6-(Alkylamino)-3-aryl-1,2,4-triazolo[3,4-a]phthalazines. A new class of benzodiazepine receptor ligands.

Some 6-(alkylamino)-3-aryl-1,2,4-triazolo[3,4-a]phthalazines have been shown to displace diazepam from rat brain specific binding sites, in vitro, with Ki (nM) values comparable to those of reference benzodiazepines and to have anticonvulsant (pentylenetetrazole test, mice) and anticonflict activity (Vogel test, rat) in vivo. Separation between the doses causing anticonflict effects (Vogel test, rat) and those impairing motor coordination (rotarod test, rat) has been shown for N,N-bis(2-methoxyethyl)-3-(4-methoxyphenyl)-1,2,4-triazolo[3,4-a] phthalazin-6-amine (80). This compound, unlike diazepam, was inactive in counteracting the strychnine (mouse) and maximal electroshock (mouse) induced convulsions and in the "aggressive monkey" model. These differences from the classical benzodiazepines in the animal tests indicate that 80 may have some selective anxiolytic activity.

Positive action of propionyl-L-carnitine on mechanical performance of papillary muscle from Syrian hamsters with hereditary dilated cardiomyopathy.

Propionyl-L-carnitine has been shown to exert a beneficial effect on cardiac function in different experimental models of cardiomyopathy in the rat, most likely by improving cardiac metabolism and energy production. We have previously shown that, in a strain of hamsters with hereditary dilated cardiomyopathy (BIO TO.2), the mechanical activity of papillary muscle (length-tension, velocity of shortening, shortening, work and power relationship) is significantly depressed when compared to the same parameter in normal hamsters (BIO F1.B). The repeated oral treatment with propionyl-L-carnitine (60 mg/kg per os for 7 weeks) to BIO TO.2 hamsters had a significant positive inotropic effect, as indicated by an increase in developed tension up to the levels observed in papillary muscles from normal hamsters. This action is most likely associated with metabolic effects similar to those observed in rats.

Protein kinase C activation and anti-amnesic effect of acetyl-L-carnitine: in vitro and in vivo studies.

Drugs belonging to different chemical classes having the ability to improve behavioral performance in animal learning and memory tests may share the common ability to stimulate protein kinase C activity in rat brain cortex. In vitro acetyl-L-carnitine (100 nM) promoted in rat brain cortex slices a significant increase in particulate activity associated with lower soluble protein kinase C activity and produced a direct stimulation of the enzyme in both the cortex and hippocampus. In vivo a significant increase in particulate protein kinase C activity was observed in the group of rats treated with 60 mg/kg acetyl-L-carnitine, a dose shown to be effective in improving the cognitive deficits induced by scopolamine in the Morris maze test. The results suggest that acetyl-L-carnitine increases particulate protein kinase C activity in the cortex both in vitro and in vivo. This effect in the in vivo experiments seems to be observed only with doses that are effective in improving the performance of rats in a spatial learning task.

Endothelins urinary excretion is increased in spontaneously diabetic rats: BB/BB.

Previously we reported (1) an increase of endothelin-1,2 (ET) content, in urine of rats made diabetic with streptozotocin (STZ), starting three days and up to 20 weeks from diabetes induction. The increased ET excretion was considered as an early marker of endothelial damage. To ascertain if this phenomenon was present also in a strain of spontaneously diabetic rats, endothelin-1,2 urinary excretion was determined in BB/BB diabetic rats, and their control (BB/WB), at different times after the onset of diabetes, (two, four, six and twelve weeks). BB/BB diabetic rats showed elevated urinary excretion of endothelins as compared to BB/WB control rats, starting two weeks after diabetes onset, and up to twelve weeks. In the same animals, Nerve Conduction Velocity (NCV), was monitored at the same time as an index of the occurrence of a diabetes complication (peripheral neuropathy). NCV resulted to be impaired in the BB/BB diabetic rats as compared to control rats; however the increase of ET in urine, is earlier in comparison to peripheral neuropathy. These data suggest the hypothesis that endothelial damages preceed the overt manifestations of peripheral neuropathy associated to diabetes.

