Axonal transport of zinc transporter 3 and zinc containing organelles in the rodent adrenergic system

Colchicine induced intraneuronal free zinc accumulation and dentate granule cell degeneration

Colchicine has been discovered to inhibit many inflammatory processes such as gout, familial Mediterranean fever, pericarditis and Behcet disease. Other than these beneficial anti-inflammatory effects, colchicine blocks microtubule-assisted axonal transport, which results in the selective loss of dentate granule cells of the hippocampus. The mechanism of the colchicine-induced dentate granule cell death and depletion of mossy fiber terminals still remains unclear. In the present study, we hypothesized that colchicine-induced dentate granule cell death may be caused by accumulation of labile intracellular zinc. 10 μg kg(-1) of colchicine was injected into the adult rat hippocampus and then brain sections were evaluated at 1 day or 1 week later. Neuronal cell death was evaluated by H&E staining or Fluoro-Jade B. Zinc accumulation and vesicular zinc were detected by N-(6-methoxy-8-quinolyl)-para-toluene sulfonamide (TSQ) staining. To test whether an extracellular zinc chelator can prevent this process, CaEDTA was injected into the hippocampus over a 5 min period with colchicine. To test whether other microtubule toxins also produce similar effects as colchicine, vincristine was injected into the hippocampus. The present study found that colchicine injection induced intracellular zinc accumulation in the dentate granule cells and depleted vesicular zinc from mossy fiber terminals. Injection of a zinc chelator, CaEDTA, did not block the zinc accumulation and neuronal death. Vincristine also produced intracellular zinc accumulation and neuronal death. These results suggest that colchicine-induced dentate granule cell death is caused by blocking axonal zinc flow and accumulation of intracellular labile zinc.

Expression analysis of zinc transporters in resting and stimulated human peripheral blood mononuclear cells

Intracellular zinc homeostasis is tightly regulated under physiological conditions; however, dysregulation of zinc levels has been reported in various chronic inflammatory and malignant diseases. In this study, we aimed to assess the expression pattern of the 24 currently known zinc transporters in resting and stimulated human peripheral blood mononuclear cells (PBMCs). The cells were isolated from healthy probands and subsequently stimulated with phytohaemagglutinin (PHA) for 3 days. The expression levels of zinc transporters [Zrt/IRT-like protein (ZIP) and cation diffusion facilitator/zinc transporter protein (CDF/ZnT) families] were analyzed by quantitative reverse transcription-polymerase chain reaction. Of the 24 genes encoding for zinc transporters, 19 were found to be ubiquitously expressed in PBMCs. ZIP5 and ZnT10 were not found in all 5 samples, whereas ZIP12, ZnT3 and ZIP2 were expressed in only 1-2 out of 5 PBMC samples. Of note, stimulation by PHA led to an overall downregulation of zinc transporters in the PBMCs of 4 out of the 5 subjects. Notably, the transcript levels of ZIP14 were consistently induced and those of ZIP3 and ZIP4 consistently downregulated in all 5 subjects, whereas the corresponding levels of the remaining 21 genes varied. Data from this study may facilitate a better understanding of the pathophysiological role of deregulated zinc transporters in chronic inflammatory diseases.

Chemical coding of zinc-enriched neurons in the intramural ganglia of the porcine jejunum

Zinc ions in the synaptic vesicles of zinc-enriched neurons (ZEN) seem to have an important role in normal physiological and pathophysiological processes in target organ innervation. The factor directly responsible for the transport of zinc ions into synaptic vesicles is zinc transporter 3 (ZnT3), a member of the divalent cation zinc transporters and an excellent marker of ZEN neurons. As data concerning the existence of ZEN neurons in the small intestine is lacking, this study was designed to disclose the presence and neurochemical coding of such neurons in the porcine jejunum. Cryostat sections (10 mμ thick) of porcine jejunum were processed for routine double- and triple-immunofluorescence labeling for ZnT3 in various combinations with immunolabeling for other neurochemicals including pan-neuronal marker (PGP9.5), substance P (SP), somatostatin (SOM), vasoactive intestinal peptide (VIP), nitric oxide synthase (NOS), leu-enkephalin (LENK), vesicular acetylcholine transporter (VAChT), neuropeptide Y (NPY), galanin (GAL), and calcitonin-gene related peptide (CGRP). Immunohistochemistry revealed that approximately 39%, 49%, and 45% of all PGP9.5- positive neurons in the jejunal myenteric (MP), outer submucous (OSP), and inner submucous (ISP) plexuses, respectively, were simultaneously ZnT3⁺. The majority of ZnT3⁺ neurons in all plexuses were also VAChT-positive. Both VAChT-positive and VAChT-negative ZnT3⁺ neurons co-expressed a variety of active substances with diverse patterns of co-localization depending on the plexus studied. In the MP, the largest populations among both VAChT-positive and VAChT-negative ZnT3⁺ neurons were NOS-positive cells. In the OSP and ISP, substantial subpopulations of ZnT3⁺ neurons were VAChT-positive cells co-expressing SOM and GAL, respectively. The broad-spectrum of active substances that co-localize with the ZnT3⁺ neurons in the porcine jejunum suggests that ZnT3 takes part in the regulation of various processes in the gut, both in normal physiological and during pathophysiological processes.

