Search PubMed⌕ Search

Biomedical subjects

E Giacobini

Publications and source records attributed to E Giacobini.

At least 109 records · Page 6Linked to original sources
PubMed1983

Acetylation of polyamines in mouse brain: subcellular and regional distribution.

The acetylation of putrescine, cadaverine, spermidine, and spermine was examined in different subcellular fractions and regions of the mouse brain. Acetylation activity was confined to nuclear and microsomal fractions, which can acetylate all of these compounds. These fractions catalyze the formation of N8 but not N1-acetylspermidine. For the nuclear fraction the Km for putrescine was 3.5 mM; for cadaverine, 4.0 mM; for spermidine, 1.0 mM; and for spermine, 2.5 mM. The Vmax obtained were (pmol/mg protein/10 min): putrescine, 424; cadaverine, 705; spermidine, 239; and spermine, 467. The acetylation of spermidine was highest in the olfactory bulb and cerebellum. Putrescine and cadaverine acetylation were high in these areas, as well as in the midbrain. Spermine acetylation was rather uniform in all areas examined, except in the brain stem (pons-medulla) where enzyme activity was very low.

Acetylation↗
PubMed1983

Metabolism of cadaverine and pipecolic acid in brain and other organs of the mouse.

Cadaverine and pipecolic acid metabolism was investigated in vitro in several organs of the mouse by measuring 14CO2 formation from labeled precursors. The liver showed the highest formation of 14CO2 from [1,5-14C]-cadaverine, whereas brain demonstrated a much lower formation. Anaerobiosis or inhibition of monoamineoxidase (MAO) activity significantly reduced 14CO2 formation in every organ, but inhibition of diamine oxidase (DAO) activity had no effect in brain and kidney. Piperidine was formed from cadaverine in vitro only in the large intestine and its content. This formation is probably of bacterial origin. Under a variety of experimental conditions we were unable to demonstrate any formation of piperidine in brain from cadaverine. Biosynthesis in vitro of [3H]-piperidine from D,L-[3H]-pipecolic acid was very low in brain and kidney. With the exception of brain and kidney, no other organs showed any formation of [3H]-piperidine. Neither MAO nor DAO inhibition influenced [3H]-piperidine formation in the large intestine with its content. Following 1 hr incubation at 37 degrees C under aerobic conditions, the levels of [14C]-pipecolic acid and [3H]-piperidine recovered from mouse brain homogenate did not indicate any significant degradation of these two substances. Our results suggest that under in vitro conditions, cadaverine is not a precursor of piperidine in brain, liver, heart, and kidney and that only very low levels of piperidine can be formed from pipecolic acid in brain. Outside the brain, formation of piperidine from pipecolic acid is detectable only in kidney and in the content of the large intestine. The latter is probably of bacterial origin. Our results do not support previous findings from other authors on an endogenous origin of piperidine in brain from cadaverine and pipecolic acid, and they suggest that a) cadaverine is not a precursor of piperidine in brain, b) the conversion of pipecolic acid into piperidine in the brain does not constitute a major metabolic pathway, and c) the main source of piperidine in the CNS may be of nonneural origin.

Animals↗
PubMed1983

Allylglycine affects acetylation of putrescine and spermidine in mouse brain.

Administration of allylglycine to mice (.8 mmole/kg, i.p.) results in a depletion of GABA levels, and it is accompanied by a decrease in SAM-DC activity and spermidine and spermine levels (Pajunen et al., 1979). Here we describe a biphasic effect on the acetylation of putrescine and spermidine in mouse brain homogenate. There appears to be an inverse correlation between the initial decrease in spermidine levels at 2 hours and the increase in the acetylation of spermidine. This is suggestive of a conversion of spermidine, probably through N1-acetylspermidine to putrescine. The peak of putrescine acetylation observed by us at 4 hours may also reflect a conversion of putrescine, via acetylputrescine to GABA. The interconversion hypothesis is supported by the fact that putrescine levels remain essentially stable in spite of a significant depletion of spermidine and spermine. In addition, there is a decrease in putrescine and spermidine acetylation at 8 hours, which coincides with the increase in ODC activity and the increase towards control levels of GAD activity (Pajunen et al., 1979). Such inverse correlations suggest a mechanism for replenishment of polyamines once GAD activity returns to control levels.

