Biomedical subjects

R L Perlman

Publications and source records attributed to R L Perlman.

At least 55 records · Page 3Linked to original sources

PubMed1986

Phorbol 12,13-dibutyrate increases tyrosine hydroxylase activity in the superior cervical ganglion of the rat.

Phorbol 12,13-dibutyrate (PDBu) increased the production of 3,4-dihydroxyphenylalanine (DOPA) in the superior cervical ganglion of the rat. This effect occurred without a detectable lag and persisted for at least 90 min of incubation. The action of PDBu was half-maximal at a concentration of approximately 0.1 microM; at high concentrations, PDBu produced about a twofold increase in DOPA accumulation. PDBu increased DOPA production in decentralized ganglia and in ganglia incubated in a Ca2+-free medium. The action of PDBu was additive with the actions of dimethylphenylpiperazinium, muscarine, and 8-Br-cyclic AMP, all of which also increase DOPA accumulation, and was not inhibited by the cholinergic antagonists hexamethonium (3 mM) and atropine (6 microM). Finally, PDBu did not increase the content of cyclic AMP in the ganglion. Thus, the action of PDBu does not appear to be mediated by the release of neurotransmitters from preganglionic nerve terminals, by the stimulation of cholinergic receptors in the ganglion, or by an increase in ganglionic cyclic AMP. PDBu also increased the incorporation of 32Pi into tyrosine hydroxylase. PDBu activates protein kinase C, which in turn may phosphorylate tyrosine hydroxylase and increase the rate of DOPA synthesis in the ganglion.

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed1986

Comparison of the effects of muscarine and vasopressin on inositol phospholipid metabolism in the superior cervical ganglion of the rat.

Both muscarine and vasopressin have been shown previously to increase the accumulation [3H]inositol phosphates in superior cervical ganglia in which the phospholipids were labeled with [3H] inositol. In this study, we have compared the effects of muscarine and of vasopressin on phospholipid metabolism in the ganglion. The effects of these agents on [3H]inositol phosphate accumulation are additive. The response to muscarine levels off after approximately 10 min, whereas the response to vasopressin increases for at least 30 min. The incorporation of [3H]inositol into phospholipids is enhanced in decentralized ganglia and in ganglia maintained in organ culture compared to freshly isolated ganglia. These treatments appear to potentiate the effect of muscarine on [3H]inositol phosphate accumulation, but do not affect the response of the ganglia to vasopressin. Muscarine and vasopressin also increase the incorporation of [3H]inositol into phospholipids in the ganglion. Autoradiographic techniques were used to localize the inositol-containing phospholipids in the ganglion. Muscarine increases phospholipid labeling primarily in the cell bodies of the principal ganglionic neurons, whereas vasopressin increases phospholipid labeling primarily in the neuropil. These data are consistent with the hypothesis that muscarine and vasopressin stimulate the hydrolysis of different pools of ganglionic phospholipids.

Animals↗

PubMed1985

Production of "ectopic" vasoactive intestinal peptide-like immunoreactivity in normal human chromaffin cell cultures.

Vasoactive intestinal peptide-like immunoreactivity (VIPLI) is not detectable in normal adult human chromaffin cells in vivo, but was demonstrated in cultured chromaffin cells from two normal adults after 22 days in vitro. Cellular content of VIPLI was markedly increased in the presence of nerve growth factor, which also stimulated neurite outgrowth. Catecholamine content decreased in the same cultures, and was not regulated in parallel with VIPLI. The amounts of VIPLI in normal human chromaffin cells in culture are comparable to those previously reported in human pheochromocytoma cell cultures. Theoretical models have attributed production of ectopic peptides by pheochromocytomas and other tumors to "immaturity" of tumor cells. Our findings, however, indicate that neither neoplasia nor cellular immaturity is a prerequisite for ectopic peptide production. Ectopic neuropeptides produced by normal chromaffin cells which undergo neuronal differentiation are of potential clinical importance in patients receiving autologous chromaffin cell transplants for Parkinsons' disease.