Elevated urinary excretion of endothelins in streptozotocin diabetic rats.

Endothelin-1,2 urinary excretion, has been determined in control and streptozotocin diabetic rats at different times after diabetes induction. Diabetic rats showed increased urinary excretion of endothelins as compared to control rats, already three days after diabetes induction and up to 20 weeks.

Decreased density of endothelin binding sites in adrenal glands but not in aorta, of long term infarcted rats.

Endothelins (Et-s) are biologically active peptides which play a physiological and pathological role in the cardiovascular regulation. The aim of our study was to verify, in a model of experimental long term myocardial ischemia (15 weeks) in rats, whether there was a modification in the ET binding sites of aorta and adrenal glands. Additionally, Ang II binding sites in adrenal glands were studied. The principal finding of the present study was the down-regulation of ET binding sites in adrenal glands of chronic infarcted rats, whereas no modification of binding parameters for Et-1, in thoracic aorta, nor for Ang II, in adrenal glands, were found.

Altered neuroexcitability in experimental diabetic neuropathy: effect of acetyl-L-carnitine.

Sciatic nerve conduction velocity (NCV) is reduced in rats made hyperglycaemic with streptozotocin (STZ). This neurophysiological dysfunction has been associated with increased nerve sorbitol and reduced nerve inositol. Treatment of STZ diabetic rats with aldose reductase inhibitors (ARIs) which reduce sorbitol and increase inositol in the nerve results in normalization of NCVs. Male Wistar rats were made diabetic with 50 mg/kg of streptozotocin given intraperitoneally. Those animals with blood glucose > 300 mg/dl two weeks later were included in this study. The STZ-diabetic rats were treated with either the ARI sorbinil (40 mg/kg per day), or acetyl-L-carnitine (ALC) (300 mg/kg per day) or sterile 0.15% aqueous NaCl for 16 weeks after 4 or 8 weeks of untreated hyperglycaemia. A control group of non-diabetic rats received no treatment during the interval. Sciatic-nerve sorbitol was elevated (1.08 +/- 0.13 nanomol/mg wet weight vs. 0.19 +/- 0.03 nm/mg wet weight) and inositol was reduced (1.21 +/- 0.12 nm/mg ww vs. 2.02 +/- 0.08 nm/mg ww) in the STZ diabetic rats, which were untreated for 4 weeks. Treatment with sorbinil was associated with normalization of the tissue sorbitol (0.10 +/- 0.05 nm/mg ww), while ALC treatment also significantly reduced the nerve sorbitol but only to a level (0.34 +/- 0.08 nm/mg ww) more elevated than the normal level. The nerves of STZ animals treated with sorbinil or ALC had inositol levels no different from untreated diabetic rats. Thus, hyperglycaemic animals treated with either ALC or sorbinil had similar improvements in NCVs as the diabetic, even though the effect on nerve sorbitol was different and nerve inositol was unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Benzodiazepine receptor ligands. Synthesis and preliminary pharmacological evaluation of 2-aminoalkyl-8-chloro- and 2-aryl-1,2,4-triazolo[3,4-a]phthalazine-3(2H)-ones.

Some 2-aminoalkyl-8-chloro- and 2-aryl-1,2,4-triazolo[3,4-a]-phthalazine-3-(2H)-ones were synthesized and preliminarily tested in vitro and in vivo as potential benzodiazepine-receptor (BZRs) ligands. 2-Aryl-1,2,4-triazolo[3,4-a]-phthalazine-3(2H)-ones displaced in vitro 3H-diazepam (3H-DZ) from rat brain specific binding sites with Ki (nM) comparable to DZ and chlordiazepoxide used as reference compounds. The specific binding of the triazolones of this study was not enhanced in vitro by 4-aminobutyric acid (GABA) and in vivo they did not show any activity in counteracting the pentylenetetrazole (PTZ) induced convulsions (mice). One of these compounds (IV a) antagonized the effects of DZ in the bicuculline (BIC) induced convulsions test (mice) and the DZ induced muscle relaxant effects in the horizontal wire test.

