas fusiform cells predominated in thoracic segments. We conclude that three distinct morphological types of lamina I STT cells are present in the monkey as in the cat. Considered with other recent findings, the present results support the possibility that these three cell types may correspond to distinct physiological classes of nociceptive and thermoreceptive lamina I STT cells.

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Section: Discussioncontrasting

confidence: 57%

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confidence: 96%

Morphology and Distribution of Spinothalamic Lamina I Neurons in the Monkey

Zhang

Craig

1997

J. Neurosci.

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“…We focused on lamina I (LI) because this layer constitutes one of the main output pathways for the relay of nociceptive information to the brain [e.g., ϳ50% of the spinothalamic tract (Lima and Coimbra, 1988)]. We evaluated the characteristics of GABA A receptor-mediated responses through monitoring of intracellular calcium ([Ca 2ϩ ] i ), perforated and whole-cell patch-clamp recordings, and measurement of Cl Ϫ extrusion capacity in spinal slices obtained from rats at different stages of postnatal development.…”

Section: Introductionmentioning

confidence: 99%

Differential Maturation of GABA Action and Anion Reversal Potential in Spinal Lamina I Neurons: Impact of Chloride Extrusion Capacity

Cordero-Erausquin¹,

Coull²,

Boudreau³

et al. 2005

J. Neurosci.

102

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A deficit in inhibition in the spinal dorsal horn has been proposed to be an underlying cause of the exaggerated cutaneous sensory reflexes observed in newborn rats. However, the developmental shift in transmembrane anion gradient, potentially affecting the outcome of GABA A transmission, was shown to be completed within 1 week after birth in the spinal cord, an apparent disparity with the observation that reflex hypersensitivity persists throughout the first 2-3 postnatal weeks.To further investigate this issue, we used several approaches to assess the action of GABA throughout development in spinal lamina I (LI) neurons. GABA induced an entry of extracellular calcium in LI neurons from postnatal day 0 (P0) to P21 rats, which involved T-and N-type voltage-gated calcium channels. Gramicidin perforated-patch recordings revealed that the shift in anion gradient was completed by P7 in LI neurons. However, high chloride pipette recordings demonstrated that these neurons had not reached their adult chloride extrusion capacity by P10 -P11. Simultaneous patch-clamp recordings and calcium imaging revealed that biphasic responses to GABA, consisting of a primary hyperpolarization followed by a rebound depolarization, produced a rise in [Ca 2ϩ ] i . Thus, even if E anion predicts GABA A -induced hyperpolarization from rest, a low chloride extrusion capacity can cause a rebound depolarization and an ensuing rise in [Ca 2ϩ ] i . We demonstrate that GABA action in LI neurons matures throughout the first 3 postnatal weeks, therefore matching the time course of maturation of withdrawal reflexes. Immature spinal GABA signaling may thus contribute to the nociceptive hypersensitivity in infant rats.

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“…These afferent fibres terminate predominantly on postsynaptic neurones in laminae I and II of the dorsal horn (Rethelyi, 1977;Ribiero-daSilva & Coimbra, 1982;Nagy & Hunt, 1983). Lamina I neurones include spinothalamic projection cells (Giesler, Menetrey & Basbaum, 1979;Granum, 1986;Lima & Coimbra, 1988) and neurones with segmental projections (Cervero, Iggo & Molony, 1979). Lamina II neurones form local interneuronal circuits which are thought to integrate afferent information from different fibre classes and to relay this information to projection neurones located in lamina I and in deeper regions of the dorsal horn (Kumazawa & Perl, 1978;Light, Trevino & Perl, 1979).…”

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confidence: 99%

Amino acid‐mediated EPSPs at primary afferent synapses with substantia gelatinosa neurones in the rat spinal cord.

Yoshimura

Jessell

1990

The Journal of Physiology

345

192

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SUMMARY1. Fast excitatory postsynaptic potentials (EPSPs) evoked by stimulation of Ad and C fibres were examined by intracellular recording from substantia gelatinosa (SG) neurones in a transverse slice preparation of adult rat spinal cord.2. Single low-intensity stimuli applied to the dorsal root activated Ad fibres and evoked monosynaptic EPSPs in 70% of SG neurones. In 5% of SG neurones, increasing the intensity and duration of stimulation evoked solely C fibre-mediated EPSPs. About 20% of neurones received both Ad and C fibre input from primary afferents.3. Low concentrations of tetrodotoxin (TTX, -50 nm) blocked EPSPs evoked by stimulation of Ad fibres without affecting those evoked by C fibre stimulation. Higher concentrations of TTX (500 nM) also blocked C fibre-evoked responses.4. EPSPs evoked by Ad and C fibre stimulation reversed in polarity at membrane potentials near 0 mV, similar to the reversal potential of spontaneous EPSPs and of the potential change evoked by exogenous glutamate.5. Ad and C fibre-evoked EPSPs were depressed by kynurenate and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX); C fibre-evoked EPSPs appeared to be less sensitive.6. In the presence of TTX, only 50% of SG neurones were depolarized by Lglutamate. However, neurones which exhibited no direct response to L-glutamate received afferent-evoked EPSPs which were sensitive to CNQX. In sensitive neurones, the depolarization evoked by L-glutamate was depressed by only -15 % in the presence of CNQX, whereas afferent-evoked EPSPs recorded from the same neurone were almost completely suppressed. Combined application of DL-2-amino-5-phosphonovaleric acid (APV) and CNQX depressed the response to L-glutamate by only -25%.7. These findings suggest that Ad and C fibres use L-glutamate or a related amino acid as a transmitter at synapses with substantia gelatinosa neurones. The * Present address and reprint requests to: M. Yoshimura, Department of Physiology, Kurume University, 67 Asahi-machi, Kurume 830, Japan. MS 8435M. YOSHIMURA AND T. JESSELL postsynaptic actions of this transmitter are mediated predominantly by non Nmethyl-D-aspartic acid (NMDA) receptors. The failure of CNQX and APV to completely block the L-glutamate-evoked depolarization of substantia gelatinosa neurones raises the possibility that exogenously applied L-glutamate activates a non-NMDA receptor distinct from that which mediates the actions of the synaptically released afferent transmitter.

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The spinothalamic system of the rat: Structural types of retrogradely labelled neurons in the marginal zone (lamina I)

Cited by 123 publications

References 34 publications

Morphology and Distribution of Spinothalamic Lamina I Neurons in the Monkey

Morphology and Distribution of Spinothalamic Lamina I Neurons in the Monkey

Differential Maturation of GABA Action and Anion Reversal Potential in Spinal Lamina I Neurons: Impact of Chloride Extrusion Capacity

Amino acid‐mediated EPSPs at primary afferent synapses with substantia gelatinosa neurones in the rat spinal cord.

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