Zur Histochemie des Ammonshorngebietes

Timm, F.

doi:10.1007/bf00342730

Cited by 120 publications

(18 citation statements)

References 4 publications

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“…The specimen was then fixed in alcohol saturated with hydrogen sufide, embedded in paraffin, cut serially 8 ,u thick and stained by hematoxylin-eosin, toluidine blue and sulfide silver methods (13).…”

Section: Methodsmentioning

confidence: 99%

Histochemical Studies on Zinc of the Hippocampal Formation in the Monkey

Otsuka

Kishimoto

Nagita

1976

Acta Histochem. Cytochem

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Section: Methodsmentioning

confidence: 99%

Histochemical Studies on Zinc of the Hippocampal Formation in the Monkey

Otsuka

Kishimoto

Nagita

1976

Acta Histochem. Cytochem

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“…Among all transition metals, zinc ions (Zn 2ϩ ) are particularly abundant in the brain, where they can be detected with the Timm's sulfide-silver staining technique (Timm, 1958). Using this method, large amounts of chelatable zinc have been localized in the cerebral cortex and in the limbic region (Frederickson, 1989).…”

Section: Abstract: Mipscs; Gaba a Receptors; ␤-Alanine; Fast Perfusimentioning

confidence: 99%

Zinc Inhibits Miniature GABAergic Currents by Allosteric Modulation of GABA_AReceptor Gating

2000

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Zinc is abundantly present in the CNS, and after nerve stimulation is thought to be released in sufficient quantity to modulate the synaptic transmission. Although it is known that this divalent cation inhibits the GABAergic synaptic currents, the underlying mechanisms were not fully elucidated. Here we report that zinc reduced the amplitude, slowed the rise time, and accelerated the decay of mIPSCs in cultured hippocampal neurons. The analysis of current responses to rapid GABA applications and model simulations indicated that these effects on mIPSCs are caused by zinc modulation of GABA A receptor gating. In particular, zinc slowed the onset of GABA-evoked currents by decreasing both the binding (k on ) and the transition rate from closed to open state (␤ 2 ). Moreover, slower onset and recovery from desensitization as well as an increased unbinding rate (k off ) were shown to underlie the accelerated deactivation kinetics in the presence of zinc. The nonequilibrium conditions of GABA A receptor activation were found to strongly affect zinc modulation of this receptor. In particular, an extremely fast clearance of synaptic GABA is implicated to be responsible for a stronger zinc effect on mIPSCs than on current responses to exogenous GABA. Finally, the analysis of currents evoked by GABA coapplied with zinc indicated that the interaction between zinc and GABA A receptors was too slow to explain zinc effects in terms of competitive antagonism. In conclusion, our results provide evidence that inhibition of mIPSCs by zinc is attributable to the allosteric modulation of GABA A receptor gating.

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“…X 10 zinc is related with several events which may be of neurochemical significance, such as catecholamine levels, enkephaline receptor binding, and concentration of circulating corticosteroids (4,19,20). Investigation of zinc-containing neurons and nerve pathways has been possible due to the development of appropriate histochemical techniques like the original Timm's technique, proposed in 1958 for the demonstration of heavy metals in brain (25,26) and by the subsequent modifications of this technique, allow- ing the rather specific demonstration of zinc stores in brain sections (6,7,10,13,14). Among the modifications of the original Timm's technique, the neo-Timm method, in which the concentration of Na2S was reduced to 0.1 % and silver lactate was replaced by silver nitrate, is the most selective for the visualization of zinc but not of heavy metals tissue stores (10).…”

Section: Discussionmentioning

confidence: 99%

Quantitative histochemistry of right-left asymmetries in the density of sulfide-silver stainable fibres in the rat cerebral cortex.

Niglio

Caporali

Rícci

et al. 1991

Acta Histochem. Cytochem

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The existence of possible right-left asymmetries in sulfide-silver stainable fibre systems in the rat frontal, parietal and occipital cortices was assessed using the neo-Timm histochemical technique associated with microdensitometry.In the cerebral cortex sulfide-silver stainable fibres are localized in the neuropil of laminae I-III and V. The density of sulfide-silver stainable fibres which is parallel to the density of zinccontaining presynaptic structures, was the highest in the right frontal cortex and the lowest in the right occipital cortex. In the frontal cortex sulfide-silver staining is stronger in the right hemisphere than in the left (P<0.001).In the parietal cortex, values of the density of sulfide-silver stainable fibres did not show significant right-left differences. In the occipital cortex the density of sulfide-silver staining was higher in the left hemisphere than in the right (P<0.001).The functional significance of the above right-left asymmetries in the density of sulfide-silver stainable fibres in the rat cerebral cortex cannot be established on the basis of our findings alone. However, our study indicates the sensitivity of specific histochemical techniques in assessing right-left asymmetries in cerebral cortex microanatomy.The concept of the existence of side differences for certain brain functions (the so-called cerebral dominance) as well as of structural and biochemical asymmetries between right and left brain hemispheres was rapidly accepted in the beginning of the second half of the last century (for a review see 11). It was probably a work of Wigan, published in 1844 (28) which first reported the structural asymmetries between the right and left hemispheres in the human brain. Now we know that the existence of differences between the right and left hemispheres is a characteristic shared by the human species with several other mammalian and non-mammalian species (1,8,11,12,15,22).In the rat brain it has been demonstrated that the neocortex of the right hemisphere is thicker than that of the left hemisphere (8). Moreover, the right hemisphere is larger and heavier than the left one (15), and the cross sectional area of the neocortex is greater for the right than for the left hemisphere (16). Rat brain is a rather useful model for cerebral cortical morphological studies. In fact, different from the human, monkey, cat and dog cerebral cortex, the rat neocortex is rather smooth and shows a clear division between the gray and white matter.Moreover, it is not difficult to obtain uniform cortical samples in different animals by using subcortical landmarks for measurements.In spite of this, the existence of anatomical-functional correlations in rat cerebral cortex asymmetry has not been so far established (16).To contribute to a better knowledge of the topic we analyzed in the present study the existence of rightleft asymmetries in the density of sulfide-silver stainable fibre systems in the rat cerebral cortex. In the rat cerebral cortex sulfide-silver stainable fibres are localized in the ...

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Zur Histochemie des Ammonshorngebietes

Cited by 120 publications

References 4 publications

Histochemical Studies on Zinc of the Hippocampal Formation in the Monkey

Histochemical Studies on Zinc of the Hippocampal Formation in the Monkey

Zinc Inhibits Miniature GABAergic Currents by Allosteric Modulation of GABA_AReceptor Gating

Quantitative histochemistry of right-left asymmetries in the density of sulfide-silver stainable fibres in the rat cerebral cortex.

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Zur Histochemie des Ammonshorngebietes

Cited by 120 publications

References 4 publications

Histochemical Studies on Zinc of the Hippocampal Formation in the Monkey

Histochemical Studies on Zinc of the Hippocampal Formation in the Monkey

Zinc Inhibits Miniature GABAergic Currents by Allosteric Modulation of GABAAReceptor Gating

Quantitative histochemistry of right-left asymmetries in the density of sulfide-silver stainable fibres in the rat cerebral cortex.

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Zinc Inhibits Miniature GABAergic Currents by Allosteric Modulation of GABA_AReceptor Gating