S-phenylpiracetam, a selective DAT inhibitor, reduces body weight gain without influencing locomotor activity

S-phenylpiracetam is an optical isomer of phenotropil, which is a clinically used nootropic drug that improves physical condition and cognition. Recently, it was shown that S-phenylpiracetam is a selective dopamine transporter (DAT) inhibitor that does not influence norepinephrine (NE) or serotonin (5-HT) receptors. The aim of the present study was to study the effects of S-phenylpiracetam treatment on body weight gain, blood glucose and leptin levels, and locomotor activity. Western diet (WD)-fed mice and obese Zucker rats were treated daily with peroral administration of S-phenylpiracetam for 8 and 12weeks, respectively. Weight gain and plasma metabolites reflecting glucose metabolism were measured. Locomotor activity was detected in an open-field test. S-phenylpiracetam treatment significantly decreased body weight gain and fat mass increase in the obese Zucker rats and in the WD-fed mice. In addition, S-phenylpiracetam reduced the plasma glucose and leptin concentration and lowered hyperglycemia in a glucose tolerance test in both the mice and the rats. S-phenylpiracetam did not influence locomotor activity in the obese Zucker rats or in the WD-fed mice. The results demonstrate that S-phenylpiracetam reduces body weight gain and improves adaptation to hyperglycemia without stimulating locomotor activity. Our findings suggest that selective DAT inhibitors, such as S-phenylpiracetam, could be potentially useful for treating obesity in patients with metabolic syndrome with fewer adverse health consequences compared to other anorectic agents.

R-phenibut binds to the α2-δ subunit of voltage-dependent calcium channels and exerts gabapentin-like anti-nociceptive effects

Phenibut is clinically used anxiolytic, mood elevator and nootropic drug. R-phenibut is responsible for the pharmacological activity of racemic phenibut, and this activity correlates with its binding affinity for GABAB receptors. In contrast, S-phenibut does not bind to GABAB receptors. In this study, we assessed the binding affinities of R-phenibut, S-phenibut, baclofen and gabapentin (GBP) for the α2-δ subunit of the voltage-dependent calcium channel (VDCC) using a subunit-selective ligand, radiolabelled GBP. Binding experiments using rat brain membrane preparations revealed that the equilibrium dissociation constants (Kis) for R-phenibut, S-phenibut, baclofen and GBP were 23, 39, 156 and 0.05μM, respectively. In the pentylenetetrazole (PTZ)-induced seizure test, we found that at doses up to 100mg/kg, R-phenibut did not affect PTZ-induced seizures. The anti-nociceptive effects of R-phenibut were assessed using the formalin-induced paw-licking test and the chronic constriction injury (CCI) of the sciatic nerve model. Pre-treatment with R-phenibut dose-dependently decreased the nociceptive response during both phases of the test. The anti-nociceptive effects of R-phenibut in the formalin-induced paw-licking test were not blocked by the GABAB receptor-selective antagonist CGP35348. In addition, treatment with R- and S-phenibut alleviated the mechanical and thermal allodynia induced by CCI of the sciatic nerve. Our data suggest that the binding affinity of R-phenibut for the α2-δ subunit of the VDCC is 4 times higher than its affinity for the GABAB receptor. The anti-nociceptive effects of R-phenibut observed in the tests of formalin-induced paw licking and CCI of the sciatic nerve were associated with its effect on the α2-δ subunit of the VDCC rather than with its effects on GABAB receptors. In conclusion, our results provide experimental evidence for GBP-like, anti-nociceptive properties of R-phenibut, which might be used clinically to treat neuropathic pain disorders.

The cognition-enhancing activity of E1R, a novel positive allosteric modulator of sigma-1 receptors

BACKGROUND AND PURPOSE

Here, we describe the in vitro and in vivo effects of (4R,5S)-2-(5-methyl-2-oxo-4-phenyl-pyrrolidin-1-yl)-acetamide (E1R), a novel positive allosteric modulator of sigma-1 receptors.

EXPERIMENTAL APPROACH

E1R was tested for sigma receptor binding activity in a [³H](+)-pentazocine assay, in bradykinin (BK)-induced intracellular Ca²⁺ concentration ([Ca²⁺](i)) assays and in an electrically stimulated rat vas deferens model. E1R's effects on cognitive function were tested using passive avoidance (PA) and Y-maze tests in mice. A selective sigma-1 receptor antagonist (NE-100), was used to study the involvement of the sigma-1 receptor in the effects of E1R. The open-field test was used to detect the effects of E1R on locomotion.

KEY RESULTS

Pretreatment with E1R enhanced the selective sigma-1 receptor agonist PRE-084's stimulating effect during a model study employing electrically stimulated rat vasa deferentia and an assay measuring the BK-induced [Ca²⁺](i) increase. Pretreatment with E1R facilitated PA retention in a dose-related manner. Furthermore, E1R alleviated the scopolamine-induced cognitive impairment during the PA and Y-maze tests in mice. The in vivo and in vitro effects of E1R were blocked by treatment with the selective sigma-1 receptor antagonist NE-100. E1R did not affect locomotor activity.

CONCLUSION AND IMPLICATIONS

E1R is a novel 4,5-disubstituted derivative of piracetam that enhances cognition and demonstrates efficacy against scopolamine-induced cholinergic dysfunction in mice. These effects are attributed to its positive modulatory action on the sigma-1 receptor and this activity may be relevant when developing new drugs for treating cognitive symptoms related to neurodegenerative diseases.

Nicotinamide phosphoribosyltransferase inhibitors, design, preparation, and structure-activity relationship

Existing pharmacological inhibitors for nicotinamide phosphoribosyltransferase (NAMPT) are promising therapeutics for treating cancer. By using medicinal and computational chemistry methods, the structure-activity relationship for novel classes of NAMPT inhibitors is described, and the compounds are optimized. Compounds are designed inspired by the NAMPT inhibitor APO866 and cyanoguanidine inhibitor scaffolds. In comparison with recently published derivatives, the new analogues exhibit an equally potent antiproliferative activity in vitro and comparable activity in vivo. The best performing compounds from these series showed subnanomolar antiproliferative activity toward a series of cancer cell lines (compound 15: IC50 0.025 and 0.33 nM, in A2780 (ovarian carcinoma) and MCF-7 (breast), respectively) and potent antitumor in vivo activity in well-tolerated doses in a xenograft model. In an A2780 xenograft mouse model with large tumors (500 mm(3)), compound 15 reduced the tumor volume to one-fifth of the starting volume at a dose of 3 mg/kg administered ip, bid, days 1-9. Thus, compounds found in this study compared favorably with compounds already in the clinic and warrant further investigation as promising lead molecules for the inhibition of NAMPT.