Adrenal Medulla↗

PubMed1985

Vasoactive intestinal peptide increases tyrosine hydroxylase activity in normal and neoplastic rat chromaffin cell cultures.

Vasoactive intestinal peptide (VIP) acutely increases tyrosine hydroxylase (TH) activity in cultures of dispersed normal adult rat chromaffin cells and of PC12 rat pheochromocytoma cells. High concentrations of VIP (10 microM) produce about 3-fold increases in TH activity in both cell types. VIP also increases the content of cyclic adenosine 3':5'-monophosphate (cAMP) in PC12 cells. VIP may increase TH activity by promoting the cAMP-dependent phosphorylation of the enzyme. Nerve fibers containing VIP-like immunoreactive material have been reported in the adrenal medulla and in other catecholamine (CA)- storing tissues. This VIPergic innervation may regulate CA synthesis and other cAMP-dependent processes in these tissues.

Adrenal Gland Neoplasms↗

PubMed1985

Immunohistochemical and biochemical detection of serotonin in the guinea pig celiac-superior mesenteric plexus.

Serotonin (5-HT) in the guinea pig celiac-superior mesenteric plexus was quantitatively measured by HPLC and visualized by an immunohistochemical method. Preincubation of the ganglia in a Krebs solution containing L-tryptophan and pargyline markedly elevated the content of 5-HT and K+ solution caused a release of 5-HT into the incubation medium. 5-HT immunoreactivity was localized to dense but unevenly distributed nerve fibers throughout the plexus and to small diameter cells commonly referred to as small intensely fluorescent cells. These findings provide evidence of an extensive network of 5-HT-containing neural elements in the guinea pig prevertebral ganglia.

Animals↗

PubMed1985

Low-Na+ medium increases the activity and the phosphorylation of tyrosine hydroxylase in the superior cervical ganglion of the rat.

Incubation of the rat superior cervical ganglion in Na+-free or low-Na+ medium increased the rate of synthesis of 3,4-dihydroxyphenylalanine (DOPA) in the ganglion fourfold and caused a concomitant stable activation of tyrosine hydroxylase. DOPA synthesis was half-maximal in medium containing about 20 mM Na+. Low-Na+ medium also increased the incorporation of 32Pi into tyrosine hydroxylase; the dependence of tyrosine hydroxylase phosphorylation on the Na+ concentration resembled that of DOPA synthesis. The stimulatory effects of low-Na+ medium on DOPA production and on tyrosine hydroxylase activity in vitro were dependent on extra-cellular Ca2+. The stimulation of DOPA synthesis in low-Na+ medium was inhibited by methoxyverapamil, an inhibitor of Ca2+ uptake, and was partially blocked by tetrodotoxin, but it was not affected by the cholinergic antagonists hexamethonium and atropine. Ionomycin, a calcium ionophore, stimulated DOPA synthesis to about the same extent as low-Na+ medium and also increased the incorporation of 32Pi into tyrosine hydroxylase. 8-Bromo cyclic AMP (1 mM) also stimulated DOPA production in the ganglion, and this stimulation was more than additive with that produced by low-Na+ medium. These data support the hypothesis that low-Na+ medium stimulates DOPA synthesis by raising intracellular Ca2+, which then promotes the phosphorylation of tyrosine hydroxylase.

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed1985

Effects of neuronal activity on inositol phospholipid metabolism in the rat autonomic nervous system.

