Acetylcholinesterase activity in the normal and retino-deprived optic tectum of the quail (original) (raw)
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Journal of Neurochemistry, 1976
The distribution of choline acetyltransferase (ChAT) and glutamate decarboxylase (GAD) in different layers of the pigeon optic tectum and in some nuclei of the optic lobe have been investigated. About 40y, of GAD and 2 % : , of ChAT were found in the superficial part of tectum. but negligible activity was found in the stratum opticum. The highest GAD activity was found in layers 3-7 (according to the nomenclature of CAJAL, 1911) with a peak in layer 4. ChAT activity peaked in layers 3. 5. 8 and l O / l l. Its distribution correlated well with the staining pattern of AChE, particularly in the superficial part of the tectum. The distribution of ChAT and GAD did not change significantly 4 weeks after enucleation. ChAT and GAD activities were high in the nucleus isthmi, pars parvocellularis (Ipc). The activity of GAD was also high in the nucleus intercollicularis (KO), the other nuclei showed less activity of both enzymes. THE PIGEON optic tectum is a highly laminated and anatomically well described structure (for review see: REPERANT, 1973) and therefore an attractive model for the study of topographical distributions of neurotransmitters. Recent electrophysiological (BARTH & FELIX, 1974; FErrx rr al., 1975) and biochemical (HENKE rt al., 1976) studies have suggested a number of putative neurotransmitters in the tectum. Among these are ACh and GABA, both reasonably well established neurotransmitters in the CNS of vertebrata (HOSKIN, 1972; FONNUM, 19750). The enzymes ChAT (acetyl CoA-choline 0-acetyl transferase, EC 2.3.1.6) and G A D (L-glutamate I-carboxylyase, EC 4.1.1.15) which govern the levels of ACh and GABA in brain are excellent markers for cholinergic and GABA-ergic structures respectively. The enzymes are better measuring parameters than the transmitters per sr which may redistribute during the preparation of the tissue or be metabolised post mortem (BAXTER. 1970; SILVER. 1974; FONNUM, 1973; FONNUM. 1975~). Furthermore, several groups of investigators have shown that there is a good correlation between GABA level and G A D activity in the nervous system of vertebrata (KURIYAMA rt a/., 1968; KURIYAMA et a/.. 1966; BAXTER. 1970). We have studied the topographical and subcellular distribution of ChAT and G A D in the optic tectum and in some of the nuclei of the optic lobe in an attempt to describe the localization of cholinergic and GABA-ergic structures in this region. The topogra-'Present address: Brain Research Institute, August Forel Ahhrcriations used: ChAT. choline acetyltransferase; Strasse I. 8029 Zurich. Switzerland. GAD. glutamate decarboxylase phical distribution of ChAT activity has been compared with the distribution of AChE visualized with histochemical techniques. MATERIALS AND METHODS Nomenclarurr. The tectal layers are named according to CAJAL (1911). For the tectal nuclei the nomenclature of KARTEN & Horns (1967) was used. Auimuls. Sixteen pigeons (Columha liuia
The Journal of Comparative Neurology, 1991
The activities of choline acetyltransferase and acetylcholinesterase were assayed in submicrogram samples from layers of red-tailed hawk and road runner retina. Both enzyme activities were concentrated in and near the inner plexiform layer. Within the inner plexiform layers of both species, activities of each enzyme were concentrated in two bands, one in each half of this layer. Little choline acetyltransferase activity was found superficial to the middle third of the inner nuclear layer. The distributions of acetylcholinesterase activities corresponded well to those of choline acetyltransferase, except in the outer plexiform layer and the outer margin of the inner nuclear layer of the hawk. These distributions of enzyme activities indicate that populations of amacrine cells in the retinae of these species are cholinergic. In addition to these same cells and presumably cholinoceptive amacrine and ganglion cells, acetylcholinesterase activity in the hawk was associated with a population of horizontal cells that may be unrelated to synaptic cholinergic neurotransmission. Choline acetyltransferase activities associated with amacrine somata and processes were about four times greater in the hawk than in the road runner, suggesting important differences in the density and function of cholinergic elements between species. Possible synaptic relationships in the inner plexiform layer consistent with the interspecies differences in enzyme activities are considered.