Mildronate and its neuroregulatory mechanisms: targeting the mitochondria, neuroinflammation, and protein expression

This review for the first time summarizes the data obtained in the neuropharmacological studies of mildronate, a drug previously known as a cardioprotective agent. In different animal models of neurotoxicity and neurodegenerative diseases, we demonstrated its neuroprotecting activity. By the use of immunohistochemical methods and Western blot analysis, as well as some selected behavioral tests, the new mechanisms of mildronate have been demonstrated: a regulatory effect on mitochondrial processes and on the expression of nerve cell proteins, which are involved in cell survival, functioning, and inflammation processes. Particular attention is paid to the capability of mildronate to stimulate learning and memory and to the expression of neuronal proteins involved in synaptic plasticity and adult neurogenesis. These properties can be useful in neurological practice to protect and treat neurological disorders, particularly those associated with neurodegeneration and a decline in cognitive functions.

[The influence of mildronate on peripheral neuropathy and some characteristics of glucose and lipid metabolism in rat streptozotocin-induced diabetes mellitus model]

Streptozotocin (STZ) was used to induce the diabetic rat model. STZ rats were treated with mildronate (100 mg/kg daily, per os or intraperitoneally for 6 weeks). Body weight, blood glucose, triglyceride, ketone body concentrations, glycated hemoglobin percent (HbA1c%), glucose tolerance, and the development of neuropathic pain were monitored throughout the experiment. In the STZ + mildronate group, mildronate treatment caused a significant decrease in mean blood glucose (on week 4) and triglyceride concentrations (on weeks 3-6), significantly slowed the increase in HbA1c% (on week 6) and improved glucose tolerance 120 minutes after glucose ingestion during oral glucose tolerance test versus the STZ group. Mildronate completely protected development of STZ-induced neuropathic pain from the first administration week up to end of the experiment. The obtained data indicate clinical usefulness of the drug for the treatment of diabetes mellitus and its complications.

Inhibitors of human histone deacetylase with potent activity against the African trypanosome Trypanosoma brucei

A number of hydroxamic acid derivatives which inhibit human histone deacetylases were investigated for efficacy against cultured bloodstream form Trypanosoma brucei. Three out of the four classes tested displayed significant activity. The majority of compounds blocked parasite growth in the submicromolar range. The most potent was a member of the sulphonepiperazine series with an IC(50) of 34nM. These results identify lead compounds with potential for the development of a novel class of trypanocidal agent.

Comparison of the effects of glibenclamide on metabolic parameters, GLUT1 expression, and liver injury in rats with severe and mild streptozotocin-induced diabetes mellitus

BACKGROUND AND OBJECTIVE

Glucose transport via GLUT1 protein could be one of additional mechanisms of the antidiabetic action of sulfonylureas. Here, the GLUT1 gene and the protein expression was studied in rats in the course of severe and mild streptozotocin-induced diabetes mellitus and under glibenclamide treatment.

MATERIAL AND METHODS

Severe and mild diabetes mellitus was induced using different streptozotocin doses and standard or high fat chow. Rats were treated with glibenclamide (2 mg/kg daily, per os for 6 weeks). The therapeutic effect of glibenclamide was monitored by measuring several metabolic parameters. The GLUT1 mRNA and the protein expression in the kidneys, heart, and liver was studied by means of real-time RT-PCR and immunohistochemistry.

RESULTS

The glibenclamide treatment decreased the blood glucose concentration and increased the insulin level in both models of severe and mild diabetes mellitus. Severe diabetes mellitus provoked an increase in both GLUT1 gene and protein expression in the kidneys and the heart, which was nearly normalized by glibenclamide. In the kidneys of mildly diabetic rats, an increase in the GLUT1 gene expression was neither confirmed on the protein level nor influenced by the glibenclamide treatment. In the liver of severely diabetic rats, the heart and the liver of mildly diabetic rats, the GLUT1 gene and the protein expression was changed independently of each other, which might be explained by abortive transcription, and pre- and posttranslational modifications of gene expression.

CONCLUSIONS

The GLUT1 expression was found to be affected by the glucose and insulin levels and can be modulated by glibenclamide in severely and mildly diabetic rats. Glibenclamide can prevent the liver damage caused by severe hyperglycemia.

Search for stroke-protecting agents in endothelin-1-induced ischemic stroke model in rats

BACKGROUND AND OBJECTIVE

Ischemic stroke may initiate a reperfusion injury leading to brain damage cascades where inflammatory mechanisms play a major role. Therefore, the necessity for the novel stroke-protecting agents whose the mechanism of action is focused on their anti-inflammatory potency is still on the agenda for drug designers. Our previous studies demonstrated that cerebrocrast (a 1,4-dihydropyridine derivative) and mildronate (a representative of the aza-butyrobetaine class) possessed considerable anti-inflammatory and neuroprotective properties in different in vitro and in vivo model systems. The present study investigated their stroke-protecting ability in an endothelin-1 (ET-1)-induced ischemic stroke model in rats.

MATERIAL AND METHODS

Male Wistar rats were pretreated (for 7 days, per os) with cerebrocrast (0.1 mg/kg), mildronate (100 mg/kg), or their combination, followed by the intracerebral injection of ET-1. Functional and behavioral tests were carried out up to 14 days after the ET-1 injection. Ex vivo, the number of degenerated neurons and the infarction size in the cerebral cortical tissue were assessed histologically.

RESULTS

Cerebrocrast and mildronate effectively normalized ET-1-induced disturbances in neurological status, improved the muscle tone, and decreased the number of degenerated cortical cells. Both drugs also reduced the infarction size, and cerebrocrast showed at least a 2-fold higher activity than mildronate. The combination of both drugs did not cause a more pronounced effect in comparison with the action of drugs administered separately.

CONCLUSIONS

The 1,4-dihydropyridine and aza-butyrobetaine structures may serve for the design of novel stroke-protecting agents to prevent severe neurological poststroke consequences.