The effect of nerve stimulation on inositol phospholipid hydrolysis in autonomic tissue was assessed by direct measurement of [3H]inositol phosphate production in ganglia that had been preincubated with [3H]inositol. Within minutes, stimulation of the preganglionic nerve increased the [3H]inositol phosphate content of the superior cervical sympathetic ganglion indicating increased hydrolysis of inositol phospholipids. This effect was blocked in a low Ca2+, high Mg2+ medium. It was also greatly reduced when nicotinic and muscarinic antagonists were present together in normal medium. However, neither the nicotinic antagonist nor the muscarinic antagonist alone appeared to be as effective as both in combination. In other experiments, stimulation of the vagus nerve caused dramatic increases in [3H]inositol phosphate in the nodose ganglion but did not increase [3H]inositol phosphate in the nerve itself. This effect was insensitive to the cholinergic antagonists. Thus, neuronal activity increased inositol phospholipid hydrolysis in a sympathetic ganglion rich in synapses, as well as in a sensory ganglion that contains few synapses. In the sympathetic ganglion, synaptic stimulation activated inositol phospholipid hydrolysis and this was primarily due to cholinergic transmission; both nicotinic and muscarinic pathways appeared to be involved.

Animals↗

PubMed1985

Spontaneous proliferative lesions of the adrenal medulla in aging Long-Evans rats. Comparison to PC12 cells, small granule-containing cells, and human adrenal medullary hyperplasia.

Aging rats of the Long-Evans strain spontaneously develop diffuse and nodular hyperplasia of the adrenal medulla in association with other abnormalities commonly encountered in human multiple endocrine neoplasia syndromes. The cells which comprise the adrenal nodules resemble those in the parent tumor of the rat PC12 pheochromocytoma cell line in that they show varying degrees of spontaneous or nerve growth factor-induced neurite outgrowth in culture and they contain little or no epinephrine. In addition, cells from at least some of the nodules contain immunoreactive neurotensin and neuropeptide-Y, which are also found in PC12 cells. There are a number of striking resemblances between the cells in adrenal nodules and the small granule-containing cells in the normal rodent adrenal. The findings suggest that spontaneous rat adrenal medullary nodules and PC12 cells might be derived from small granule-containing cells, or that cells within the nodules might regain properties of immature chromaffin cells and acquire characteristics of small granule-containing cells and of PC12 cells in the course of neoplastic progression. They further suggest a possible relationship between proliferative capacity and neurotransmitter phenotype in the adult rat adrenal medulla. By virtue of their sparse epinephrine content and their small granules, the cells in adrenal medullary nodules of Long-Evans rats differ from those in adrenal medullary nodules of humans with multiple endocrine neoplasia syndromes.

Acetylcholinesterase↗

PubMed1985

Muscarine stimulates the hydrolysis of inositol-containing phospholipids in the superior cervical ganglion.

Previous studies have shown that muscarine increases the incorporation of 32Pi and [3H]inositol into phosphatidylinositol in the superior cervical ganglion of the rat. Because the first event in agonist-stimulated phospholipid turnover is thought to be the hydrolysis of phosphatidylinositol or of phosphatidylinositol phosphates, we measured the accumulation of [3H]inositol phosphates in ganglia in which these lipids had been labeled by preincubation with [3H]inositol. The production of [3H]inositol phosphates under these conditions presumably reflects the activity of a phospholipase C in the ganglion. Muscarine caused a large increase in the formation of [3H]inositol phosphates. Most of this increase was in the form of [3H]inositol-1-phosphate. The stimulation of [3H]inositol phosphate accumulation by muscarine was not dependent upon the presence of extracellular Ca++. Agents that increase Ca++ influx caused only a small increase in the accumulation of [3H]inositol phosphates. We also measured the formation of [3H]inositol phosphates in extracts of the ganglion. These extracts contained a phospholipase C activity that was stimulated by deoxycholate and that hydrolyzed phosphatidylinositol phosphates more actively than phosphatidylinositol. This phospholipase C activity was Ca++-dependent. We propose that muscarine may activate this phospholipase C in the intact ganglion and that muscarine increases phospholipase C activity by some mechanism other than by increasing the influx of Ca++.

Animals↗

PubMed1984

Myosin and myosin phosphorylation in pheochromocytoma (PC12) cells.