Acetylation↗
PubMed1983

Increased uptake of [3H]choline by rat superior cervical ganglion: an effect of dexamethasone.

The high affinity uptake of [3H]choline by the superior cervical ganglion, isolated from the rat, was found to be increased by dexamethasone. Maximal increase (60-65% above control values) occurred at the steroid concentration of 5 X 10(-5) M. Other glucocorticoids (triamcinolone, corticosterone and hydrocortisone) were without an effect on the [3H]choline uptake. Following administration of dexamethasone (25 mg/kg, i.p.), there was a marked increase in the level of choline in the ganglion. The increase was 3-fold at 1 hr and 10-fold at 6 hr, and by 24 hr the choline levels still remained higher in the steroid-treated animals than in the controls. Levels of acetylcholine in the ganglion were also increased, beginning at 1 hr after the injection of steroid. The increase was 85% by 3 hr and 60% by 6 hr. Triamcinolone, a glucocorticoid that was without an effect on [3H]choline uptake in vitro, was also ineffective in altering the levels of choline and acetylcholine in vivo. It seems probable that the increase of choline uptake in the ganglion induced by dexamethasone may, at least in part, occur in the preganglionic cholinergic terminals, leading to increased synthesis of acetylcholine. Such an effect of dexamethasone provides another case of a selective steroid acting directly on nerve terminals by altering a transport mechanism.

Acetylcholine↗
PubMed1983

Accumulation and metabolism of pipecolic acid in the developing brain of the mouse.

In newborn mice, following i.p. injections of D,L-[3H]PA (pipecolic acid, 28 micrograms/kg), accumulation of radioactivity continues to increase up to 24 h. In adults, radioactivity peaks at 5 min and remains approximately constant up to 5 h, and then declines slowly to 24 h. Fifteen-day-old mice follow the newborn pattern, while 30-day-old mice show the same trend as the adult. Radioactivity in plasma shows essentially the same pattern of accumulation in adult and newborn animals with some quantitative differences. Secretion of radioactivity in the urine is significantly higher in the adult than in the newborn during the interval between 10 min and 5 h. Accumulation of radioactivity at 24 h in the newborn brain shows a preferential localization to the olfactory bulb, the anterior telencephalon and the diencephalon. Two hours after the i.p. injection, approximately 70% of the radioactivity recovered in brain is due to PA. This percentage increases to 75% and 87% at 5 and 24 h respectively. Alpha-aminoadipic acid (alpha-Aaa) a major metabolite of PA was identified in brain extracts at 5 h. The maximal formation of alpha-Aaa in relation to PA occurs approximately at 5 h. No other brain metabolites of PA could be identified with this chromatographic system. The present results show that access of PA to the brain is easier in the newborn mouse than in the adult. In addition, our results demonstrate, for the first time, the presence of PA metabolism in the newborn mouse.

2-Aminoadipic Acid↗
PubMed1982

Accumulation, elimination, release and metabolism of pipecolic acid in the mouse brain following intraventricular injection.

Following i.c.v. (intracerebral ventricular) injections of D,L-[3H]pipecolic acid (PA), it is reabsorbed from the ventricles and redistributed to various brain regions. The highest accumulation is found in three brain regions ipsilateral to the injection site, hippocampus, neocortex, striatum, and in the diencephalon. Following preloading in vivo, the radioactivity is released from hippocampus slices in the perfusion medium after depolarization induced by high K+. During perfusion with a Ca++ free medium containing EGTA, a significant reduction of release is observed. The radioactivity of D,L-[3H]PA in the brain shows a more rapid phase of decrease from 0 to 2 hours and a slower phase from 2 to 5 hours. At 5 hours, only 28% radioactivity, represented mainly by PA, is left in the brain. Kidney secretion represents the major route of elimination of the injected PA. The presence of alpha-aminoadipic acid both in brain and urine was observed. Probenecid (200 mg/kg) significantly increases the accumulation of i.c.v. injected D,L-[3H]PA in brain and kidney. The presence of a regional accumulation of PA in certain brain regions, its metabolism in brain, its enhanced retention following probenecid administration and its Ca++ dependent release following high K+ stimulation, all constitute indirect evidence for a neuronal localization of this brain endogenous aminoacid.

