PubMed Health⌕ Search

PubMed · 1388081

NMDA receptors in sensory information processing.

Abstract

During the past year electrophysiological studies, particularly in the visual and somatosensory systems, have begun to uncover the specific roles played by NMDA receptors in the processing of sensory information. Many of the features of NMDA-receptor-mediated sensory responses reflect known properties of the receptor.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

S B Nelson, M Sur. 1992. NMDA receptors in sensory information processing.. https://doi.org/10.1016/0959-4388(92)90184-m

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

Vesicular glutamate transporters in the spinal cord, with special reference to sensory primary afferent synapses.

Spinal cord sensory synapses are glutamatergic, but previous studies have found a great diversity in synaptic vesicle structure and have suggested additional neurotransmitters. The identification of several vesicular glutamate transporters (VGLUTs) similarly revealed an unexpected molecular diversity among glutamate-containing terminals. Therefore, we quantitatively investigated VGLUT1 and VGLUT2 content in the central synapses of spinal sensory afferents by using confocal and electron microscopy immunocytochemistry. VGLUT1 localization (most abundant in LIII/LIV and medial LV) is consistent with an origin from cutaneous and muscle mechanoreceptors. Accordingly, most VGLUT1 immunoreactivity disappeared after rhizotomy and colocalized with markers of cutaneous (SSEA4) and muscle (parvalbumin) mechanoreceptors. With postembedding colloidal gold, intense VGLUT1 immunoreactivity was found in 88-95% (depending on the antibody used) of C(II) dorsal horn glomerular terminals and in large ventral horn synapses receiving axoaxonic contacts. VGLUT1 partially colocalized with CGRP in some large dense-core vesicles (LDCVs). However, immunostaining in neuropeptidergic afferents was inconsistent between VGLUT1 antibodies and rather weak with light microscopy. VGLUT2 immunoreactivity was widespread in all spinal cord laminae, with higher intensities in LII and lateral LV, complementing VGLUT1 distribution. VGLUT2 immunoreactivity did not change after rhizotomy, suggesting a preferential intrinsic origin. However, weak VGLUT2 immunoreactivity was detectable in primary sensory nociceptors expressing lectin (GSA-IB4) binding and in 83-90% of C(I) glomerular terminals in LII. Additional weak VGLUT2 immunoreactivity was found over the small clear vesicles of LDCV-containing afferents and in 50-60% of C(II) terminals in LIII. These results indicate a diversity of VGLUT isoform combinations expressed in different spinal primary afferents.

Afferent Pathways↗

Rostrocaudal distribution of motoneurones and variation in ventral horn area within a segment of the feline thoracic spinal cord.

Retrograde transport of horseradish peroxidase, applied to cut peripheral nerves, was used to determine the rostrocaudal distribution of motoneurones supplying different branches of the ventral ramus for a single mid- or caudal thoracic segment in the cat. The motoneurones occupied a length of spinal cord equal to the segmental length but displaced rostrally from the segment as defined by the dorsal roots, with the number of motoneurones per unit length of cord higher in the rostral part of a segment (close to the entry of the most rostral dorsal root) than in the caudal part. The cross-sectional area of the ventral horn showed a rostrocaudal variation that closely paralleled the motoneurone distribution. The ratio between the number of motoneurones per unit length in the caudal and rostral regions of a segment (0.70) was similar to the ratio previously reported for the strength of functional projections of expiratory bulbospinal neurones (0.63). This is consistent with the motoneurones being the main targets of the bulbospinal neurones.

Afferent Pathways↗

Medullary adrenergic neurons contribute to the cocaine- and amphetamine-regulated transcript-immunoreactive innervation of thyrotropin-releasing hormone synthesizing neurons in the hypothalamic paraventricular nucleus.

Cocaine- and amphetamine-regulated transcript (CART)-IR axons densely innervate the thyrotropin-releasing hormone (TRH) neurons in the hypothalamic paraventricular nucleus (PVN), partly arising from neuronal perikarya in the hypothalamic arcuate nucleus. The source of the remaining CART innervation, however, is unknown. We have recently demonstrated that neurons co-containing adrenaline and CART in the C1-3 areas of the medulla project to the PVN. Since adrenergic neurons densely innervate the hypophysiotropic TRH neurons, we raised the possibility that adrenergic neurons contribute to the CART-IR innervation of hypophysiotropic TRH neurons. Combined in situ hybridization and immunocytochemistry was performed to study the colocalization of CART and phenylethanolamine N-methyltransferase (PNMT), the synthesizing enzyme of adrenaline, in axons innervating the hypophysiotropic TRH neurons. PNMT was observed in 44% of CART-IR axons in juxtaposition to the hypophysiotropic TRH neurons and CART-IR was observed in approximately 50% of all PNMT axons in contact with proTRH perikarya in the PVN. We conclude that adrenergic neurons of the medulla give rise to approximately half of the CART-IR axons innervating hypophysiotropic TRH neurons in the PVN, and propose that CART may play important role in the modulation of adrenergic input to the hypothalamic-pituitary-thyroid axis.

Afferent Pathways↗