Cytochemical techniques for zinc and heavy metals localization in nerve cells

Abstract

Zinc is one of the most abundant oligoelements in the living cell. It appears tightly bound to metallothioneins, loosely bound to some metalloproteins and nucleic acids, or even as free ion. Small amounts of zinc ions (in the nanomolar range) regulate a plentitude of enzymatic proteins, receptors, and transcription factors; thus, cells need accurate homeostasis of zinc ions. Some neurons have developed mechanisms to accumulate zinc in specific membrane compartments ("vesicular zinc") which can be revealed using histochemical techniques. This article is a short report on the different direct-indirect experimental approaches for zinc and heavy metal detection in neurons. Substances giving a bright color or emitting fluorescence when in contact with divalent metal ions are currently used to detect them inside cells; their use leads to the so called "direct" methods. The fixation and precipitation of metal ions as insoluble salt precipitates, their maintenance along the histological process, and their demonstration after autometallographic development are essential steps for other methods, the so-called "indirect methods" (Timm and Danscher Neo-Timm methods).

Capture of extracellular zinc ions by astrocytes

“…The neuroblastoma cell line N1E‐115 is a general model widely used for studies of ionic channel behavior in neurons (Clejan et al, 1996; Li et al, 1995; Moolenaar and Spector, 1978; O'Reilly et al, 2002; Roth et al, 2002). These cells are derived from the clone C1300 (Amano et al, 1972) and can be easily differentiated into neurons by simply lowering the level of serum and adding dimetilsulfoxide to the medium (Clejan et al, 1996; Kimhi et al, 1976).…”

Pathogenic implications of distinct patterns of iron and zinc in chronic MS lesions

“…While some magnetic resonance imaging (MRI) sequences have been used to image iron in vivo in MS [1, 3, 26, 39, 75, 76], histochemistry is the gold standard to localize metals in tissue. However, iron histochemistry detects only nonheme iron [38], and histochemistry for zinc has poor sensitivity, specificity and is complex [15, 32]. Each method employs a different chemical reaction, and therefore cannot be used on the same tissue section.…”

Iron, Copper, and Zinc Distribution of the Cerebellum

“…However, Perls' and Turnbull's methods are not able to detect heme iron [14,15], copper histochemistry lacks sensitivity and specificity [16,17], and zinc histochemistry detects only part of the tissue zinc pool [18,19].…”