Myosin was isolated from extracts of a clonal cell line of pheochromocytoma (PC12) cells by ammonium sulfate fractionation and gel filtration. This myosin consisted of heavy chains and two light chains (20 and 17 kDa). The 20 kDa light chain could be phosphorylated by a protein kinase which was also present in the extracts and which eluted after myosin from the gel filtration column. Myosin phosphorylation was partly inhibited by EGTA and by the calmodulin-inhibiting drug trifluoperazine. The Mg2+-ATPase of phosphorylated myosin, but not of unphosphorylated myosin, was activated by skeletal muscle actin. Ca2+ did not affect the Mg2+-ATPase activity of either myosin preparation at low ionic strength. The phosphorylation of myosin may activate a contractile mechanism controlling the Ca2+-dependent secretion of norepinephrine from the cells.

Actins↗

PubMed1984

Phosphorylation of tyrosine hydroxylase in the superior cervical ganglion.

We studied the phosphorylation of tyrosine hydroxylase in the superior cervical ganglion of the rat. Ganglia were preincubated with [32P]Pi and were then incubated in non-radioactive medium containing a variety of agents that are known to activate tyrosine hydroxylase in this tissue. Tyrosine hydroxylase was isolated from homogenates of the ganglia by immunoprecipitation followed by polyacrylamide gel electrophoresis. 32P-labelled tyrosine hydroxylase was visualized by radioautography, and the incorporation of 32P into the enzyme was quantitated by densitometry of the autoradiograms. Veratridine produced a concentration-dependent increase in the incorporation of 32P into tyrosine hydroxylase, with 50 microM veratridine producing a 5-fold increase in 32P incorporation. The nicotinic agonist, dimethylphenylpiperazinium (100 microM), caused a 7-fold increase in the phosphorylation of tyrosine hydroxylase. The effect of dimethylphenylpiperazinium was maximal within 1 min and decreased upon continued exposure of the ganglia to this agent. The actions of dimethylphenylpiperazinium and of veratridine were dependent on extracellular Ca2+. Muscarine, 8-Br-cAMP, forskolin, vasoactive intestinal peptide, isoproterenol, deoxycholate and phospholipase C also stimulated the incorporation of 32P into tyrosine hydroxylase. These data support the hypothesis that phosphorylation plays a role in activation of tyrosine hydroxylase produced by all of these agents.

Animals↗

PubMed1984

Excretion of catecholamines and their metabolites in transplantable rat phaeochromocytoma.

The urinary excretion pattern of catecholamines and their metabolites was studied in rats bearing a subcutaneous transplantable phaeochromocytoma. Compared with normal rats, tumour-bearing animals showed a markedly raised excretion of dopamine, noradrenaline and adrenaline, together with certain of their major acidic and alcoholic metabolites. No evidence of increased octopamine production could be obtained. There was a significant correlation between the output of dopamine and its metabolites, allowing accurate assessment of dopamine turnover rates which were comparable with those observed in human phaeochromocytoma. Tumour development, as determined by tumour weight, also correlated significantly with urinary excretion of noradrenaline and dopamine. Rat phaeochromocytoma appears to be a useful model for the human tumour.

3-Methoxy-4-hydroxyphenylethanol↗

PubMed1984

Electrical stimulation increases phosphorylation of tyrosine hydroxylase in superior cervical ganglion of rat.