The cardioprotective effect of mildronate is diminished after co-treatment with L-carnitine

Mildronate, an inhibitor of L-carnitine biosynthesis and uptake, is a cardioprotective drug whose mechanism of action is thought to rely on the changes in concentration of L-carnitine in heart tissue. In the present study, we compared the cardioprotective effect of mildronate (100 mg/kg) and a combination of mildronate and L-carnitine (100 + 100 mg/kg) administered for 14 days with respect to the observed changes in l-carnitine level and carnitine palmitoyltransferase I (CPT-I)-dependent fatty acid metabolism in the heart tissues. Concentrations of L-carnitine and its precursor γ-butyrobetaine (GBB) were measured by ultraperformance liquid chromatography with tandem mass spectrometry. In addition, mitochondrial respiration, activity of CPT-I, and expression of CPT-IA/B messenger RNA (mRNA) were measured. Isolated rat hearts were subjected to ischemia-reperfusion injury. Administration of mildronate induced a 69% decrease in L-carnitine concentration and a 6-fold increase in GBB concentration in the heart tissue as well as a 27% decrease in CPT-I-dependent mitochondrial respiration on palmitoyl-coenzyme A. In addition, mildronate treatment induced a significant reduction in infarct size and also diminished the ischemia-induced respiration stimulation by exogenous cytochrome c. Treatment with a combination had no significant impact on L-carnitine concentration, CPT-I-dependent mitochondrial respiration, and infarct size. Our results demonstrated that the mildronate-induced decrease in L-carnitine concentration, concomitant decrease in fatty acid transport, and maintenance of the intactness of outer mitochondrial membrane in heart mitochondria are the key mechanisms of action for the anti-infarction activity of mildronate.

Investigation into stereoselective pharmacological activity of phenotropil

Phenotropil [N-carbamoylmethyl-4-aryl-2-pyrrolidone (2-(2-oxo-4-phenyl-pyrrolidin-1-yl) acetamide; carphedon)] is clinically used in its racemic form as a nootropic drug that improves physical condition and cognition. The aim of this study was to compare the stereoselective pharmacological activity of R- and S-enantiomers of phenotropil in different behavioural tests. Racemic phenotropil and its enantiomers were tested for locomotor, antidepressant and memory-improving activity and influence on the central nervous system (CNS) using general pharmacological tests in mice. After a single administration, the amount of compound in brain tissue extracts was determined using an ultra performance liquid chromatography-tandem mass spectrometry (UPLC/MS/MS) method in a positive ion electrospray mode. In the open-field test, a significant increase in locomotor activity was observed after a single administration of R-phenotropil at doses of 10 and 50 mg/kg and S-phenotropil at a dose of 50 mg/kg. In the forced swim test, R-phenotropil induced an antidepressant effect at doses of 100 and 50 mg/kg, and S-phenotropil was active at a dose of 100 mg/kg. R-phenotropil significantly enhanced memory function in a passive avoidance response test at a dose of 1 mg/kg; the S-enantiomer did not show any activity in this test. However, the concentrations of R- and S-phenotropils in brain tissue were similar. In conclusion, the antidepressant and increased locomotor activity relies on both R- and S-phenotropils, but the memory-improving activity is only characteristic of R-phenotropil. These results may be important for the clinical use of optically pure isomers of phenotropil.

Mildronate treatment alters γ-butyrobetaine and l-carnitine concentrations in healthy volunteers

OBJECTIVES

In this study, we aimed to investigate the effects of long-term administration of the cardioprotective drug mildronate on the concentrations of l-carnitine and γ-butyrobetaine in healthy volunteers.

METHODS

Mildronate was administered perorally, at a dosage of 500mg, twice daily. Plasma and urine samples were collected weekly. Daily meat consumption within an average, non-vegetarian diet was monitored. l-Carnitine, γ-butyrobetaine and mildronate concentrations were measured using the UPLC/MS/MS method.

KEY FINDINGS

After 4 weeks, the average concentrations of l-carnitine in plasma significantly decreased by 18%. The plasma concentrations of γ-butyrobetaine increased about two-fold, and this effect was statistically significant in both the male and female groups. In urine samples, a significant increase in l-carnitine and γ-butyrobetaine levels was observed, which provides evidence for increased excretion of both substances during the mildronate treatment. At the end of the treatment period, the plasma concentration of mildronate was 20µm on average. There were no significant differences between the effects observed in female and male volunteers. Meat consumption partially reduced the l-carnitine-lowering effects induced by mildronate.

CONCLUSIONS

Long-term administration of mildronate significantly lowers l-carnitine plasma concentrations in non-vegetarian, healthy volunteers.

Correction of glycaemia and GLUT1 level by mildronate in rat streptozotocin diabetes mellitus model

Anti-ischaemic drug mildronate suppresses fatty acid metabolism and increases glucose utilization in myocardium. It was proposed that it could produce a favourable effect on metabolic parameters and glucose transport in diabetic animals. Rats with streptozotocin diabetes mellitus were treated with mildronate (100 mg/kg daily, per os, 6 weeks). Therapeutic effect of mildronate was monitored by measuring animal weight, concentrations of blood glucose, insulin, blood triglycerides, free fatty acids, blood ketone bodies and cholesterol, glycated haemoglobin per cent (HbA1c%) and glucose tolerance. GLUT1 mRNA and protein expression in kidneys, heart, liver and muscles were studied by means of real time RT-PCR and immunohistochemistry correspondingly. In the streptozotocin + mildronate group, mildronate treatment caused a significant decrease in mean blood glucose, cholesterol, free fatty acid and HbA1c concentrations and improved glucose tolerance. Induction of streptozotocin diabetes mellitus provoked increase of both GLUT1 gene and protein expression in kidneys, heart and muscle, mildronate treatment produced normalization of the GLUT1 expression levels. In the liver a similar effect was observed for GLUT1 protein expression, while GLUT1 gene expression was increased by mildronate. Mildronate produces therapeutic effect in streptozotocin diabetes model. Mildronate normalizes the GLUT1 expression up-regulated by streptozotocin diabetes mellitus in kidneys, heart, muscle and liver. Copyright © 2011 John Wiley & Sons, Ltd.

Mildronate as a regulator of protein expression in a rat model of Parkinson's disease

BACKGROUND

Mildronate (3-[2,2,2-trimethylhydrazinium] propionate dihydrate) traditionally is a well-known cardioprotective drug. However, our recent studies convincingly demonstrated its neuroprotective properties. The aim of the present study was to evaluate the influence of mildronate on the expression of proteins that are involved in the differentiation and survival of the nigrostriatal dopaminergic neurons in the rat model of Parkinson's disease (PD). The following biomarkers were used: heat shock protein 70 (Hsp70, a molecular chaperone), glial cell line-derived nerve growth factor (GDNF, a growth factor promoting neuronal differentiation, regeneration, and survival), and neural cell adhesion molecule (NCAM).