Animals↗
PubMed1982

Synaptogenesis in chick paravertebral sympathetic ganglia: a morphometric analysis.

Synaptogenesis was studied in lumbar sympathetic ganglia of chicken by light and electron microscopic morphometric methods. At 10 days in ovo, fewer than 1% of the adult number of synapses are present. The total numbers of synapses and of synaptic vesicles per ganglion increase progressively with age; however, the majority of both are formed after 30 days after hatching. The average number of synaptic vesicles per synapse increases several fold after hatching. The numbers of synapses and of synaptic vesicles per ganglion increase roughly in concert with biochemical markers of presynaptic development (activity of choline acetyltransferase and levels of acetylcholine) as well as postsynaptic development (tyrosine hydroxylase; based on biochemical data reported elsewhere). The amount of acetylcholine and activity of choline acetyltransferase per synaptic vesicle at 10 days in ovo are 8 and 27 times the corresponding adult values. By 1 day after hatching, these ratios have fallen to near adult levels. These data are consistent with the early presence of cholinergic neuroblasts, as suggested by others, and suggest further that such cholinergic neuroblasts are eliminated, or their cholinergic properties suppressed, before hatching.

Animals↗
PubMed1981

3H-thymidine long survival autoradiography as a method for dating the time of neuronal origin in the chick embryo: the locus coeruleus and cerebellar Purkinje cells.

Contrary to previous assumptions, we have found that a single dose of 3H-thymidine (25 muCi), injected into the yolk sac of White Leghorn chick eggs on 2 days of incubation (d.i.) only remains available for DNA-synthesizing (proliferating) cells for 48 hours following the time of injection. This finding now makes it possible to date the time of neuronal origin in the avian embryo using a single injection of isotope and a long survival time (30 days posthatch) as in mammalian studies where 3H-thymidine is only available as a short "pulse." Using this method, we have determined that neurons in the chick locus coeruleus (LC) cease proliferation on 2-6 d.i. with a peak of neuronal genesis on 3-5 d.i. In addition, neuronal genesis is not homogeneous throughout the LC cell population, but occurs in a predominantly caudorostral gradient. Conversely, the cerebellar Purkinje cells cease division on 3-8 d.i. with a peak of heavy labeling on 4-6 d.i., 1 day later than that observed in the LC.

Animals↗
PubMed1981

Development and aging of noradrenergic cell bodies and axon terminals in the chicken.

Tyrosine hydroxylase activity was measured in the region of locus coeruleus, cerebellum, cervical spinal cord, lumbar sympathetic ganglia, and iris throughout most of the life span of the chicken (8 days of incubation to 5 years) to compare developmental trends in tyrosine hydroxylase activity in noradrenergic cell bodies and in axon terminals in both the central and peripheral nervous system. Fluorescence histochemistry and retrograde transport of horseradish peroxidase were used to characterize further the coeruleo-cerebellar projections. Tyrosine hydroxylase activity was detected in the cerebellum as early as 8 days of incubation, which is the earliest stage so far reported. The greatest increase in total tyrosine hydroxylase activity in the region of the locus coeruleus and cerebellum occurred during the embryonic period. There was a more pronounced increase in the cerebellum than in the locus coeruleus region. This is in contrast to the cervical spinal cord where tyrosine hydroxylase activity increased at approximately the same rate during the embryonic and post-hatching periods. Moreover, the cerebellum and cervical spinal cord, two locus coeruleus target sites, displayed different trends in tyrosine hydroxylase activity throughout development and aging. In both structures examined in the peripheral nervous system, the greatest increase in total tyrosine hydroxylase activity occurred during the post-hatching period, with a greater rise in the cell bodies of the lumbar sympathetic ganglia than in the noradrenergic terminals of the iris. In both the central and peripheral nervous system, total tyrosine hydroxylase activity continued to increase in noradrenergic terminals long after hatching reaching the highest levels at 7 months when the chicken is considered fully mature. During aging, 16 months to 5 years, there was a greater decrease in total tyrosine hydroxylase activity in the terminals of noradrenergic neurons than in the cell bodies in both the central and peripheral nervous system, a phenomenon that was more marked in the peripheral nervous system than in the brain.

