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S Korsching

Publications and source records attributed to S Korsching.

28 records · Page 2Linked to original sources
PubMed1985

Levels of nerve growth factor and its mRNA in the central nervous system of the rat correlate with cholinergic innervation.

The levels of nerve growth factor (NGF) and its mRNA in the rat central nervous system were determined by two-site enzyme immunoassay and quantitative Northern blots, respectively. Relatively high NGF levels (0.4-1.4 ng NGF/g wet weight) were found both in the regions innervated by the magnocellular cholinergic neurons of the basal forebrain (hippocampus, olfactory bulb, neocortex) and in the regions containing the cell bodies of these neurons (septum, nucleus of the diagonal band of Broca, nucleus basalis of Meynert). Comparatively low, but significant NGF levels (0.07-0.21 ng NGF/g wet weight) were found in various other brain regions. mRNANGF was found in the hippocampus and cortex but not in the septum. This suggests that magnocellular cholinergic neurons of the basal forebrain are supplied with NGF via retrograde axonal transport from their fields of innervation. These results, taken together with those of previous studies showing that these neurons are responsive to NGF, support the concept that NGF acts as trophic factor for magnocellular cholinergic neurons.

Animals↗
PubMed1985

Treatment with 6-hydroxydopamine and colchicine decreases nerve growth factor levels in sympathetic ganglia and increases them in the corresponding target tissues.

A two-site enzyme immunoassay was used to determine the nerve growth factor (NGF) contents of sympathetic ganglia and their corresponding target tissues in adult rats. The destruction of sympathetic nerve terminals by 6-hydroxydopamine (6-OHDA) and the blockade of axonal transport by colchicine resulted in a rapid increase in the NGF levels of sympathetically innervated organs and a rapid decrease in the sympathetic ganglia. NGF levels in heart atrium, heart ventricle, submandibular gland, and iris increased 2- to 4-fold 12 hr after injection of 6-OHDA, whereas the NGF contents of stellate and superior cervical ganglia dropped to a minimal level of 3 to 4% of control 24 hr after injection. Twelve hours after treatment with colchicine the NGF levels in sympathetically innervated organs increased 2- to 3-fold, whereas the NGF contents of sympathetic ganglia fell to one-third of control values. The half-lives of NGF in the superior cervical and stellate sympathetic ganglia were 4.5 and 4.8 hr, respectively, as determined by the decrease of NGF content after treatment with 6-OHDA. These results indicate that the synthesis of NGF is normally confined to the innervated target organs with no significant contribution of ganglionic cells. This is consistent with the concept that NGF acts as a retrograde messenger between target organs and innervating sympathetic neurons.

Animals↗
PubMed1984

Relationship between levels of nerve growth factor (NGF) and its messenger RNA in sympathetic ganglia and peripheral target tissues.

We have developed a sensitive assay for the quantification of nerve growth factor mRNA (mRNANGF) in various tissues of the mouse using in vitro transcribed RNANGF. Probes of both polarities were used to determine the specificity of the hybridization signals obtained. Comparison of NGF levels with its mRNA revealed that both were correlated with the density of sympathetic innervation. Thus, vas deferens contained high levels of both NGF and mRNANGF, whereas skeletal muscle levels were barely detectable, indicating that in peripheral tissues NGF levels are primarily regulated by the quantity of mRNANGF and not by the rate of processing of NGF precursor to NGF. However, although superior cervical ganglia contained the highest levels of NGF, its mRNA was barely detectable. Thus, the high levels of NGF in sympathetic ganglia result from retrograde axonal transport rather than local synthesis. The quantity of NGF found in the submandibular glands of female animals was three orders of magnitude higher than expected from their mRNA levels. This observation is discussed in the context of the difference between the mechanism of storage and exocytosis of exocrine glands versus the constitutive release from other tissues.

Animals↗
PubMed1984

Regulation of nerve growth factor synthesis and release in organ cultures of rat iris.

We studied the synthesis and release of nerve growth factor (NGF) in cultured rat iris with a two-site enzyme immunoassay by measuring the time course of NGF levels remaining in the iris and relased into the medium up to 72 h. For up to 3 h, the NGF levels in the iris did not change significantly. After that, they increased to a maximal level of 350 +/- 30 pg NGF/iris at 19 h, which is 200 times higher than the in vivo content. Between 20 and 72 h in culture, the NGF level decreased to 130 +/- 10 pg NGF/iris, whereas general protein synthesis did not change during that time period. Maximal rate of NGF production (203 pg NGF/h/iris) was seen between 9 and 12 h in culture. In the medium, NGF levels were first detectable after 6 h. Levels then increased with a time course similar to that seen within the iris, reaching a maximal level of 1,180 +/- 180 pg after 19 h in vitro, and then did not significantly change for up to 48 h. The NGF production of the densely sympathetically innervated dilator was three times higher than that of the predominantly cholinergically innervated sphincter. The NGF production was blocked by inhibitors of messenger RNA synthesis (actinomycin D) and of polyadenylation (9-beta-D-arabinofuranosyladenine) as well as by inhibitors of translation (cycloheximide). Monensin, which interferes with the transport of proteins through the Golgi apparatus, decreased NGF levels to 8-12% of controls in the medium, suggesting that the Golgi apparatus is involved in the intracellular processing of NGF.

