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R Ientile

Publications and source records attributed to R Ientile.

68 records · Page 4Linked to original sources
PubMed1981

GABA depletion in chick brain-stem after intraventricular injection of cefazolin.

The effects of cefazolin, given into the III cerebral ventricle at different doses were studied on GABA content, GAD and GABA-T in the brain-stem of young chickens (Gallus domesticus). A dose-dependent fall in GABA content was observed; GABA decrease was evident 15 min after the administration, reached its nadir at 60 min and disappeared at 120 minutes. Glutamate decarboxylase and GABA-transaminase activity were not significantly changed. Present experiments suggest the excitatory and convulsant effects of cefazolin in chicks are related to GABA depletion in the brain-stem.

4-Aminobutyrate Transaminase↗
PubMed1981

Evidence for the existence of a dopamine-sensitive adenylate cyclase in chick optic tectum.

The effects of several concentrations of dopamine on chick optic tectum adenylate cyclase were studied. Dopamine produced a dose-dependent increase in the intracellular content of c-AMP. These effects were specifically antagonized by haloperidol and chlorpromazine, whereas antagonists at alpha-and beta-adrenoceptors were significantly less effective. In conclusion, the present experiments provide evidence for the existence within the avian optic tectum of a dopamine-sensitive adenylate cyclase activity.

Adenylyl Cyclases↗
PubMed1979

Light-evoked changes in chick optic lobe GABA system.

In young chicks the effects of 3 min stroboscope stimulation on GABA and free glutamic acid content and on GAD and GABA-T activity in optic lobes were studied. A significant depletion in GABA and glutamic acid levels was found to occur. In addition a sustained increase in GABA-T and GAD activity was observed. In conclusion present experiments are in favour of an inhibitory role played by GABA in chick optic tectum during stroboscope stimulation.

4-Aminobutyrate Transaminase↗
PubMedDate not supplied

Serum ionized magnesium levels in type 2 diabetic patients with microalbuminuria or clinical proteinuria.

BACKGROUND/AIMS: The association between microalbuminuria and magnesium depletion is a controversial issue, and serum ionized magnesium levels have not been previously studied in patients with different grades of diabetic nephropathy. Therefore, the aim of this study was to evaluate circulating ionized magnesium concentrations in patients with non-insulin-dependent diabetes mellitus (NIDDM) and incipient or overt diabetic nephropathy. METHODS: We measured fasting plasma glucose, creatinine, creatinine clearance estimate, total cholesterol and triglycerides, and serum ionized magnesium (ion-selective electrodes, ISE) in 30 NIDDM patients with urinary albumin excretion rate (UAER) <20 microg/min (normoalbuminuria), 30 NIDDM patients with microalbuminuria (20 < UAER < 200 microg/min), 30 NIDDM patients with clinical proteinuria (UAER >200 microg/min), and 20 healthy subjects. RESULTS: Serum ionized magnesium levels were significantly reduced in diabetic patients when compared to control subjects (0.39 +/- 0.06 vs. 0.58 +/- 0.05 mmol/l, p < 0.001). Moreover, diabetic patients with microalbuminuria or clinical proteinuria showed a significant decrease in serum ionized magnesium with respect to normoalbuminuria group (normoalbuminuria: 0.45 +/- 0. 02 mmol/l; microalbuminuria: 0.36 +/- 0.05 mmol/l, p < 0.001; clinical proteinuria: 0.35 +/- 0.04 mmol/l, p < 0.001). Serum ionized magnesium showed a significant negative correlation with plasma HbA1c and triglycerides in both microalbuminuria and clinical proteinuria groups. Multiple linear regression analysis showed that circulating ionized magnesium levels decrease together with the increase of plasma HbA1c and triglycerides in NIDDM patients with incipient or overt nephropathy, also after adjusting for age, sex, BMI, diabetes duration, systolic and diastolic blood pressure, hypoglycemic therapy, plasma creatinine, creatinine clearance, plasma cholesterol and fasting glucose. CONCLUSIONS: Microalbuminuria and clinical proteinuria, as well as poor glycometabolic control and hypertriglyceridemia, are associated to relevant alterations in magnesium metabolism, and the measurement of serum ionized magnesium seems to represent a useful biochemical tool for the study of magnesium disturbances in patients with different grades of diabetic nephropathy.

Albuminuria↗
PubMedDate not supplied

Excess of taurine supplementation in rat: effects on GABA-related amino acids in developing nervous tissues.