Aging↗
PubMed1981

Comparison of synaptosomal and glial uptake of pipecolic acid and GABA in rat brain.

The active uptake of [3H]pipecolic acid increased with incubation time and its uptake at 3 min was half of that at 20 min. On the other hand, a ratio (pellet/medium) of [3H]pipecolic acid uptake into glial cell-enriched fractions, was much less (0.4 - 0.6) than that of [14C]GABA (25.8 - 74.1). GABA, 10(-4) M, and pipecolic acid, 10(-4) M, produced a significant inhibitor of [3H]pipecolic acid uptake into P2 fractions. Pipecolic acid, 10(-4) M, significantly reduced the synaptosomal and glial uptake of [14C]GABA. GABA, 10(-4) M, affected neither spontaneous nor high K+-induced release of [3H]pipecolic acid from brain slices. It is suggested that pipecolic acid is involved in either synaptic transmission or in its modulation at GABA synapses in the central nervous system.

Animals↗
PubMed1981

Brain uptake of pipecolic acid, amino acids, amines following intracarotid injection in the mouse.

The uptake of pipecolic acid by the mouse brain was compared to that of several amino acids and amines, following an injection of a double-labeled mixture into the carotid artery. In general, BUI (brain uptake index) values were lower in the mouse than those previously reported in the rat. The only exception was proline. Lysine, a precursor of pipecolic acid biosynthesis in brain, showed a higher BUI than pipecolic acid. The BUI of D,L-[3H]pipecolic acid was found to be 3.39 (at 0.114 mM). This was saturable between a concentration of 0.114 and 3.44 mM. Kinetic analysis suggests the presence of two kinds of transport systems. Substances structurally related to pipecolic acid, such as nipecotic acid, isonipecotic acid, L-proline, and piperidine show a significant inhibitory effect. Amont the amino acids tested, only GABA showed an inhibitory effect. Data are reported which, when considered with other findings (5), present evidence that pipecolic acid is (1) synthesized both in vitro and in vivo in the mouse brain, (2) actively transported in vivo into the brain, and (3) taken up in vitro by synaptosomal preparations.

Amines↗
PubMed1981

Development and aging of cholinergic synapses. V. Changes in nicotinic cholinergic receptor binding in ciliary ganglia and irises of the chicken.

In order to study possible age-dependent changes in the number of cholinergic binding sites, we have examined alpha-bungarotoxin (ABTX) binding in the ciliary ganglion and iris of the chicken from 3 months after hatching (a.h.) to 5 years of age and have compared it to acetylcholinesterase (AChE) activity and acetylcholine (AChE) levels. In ciliary ganglia the amount of ABTX binding per ganglion increases 16-fold between 3 and 7 months, after which it returns almost to the 3-month level, at 1.3 years. It then remains virtually unchanged to 5 years. A similar pattern is observed in the amount of binding per protein. ACh levels and AChE activity show a different pattern than ABTX binding. In the iris the amount of ABTX binding remains constant between 3 months and 1.3 years and then it increases 1.6-fold up to 3 years. This period is followed by a decrease to 5 years. The amount of ABTX binding per protein which has increased continuously in the iris from the period following hatching up to 7 months, decreases continuously from 7 months to 5 years. In the iris, both ACh levels and AChE activity per protein follow a pattern which is similar to ABTX binding, decreasing from 3 months to 2 years and then remaining relatvely unvaried between 2 and 6-7 years. Our results suggest that a decrease in receptor number begins during early adulthood in the ganglia, whereas this event occurs at a later stage in the iris. However, the total amount of ABTX binding is still relatively high at late stages. These results support our view that the presynaptic component is more affected by the aging process than the postsynaptic component.

Acetylcholine↗
PubMed1981

[Abdominal angio-CT: technique of injection and scanning (author's transl)].

Angio-CT consists in a rapid bolus intravenous injection of contrast medium followed by serial sequential fast scanning to include the arterial and the venous phases. Injection of contrast medium of 50 cm3 are made 3 or 4 times for a total of 150 divided by 200 cm3 of contrast medium at an iodine concentration of 29 g/100 cm3. At the beginning, scans are intercalated with injections, until the total amount of contrast medium is reached. Thereafter, the scans are rapidly continued to cover the whole organ under study. The scanning during the vascular enhancement has considerably helped our diagnostic accuracy and has a made the drip-infusion technique out-moded.