MATERIAL AND METHODS

PD was modeled by 6-hydroxydopamine (6-OHDA) unilateral intrastriatal injection in rats. Mildronate was administered at doses of 10, 20, and 50 mg/kg for 2 weeks intraperitoneally before 6-OHDA injection. Rat brains were dissected on day 28 after discontinuation of mildronate injections. The expression of biomarkers was assessed immunohistochemically and by western blot assay.

RESULTS

6-OHDA decreased the expression of Hsp70 and GDNF in the lesioned striatum and substantia nigra, whereas in mildronate-pretreated (20 and 50 mg/kg) rats, the expression of Hsp70 and GDNF was close to the control group values. NCAM expression also was decreased by 6-OHDA in the striatum and it was totally protected by mildronate at a dose of 50 mg/kg. In contrast, in the substantia nigra, 6-OHDA increased the expression of NCAM, while mildronate pretreatment (20 and 50 mg/kg) reversed the 6-OHDA-induced overexpression of NCAM close to the control values.

CONCLUSION

The obtained data showed that mildronate was capable to regulate the expression of proteins that play a role in the homeostasis of neuro-glial processes.

Neuroprotective properties of mildronate, a small molecule, in a rat model of Parkinson's disease

Previously, we have found that mildronate [3-(2,2,2-trimethylhydrazinium) propionate dihydrate], a small molecule with charged nitrogen and oxygen atoms, protects mitochondrial metabolism that is altered by inhibitors of complex I and has neuroprotective effects in an azidothymidine-neurotoxicity mouse model. In the present study, we investigated the effects of mildronate in a rat model of Parkinson's disease (PD) that was generated via a unilateral intrastriatal injection of the neurotoxin 6-hydroxydopamine (6-OHDA). We assessed the expression of cell biomarkers that are involved in signaling cascades and provide neural and glial integration: the neuronal marker TH (tyrosine hydroxylase); ubiquitin (a regulatory peptide involved in the ubiquitin-proteasome degradation system); Notch-3 (a marker of progenitor cells); IBA-1 (a marker of microglial cells); glial fibrillary acidic protein, GFAP (a marker of astrocytes); and inducible nitric oxide synthase, iNOS (a marker of inflammation). The data show that in the 6-OHDA-lesioned striatum, mildronate completely prevented the loss of TH, stimulated Notch-3 expression and decreased the expression of ubiquitin, GFAP and iNOS. These results provide evidence for the ability of mildronate to control the expression of an array of cellular proteins and, thus, impart multi-faceted homeostatic mechanisms in neurons and glial cells in a rat model of PD. We suggest that the use of mildronate provides a protective effect during the early stages of PD that can delay or halt the progression of this neurodegenerative disease.

Influence of metformin on GLUT1 gene and protein expression in rat streptozotocin diabetes mellitus model

CONTEXT

Metformin improves hyperglycaemia via mechanisms which include activation of AMP-activated protein kinase (AMPK). Recent findings indicate that some metabolic actions of metformin occur also by AMPK-independent mechanisms.

OBJECTIVE

To study the action of metformin on expression of GLUT1 glucose transporter in rat streptozotocin model of diabetes mellitus.

MATERIALS AND METHODS

Streptozotocin-induced rats were treated with metformin while monitoring parameters of carbohydrate and lipid metabolism. GLUT1 mRNA and protein expression in kidneys, heart, liver and muscles were studied by means of real time quantitative RT-PCR and immunohistochemistry correspondingly.

RESULTS

Metformin treatment decreased glucose concentration, glycated haemoglobin % and improved glucose tolerance. Streptozotocin diabetes provoked increase of both GLUT1 gene and protein expression in kidneys, metformin treatment produced normalization of the GLUT1 expression levels. In the liver, diabetes triggered an increase in GLUT1 protein expression, which was normalized by metformin.

CONCLUSION

Metformin is prospective for treatment of diabetic nephropathy.

Inhibition of carnitine acetyltransferase by mildronate, a regulator of energy metabolism

Carnitine acetyltransferase (CrAT; EC 2.3.1.7) catalyzes the reversible transfer of acetyl groups between acetyl-coenzyme A (acetyl-CoA) and L-carnitine; it also regulates the cellular pool of CoA and the availability of activated acetyl groups. In this study, biochemical measurements, saturation transfer difference (STD) nuclear magnetic resonance (NMR) spectroscopy, and molecular docking were applied to give insights into the CrAT binding of a synthetic inhibitor, the cardioprotective drug mildronate (3-(2,2,2-trimethylhydrazinium)-propionate). The obtained results show that mildronate inhibits CrAT in a competitive manner through binding to the carnitine binding site, not the acetyl-CoA binding site. The bound conformation of mildronate closely resembles that of carnitine except for the orientation of the trimethylammonium group, which in the mildronate molecule is exposed to the solvent. The dissociation constant of the mildronate CrAT complex is approximately 0.1 mM, and the K(i) is 1.6 mM. The results suggest that the cardioprotective effect of mildronate might be partially mediated by CrAT inhibition and concomitant regulation of cellular energy metabolism pathways.

Effects of kaempferol and myricetin on inducible nitric oxide synthase expression and nitric oxide production in rats

When administered as drugs or consumed as food components, polyphenolic compounds synthesized in plants interfere with intracellular signal transduction pathways, including pathways of nitric oxide synthase expression. However, effects of these compounds in vivo do not always correlate with nitric oxide synthase-inhibiting activities revealed in experiments with cultured cells. The initial goal of this work was to compare effects of flavonoids kaempferol and myricetin on inducible nitric oxide synthase mRNA and protein expression monitored by real-time RT-PCR and immunohistochemistry and to evaluate the impact of these effects on nitric oxide production in rat organs measured by means of electron paramagnetic resonance spectroscopy. Kaempferol and myricetin attenuated the lipopolysaccharide-induced outburst of inducible nitric oxide synthase gene expression; kaempferol also significantly decreased the lipopolysaccharide-induced outburst of inducible nitric oxide synthase protein expression in the liver. Myricetin decreased nitric oxide production in intact rat liver. Kaempferol did not decrease nitric oxide production neither in intact rats nor in the lipopolysaccharide-treated animals. Kaempferol even enhanced the lipopolysaccharide-induced increase of nitric oxide production in blood. Myricetin did not interfere with lipopolysaccharide effects. As both kaempferol and myricetin are known as inhibitors of inducible nitric oxide synthase expression, our results suggest that modifications of nitric oxide level in tissues by these compounds cannot be predicted from data about its effects on nitric oxide synthase expression or activity.

