Autonomic neuroscience : basic & clinical
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The rat L5/6 facet joint is innervated from L1 to L6 by the dorsal root ganglia (DRG). The presence of substance P- and calcitonin gene-related peptide-immunoreactive (ir) DRG neurons innervating the L5/6 facet joint has been demonstrated. ⋯ Fluoro-gold (FG)-labeled neurons innervating the L5/6 facet joint were distributed throughout the DRGs from T13 to L6 levels. Of the FG-labeled neurons, the proportions of BDNF-ir in L1, L2, L3, L4 and L5 DRG neurons were 9%, 15%, 21%, 17% and 20% and the proportions of VR1-ir L1, L2, L3, L4 and L5 DRG neurons were 8%, 9%, 15%, 16% and 15%, respectively.
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These studies have demonstrated that ipsilateral renal artery occlusion (RAO) in rat results in the phosphorylation of cyclic AMP (cAMP) response element binding protein (p-CREB) in the thoracolumbar (T8-L2) spinal cord and associated dorsal root ganglia (DRG). p-CREB-immunoreactivity (IR) was expressed bilaterally in the thoracolumbar spinal cord, whereas expression in the DRG was ipsilateral relative to RAO. p-CREB-IR was primarily expressed in four distinct regions of the spinal cord: medial or lateral dorsal horn (MDH or LDH), dorsal commissural nucleus (DCN) and the region of the intermediolateral cell column (IML). After RAO, p-CREB-IR was greatest in the T13-L2 spinal segments. Within the T13-L1 spinal segments, p-CREB-IR was greatest in the MDH, LDH and DCN and expression in each of these regions was comparable within a segment. ⋯ Retrograde tracing with Fluorogold (FG) to label renal afferent cells in the DRG revealed a significant (p < or = 0.01) increase in the percentage (75-86%) of renal afferent cells expressing p-CREB-IR after ipsilateral RAO. These studies demonstrate that p-CREB-IR is a useful tool for examining the distribution of spinal neurons and DRG involved in reflexes of renal origin. In addition, expression of p-CREB-IR may be coupled to late response genes that may exert long-term changes in neuronal function after RAO.