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Biomedical subjects

G Guroff

Publications and source records attributed to G Guroff.

At least 91 records · Page 5Linked to original sources
PubMed1981

The receptor-mediated activation of tyrosine hydroxylation in the superior cervical ganglion of the rat.

The addition of carbachol to superior cervical ganglia causes a rapid increase in tyrosine hydroxylation in situ. The increase occurs in ganglia from both newborn and adult animals, and in ganglia from animals pretreated with reserpine. The increase is not due to increased transport of the substrate. The increase is dependent upon the presence of calcium, and is additive to the stimulation produced by dibutyryl cyclic AMP. The stimulation seems specific for tyrosine hydroxylation; dopamine beta-hydroxylation is not increased. Preincubation experiments suggest that the carbachol-induced stimulation is due to a change in the availability of, or the affinity of the enzyme for, reduced pterin cofactor. The stimulation is inhibited by atropine and also by low concentrations of phenoxybenzamine or haloperidol, which suggests that it is caused by an action of carbachol on the interneurons in the ganglia.

Aging↗
PubMed1981

The induction of ornithine decarboxylase by nerve growth factor and epidermal growth factor in PC12 cells.

Both nerve growth factor and epidermal growth factor cause an induction of ornithine decarboxylase in the rat pheochromocytoma clone PC12. The induction by nerve growth factor is transcription-dependent and occurs within 4 to 6 h. Antibody studies indicate that nerve growth factor must be present for 2-3 h to obtain full induction. Nerve growth factor is synergistic with either N6, O2-dibutyryl cyclic 3',5'-adenosine monophosphate (dBcAMP) or 3-isobutyl-1-methylxanthine (IBMX) in the induction. The magnitude of ornithine decarboxylase induction is influenced by the density of the culture. Synchronized cell populations show the greatest sensitivity to nerve growth factor just before, or immediately upon, entering S phase. The induction of ornithine decarboxylase by epidermal growth factor appears to be quite similar to that exhibited by nerve growth factor. Epidermal growth factor is active in the range of ng/ml. The time course of the induction is the same, as is the need for the peptide to remain in contact with the cells for several hours. Putrescine inhibits the induction and dBcAMP and IMBX accentuate it. Cells appear to be sensitive to epidermal growth factor also near the G1/S border. In spite of the marked similarities in these inductions, a maximal level of nerve growth factor plus a maximal level of epidermal growth factor yields greater induction than either alone, indicating the inductions occur by somewhat different mechanisms.

Adrenal Gland Neoplasms↗
PubMed1981

The action of adenosine analogs on PC12 cells.

PC12 cells, a nerve growth factor-responsive clone of rat pheochromocytoma, contain a membrane-bound adenylate cyclase, which can be activated by adenosine analogs. The characteristics of the cyclase response indicate the presence of stimulatory adenosine receptors. Adenosine analogs also produce a marked increase in the ornithine decarboxylase levels of the cells, and the characteristics of this response suggest that it is linked to the adenylate cyclase-stimulatory adenosine receptors. The ornithine decarboxylase response elicited by 5'-N-ethylcarboxamideadenosine (NECA), a potent stimulatory adenosine analog, is synergistic with that produced by nerve growth factor. Differentiation of the cells with nerve growth factor, however, does not substantially alter either the response of cyclase to the adenosine analog or the magnitude of the adenosine-evoked ornithine decarboxylase response. Treatment of the cells with NECA produces an increase in the phosphorylation of a specific non-histone nuclear protein. While causing little or no morphological alteration by itself, NECA is synergistic with nerve growth factor in producing neurite outgrowth in PC12 cells. NECA does not cause an induction of acetylcholinesterase in the cells. NECA does not cause an induction of acetylcholinesterase in the cells, nor does it appear to affect the induction of this enzyme by nerve growth factor.

Acetylcholinesterase↗
PubMed1981

Increased levels of neuron-specific enolase in PC12 pheochromocytoma cells as a result of nerve growth factor treatment.

Treatment of PC12 pheochromocytoma cells with nerve growth factor (NGF) resulted in increased levels of neuron-specific enolase (NSE). Neither insulin, growth hormone, cytochrome c, nor sodium butyrate increased NSE levels. Epidermal growth factor (EGF) did increase NSE levels, although not to the same extent as NGF. As little as 1 ng/ml NGF induced the maximal increase in NSE. As PC12 cells increased in density, the NSE levels increased even in untreated cells.

Adrenal Gland Neoplasms↗
PubMed1980

Increased phosphorylation of specific nuclear proteins in superior cervical ganglia and PC12 cells in response to nerve growth factor.