Neuroprotective properties of mildronate, a mitochondria-targeted small molecule

Mildronate, a representative of the aza-butyrobetaine class of drugs with proven cardioprotective efficacy, was recently found to prevent dysfunction of complex I in rat liver mitochondria. The present study demonstrates that mildronate also acts as a neuroprotective agent. In a mouse model of azidothymidine (anti-HIV drug) neurotoxicity, mildronate reduced the azidothymidine-induced alterations in mouse brain tissue: it normalized the increase in caspase-3, cellular apoptosis susceptibility protein (CAS) and iNOS expression assessed by quantitative and semi-quantitative analysis. Mildronate also normalized the changes in cytochrome c oxidase (COX) expression, reduced the expression of glial fibrillary acidic protein (GFAP) and cellular infiltration. The present results show that the neuroprotective action of mildronate results at least partially from anti-neurodegenerative (anti-apoptotic) and anti-inflammatory mechanisms. It might be suggested that the molecular conformation of mildronate can facilitate its easy binding to mitochondria, and regulate the expression of different signal molecules, hence maintaining cellular signaling and survival.

Effects of long-term mildronate treatment on cardiac and liver functions in rats

Mildronate is a cardioprotective drug that improves cardiac function during ischaemia and functions by lowering l-carnitine concentration in body tissues and modulating myocardial energy metabolism. The aim of the present study was to characterise cardiovascular function and liver condition after long-term mildronate treatment in rats. In addition, changes in the plasma lipid profile, along with changes in the concentration of mildronate, l-carnitine and gamma-butyrobetaine were monitored in the rat tissues. Wistar rats were perorally treated daily with a mildronate dose of either 100, 200 or 400 mg/kg for 4, 8 or 12 weeks. The l-carnitine-lowering effect of mildronate was dose-dependent. However, the carnitine levels reached a plateau after about four weeks of treatment. During the additional weeks of treatment, the carnitine levels were not considerably changed. The obtained results provide evidence that even a high dose of mildronate does not alter cardiovascular parameters and the function of isolated rat hearts. Furthermore, the histological evaluation of liver tissue cryosections and measurement of biochemical markers of hepatic toxicity showed that all the measured values were within the normal reference range. Our results provide evidence that long-term mildronate administration induces significant changes in carnitine homeostasis, but it is not associated with cardiac impairment or disturbances in liver function.

Protective effects of mildronate in an experimental model of type 2 diabetes in Goto-Kakizaki rats

BACKGROUND AND PURPOSE

Mildronate [3-(2,2,2-trimethylhydrazinium) propionate] is an anti-ischaemic drug whose mechanism of action is based on its inhibition of L-carnitine biosynthesis and uptake. As L-carnitine plays a pivotal role in the balanced metabolism of fatty acids and carbohydrates, this study was carried out to investigate whether long-term mildronate treatment could influence glucose levels and prevent diabetic complications in an experimental model of type 2 diabetes in Goto-Kakizaki (GK) rats.

EXPERIMENTAL APPROACH

GK rats were treated orally with mildronate at doses of 100 and 200 mg.kg(-1) daily for 8 weeks. Plasma metabolites reflecting glucose and lipids, as well as fructosamine and beta-hydroxybutyrate, were assessed. L-carnitine concentrations were measured by ultra performance liquid chromatography with tandem mass spectrometry. An isolated rat heart ischaemia-reperfusion model was used to investigate possible cardioprotective effects. Pain sensitivity was measured with a tail-flick latency test.

KEY RESULTS

Mildronate treatment significantly decreased L-carnitine concentrations in rat plasma and gradually decreased both the fed- and fasted-state blood glucose. Mildronate strongly inhibited fructosamine accumulation and loss of pain sensitivity and also ameliorated the enhanced contractile responsiveness of GK rat aortic rings to phenylephrine. In addition, in mildronate-treated hearts, the necrosis zone following coronary occlusion was significantly decreased by 30%.

CONCLUSIONS AND IMPLICATIONS

These results demonstrate for the first time that in GK rats, an experimental model of type 2 diabetes, mildronate decreased L-carnitine contents and exhibited cardioprotective effects, decreased blood glucose concentrations and prevented the loss of pain sensitivity. These findings indicate that mildronate treatment could be beneficial in diabetes patients with cardiovascular problems.

Mildronate decreases carnitine availability and up-regulates glucose uptake and related gene expression in the mouse heart

AIMS

l-carnitine has been shown to play a central role in both fat and carbohydrate metabolisms. This study investigated whether acute and long-term treatments with an l-carnitine biosynthesis inhibitor, mildronate (3-(2,2,2-trimethylhydrazinium) propionate), modulate glucose uptake.

MAIN METHODS

The effects of acute and long-term administration of mildronate at a dose of 200 mg/kg (i.p. daily for 20 days) were tested in mouse blood plasma and heart.

KEY FINDINGS

Acute administration of mildronate in vivo, or in vitro administration with perfusion buffer in isolated heart experiments, did not induce any effects on glucose blood concentration and uptake in the heart. Mildronate long-term treatment significantly decreased carnitine concentration in plasma and heart tissues, as well as increased the rate of insulin-stimulated glucose uptake by 35% and the expression of glucose transporter 4, hexokinase II, and insulin receptor proteins in mouse hearts. In addition, expression of both carnitine palmitoyltransferases IA and IB were significantly increased. Mildronate long-term treatment statistically significantly decreased fed state blood glucose from 6+/-0.2 to 5+/-0.1 mM, but did not affect plasma insulin and C-peptide levels.

SIGNIFICANCE

Our experiments demonstrate for the first time that long-term mildronate treatment decreases carnitine content in the mouse heart and leads to increased glucose uptake and glucose metabolism-related gene expression.