Animals↗
PubMed1983

Quantitative demonstration of the retrograde axonal transport of endogenous nerve growth factor.

The level of endogenous nerve growth factor (NGF) in rat sciatic nerve was determined using a highly sensitive two-site enzyme immunoassay. After crushing this nerve NGF accumulated linearly distal to the crush during the first 12 h to reach levels 13-fold higher than in the uncrushed contralateral side. In contrast, proximal to the crush NGF levels approached or were below the detection limit of the assay. The asymmetrical distribution of NGF on the two sides of a crush is direct evidence for the retrograde axonal transport of endogenous NGF.

Animals↗
PubMed1983

Nerve growth factor in sympathetic ganglia and corresponding target organs of the rat: correlation with density of sympathetic innervation.

A two-site enzyme immunoassay is described which does not suffer from artifacts inherent in previous assays and has the necessary high sensitivity to determine the endogenous levels of nerve growth factor (NGF) in the sympathetic nervous system and its target organs. Monoclonal and affinity-purified polyclonal antibodies against mouse NGF (mNGF) were covalently linked to glass beads as the first site and coupled to the enzyme beta-galactosidase as the second site. Detection of the fluorescent beta-galactosidase reaction product permitted the determination of 0.01-0.02 fmol of mNGF per assay. The recovery of mNGF added to homogenates varied between 50% and 100%, depending on the tissue. Rat superior cervical and stellate ganglia were found to contain (mean +/- SEM) 25 +/- 4 and 19 +/- 3 ng of NGF per g wet weight, respectively, and the densely innervated submandibular gland, heart atrium, and iris contained 0.5 +/- 0.1, 1.0 +/- 0.1, and 1.9 +/- 0.3 ng of NGF per g wet weight, respectively. Heart ventricle and skeletal muscle, which are poorly innervated by the sympathetic nervous system, did not contain detectable levels of NGF (less than 0.3 ng/g wet weight). Serum contained less than 0.05 ng of NGF per ml. The correlation between NGF levels and density of innervation is consistent with the concept that the production of NGF in target organs determines their density of innervation by the sympathetic nervous system.

Animals↗
PubMed1982

Internalization of nerve growth factor by pheochromocytoma PC12 cells: absence of transfer to the nucleus.

The intracellular distribution of 125I-labeled nerve growth factor (NGF) in rat pheochromocytoma PC12 cells was studied by quantitative electron microscopic (EM) autoradiography and by subcellular fractionation. PC12 cells were grown as monolayer cultures in medium supplemented with serum in the presence of 125I-NGF. EM autoradiography showed that 125I-NGF was localized at the plasma membrane and cytoplasmic compartments but did not accumulate in the nuclear chromatin or in the nuclear membrane compartment of cells analyzed after 1 hr and 1, 2, and 8 d of incubation with 125I-NGF. 125I-NGF also was not detected in nuclear subcellular fractions prepared from cells grown in serum-supplemented medium either in suspension for 1 d or in monolayer cultures for 1 to 8 d. In contrast, and in confirmation of the results of Yankner and Shooter (Yankner, B. A., and E. M. Shooter (1979) Pro. Natl. Acad. Sci. U. S. A. 76: 1269-1273), about 60% of the cell-bound 125I-NGF was found in the nuclear pellet after cell fractionation if the cells had been kept previously in suspension for 1 d in phosphate-buffered saline supplemented with 0.2% glucose, 0.1% bovine serum albumin, and 125I-NGF. The ultrastructure of PC12 cells grown under such conditions, however, revealed signs of varying degrees of damage. Autoradiography of the nuclear pellet from these cells showed the grains to be located mainly over damaged nuclei or over cell debris between nuclei. It is concluded that NGF, after binding to specific receptors at the plasma membrane, is transferred to membrane-confined cytoplasmic compartments but does not have to be transferred further to the nuclear membrane or to the nuclear chromatin as a prerequisite for its physiological action.

Animals↗
PubMedDate not supplied

Timing and site of nerve growth factor synthesis in developing skin in relation to innervation and expression of the receptor.

We show that nerve growth factor (NGF) synthesis in developing skin begins with sensory innervation and that sensory neurons do not express NGF receptors until their fibres reach their cutaneous targets. Both cutaneous epithelium and mesenchyme synthesize NGF, the concentration of messenger RNA for NGF being higher in the more densely innervated epithelium.

Animals↗