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Re‐evaluation of connexins associated with motoneurons in rodent spinal cord, sexually dimorphic motor nuclei and trigeminal motor nucleus
Author(s) -
Bautista W.,
Rash J. E.,
Vanderpool K. G.,
Yasumura T.,
Nagy J. I.
Publication year - 2014
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/ejn.12450
Subject(s) - spinal cord , gap junction , connexin , electrical synapses , neuroscience , nucleus , biology , motor neuron , anatomy , spinal trigeminal nucleus , lumbar spinal cord , microbiology and biotechnology , nociception , intracellular , biochemistry , receptor
Electrical synapses formed by neuronal gap junctions composed of connexin36 ( C x36) are a common feature in mammalian brain circuitry, but less is known about their deployment in spinal cord. It has been reported based on connexin m RNA and/or protein detection that developing and/or mature motoneurons express a variety of connexins, including C x26, C x32, C x36 and C x43 in trigeminal motoneurons, C x36, C x37, C x40, C x43 and C x45 in spinal motoneurons, and C x32 in sexually dimorphic motoneurons. We re‐examined the localization of these connexins during postnatal development and in adult rat and mouse using immunofluorescence labeling for each connexin. We found C x26 in association only with leptomeninges in the trigeminal motor nucleus ( M o5), C x32 only with oligodendrocytes and myelinated fibers among motoneurons in this nucleus and in the spinal cord, and C x37, C x40 and C x45 only with blood vessels in the ventral horn of spinal cord, including those among motoneurons. By freeze‐fracture replica immunolabeling, > 100 astrocyte gap junctions but no neuronal gap junctions were found based on immunogold labeling for C x43, whereas 16 neuronal gap junctions at postnatal day ( P )4, P 7 and P 18 were detected based on C x36 labeling. Punctate labeling for C x36 was localized to the somatic and dendritic surfaces of peripherin‐positive motoneurons in the M o5, motoneurons throughout the spinal cord, and sexually dimorphic motoneurons at lower lumbar levels. In studies of electrical synapses and electrical transmission between developing and between adult motoneurons, our results serve to focus attention on mediation of this transmission by gap junctions composed of C x36.