Paradoxical effects of two oximes on nitric oxide production by purified NO synthases, in cell culture and in animals

We have studied the impact of two novel compounds TO-85 (2,6-di-(alpha-aziridino-alpha-hydroxyiminomethyl)pyridine and TO-133 (bis-(diaziridinoglyoximato)copper), designed as NO donors, on nitrite production by cell cultures, NO production in rat tissues and their ability to inhibit purified NO synthases (NOS). Both substances induced considerable increase of nitrite production in cell cultures. When NO production was assayed in rat organs by means of ESR using Fe(DETC) as a spin trap the anticipated NO-increasing activity of TO-85 was observed only in kidneys; the NO level increasing almost 10-fold. Treatment of rats with TO-133, decreased the NO concentration in brain cortex, cerebellum and liver. When the drugs were administered to animals with high level of iNOS expression induced by LPS, TO-85 did not significantly modify the LPS-induced NO production; administration of TO-133 caused a significant decrease of NO production in blood, brain cortex and cerebellum. Only high concentrations of TO-85 were capable of inhibiting iNOS (IC50=7 mM), the substance inhibited eNOS at lower concentrations (IC50=250 microM). Inhibitory activities of TO-85 on nNOS were dependent on BH4 concentrations, suggesting eventual competition of TO-85 with BH4 when the substance interacts with nNOS. TO-133 reduced eNOS activity with IC50=200 microM, nNOS activity with IC50=200 microM, iNOS activity was not much affected by this substance. Thus, the two tested compounds manifest opposite effects on NO production by purified enzymes and in cell culture. The pattern of the NO synthesis modification in a living animal appears to be even more complex. Our results stress the importance of direct measurements of NO in the tissues using the ESR method.

Mildronate, an inhibitor of carnitine biosynthesis, induces an increase in gamma-butyrobetaine contents and cardioprotection in isolated rat heart infarction

The inhibition of gamma-butyrobetaine (GBB) hydroxylase, a key enzyme in the biosynthesis of carnitine, contributes to lay ground for the cardioprotective mechanism of action of mildronate. By inhibiting the biosynthesis of carnitine, mildronate is supposed to induce the accumulation of GBB, a substrate of GBB hydroxylase. This study describes the changes in content of carnitine and GBB in rat plasma and heart tissues during long-term (28 days) treatment of mildronate [i.p. (intraperitoneal) 100 mg/kg/daily]. Obtained data show that in concert with a decrease in carnitine concentration, the administration of mildronate caused a significant increase in GBB concentration. We detected about a 5-fold increase in GBB contents in the plasma and brain and a 7-fold increase in the heart. In addition, we tested the cardioprotective effect of mildronate in isolated rat heart infarction model after 3, 7, and 14 days of administration. We found a statistically significant decrease in necrotic area of infarcted rat hearts after 14 days of treatment with mildronate. The cardioprotective effect of mildronate correlated with an increase in GBB contents. In conclusion, our study, for the first time, provides experimental evidence that the long-term administration of mildronate not only decreases free carnitine concentration, but also causes a significant increase in GBB concentration, which correlates with the cardioprotection of mildronate.

Protection of azidothymidine-induced cardiopathology in mice by mildronate, a mitochondria-targeted drug

Azidothymidine, a nucleoside-analogue reverse transcriptase inhibitor (NRTI), is a commonly used antiretroviral drug in AIDS treatment, however its use is limited by severe toxic side effects due to its influence on mitochondria that result in myopathy, particularly affecting the cardiac muscle. We suggest that effective protection of azidothymidine-induced cardiopathology can be expected from drugs that are capable of targeting mitochondria. Therefore the present study in mice was carried out with mildronate, a cardioprotective drug of the aza-butyrobetaine class, which previously has been shown to act as a highly potent protector of mitochondrial processes. In our study, saline (control), azidothymidine (50 mg/kg), mildronate (50, 100 and 200 mg/kg), and azidothymidine + mildronate (at the doses mentioned) were injected intraperitoneally daily in separate groups of mice for two weeks. At the termination of the experiment, mice were sacrificed, the hearts were removed and cardiac tissue was examined morphologically and immunohistochemically. It was found that azidothymidine, compared to control and mildronate groups, induced major morphologic changes in cardiac tissue, which were manifestated as degeneration and inflammation. These changes were prevented when mildronate was co-administered with azidothymidine. Mildronate also reduced the azidothymidine-induced expression of nuclear factor kappaBp65 (NF-kappaBp65). The obtained data demonstrate a high ability of mildronate of preventing azidothymidine-induced cardiopathologic changes, and suggest mildronate's indirect action on azidothymidine-caused oxidative stress reactions leading to mitochondrial dysfunction. This offers a rational combination of mildronate with azidothymidine or other anti-HIV drugs for beneficial application in AIDS therapy.

Mildronate, a novel fatty acid oxidation inhibitor and antianginal agent, reduces myocardial infarct size without affecting hemodynamics

Mildronate is a fatty acid oxidation inhibitor approved as an antianginal drug in parts of Europe. We carried out the first study to determine whether a 10-day course of mildronate could reduce myocardial infarct size (IS) during acute myocardial ischemia. Sprague Dawley rats received 200 mg/kg/d of mildronate (treated group, n = 16) or sterile water (control group, n = 14) subcutaneously for 10 days before ischemia-reperfusion. Rats were then subjected to 45 minutes of left coronary artery occlusion and 2 hours of reperfusion. The 2 groups had identical areas at risk: treated 38 +/- 3%; controls 38 +/- 2%. The amount of necrosis was smaller in the mildronate group at 16 +/- 2% of the left ventricle versus controls, 22 +/- 2% (P = 0.05); and for any amount of risk >25%, necrosis was smaller in the treated group (P = 0.0035). Myocardial IS (% of risk zone) was 43+/-3% in the mildronate-treated rats, and 57+/-4% in controls (P = 0.004). During occlusion, there were no differences between the 2 groups in heart rate (216 +/- 12 bpm, mildronate and 210 +/- 9 bpm, control), in mean arterial pressure (60 +/- 2 mm Hg, mildronate and 64 +/- 3 mm Hg, control) or in the frequency of arrhythmias. Our study for the first time demonstrated that a 10-day treatment with mildronate reduced myocardial IS in an experimental model of acute myocardial ischemia, without any effect on hemodynamics.