Electrical stimulation of the superior cervical ganglion of the rat increased the phosphorylation of tyrosine hydroxylase (tyrosine 3-monooxygenase, EC 1.14.16.2) in this tissue. Ganglia were incubated with [32P]Pi for 90 min and were then electrically stimulated via the preganglionic nerve. Tyrosine hydroxylase was isolated from homogenates of the ganglia by immunoprecipitation followed by polyacrylamide gel electrophoresis. 32P-labeled tyrosine hydroxylase was visualized by radioautography, and the incorporation of 32P into the enzyme was quantitated by densitometry of the radioautograms. Stimulation of ganglia at 20 Hz for 5 min increased the incorporation of 32P into tyrosine hydroxylase to a level 5-fold that found in unstimulated control ganglia. The increase in phosphorylation of tyrosine hydroxylase was dependent on the duration and frequency of stimulation. Preganglionic stimulation did not increase the phosphorylation of tyrosine hydroxylase in a medium that contained low Ca2+ and high Mg2+. Increases in phosphorylation were reversible; within 30 min after the cessation of stimulation, the incorporation of 32P into tyrosine hydroxylase decreased to the level found in unstimulated ganglia. The nicotinic antagonist hexamethonium reduced the increase in 32P incorporation into tyrosine hydroxylase by about 50%, while the muscarinic antagonist atropine had no effect. Thus, preganglionic stimulation appeared to increase the phosphorylation of tyrosine hydroxylase in part by a nicotinic mechanism and in part by a noncholinergic mechanism. Antidromic stimulation of ganglia also increased the phosphorylation of tyrosine hydroxylase. Two-dimensional gel electrophoresis revealed that electrical stimulation also increased the incorporation of 32P into at least six other phosphoproteins in the ganglion.

Animals↗

PubMed1984

Activation of tyrosine hydroxylase in the superior cervical ganglion by nicotinic and muscarinic agonists.

Both dimethylphenylpiperazinium (DMPP), a nicotinic agonist, and bethanechol, a muscarinic agonist, increase 3,4-dihydroxyphenylalanine (DOPA) synthesis in the superior cervical ganglion of the rat. DMPP causes approximately a fivefold increase in DOPA accumulation in intact ganglia whereas bethanechol causes about a two-fold increase in DOPA accumulation. These effects are additive with each other and with the increase in DOPA accumulation produced by 8-bromo cyclic AMP. The action of DMPP is dependent on extracellular Ca2+ while the actions of bethanechol and 8-bromo cyclic AMP are not dependent on extracellular Ca2+. Cholinergic agonists and cyclic nucleotides produce a stable activation of tyrosine hydroxylase (TH) in the ganglion. The activation of TH by nicotinic and muscarinic agonists can be detected after 5 min of incubation of the ganglia with these agents. The nicotinic response disappears after 30 min of incubation, whereas the muscarinic response persists for at least 30 min. The Ca2+ dependence of the TH activation produced by these agents is similar to the Ca2+ dependence of their effects on DOPA accumulation in intact ganglia. These data are consistent with the hypothesis that nicotinic agonists, muscarinic agonists, and cyclic AMP analogues increase TH activity by three distinct mechanisms. The activation of TH presumably underlies the increase in DOPA synthesis produced by these agents.

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed1984

Stimulation of DOPA synthesis in the superior cervical ganglion by veratridine.

We have investigated the effect of veratridine on DOPA (3,4-dihydroxyphenylalanine) accumulation by the superior cervical ganglion of the rat. Incubation of the ganglion with veratridine (50 microM) causes a 10-fold increase in the rate of DOPA accumulation. Veratridine-stimulated DOPA accumulation is blocked by tetrodotoxin, but not by cholinergic or adrenergic antagonists or by decentralization of the ganglion. The cyclic nucleotide 8-bromo cyclic GMP does not increase DOPA accumulation, and 8-bromo cyclic AMP causes only a 2-fold increase in DOPA accumulation, which is additive with the effect of veratridine. Thus, the action of veratridine appears to be independent of these cyclic nucleotides. The effect of veratridine on DOPA accumulation is probably due to a stable modification of tyrosine hydroxylase, since an increase in tyrosine hydroxylase activity can be measured in cell-free extracts of veratridine-treated ganglia. Both the increase in DOPA accumulation and the stable activation of tyrosine hydroxylase are dependent upon extracellular Ca2+. The activation of tyrosine hydroxylase by veratridine may be mediated by the depolarization of, and the subsequent entry of Ca2+ into, ganglionic neurons.

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed1984

Muscarine increases tyrosine 3-monooxygenase activity and phospholipid metabolism in the superior cervical ganglion of the rat.