Treatment of rat superior cervical ganglia in culture with nerve growth factor (NGF) increases the amount of radioactive phosphate incorporated into a nuclear protein band. This band migrates coincidentally with H1 histone on 10% sodium dodecyl sulfate/polyacrylamide gels. The increase in phosphate incorporation is at least 70% and occurs only in tissues known to be responsive to NGF. It is not produced by treatment with related peptides, but is observed after the addition of dibutyryl cyclic AMP. An increase in phosphorylation can be detected after 1 h, and can be seen with as little as 10 ng/ml of NGF in the medium. Neither actinomycin D nor cycloheximide inhibits the effect. When the nuclei are extracted with 0.2 M H2SO4 and the extract analyzed on acid-urea/polyacrylamide gels, two NGF-responsive proteins can be detected. One protein again migrates with the H1 histone marker; the other migrates more slowly than H1. These two NGF-responsive proteins have molecular weights of approximately 30,000 and are chromatin-bound. They are not soluble in 5% perchloric acid, but can be extracted from the nuclei with 0.35 M NaCl. No increase in the phosphorylation of these proteins was seen in ganglia from 6-hydroxydopamine-treated rats. The phosphorylation of the proteins in both control and NGF-treated ganglia occurs almost exclusively on serine residues. The amino acid compositions of the two nuclear proteins show that they are different from the H1 histone and different from each other. Both nerve growth factor (NGF) and epidermal growth factor (EGF) increase the incorporation of radioactive phosphate into a specific nuclear protein in cultures of PC12, a clone of rat pheochromocytoma. Purified NGF antibody blocks the effect of NGF, but not that of EGF; EGF antiserum neutralizes the effect of EGF, but not that of NGF. Insulin, glucagon, and dexamethasone are without effect. The increase in phosphorylation due to NGF can be detected within 1 h. Dibutyryl cyclic AMP increases the phosphorylation of this protein, but dibutyryl cyclic GMP does not. Neither the uptake nor the overall incorporation of [32P]orthophosphate is altered by NGF, EGF, or dibutyryl cAMP under the present experimental conditions. The nuclear protein exhibiting increased radioactivity is similar in solubility, size, and amino acid composition to one of the NGF-responsive nuclear proteins from sympathetic ganglia.

Adrenal Gland Neoplasms↗
PubMed1980

Induction of ornithine decarboxylase by renin-free nerve growth factor.

Renin-free nerve growth factor causes the induction of ornithine decarboxylase (L-ornithine carboxy-lyase, EC 4.1.1.17) in superior cervical ganglia from neonatal rats but not in the brain of mature rats. Less pure preparations of nerve growth factor induce the enzyme in both brain and ganglia. The induction of ornithine decarboxylase in the central nervous system appears to be due to renin, not to nerve growth factor itself.

Angiotensin II↗
PubMed1979

Growth regulation by nerve growth factor.

Although a great deal of descriptive information has been obtained about the actions of nerve growth factor on its target tissues, its structure, its receptors, and even its biosynthesis, there is no clear understanding, as yet, of the intracellular events mediating its transcriptional involvements. Work in this laboratory over the past five years has uncovered a number of nerve growth factor-initiated intracellular changes in sympathetic neurons and other nerve growth factor-sensitive systems, and has provided a framework into which they might fit. This article is written in an attempt to collect the data in a single communication and to suggest at least one mechanism by which the nerve growth factor may work.

Animals↗
PubMed1978

Nerve growth factor increases activity of ornithine decarboxylase in rat brain.

Intraventricular administration of nanogram quantities of nerve growth factor to adult rats results in a marked increase in the activity of ornithine decarboxylase (L-ornithine carboxy-lyase, EC 4.1.1.17) in the brain. The increase occurs in all major brain regions and the activity is maximal by 7.5 hr after administration. The enzyme response to nerve growth factor increases in magnitude during maturation; the relative increase in ornithine decarboxylase activity in adult animals is much greater than that in young. Neither insulin nor bovine growth hormone was able to increase ornithine decarboxylase activity to the same extent as did nerve growth factor. When brain was separated into neuronal- and glial-enriched fractions, induction of ornithine decarboxylase was found in both, but a greater increase was observed in the glial fraction.

Journal Article↗
PubMed1978

Intraventricular administration of nerve growth factor induces ornithine decarboxylase in peripheral tissues of the rat.

Intraventricular administration of nerve growth factor causes an increase in the activity of ornithine decarboxylase (L-ornithine carboxy-lyase, EC 4.1.1.17) in liver, kidney, and adrenal as well as in brain itself. An increase in the concentration of corticosterone in the blood was also observed. Adrenalectomy, hypophysectomy, or pituitary stalk section inhibits the increase of ornithine decarboxylase activity in the peripheral tissues. Ornithine decarboxylase activity in the brain, however, responds to nerve growth factor in these animals. The data indicate that nerve growth factor causes an acitivation of the hypothalamo-hypophyseal endocrine system.

Adrenal Glands↗