Effect of acetyl-L-carnitine treatment on the levels of levocarnitine and its derivatives in streptozotocin-diabetic rats.

The effect of diabetes induced by streptozotocin and that of acetyl-L-carnitine (ALC) hydrochloride (CAS 5080-50-2) treatment on the homeostasis of the levocarnitine (L-carnitine) moiety was investigated in Sprague-Dawley rats. The diabetic status was ascertained by measuring blood glucose. L-carnitine (LC), total acid soluble L-carnitine (TC) and ALC were measured in serum, tissues and urine by radioenzymatic methods. Short-chain L-carnitine esters (SCLCE) were obtained by subtracting LC from TC. Serum concentration of L-carnitine moiety was decreased in diabetic when compared to normal rats; whereas ALC oral treatment (50 and 150 mg/kg p.o. for 4 weeks) in diabetic rats increased, dose-dependently, all the components of L-carnitine moiety, SCLCE and ALC being completely restored. In the liver of diabetic rats all the analytes proved to be higher than in normal rats, mainly LC and TC. A similar trend was observed in skeletal muscle, at least with LC and TC, whereas SCLCE and ALC were not affected. The treatment with ALC increased the liver concentration of all the analytes in a dose-related way whereas in skeletal muscle only LC and TC showed an increase with the highest dose of ALC. Myocardium and kidneys showed a decrease of all the analytes in diabetes; the treatment with ALC normalized the situation in kidneys, in a dose-related way, but not in the myocardium. Urinary excretion and renal clearance of L-carnitine moiety increased in diabetes; an additional dose-related increase was observed with the ALC treatment.

Acetyl-L-carnitine effect on nerve conduction velocity in streptozotocin-diabetic rats.

Measurement of nerve conduction velocity (NCV) is a useful and sensitive tool for evaluating diabetes related neurological dysfunctions. The method used allows to monitor the parameter at different times in the same group of rats, so that it is possible to observe simultaneously the development of the damage in time, and to evaluate the improvement related to the treatment. The repeated oral treatment with acetyl-L-carnitine (ALC, CAS 5080-50-2) 250 mg/kg caused an improvement in NCV of the diabetic rats; the effect was higher when the treatment started early with respect to the diabetes induction. The improvement in NCV was constant in time and comparable from 2 to 6 weeks of the treatment. In conclusion, oral treatment with ALC was able to normalize the impairment of NCV in streptozotocin rats, the effect being constant in time from 2 to 6 weeks of treatment and up to 8 weeks after induction when administration started in early stage of diabetes (2-3 weeks after induction); however, at this time the NCV is already significantly decreased.

Serum and urine levels of levocarnitine family components in genetically diabetic rats.

Serum concentration and urinary excretion of levocarnitine (L-carnitine, CAS 541-15-1) family components were evaluated in a Wistar derived strain of genetically diabetic rats BB/BB, in comparison with normal Wistar rats, and their control rats BB/WB of both sexes. BB/BB diabetic animals have lower serum concentration of total-L-carnitine (TC), L-carnitine (LC), acetyl-L-carnitine (ALC), and short chain L-carnitine esters (SCLCE) than both the strains of non-diabetic rats, as previously observed in streptozotocin diabetic rats. No or marginal variations between control and diabetic rats were detected in cumulative urinary excretion of L-carnitine family components. A strain difference was observed between Wistar and BB/WB non-diabetic rats, BB/WB showing higher serum concentration and lower cumulative urinary excretion of LC and TC than Wistar animals. Renal clearance of L-carnitine components proved to be markedly higher in BB/BB diabetic rats, as previously shown in streptozotocin rats. The reduction of serum concentration of the carnitines endogenous pool may explain this finding. The lack of an increased urinary excretion of L-carnitine components in diabetic animals despite the high increase of diuresis suggests that the saturable tubular reabsorption of L-carnitine family components also in diabetes is the primary mechanism to preserve the homeostatic equilibria of the L-carnitine family, the variation in serum concentration being attributable to the complex systemic metabolic alterations typical of diabetes. In agreement with previous investigations, male animals of all the strains showed higher serum concentration and urinary excretion of L-carnitine components as compared to females.