The effects of taurine supplementation on GABA-related amino acid homeostasis in developing nervous tissues of suckling rats were studied. In the first two weeks of postnatal growth, cerebral cortex and cerebellum appear more accessible to taurine supplementation in comparison to retina; in addition, different changes in excitatory/inhibitory amino acids were observed. After the 5th day of life, in the retina and cerebellum of taurine-supplemented pups a decrease in GABA levels was found; in contrast, in cerebral cortex GABA content significantly increased throughout 20 days of postnatal growth. In all nervous tissues studied (except for cerebellum) glutamine concentration increased at the 5th day; then in cerebellum and in retina, but not in cerebral cortex, a significant decrease until the 20th day occurred. Furthermore, in cerebellum and retina taurine supplementation decreased glutamate levels, in comparison to controls, at the 10th and until the 20th day of postnatal life, respectively, whereas in cerebral cortex an increase in glutamate level was observed only at the 5th day. In conclusion, taurine supplementation, in excess to the usual amount from the mother's milk, affected the glutamate compartments in various cell types. The changes in GABA-related amino acid concentrations in cerebral cortex, cerebellum, and retina may depend on the different pattern of the metabolic processes at different maturative stages.

Animals↗
PubMedDate not supplied

GABA-ergic system in brain regions of glutamate-lesioned rats.

Subcutaneous administration of high doses of glutamate to rats during their first 10 days after birth produced a great reduction of GABA content and GAD activity in the adult mediobasal hypothalamus, both in male and female. In addition GABA content and GAD activity showed a slight significant decrease in female cerebellum and male striatum. Glutamate treatment was also followed by a significant increase in GABA content and GAD activity of male substantia nigra, cerebellum, hippocampus and of female olfactory bulb. No reduction in GABA-T activity was observed in different brain areas studied except in mediobasal hypothalamus. The results support the view that glutamate treatment had a direct toxic effect on GABA-ergic neurons in mediobasal hypothalamus. The changes in GAD activity observed in all areas studied may reflect the neuroendocrine changes determined by nucleus arcuate lesions.

4-Aminobutyrate Transaminase↗
PubMedDate not supplied

Thyroxine effects on polyamine metabolism in rat cerebellum and brain cortex during postnatal development.

Polyamine content, ODC and SAMDC activities have been assayed in cerebellum and brain cortex of hyperthyroid rats during postnatal development. Daily thyroxine treatment induced ODC and SAMDC biosynthesis in early periods of postnatal life in both cerebellum and brain cortex. In addition, in comparison to controls an increase in spermidine and spermine content was shown to occur in hyperthyroid rats. A functional correlation between polyamine content and nucleic acids could explain a correlation between polyamine biosynthesis and morphofunctional maturative processes in the brain.

Animals↗
PubMedDate not supplied

Effects of estrogens and progesterone on GABA system in ovariectomized rat retina.

In an attempt to characterize the effect of estrogens and progesterone on retinal GABA metabolism, female Wistar Nossan rats were ovariectomized and treated for three days with 17 beta-estradiol (1 microgram/day), estrone (2 micrograms/day), estriol (200 micrograms/day) and progesterone (500 micrograms/day) or vehicle. After 3 days of steroid hormones treatment, GAD, GABA-T activities and GABA content were measured in retina homogenate. Progesterone did not reduce GAD, GABA-T activities and GABA content from ovariectomized levels. 17 beta-estradiol, estrone and estriol decreased the GAD activity. Furthermore the decrease in GAD activity was maximal for 17 beta-estradiol whereas the estrogens treatment was ineffective on GABA-T. GABA content was significantly decreased only by 17 beta-estradiol. Estrogens reduced the Vmax of GAD for glutamate as a substrate without changing the Km.

4-Aminobutyrate Transaminase↗
PubMedDate not supplied

Putrescine, polyamines, and N1-acetylpolyamine levels in retina, visual cortex and cerebellum of free-running mice kept under continuous light or darkness.

Putrescine, spermidine and spermine levels were detected in the retina, visual cortex, cerebellum and parietal cortex of CD1 mice exposed to 36h continuous light or darkness. Retinal putrescine and polyamine concentrations were found to be highest in dark-adapted mice, and the stimulation of dark-adapted retina with flicker illumination was also accompanied by a significant decrease in putrescine, spermidine and spermine levels. In visual cortex as well as in cerebellum spermidine and spermine contents were higher in dark-adapted mice in comparison to light-exposed animals, while in parietal cortex no significant change was found neither in spermidine nor spermine levels. In the brain areas studied flicker illumination produced no significant decreases in putrescine and polyamine contents. The total polyamines expressed as putrescine equivalents were noticeably decreased in retina, visual cortex and cerebellum of light-adapted mice. In the retina spermine/spermidine molar ratio was significantly higher than in dark-adapted mice. The administration of N1, N2-bis-(2,3-butadienyl)-1,4-butanediamine (MDL 72527) produced a strong decrease of retinal putrescine and spermidine concentrations in both dark-adapted and light-exposed mice, and in the retina of mice exposed to continuous light a significant decrease in the spermine level was also observed. According to the influence on polyamine reutilization, after the irreversible inhibition of polyamine oxidase by MDL 72527, in the retina N1-acetylspermidine and N1-acetylspermine accumulation was highest in light-adapted mice. On the contrary in visual cortex, cerebellum and parietal cortex the MDL 72527 administration produced a more marked decrease of putrescine and spermidine contents in mice kept in continuous darkness.

Animals↗