Disease relevance of Adrenergic Fibers

• Latex-induced transmural myocardial infarction or epicardial application of phenol interrupts sympathetic fibers innervating myocardium apical to the infarction or to the phenol-painted area [1].
• CONCLUSION: Our results indicate a key role of renal sympathetic fibers in mediating renin release during hypotension in humans, and that epidural anesthesia interferes with the functional integrity of the renin-angiotensin system [2].
• Since the spillover rate is closely related to the NE release rate from sympathetic endings, this study supports the hypothesis that DOCA-salt hypertension is clearly associated with an enhanced basal sympathetic fibers activity [3].

High impact information on Adrenergic Fibers

• We describe an early length-dependent dysfunction of sensory small-diameter fibers, prior to dysfunction of sympathetic fibers, with depletion of skin NGF and the sensory neuropeptide substance P [4].
• In DBH-NGF mice, the sympathetic trunk and nerves growing to peripheral tissues were enlarged and contained an increased number of sympathetic fibers [5].
• The lack of change in the arteriovenous balance for norepinephrine across the heart, in the face of the lowered uptake for this amine, suggested that the liberation of norepinephrine by cardiac sympathetic fibers was reduced [6].
• It is concluded that 5-HT is taken up by both serotonergic and adrenergic fibers of the iris-ciliary body [7].
• However, mutant SHP-2 expression resulted in an overproduction of sympathetic fibers in sympathetic target organs [8].

Biological context of Adrenergic Fibers

• To explore the possibility that adrenergic fibers influence epithelial wound healing in the rabbit cornea, chronic electrodes were implanted in the left cervical sympathetic nerve, and symmetrical wounds were produced on the corneal epithelium of both eyes by means of n-heptanol [9].
• After bilateral RVLM inactivation, tail sympathetic fibers could still be excited by chemical stimulation of raphé neurons (l-glutamate, 120 nl, 50 mM), and strong cooling (rectal temperature approximately 33 degrees C) caused a low level of ongoing activity [10].
• However, capsaicin bolus injection also resulted in a marked increase in the mean arterial blood pressure which may be due to reflex activation of sympathetic fibers [11].
• Hepatic blood volume and interstitial space increased with increased blood flow; and elevated plasma norepinephrine levels, especially in portal vein (following either exogenous infusion or activation of peripheral sympathetic fibers) selectively reduced the distending effect of hepatic inflow on the vascular volume [12].
• Therefore, we conclude that the lipolysis on the central administration of glucagon, is caused by the endogenous glucagon secreted from the pancreas through the sympathetic fibers [13].

Anatomical context of Adrenergic Fibers

• Neuropeptide Y is colocalized with noradrenaline in sympathetic fibers innervating the rat pineal gland [14].
• To determine if the invasion of sympathetic fibers from the superior cervical ganglion (SCG) correlates with the initiation of SR light/dark population differences, we employed tyrosine hydroxylase immunofluorescence to reveal the distribution of catecholaminergic fibers in chick pineal follicles [15].
• Phenylethanolamine N-methyltransferase-positive fibers from the C1 and C3 cell groups form an adrenergic fiber bundle in the dorsomedial medulla; in the pons, these fibers appear to exit this bundle and innervate the locus coeruleus [16].
• Only these large axon bundles display prominent immunostaining for GAP-43, which is preferentially localized to the sympathetic fibers, since nonmyelinating Schwann cells are not associated with these axon bundles [17].
• The sympathetic fibers associated with sweat glands contain acetylcholinesterase and immunoreactivity for vasoactive intestinal peptide [18].

Associations of Adrenergic Fibers with chemical compounds

• These results support the existence of both negative and positive feedback mechanisms on the release of norepinephrine by cardiac sympathetic fibers mediated through presynaptic alpha- and beta-adrenoreceptors, respectively [19].
• These results are discussed in terms of the hypothesis that carbachol may act on the sympathetic fibers on the pial arteries by a nonmuscarinic mechanism to reduce the liberation of the transmitter [20].
• We also found that rat lumbar sympathetic fibers projecting to the hindquarter vasculature contain NADPH diaphorase, a marker for NO synthase in paraformaldehyde-perfused tissue.(ABSTRACT TRUNCATED AT 250 WORDS)[21]
• Although VIP is predominantly a parasympathetic mediator, it seemed to be conveyed by sympathetic fibers, as shown by the marked effect of guanethidine treatment [22].
• Since, in mice, sympathetic activation appears to induce thyroid hormone secretion by a direct action of norepinephrine released from intrathyroidal sympathetic fibers, the recorded variations are presumed to have functional importance [23].

Gene context of Adrenergic Fibers

• In the periphery, NPY coexists with noradrenaline (NA) in perivascular sympathetic fibers [24].
• However, all sympathetic TH- and NPY-immunoreactive axons are totally responsive to 6-OHDA; but no change was seen in VIP-immunoreactive axons, suggesting some demarcation of cutaneous adrenergic and cholinergic sympathetic fibers [25].
• Surprisingly, the growth response of sympathetic fibers into the cerebellar white matter of NGF/p75(-/-) mice is enhanced, such that both the density and extent of axon ingrowth are increased, compared with age-matched NGF/p75(+/+) mice [26].
• Immunohistochemistry for substance P, a substance P enzyme immunoassay, and catecholamine histofluorescence indicated that both tachykinin-containing sensory fibers and sympathetic fibers were increased around the airways of CCSP-NGF mice [27].
• Sympathetic fibers were labeled with an antibody raised against tyrosine hydroxylase [28].

Analytical, diagnostic and therapeutic context of Adrenergic Fibers

• Application of clonidine, an alpha(2)-agonist, (0.1 microM) abolished the expression of c-Fos protein in all preparations (n=5), while denervation of the sympathetic fibers in the lumbar colonic and hypogastric nerves in vivo increased the number of c-Fos-positive neurons (n=5) [29].
• Chemical and surgical sympathectomy greatly reduced the neuropeptide Y- and catecholamine-containing fibers in the erectile tissue but had no clear effect on the neuropeptide Y fibers around the paraurethral glands; a tissue that is not innervated by adrenergic fibers [30].
• The accumulation of infused NGF in the trigeminal was assessed using ELISA and sympathetic fibers were localized immunohistochemically with an antibody to tyrosine hydroxylase (TH) [31].
• In contrast, the electrically evoked sweating rate was higher than that evoked chemically (acetylcholine, or ACh; sweating rate 0.31 vs. 0.21 microl/cm2/min, p<0.01), which might be attributed to an increased effectiveness of synchronized discharge in sympathetic fibers upon electrical stimulation [32].

References