Angiography↗
PubMed1980

Characteristics of norepinephrine uptake in developing peripheral nerve terminals.

In the chick the various characteristics of [3H]norepinephrine (NE) uptake do not appear simultaneously during the development of the iris. Na+-dependence and ouabain sensitivity are both first seen at a significant level at 10 days of incubation (d.i.). Na+-dependence achieves its peak value at 14 d.i. and is unchanged at 3 months after hatching (a.h.). Ouabain sensitivity increases after its initial appearance to 14 days a.h. and then slowly declines. Temperature sensitivity develops only at hatching and is modified subsequently. Both desmethylimipramine (DMI) and cocaine inhibition develop at 10 d.i. and follow the same developmental pattern; however, DMI appears to be a more effective inhibitor than cocaine. Metanephrine, an inhibtor of extraneuronal uptake, first inhibits NE uptake to a significant degree at hatching. These changes may be related to changes in membrane structure and metabolic function in the developing neuronal membrane. No evidence of [3H]NE uptake is seen at 7 d.i. After this age the Km values tend to fall into two groups, the first 1.3--1.9 X 10(-5) M, up to one month a.h., the second, 3.5--5.0 X 10(-6) M, after one month a.h. There is a large increase in Vmax from 10 to 14 d.i., a period of rapid growth of sympathetic innervation of the iris. Our study suggests that Na+-dependent uptake is a more reliable and constant index of innervation in development than temperature-dependent uptake. It also indicates that in longitudinal developmental studies it is necessary to determine the characteristrics of the transport process of each stage, as characteristics such as N1+-, drug- and temperature-sensitivity may all have unique developmental profiles.

Aging↗
PubMed1980

Age dependent changes in choline uptake of the chick iris.

The kinetics of the uptake of choline, the rate-limiting substrate in the in vivo synthesis of acetylcholine, were studied during the period 1--7 years in the iris of the chick. These changes were correlated to the endogenous levels of acetylcholine and choline in the same organ. Vmax values per iris decrease significantly at 5 years and continue to decrease at 7 years, to 64% and 37% of the one year value, respectively. If the variation in Vmax is calculaed per protein the decline is 34% between 1 and 5 years. Km does not change significantly during the period 1--7 years. Total acetylcholine and choline levels follow a similar trend, decreasing progressively from 1 to 7 years. Sensitivity to hemicholinium (5.5 X 10(-5) M) decreases significantly between 5 days of incubation (d.i.) and 5 years. Inhibition by ouabain (10(-4) M) shows an opposite trend, increasing significantly from 20% at 5 d.i. to 52% at 3 months. At 5 years sensitivity to ouabain is the same as at 3 months. Nardependence decreases significantly between 5 d.i. and 5 years but no significant changes are seen between 5 d.i. and 3 months. Uptake at 27 degrees C decreases from 59% of control at 5 d.i. to 45% at 3 months, and is not changed at 5 years. Our observations suggest that the effect of aging on peripheral cholinergic neurons is not generalized, but is specifically directed toward the neuronal periphery (terminals) as opposed to cell bodies.

Acetylcholine↗
PubMed1980

The fate of tritium-labeled reserpine in the chick embryo: a preliminary report.

After a single administration of EH-reserpine, 10 mugm 2.5 microCi, into the yolk of fertilized chicken eggs, gross radioactivity (reserpine plus degradation products) and the unchanged labeled drug, separated by thin layer chromatography, were assayed on the 8th and 19th day of incubation. Nanogram per gram concentrations of unchanged 3H-reserpine were recovered at both times. The 3H-reserpine recovered in the whole egg on the 8th day of incubation accounted for up to 20% of the administered dose. On the 19th day of incubation, brain showed the largest share (28%) of 3H-reserpine as a percentage of gross radioactivity of all organs investigated. Reserpine underwent considerable biodegradation in the developing chick embryo, but the concentrations of unchanged drug recovered in embryonal tissues throughout development were of the same order as those persisting in target organs of rats given a pharmacological dose of reserpine.

Animals↗