Evidence of intrinsic cholinergic circuits in the optic tectum of teleosts
Brain Research, 1980
Choline acetyltransferase (CAT) was assayed in the optic tectum of 4 teleost species with different visual powers. The results showed a close relationship between the enzyme levels in the optic tectum and the development of the visual system. In the more visual species, the trout, CAT activity in the optic tectum was about 30-fold higher than in the catfish, whose visual system is much less developed. Two species with intermediate development of the visual system, the goldfish and the tench, showed intermediate levels of CAT activity. Kainic acid treatment caused a significant decrease of both CAT and acetylcholinesterase (ACHE) in the goldfish optic tectum. Concomitant histological examination showed, among other effects, the disappearance of most neurons belonging to the pyramidal and fusiform type in the stratum fibrosum and griseum superficiale of the tectum. The comparative and experimental data therefore suggest that the relationship between cholinergic mechanisms and the visual function is, to a significant extent, connected with the presence of intrinsic cholinergic circuits in the optic tectum. The relevance of these findings, also in relation to the problem of the identification of the retino-tectal transmitter, is discussed.
The Journal of physiology, 1979
1. The activities of choline acetyltransferase (CAT) and acetylcholinesterase (AChE) were assayed in adult pigeon ciliary ganglia, in the post-synaptic ciliary and choroid nerves, and in ciliary nerve iris terminals isolated from control birds and from animals from which the oculomotor nerve was previously transected. Enzyme activity levels were also measured in the iris terminals after surgical section of the ciliary nerves. From differences in enzyme activity between control and 3-day denervated tissues, the localization of CAT and AChE in pre- and post-synaptic elements of the ganglia and at the iris neuromuscular junctions was estimated. The fate of the preganglionic nerve terminals after denervation was investigated by electron microscopic examination of ganglia after surgical section of the oculomotor nerve.2. The CAT activity in the ganglion was distributed as follows: 60% in presynaptic elements, 31% in cell somas, and 9% in intraganglionic post-synaptic axons; in the iris j...
Vision Research, 1990
The activities of choline acetyltransferase and acetylcholinesterase were assayed in submicrogram samples from layers of red-tailed hawk and road runner retina. Both enzyme activities were concentrated in and near the inner plexiform layer. Within the inner plexiform layers of both species, activities of each enzyme were concentrated in two bands, one in each half of this layer. Little choline acetyltransferase activity was found superficial to the middle third of the inner nuclear layer. The distributions of acetylcholinesterase activities corresponded well to those of choline acetyltransferase, except in the outer plexiform layer and the outer margin of the inner nuclear layer of the hawk. These distributions of enzyme activities indicate that populations of amacrine cells in the retinae of these species are cholinergic. In addition to these same cells and presumably cholinoceptive amacrine and ganglion cells, acetylcholinesterase activity in the hawk was associated with a population of horizontal cells that may be unrelated to synaptic cholinergic neurotransmission. Choline acetyltransferase activities associated with amacrine somata and processes were about four times greater in the hawk than in the road runner, suggesting important differences in the density and function of cholinergic elements between species. Possible synaptic relationships in the inner plexiform layer consistent with the interspecies differences in enzyme activities are considered.
Neuroscience Letters, 1990
Freshly dissected chick neural retina and pigmented epithelium do not apparently contain asymmetric molecular forms (A-forms) of acetylcholinesterase (ACHE). The neighboring choroid, and the ciliary muscles and iris, are however rich in type II A-forms (high salt/EDTA-extractable). Most if not all the asymmetric AChE activity detected in chick 'whole retina" preparations could then be explained in terms of contamination by non-retinal eye tissues. Asymmetric acetylcholinesterase (ACHE: EC 3.1.1.7) molecular forms (A-forms) are known to be mainly associated with extracellular matrix components in peripheral cholinergic synapses, while most globular AChE forms (G-forms) are either intracellular or membrane-bound [11]. Our previous developmental studies on chick retinal AChE [1, 13] have shown the presence of small amounts of asymmetric enzyme in embryonic retinas, increasing to about 8% of the total AChE activity 10 days after hatching. These A-forms are of particular interest since both high ionic strength and chelating agents are necessary for their solubilization (class or type II A-forms [2, 10]). In a recent paper, Martelly and Gautron [8] conclude that retinal A-forms belong exclusively in the pigmented epithelium, routinely taken by us as part of our 'whole retina' samples [3]. This somewhat surprising development has prompted us to extend our search for A-forms to different eye tissues. Our results show the presence of AII-forms in the choroid, ciliary muscles and iris, to the exclusion of both neural retina and pigmented epithelium, which apparently contain only globular forms of the enzyme (G-forms).
