Ontogeny of peptide‐ and amine‐containing neurones in motor, sensory, and autonomic regions of rat and human spinal cord, dorsal root ganglia, and rat skin

Abstract

The developmental patterns of neurofilament triplet proteins, peptide and amine immunoreactivities were compared in motor (ventral spinal cord), sensory (dorsal spinal cord, dorsal root ganglia, epidermis), and autonomic (intermediolateral cell columns, dermis) regions in the rat and human. In the rat, neurofilament triplet proteins first appeared in motoneurones (embryonic day 13). In the youngest human fetuses studied (6 weeks), immunoreactivity was present throughout the spinal cord. Peptides and amines occurred later. Calcitonin gene-related peptide, galanin, somatostatin, neuropeptide Y and its C-flanking peptide (CPON) were the first to appear localized to motoneurones (embryonic days 15-17 rat; fetal weeks 6-14 human). Numbers of immunoreactive motoneurones decreased toward birth, but immunoreactive fibers increased in the ventral horn with enkephalin, thyrotrophin-releasing hormone, and the monoaminergic markers 5-hydroxytryptamine and tyrosine hydroxylase (all presumably of supraspinal origin) the last to appear perinatally. In the dorsal horn, particularly in the rat, a transient expression of substance P-, somatostatin-, and neuropeptide Y/CPON-immunoreactive cells was detected (embryonic days 15-17). A pronounced increase of calcitonin gene-related peptide-, galanin-, somatostatin- and substance P- immunoreactive fibers was found perinatally in both species. This coincided with an increased detection of cells in the dorsal root ganglia containing these peptides and the earliest appearance of calcitonin gene-related peptide-, somatostatin-, and substance P-immunoreactive fibers in the rat epidermis. Few antigens were localized to the intermediolateral cell columns before embryonic day 20 (rat), fetal week 20 (human), with thyrotrophin-releasing hormone-, 5-hydroxytryptamine-, tyrosine hydroxylase-, and vasoactive intestinal polypeptide-immunoreactive nerves appearing perinatally. In the rat dermis, tyrosine hydroxylase-immunoreactive fibers (sympathetic fibers) and fibers immunoreactive for neuropeptide Y/CPON and vasoactive intestinal polypeptide were detected from postnatal day 1. In conclusion, 1) peptide and amine immunoreactivity develops in motor before sensory or autonomic regions, 2) many peptide-containing cells are transient in fetal life, and 3) central terminals of dorsal root ganglion cells express peptides before terminals in the skin.

Role of neurotrophin signalling in the differentiation of neurons from dorsal root ganglia and sympathetic ganglia

“…Of the cells in rat L4/ 5 DRG that express preprotachykinin (PPT) mRNA coding for SP, 78% are also positive for trkA, as shown by ISH, whereas no overlap exists with trkB and trkC expression (Kashiba et al 1996). During development, no SPimmunoreactive neurons are detected in rat DRG at E14.5, few positive cells are found at E19.5 and adult numbers are reached at birth (Hall et al 1997; see also Marti et al 1987).…”

Hyperinsulinemia induces hypertension associated with neurogenic vascular dysfunction resulting from abnormal perivascular innervations in rat mesenteric resistance arteries

“…16,17 A prominent site of CGRP synthesis has been shown to be the DRG, which contains the cell bodies of primary afferent neurons that extend CGRPergic nerves to peripheral sites such as blood vessels. 19 In addition to neurogenic vascular responsiveness in the perfused mesenteric vascular beds, to clarify the effect of insulin resistance and chronic hyperinsulinemia on CGRPergic nerves activity, we investigated the content of CGRP in DRG isolated from control rats and FDR by an ELISA. Consequently, CGRP content in FDR (248.9 ± 25.1 pg ml -1 , Po0.05) was significantly smaller than that in age-matched control rats (358.4 ± 27.0 pg ml -1 ).…”

Tlx1 and Tlx3 Coordinate Specification of Dorsal Horn Pain-Modulatory Peptidergic Neurons

“…Morphological and functional studies have revealed a tremendous diversity of dorsal horn neurons (Christensen and Perl, 1970;Lima and Coimbra, 1986;Todd and Spike, 1993;Han et al, 1998;Grudt and Perl, 2002;Todd and Koerber, 2006). Diversity of the dorsal horn neurons is further suggested by the expression of neuropeptides, including the opioid-like peptides Dynorphin (DYN) and enkephalin (ENK), the anti-opioid peptide cholecystokinin (CCK), the tachykinin peptides Substance P (SP) and Neurokinin B (NKB), somatostatin (SOM), and others (Marti et al, 1987;Todd and Spike, 1993;Todd and Koerber, 2006;Polgar et al, 2006). Functionally, neuropeptides modulate the transmission of somatic sensory information, particularly those involved with pain perception (Kajander et al, 1990;Xu et al, 1993;Wang et al, 2001;Wiesenfeld-Hallin et al, 2002).…”