The MC3 receptor binding affinity of melanocortins correlates with the nitric oxide production inhibition in mice brain inflammation model

Melanocortins possess strong anti-inflammatory effects acting in the central nervous system via inhibition of the production of nitric oxide (NO) during brain inflammation. To shed more light into the role of melanocortin (MC) receptor subtypes involved we synthesized and evaluated some novel peptides, modified in the melanocyte-stimulating hormone (MSH) core structure, natural MCs and known MC receptor selective peptides - MS05, MS06. Since the study included both selective, high affinity binders and the novel peptides, it was possible to do the correlation analysis of binding activities and the NO induction-related anti-inflammatory effect of the peptides. beta-MSH, gamma1-MSH, gamma2-MSH, alpha-MSH, MS05, Ac-MS06 and Ac-[Ser12]MS06 caused dose dependent inhibition of the lipopolysaccharide (LPS)-induced increase of NO overproduction in the mice forebrain whereas MSH core modified peptides Ac-[Asp9,Ser12]MS06, [Asp9]alpha-MSH and [Asp16]beta-MSH were devoid of this effect in doses up to 10 nmol per mouse. When the minimal effective dose required for inhibition of NO production was correlated with the in vitro binding activity to MC receptor subtypes a strong and significant correlation was found for the MC3 receptor (r = 0.90; p = 0.0008), whereas weak correlation was present for the other receptors. Our results suggest that the MC3 receptor is the major player in mediating the anti-inflammatory activity of MCs in the central nervous system.

[Mildronate in geriatric patients with cardiac failure]

AIM

To study efficacy of mildronate in the treatment of elderly patients with cardiac failure (CF).

MATERIAL AND METHODS

A total of 91 patients with chronic CF (NYHA FC I-III) entered the study. The study group of 63 patients received standard therapy for a month and mildronate in a dose 750 mg/day. The control group of 28 patients was treated conventionally. Subjective and objective assessment of the patients' condition, quality of life questionnaire, ECG, 6-min walk test were used for evaluation of the treatment efficacy.

RESULTS

In the study group daily frequency of anginal attacks reduced from 1.6 to 0.7 (in the control group from 1.46 to 1.25, p > 0.05), intensity of the attacks--from 1.4 to 0.7 points by 7-score scale (p < 0.05). Crepitation disappeared in 8 (12.8%) patients, edema of the legs--in 3 (4.8%) patients. Systolic blood pressure went down by 8 mmHg, diastolic one--by 4 mmHg. In the control group clinical changes were insignificant.

CONCLUSION

Elderly patients tolerated mildronate well. It was a safe drug attenuating CF symptoms, increasing exercise tolerance and improving quality of life.

Mildronate: an antiischemic drug for neurological indications

Mildronate (3-(2,2,2-trimethylhydrazinium)propionate; MET-88; meldonium, quaterine) is an antiischemic drug developed at the Latvian Institute of Organic Synthesis. Mildronate was designed to inhibit carnitine biosynthesis in order to prevent accumulation of cytotoxic intermediate products of fatty acid beta-oxidation in ischemic tissues and to block this highly oxygen-consuming process. Mildronate is efficient in the treatment of heart ischemia and its consequences. Extensive evaluation of pharmacological activities of mildronate revealed its beneficial effect on cerebral circulation disorders and central nervous system (CNS) functions. The drug is used in neurological clinics for the treatment of brain circulation disorders. It appears to improve patients' mood; they become more active, their motor dysfunction decreases, and asthenia, dizziness and nausea become less pronounced. Since the brain does not utilize fatty acids as fuel other mechanisms of action of mildronate in CNS should be considered. Several reports indicate the possible existence of an alternative, non-carnitine dependent mechanism of action of mildronate. Our recent findings suggest that CNS effects of mildronate could be mediated by stimulation of the nitric oxide production in the vascular endothelium by modification of the gamma-butyrobetaine and its esters pools. It is hypothesized that mildronate may increase the formation of the gamma-butyrobetaine esters. The latter are potent cholinomimetics and may activate eNOS via acetylcholine receptors or specific gamma-butyrobetaine ester receptors. This article summarizes known pharmacological effects of mildronate, its pharmacokinetics, toxicology, as well as the proposed mechanisms of action.

Beta-MSH inhibits brain inflammation via MC(3)/(4) receptors and impaired NF-kappaB signaling

The anti-inflammatory effects of melanocortin peptides have been demonstrated in different inflammation models. This is the first report describing the molecular mechanisms for the beta-MSH-induced suppression of bacterial lipopolisaccharide (LPS)-caused brain inflammation. We found that beta-MSH suppresses LPS-induced nuclear translocation of the transcription factor NF-kappaB, and inhibits the expression of inducible nitric oxide synthase, and the following nitric oxide overproduction in the brain, in vivo. Moreover, administering the preferentially MC(4) receptor selective antagonist HS014 blocked completely these effects, suggesting a tentative MC(4) receptor mediated mechanism of action for the beta-MSH. However, as HS014 shows quite low selectivity vis-à-vis the MC(3) receptor, a role for the MC(3) receptor cannot be excluded. In conclusion, our results show that beta-MSH is capable of inhibiting brain inflammation via activation of melanocortin receptors, of the subtypes 4 and/or 3.

Endothelium- and nitric oxide-dependent vasorelaxing activities of gamma-butyrobetaine esters: possible link to the antiischemic activities of mildronate

Mildronate [3-(2,2,2-trimethylhydrazine) propionate (THP)] is an antiischemic drug acting mainly via inhibition of fatty acid beta-oxidation. Some effects of the drug cannot be explained by the latter mechanism. We tested the eventual nitric oxide (NO) dependence of the mildronate action. Mildronate, gamma-butyrobetaine (GBB) and GBB methyl ester induced transient increases in nitric oxide (NO) concentrations in rat blood and myocardium. In vitro, these compounds neither modified the activities of purified neuronal and endothelial recombinant nitric oxide synthases (NOSs) nor were able to interact with their active site. GBB induced vasodilatation at high concentrations only (EC50 = 5 x 10(-5) M) while mildronate alone displayed no vasodilating effect although it enhanced the GBB vasodilating activity. GBB methyl and ethyl esters were found more potent vasodilators (EC50 = 2.5 x 10(-6) M). Pretreatment of aortic rings with NOS inhibitor Nomega-nitro-L-arginine methyl ester (L-NAME) abolished vasodilating effects of the compounds. A hypothesis explaining NO and endothelium-dependent effects of mildronate and its analogues is proposed.