Multiple forms of acetylcholinesterase in the ciliary ganglion and iris of the pigeon
Neuroscience, 1977
Different methods of extraction and analysis have been used to investigate the cholinesterase activity of the ciliary ganglion and iris from the adult pigeon. The molecular forms of acetylcholinesterase in the extracts have also been separated either by gel electrophoresis or by sedimentation velocity in a density gradient. The activity and molecular forms in (i) a 'soluble fraction' (the high-speed supematant of an isotonic sucrose homogenate) and (ii) a 'Triton extract' (as above. but with 0.2% Triton X-100 in the homogenate) were examined. The cholinesterase activity in whole homogenates and in the two extracts was characterized by enzyme kinetics and use of different substrates and inhibitors.
Brain Research, 2007
We investigated the effects of neonatal optic nerve transection on cortical acetylcholinesterase (AChE) activity in hooded rats during postnatal development and following behavioral manipulation after weaning. AChE reaction product was quantified on digitized images of histochemically stained sections in layer IV of primary somatic sensory, primary visual and visual association cortex. Rats with optic nerve transection were compared to shamoperated littermates. In all cortical regions of both types of animal, AChE reaction product was increased to peak 2 weeks after birth and decreased thereafter, reaching adult levels at the end of the third postnatal week. During postnatal development, reaction product in primary visual cortex was lower in rats deprived of retinal input than in sham-operated littermates and the area delineated by reaction product was smaller. However, optic nerve transection did not modify the time course of postnatal development or statistically significantly diminish adult levels of AChE activity. Behavioral manipulations after weaning statistically significantly increased enzyme activity in sham-operated rats in all cortical areas examined. Compared with cage rearing, training in a discrimination task with food reward had a greater impact than environmental enrichment. By contrast, in the rats with optic nerve transection enrichment and training resulted in statistically significantly increased AChE activity only in lateral visual association cortex. Our findings provide evidence for intra-and supramodal influences of the neonatal removal of retinal input on neural activity-and use-dependent modifications of cortical AChE activity. The laminar distribution of the AChE reaction product suggests that the observed changes in AChE activity were mainly related to cholinergic basal forebrain afferents. These afferents may facilitate the stabilization of transient connections between the somatic sensory and the visual pathway.
Localization of choline acetyltransferase in the developing and adult retina of Xenopus laevis
Neuroscience Letters, 2002
We report the distribution of choline acetyltransferase (ChAT) activity in the laminae of the rat olfactory tubercle. Within its posterior medial portion, the tubercle contains three parallel histological laminae that can be separated by cutting tangential sections from frozen tissue. ChAT was measured in homogenates of consecutive sections (16 g m ) cut parallel to these laminae. The distribution of ChAT activity, as a function of tubercle depth, showed a broad peak centered at 500 g m from the ventral surface of the brain. Enzyme activity measured at this depth (85 pmol acetylcholine formed/gg proteidh) was 2% times greater than that measured in the outermost, plexiform, layer. Stereotaxic injections of kainic acid (1 pg in 1 pl) made directly into the tubercle were used to eliminate intrinsic neurons. Three days after injection, histological examination revealed the almost total absence of neuronal cell bodies and the proliferation of glial cells. The greatest decreases in ChAT activity (50%) were seen at depths of 300-600 p m whereas no loss of activity occurred in the plexiform layer. Key Words: Choline acetyltransferase-Olfactory tubercle-Laminar localization-Limbic cortex. Gordon C. R. and Krieger N. R. Localization of choline acetyltransferase in laminae of the rat olfactory tubercle. J. Neurochem. 40, 79-83 (1983).