[A formulation of iopamidol for the radiologic examination of the gastrointestinal tract. Preclinical studies]. / Formulazione di iopamidolo per l'esame radiologico del tratto gastro-intestinale. Studi preclinici.

Animal studies were carried out using an oral solution of a low osmolality non ionic contrast medium iopamidol, developed for gastrointestinal examinations. The new formulation was evaluated for image quality in studies of the upper and lower gastrointestinal tract. Margins of safety were defined by subjecting the compound to a number of toxicological and pharmacological experiments. The experiments were designed to reveal qualitative and quantitative differences between the formulation of iopamidol and Gastrografin, a conventional ionic contrast medium. The results indicate that the formulation of iopamidol is safer than a conventional hypertonic water soluble contrast medium and diagnostically superior in the gastrointestinal tract examinations.

[Derivatives of 2,3,5,6,7,7a-hexahydro-1,3-dioxo-1H-pyrrolo[1,2-c]imidazol -5-carboxylic acids]. / Derivati degli acidi 2,3,5,6,7,7a-esaidro-1,3-dioxo-1H-pirrolo[1,2-]i midazolo-5-carbossilici.

The synthesis of the above-mentioned compounds, starting from the diethyl ester of 2,5-pyrrolidine dicarboxylic acid, is reported. The cis and trans isomers od the 2-phenylsubstituted acid were separated, and the trans form was resolved into the two chiral forms. Some amides were also prepared from these acids. The thio analogs (XIII) and (XVI) and the partially reduced derivatives (XIV) were synthesized. Some amides (VI) showed an interesting anti-anxiety effect in pharmacological models.

[Substances with central nervous system activity. Derivatives of octahydro-1,4-dihydroxypyrrolo(1,2-a)pyrazine-6-carboxylic acids]. / Sostanze attive sul sistema nervoso centrale. Derivati di acidi ottaidro-1,4-diossopirrolo[1,2-a]pirazino-6-carbossilici.

Compounds with potential activity on the Central Nervous System were prepared starting either from 2,5-diethoxycarbonylpyrrolidine or from N-benzyloxycarbonyl-2,5-pyrrolidinedicarboxylic acid anhydride. By the Arndt-Eistert reaction it was possible to obtain chain lengthening at position 6. The carboxy group was also successfully reduced to a hydroxymethyl group. The synthetic work was completed with the synthesis of some derivatives having a phenyl ring condensed at position 7 and 8. Some pharmacological data on the Central Nervous System depressant activity of the prepared compounds are also reported.

[Hexahydroimidazo[1,5-a]-pyrazine. II. Synthesis of 7-phenyl-1,5,6,7,8,8a-hexahydroimidazo[,5-a]pyrazine-3(2H)-one and derivatives]. / Esaidroimidazo[1,5-a]pirazine. Nota II. Sintesi del 7-fenil-1,5,6,7,8,8a-esaidroimidazo[1,5-a]pirazin-3(2H)-one e derivati.

The synthesis and activity on the central nervous system of a series of 2-aryl or 2-alkyl-7-phenylhexahydroimidazo[1,5-a] pyrazin-3(2H)-ones (II a-f) are reported. The intermediate 3-carbomethoxy-1-phenylpiperazine (X) was prepared in six steps from aniline and methyl-2-chloroacrylate. Compared with that of derivatives of Zetidoline, the depressant activity of (II a-f) is markedly reduced.