Investigations on the pharmacology of the cardioprotective guanidine ME10092

The guanidine compound ME10092 (1-(3,4-dimethoxy-2-chlorobenzylideneamino)-guanidine), which possesses a strong cardioprotective effect to ischemia-reperfusion, was assessed for different pharmacological actions that may underlie its cardioprotective effect. In the living rat ME10092 decreased the blood pressure and heart rate in a dose-dependent manner. We found ME10092 to bind to alpha 1- and alpha 2-adrenoreceptors with moderate affinity (Ki values 1-4 microM), and to block adrenaline-elicited contractile responses in isolated guinea pig aortas. Our results indicate that ME10092 possesses a certain anti-oxidant profile. Thus, in a competitive manner and with low affinity it inhibited the bovine milk xanthine oxidase enzyme, as well as NAD(P)H oxidase driven oxyradical formation in membrane fractions isolated from the rat brain. By using electron paramagnetic resonance we here show that, after its systemic administration, ME10092 modulates the nitric oxide (NO) content in several tissues of the rat in a time-dependent manner. However, in vitro ME10092 inhibited the activities of nitric oxide synthases nNOS and eNOS, but not that of iNOS. Our data give evidence that the cardioprotective effect of ME10092 could be mediated through pharmacological mechanisms that include some modulation of NO production, as well as possible inhibition of radical formation during ischemia-reperfusion.

Putative role of nitric oxide synthase isoforms in the changes of nitric oxide concentration in rat brain cortex and cerebellum following sevoflurane and isoflurane anaesthesia

We have previously observed an increase in nitric oxide (NO) content in rat brain cortex following halothane, sevoflurane or isoflurane anaesthesia. This study was undertaken in order to determine whether isoform-specific nitric oxide synthase (NOS) inhibitors and inducers could modify these increases in NO contents. Rats were subjected to isoflurane and sevoflurane anaesthesia with concomitant administration of neuronal nitric oxide synthase (nNOS) inhibitor 7-Nitro-indazole (7-NI), inducible nitric oxide synthase (iNOS) inhibitor 2-amino-5,6-dihydro-6-methyl-4H-1,3-thiazine (AMT) or lipopolysaccharide. NO concentration in different organs was measured by electron paramagnetic resonance (EPR) spectroscopy. 7-NI significantly decreased NO concentration in cerebellum but not in brain cortex, whereas AMT decreased NO in all the organs studied. Anaesthesia significantly increased NO concentration in brain cortex and decreased that in cerebellum. AMT abolished the NO increase in brain cortex. Anaesthesia enhanced the drastic increase in NO concentration in brain cortex after intraventricular lipopolysaccharide administration. Isoflurane was found to inhibit recombinant nNOS and iNOS activities at high concentrations (EC50=20 mM). Our data suggest a putative role for iNOS in the increase in NO levels produced by isoflurane and sevoflurane, whereas nNOS activity is probably inhibited during anaesthesia.

Synthesis and quantitative structure-activity relationship of hydrazones of N-amino-N'-hydroxyguanidine as electron acceptors for xanthine oxidase

A series of new N-hydroxyguanidines were synthesized and tested for electron acceptor activity on bovine milk xanthine oxidase using xanthine as reducing substrate. Manual inspection of the structure-activity data revealed that molecules containing nitro groups ("set A") show a different structure-activity relationship pattern compared to non-nitro compounds ("set B"). Accordingly separate QSAR models were built and validated for the two sets. Substantial differences were found in properties governing acceptor activity for the models, the only common property being sterical access to the imino nitrogen atom of the hydroxyguanidinimines. For set A molecules the presence of a nitro substituent at a certain distance range from the hydroxuguanidino group was most important. In addition, the presence of a nitro group in the ortho position interacting with NH(2) of the hydroxyguanidino group, and the mutual geometry of the phenyl ring, hydroxyguanidine, and imine groups was important for this set. By contrast, for set B molecules the acceptor activity was most influenced by the geometry of methoxy groups and the size and geometry of meta and para substituents of the phenyl ring.

The methylester of gamma-butyrobetaine, but not gamma-butyrobetaine itself, induces muscarinic receptor-dependent vasodilatation

Gamma-butyrobetaine (GBB) is known mostly as a bio-precursor of carnitine, a key molecule in the regulation of myocardial energy metabolism. The metabolites of carnitine and GBB were investigated for acetylcholine-like activity decades ago. The present study shows that the methylester of GBB (GBB-ME) exerts its biological activity by binding to muscarinic acetylcholine receptors. GBB-ME dose-dependently decreased the blood pressure in anaesthetised rats and also produced endothelium-dependent vasodilation in the isolated guinea-pig heart. The biological effects of GBB-ME were inhibited partially by the NOS inhibitor N(omega)-nitro-L-arginine methylester (L-NAME) and abolished by the acetylcholine receptor antagonist atropine, thus supporting the hypothesis that GBB-ME acts as muscarinic agonist. Moreover, we have shown here for the first time that GBB-ME binds directly to transfected human muscarinic (m) acetylcholine receptors, the potency order being m2>m5> or =m4> or =m1>m3. GBB itself showed neither biological activity nor significant affinity for the m1-5 receptors. We conclude that GBB-ME, but not the parent GBB, possesses acetylcholine-like activity in vivo and in vitro.

Effects of gamma-butyrobetaine and mildronate on nitric oxide production in lipopolysaccharide-treated rats

Production of nitric oxide was measured in lipopolysaccharide-treated rats (10 mg/kg, 4 hr) using the electron paramagnetic resonance method. As compared to the control animals, the nitric oxide level in liver of lipopolysaccharide-treated rats increased from 27.6+/-4.7 to 1485+/-129 ng/g tissue, in heart from 4.8+/-0.7 to 271+/-26 ng/g tissue, in blood from 33.6+/-12.4 to 638+/-136 ng/g tissue, in kidney from 3.3+/-0.5 to 356+/-31 ng/g tissue, in brain cortex from 46.0+/-3.4 to 227+/-27 ng/g tissue, in cerebellum from 27.7+/-2.6 to 218+/-30 ng/g tissue, and in testes from 13.8+/-1.1 to 86+/-8 ng/g tissue. Administration of the antiischaemic drug, mildronate (120 mg/kg) caused a significant twofold decrease of the nitric oxide level in brain cortex and cerebellum 1 hr after drug administration. Its natural analogue gamma-butyrobetaine (30 mg/kg) triggered a twofold decrease of the nitric oxide concentration in all studied tissues 30 min. after the administration. Nitric oxide reached the initial level 2 hr later. Neither mildronate nor gamma-butyrobetaine could inhibit the inducible nitric oxide synthase in vitro. Analogues of gamma-butyrobetaine appear to be prospective drugs for the treatment of circulatory complications of sepsis.