Ganglioside content and composition in rat cerebellum after prolonged diazepam treatment.

The main purpose of this study was to determine the content and composition of cerebellar gangliosides after prolonged diazepam treatment and their possible recovery after diazepam withdrawal. Male Wistar rats were administered diazepam in a dose of 10 mg/kg/day in drinking water for 3, 5 or 6 months. A additional group of rats had a one-month recovery period after five months of diazepam treatment. Control animals were age-matched and pair-fed. At the end of the experiment, the animals were sacrificed and the total cerebellar contents of ganglioside-NeuAc as well as its content in particular ganglioside fractions were estimated. After three months of diazepam consumption, no changes of ganglioside-NeuAc in investigated fractions (G(Q1b), G(T1b), G(D1b), G(D1a), G(M1), G(M2), and G(M3)) were observed. Five months of diazepam treatment caused a significant decrease in the total amount of gangliosides, which was evident in most of the investigated fractions, with the exception of the monosialoganglioside G(M2). Six months of treatment induced a generalized decrease in all the investigated ganglioside fractions. The diazepam-induced ganglioside reduction found after five months of treatment was also present after a one-month recovery period. The only fraction, which recovered and reached its control value, was monosialoganglioside G(M3).     

Diurnal variations in the catecholamine content in rat tissues. Effects of exogenous noradrenaline

Endogenous noradrenaline (NA) content of the interscapular brown adipose tissue (IBAT), and of the hypothalamus, as well as adrenaline (A) and NA content of the adrenals were measured in the morning and in the evening in rats treated with saline (controls) or with NA (1.6 mg kg-1 pp). NA content in IBAT and in hypothalamus of control animals varies diurnally. NA content in IBAT was significantly higher in the evening than in the morning. In the hypothalamus, these variations were different of those found in the IBAT. Exogenous NA applied both in the morning and in the evening increases significantly NA content in IBAT both in the morning and in the evening, but more in the evening. Unlike IBAT, NA content of the hypothalamus after NA administration does not change essentially. In the adrenal gland of control rats, A content only is changed during the day, being markedly lower in the evening. After NA injection both A and NA are not changed significantly.     

Increase in cystathionine content in rat liver mitochondria after D,L-propargylglycine administration

Summary Intraperitoneal administration of D,L-propargylglycine to rats resulted in an increase in the cystathionine content of whole liver and liver mitochondria. Cystathionine in mitochondria was identified by amino acid analysis, thin layer chromatography, high-voltage paper electrophoresis and liquid chromatography-mass spectrometry. The cystathionine content of whole liver was 5.37 ± 1.59µmol per g of fresh liver at 14 h after the administration of 50 mg of D,L-propargylglycine per kg of body weight, while 0.07 ± 0.02µmol of cystathionine per g of fresh liver was detected in the control rats. The cystathionine content of liver mitochondria from both groups of rats was 9.40 ± 1.20 and 0.19 ± 0.04 nmol of cystathionine per mg of protein, respectively. The mitochondrial cystathionine increased dose-dependently with the increase of D,L-propargylglycine administered. The increase was proportional to the time after the administration up to 12 h, and then decreased. The increase of cystathionine in the liver mitochondria was linearly proportional to that in the whole liver. These results suggest that cystathionine in liver mitochondria is in an equilibrium with that in the cytosol.     

Effects of bilateral splanchnic-nerve section and chemical sympathectomy on PACAP38 content in the rat adrenals.

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a basic 38-amino acid regulatory peptide contained in the adrenal gland and involved in the control of its secretory activity. Bilateral splanchnic-nerve section caused in the rat a significant decrease in PACAP38 adrenal content and concentration, as measured by RIA. In contrast, chemical sympathectomy, obtained by administering newborn rats with 6-hydroxydopamine, was ineffective. Our findings support the view that splanchnic nerves play an important role in the control of rat adrenal function.     

Effects of bilateral splanchnic-nerve section and chemical sympathectomy on PACAP38 content in the rat adrenals.

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a basic 38-amino acid regulatory peptide contained in the adrenal gland and involved in the control of its secretory activity. Bilateral splanchnic-nerve section caused in the rat a significant decrease in PACAP38 adrenal content and concentration, as measured by RIA. In contrast, chemical sympathectomy, obtained by administering newborn rats with 6-hydroxydopamine, was ineffective. Our findings support the view that splanchnic nerves play an important role in the control of rat adrenal function.     

Insulin-like growth factors decrease catecholamine content in PC12 rat pheochromocytoma cells.