Neurochemical characterization of zinc transporter 3-like immunoreactive (ZnT3(+)) neurons in the intramural ganglia of the porcine duodenum

The SLC30 family of divalent cation transporters is thought to be involved in the transport of zinc in a variety of cellular pathways. Zinc transporter 3 (ZnT3) is involved in the transport of zinc into synaptic vesicles or intracellular organelles. As the presence of ZnT3 immunoreactive neurons has recently been reported in both the central and peripheral nervous systems of the rat, the present study was aimed at disclosing the presence of a zinc-enriched neuron enteric population in the porcine duodenum to establish a preliminary insight into their neurochemical coding. Double- and triple-immunofluorescence labeling of the porcine duodenum for ZnT3 with the pan-neuronal marker (PGP 9.5), substance P, somatostatin, vasoactive intestinal peptide (VIP), nitric oxide synthase (NOS), leu-enkephalin, vesicular acetylcholine transporter (VAChT), neuropeptide Y, galanin (GAL), and calcitonin gene-related peptide were performed. Immunohistochemistry revealed that approximately 35, 43, and 48 % of all PGP9.5-postive neurons in the myenteric (MP), outer submucous (OSP), and inner submucous (ISP) plexuses, respectively, of the porcine duodenum were simultaneously ZnT3⁺. In the present study, ZnT3⁺ neurons coexpressed a broad spectrum of active substances, but co-localization patterns unique to the plexus were studied. In the ISP, all ZnT3⁺ neurons were VAChT positive, and the largest populations among these cells formed ZnT3⁺/VAChT⁺/GAL⁺ and ZnT3⁺/VAChT⁺/VIP⁺ cells. In the OSP and MP, the numbers of ZnT3⁺/VAChT⁺ neurons were two times smaller, and substantial subpopulations of ZnT3⁺ neurons in both these plexuses formed ZnT3⁺/NOS⁺ cells. The large population of ZnT3⁺ neurons in the porcine duodenum and a broad spectrum of active substances which co-localize with this peptide suggest that ZnT3 takes part in the regulation of various processes in the gut both in normal physiology and during pathological processes.

Sciatic nerve of diabetic rat treated with epoetin delta: effects on C-fibers and blood vessels including pericytes

In diabetes mellitus (DM) reduced motor and sensory properties of peripheral nerves are linked with the dysfunction of neural vasculature. We investigated C-fibers and microvessels of sciatic nerve of normal, DM, and DM + epoetin delta-treated rats. C-fibers immunoreactive for calcitonin gene-related peptide (CGRP), tyrosine hydroxylase (TH), epoetin receptor (EpoR), and common beta receptor subunit of the interleukin 3 receptor (IL-3Rbeta) were present in all rats, whereas in DM and epoetin-treated rats C-fibers also showed neuronal (nNOS) and inducible (iNOS) nitric oxide synthases. The cross-sectional area of CGRP-positive C-fibers was decreased in DM, but it recovered after epoetin treatment. In all conditions, vascular endothelium showed scarce immunolabeling for endothelial nitric oxide synthase (eNOS); the profound immunoreactivity for eNOS, EpoR, and IL-3Rbeta was in pericytes. Some perivascular autonomic nerves were damaged and IL-3Rbeta positive. Findings are discussed in terms of declined sensory conduction velocity in DM, its improvement after epoetin treatment, and the possible vascular contribution to these phenomena.