Muscarinic agonists cause a stable activation of tyrosine 3-monooxygenase in the superior cervical ganglion and increase the incorporation of 32Pi into phospholipids in the ganglion. We have studied the relationship between muscarine-stimulated phospholipid turnover and the muscarine-induced activation of tyrosine 3-monooxygenase. Both effects of muscarine are apparent within 2 min of incubation, and both are essentially independent of extracellular Ca++. All concentrations of muscarine that increase dopa synthesis also stimulate phospholipid turnover. Bethanechol is less efficacious than muscarine in producing both of these effects. Lithium, which disrupts phospholipid metabolism, inhibits the muscarine-stimulated accumulation of dopa. Other agents which affect phospholipid metabolism, including phospholipase C and deoxycholate, also increase the synthesis of dopa in the ganglion. These data support the hypothesis that changes in phospholipid metabolism mediate the activation of tyrosine 3-monooxygenase by muscarinic agonists.

Animals↗

PubMed1984

Production of "ectopic" vasoactive intestinal peptide-like and neurotensin-like immunoreactivity in human pheochromocytoma cell cultures.

Neoplastic chromaffin cells from human pheochromocytomas can exhibit extensive spontaneous and nerve growth factor (NGF)-induced outgrowth of neurite-like processes in vitro, despite the absence of such processes in vivo. To determine whether acquisition of neuron-like features by human pheochromocytoma cells in culture is accompanied by functional alterations, process outgrowth, vasoactive intestinal peptide-like immunoreactivity ( VIPLI ), neurotensin-like immunoreactivity (NTLI), and catecholamine content were studied in freshly dissociated cells and in 21-day-old cultures from six human pheochromocytomas. All of the cultures produced VIPLI and exhibited spontaneous process outgrowth. NGF stimulated process outgrowth and enhanced production of VIPLI . Dexamethasone inhibited process outgrowth and tended to decrease production of VIPLI . NTLI was detected in cells from only one of the tumors, and its production appeared to be regulated comparably to that of VIPLI . Catecholamine content decreased markedly in all of the cultures and was not regulated in parallel with either VIPLI or NTLI. The findings suggest that human pheochromocytoma cultures may help to elucidate cellular and molecular mechanisms regulating ectopic and normal VIP production.

Adrenal Gland Neoplasms↗

PubMed1983

Both nicotinic and muscarinic receptors mediate catecholamine secretion by isolated guinea-pig chromaffin cells.

We have studied the roles of nicotinic and muscarinic receptors in the acetylcholine-evoked secretion of catecholamine from guinea-pig chromaffin cells. Isolated guinea-pig chromaffin cells secrete catecholamine in response to acetylcholine, nicotine, and a variety of muscarinic agonists. Optimal concentrations of acetylcholine (50-200 microM) induce the release of 10-25% of the catecholamine content of the cells in 10 min. Maximal secretion evoked by nicotine or by muscarinic agonists is 5-12% of the catecholamine content of the cells. Secretion evoked by optimal concentrations of nicotine (50 microM) and muscarine (200 microM) are additive, and together these agonists cause catecholamine release equivalent to that produced by optimal concentrations of acetylcholine. Atropine causes a biphasic inhibition of acetylcholine-induced catecholamine secretion; low concentrations of atropine (0.02-0.01 microM) inhibit by 35-45% the catecholamine secretion evoked by 100 microM acetylcholine. Increasing the atropine concentration from 0.1 to 5 microM causes no further decrease in acetylcholine-evoked release, but at concentrations above 5 microM, a second distinct phase of inhibition appears. At 100 microM, atropine reduces acetylcholine-evoked secretion by 85%. At 0.1 microM, atropine significantly inhibits secretion induced by muscarinic, but not nicotinic, agonists. Tubocurarine (50 microM) does not block muscarinic stimulation of release, but inhibits acetylcholine- and nicotine-evoked release by 70 and 80%, respectively. Our experiments indicate that nicotinic and muscarinic stimulation represent distinct mechanisms for the activation of catecholamine release from guinea-pig chromaffin cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