Insulin-like growth factors (IGFs) stimulate proliferation and differentiation of PC12 rat pheochromocytoma cells and modulate catecholamine release in bovine adrenal medullary cells. Dexamethasone increases catecholamine synthesis in PC12 cells. We therefore studied the effects of IGFs and dexamethasone on catecholamine content in PC12 cells. Dopamine (DA) and norepinephrine (NE) content of PC12 cells were measured after incubation for 72 h with IGFs (100 ng/ml) and/or dexamethasone (500 nM). IGF-I (100 ng/ml) and IGF-II (100 ng/ml) decreased DA and NE content to approximately 35% and approximately 25% of control, respectively. [Leu27]IGF-II, which binds to the IGF-I receptor with markedly decreased affinity, did not reduce catecholamine levels, indicating that the effect is likely to be mediated by the IGF-I receptor. Dexamethasone (500 nM) increased levels of DA and NE to 173 +/- 20% and 331 +/- 48% of controls, respectively. Coincubation with IGFs did not significantly affect the stimulation of DA by dexamethasone, but abolished the rise in NE. Levels of tyrosine hydroxylase mRNA, protein and activity were increased following incubation with dexamethasone, but were unchanged by IGFs. These results indicate that IGFs decrease catecholamine content in PC12 cells via the IGF-I receptor. Complex regulation involving multiple synthetic and/or degradative steps is implicated in this process.     

Increase in the calcium content of cardiac tissue after postfixation with osmium tetroxide

The concentration of osmium has been measured by destructive chemical analysis in glutaraldehyde fixed heart tissue postfixed with osmium tetroxide and embedded in epoxy resin. After such treatment, the mean atomic number of the specimen (Z) is close to 10, which permits a quantitative analysis of calcium (Ca) by the continuum method, using Z2/A as a correcting factor (A: atomic weight). Wavelength-dispersive X-ray microanalysis has been used to determine the Ca concentration of frog cardiac tissue fixed in glutaraldehyde and embedded in resin. These measurements have been repeated on tissue postfixed in osmium tetroxide; contrary to expectations, the apparent Ca concentration is much higher in osmium treated than in nontreated tissue. However, this result is observed with OsO4 solutions prepared in glass, not with solutions prepared in plastic. It is shown by energy dispersive X-ray analysis of droplets that OsO4 solutions prepared in glass contain large amounts of calcium, potassium and silicon. Care must be taken in preparing OsO4 fixatives when the fixed tissues are to be subjected to X-ray microanalysis of such elements as Ca or Si.     

Brain lipids in rat after chronic diazepam treatment

Male Wistar rats with an initial weight of 170g were maintained on a nutritionally adequate diet, and diazepam was administered at a dose of 10 mg/kg/d. Control animals were pair-fed an adequate diet. The feeding was continued for 180 d, and the effects on brain lipid contents were studied. It was found that the contents of the phospholipids, phosphatidylethanolamine and phosphatidylserine, the monogalactosyl glycolipids, hydroxy and nonhydroxy fatty acyl galactocerebroside, sulfoglycolipids, and the gangliosides, GM1, GD1a, GD1b, and GT1b, were significantly reduced in the brain of diazepam-treated rats. There was a significantly increased content of phosphatidylinositol after 180 d of diazepam treatment. The results suggest that changes in brain lipid content may mediate the adaptive changes that occur upon prolonged exposure to diazepam.     

Effect of metopirone and glucocorticoids on the glycogen content in the adrenals of rat fetuses]

Metopiron, hydrocortisone and dexamethazone are able to influence different links of the hypothalamo-hypohysial-adrenal system and induce the inhibition of glucocorticoid function. Changes in glycogen content in the adrenal gland and liver of rat foetuses under the effect of the drugs in question were studied. It was shown that metopiron exerted no marked influence on the level of glycogen in the adrenal gland and decreased 2.5 times that in the liver. On the contrary, hydrocortisone and dexamethazone increased the glycogen content 2 times in the adrenal gland and did not change that in the liver. The results obtained agree with the hypothesis on the relation between the glycogen level in the adrenal gland and the level of its hormonal activity and are considered as an additional proof of the functioning of hypothalamo-hypophysial-adrenal system during the last days of the rat prenatal development.     

CO2 and the catecholamine content of the adrenal medulla of the rat

In Wistar rats exposed during one hour to mixtures of oxygen and carbon dioxide producing hypoxia, hypercapnia, hyperoxia and hypocapnia, and so on, adrenaline contents of the suprarenals is reduced by high concentration of carbon dioxide (30%), with or without hypoxia. Noradrenaline contents is increased by carbon dioxide (15 to 30%). Hypercapnia is more potent than hypoxia as a suprarenal stimulus.     

Increase in rat striatal acetylcholine content by d-fenfluramine, a serotonin releaser.

The anorectic agent, d-fenfluramine, maximally increased the acetylcholine content in the striatum by 50% at doses of 5–10 mg/kg. The action of the drug was completely prevented by treatments designed to interfere with serotonergic transmission (e.g., combined electrolytic lesion of the nucleus raphe medianus and dorsalis; pretreatments with methergoline, parachlorophenylalanine or fluoxetine). By contrast, interference with dopaminergic transmission (e.g., lesion of the nigrostriatal dopaminergic tract with 6-OHDA; pre-treatment with penfluridol) did not impede the action of d-fenfluramine. The administration of d-fenfluramine to animals given a supramaximal dose of apomorphine, 1.5 mg/kg, produced a summated increase in striatal acetylcholine. The data are consistent with the hypothesis that there may exist in the striatum different populations of cholinergic interneurons regulated by serotonin and dopamine, respectively.