Ferroptosis and Photodynamic Therapy Synergism: Enhancing Anticancer Treatment.

Photodynamic therapy (PDT) is widely used in cancer treatment; however, several challenges compromise its efficiency. We propose a synergistic action between PDT and ferroptotic cell death. PDT acts as a source of reactive oxygen species for the Fenton reaction, which may reinforce ferroptosis induction and increase PDT efficacy in anticancer therapy.

Bioactive ß-Carbolines in Food: A Review.

Harman and norharman, two neuroactive ß-carbolines, are present in several plants and in thermally processed foods. They exhibited a wide spectrum of biological and pharmacological effects, including antioxidant, neuroprotective, and anti-inflammatory effects. In this article, we review the progress of recent research on the presence of these compounds in food, as well as their various biological and neuroactive properties. Our findings strongly suggest that some foods, especially coffee, can act as a rich source of ß-carbolines, which may possibly be associated with a reduced risk for serious neurodegenerative diseases, such as Parkinson's and Alzheimer's.

In vitro metabolism of 4, 5-dimethoxycanthin-6-one by human liver microsomes and its inhibition on human CYP1A2.

AIMS: P. quassioides is a traditional Chinese medicine used for the treatment of gastroenteritis, snakebite, infection and hypertension in China. 4, 5-dimethoxycanthin-6-one is one of the main active canthinone alkaloid isolated from P. quassioides. The aim of this work was to identify the cytochrome P (CYP) 450 enzymes responsible for the metabolism of 4, 5-dimethoxycanthin-6-one (DCO) and to evaluate the inhibitory effect of DCO on CYP activity in human liver microsomes (HLM) in vitro. MATERIALS AND METHODS: the CYP isoforms responsible for DCO metabolism and the inhibitory effects of DCO on CYP activity was studied in HLM. KEY FINDINGS: The in vitro metabolic enzyme of DCO was CYP3A4 (mediated the formation of metabolites M1-M5), CYP2C9 (mediated the formation of metabolites M1-M3, M6 and M8) and CYP2D6 (mediated the formation of metabolite M3) in HLM. Furthermore, the present work found that DCO uncompetitively inhibited CYP1A2-mediated phenacetin O-deethylation with an IC50 value of 1.7µM and a Ki value of 2.6µM. SIGNIFICANCE: The results suggested that the metabolic interaction should be existed when the substrate drugs of CYP1A2 were co-administered with DCO or traditional Chinese medicine containing it, such as the extract of P. quassioides and Kumu injection.

Pharmacokinetics and tissue distribution of 4,5-dimethoxycanthin-6-one and its major metabolites in rats.

4,5-Dimethoxycanthin-6-one and 5-hydroxy-4-methoxycanthin-6-one are the active ingredients of P. quassiodes. In the present work, a LC-MS/MS method was developed for the determination of 4,5-dimethoxycanthin-6-one and its major metabolites 5-hydroxy-4-methoxycanthin-6-one (M1) and 4-hydroxy-5-methoxycanthin-6-one (M2) in rat plasma and tissues, and applied to study their pharmacokinetics and tissue distribution after intramuscular administration of 4,5-dimethoxycanthin-6-one to rats. By protein precipitation with methanol for plasma samples and liquid-liquid extraction with ethyl acetate for tissue samples, the analytes were separated on an ODS C18 column with a mobile phase consisted of methanol and water (0.1% formic acid), and quantified by a MS detector in positive multiple reaction monitoring (MRM) mode. MS transitions were m/z 281.0→167.1 for 4,5-dimethoxycanthin-6-one, m/z 267.0→168.1 for M1 and M2, m/z 251.0→195.1 for 3-methylcanthin-2,6-dione (IS). The pharmacokinetic results indicate that 4,5-dimethoxycanthin-6-one is absorbed rapidly (Tmax=5.4-6.4min), distributed rapidly and widely in the order of liver>kidney≈lung≈large intestine≈small intestine, and eliminated quickly (t1/2z=64.9-77.7min) following the intramuscular administration. Furthermore, M1 and M2 were detected only in rat plasma and liver at the indicated times after the intramuscular administration.

[Protective effect of tadalafil against ischemia-reperfusion injury in rats].

OBJECTIVE: To investigate the protective effect of phosphodiesterase type 5 inhibitors (tadalafil) on the testis following testicular ischemia-reperfusion injury in rats. METHODS: Eighty-four healthy adult male SD rats were randomly and equally divided into groups A (sham operation), B (testicular torsion + low-dose tadalafil), C (testicular torsion + high-dose tadalafil), and D (testicular torsion + placebo). Models were established in the latter three groups by 7200 torsion of the right testis for 2 hours. The animals in groups A and B were treated by gavage with tadalafil at the dose of 0. 5 mg per kg per day, those in group C at 2 mg per kg per day, and those in group D with saline at the same dose. After 3, 7, and 14 days of treatment, the torsioned testes were harvested for evaluation of the superoxide dismutase (SOD) activity and malondialdehyde (MDA) content in the testis tissue. The pathological changes in the testis were observed under the light microscope. RESULTS: At 3, 7, and 14 days, the SOD activity was (254.46 +/- 7.43), (278.49 +/- 8.33), and (317.99 +/- 3.31) nU/mg prot in group B, and (277.12 +/- 8.80), (309.40 +/- 2.14), and (320.39 +/- 4.72) nU/mg prot in group C, all obviously higher than in D ([223.21 +/- 4.65], [231.45 +/- 4.16] and [248.28 +/- 5.74] nU/mg prot), while the MDA content was lower in the former two groups than in the latter. At 3 and 7 days, the SOD activity was significantly higher and the MDA level significantly lower in group C than in B (both P < 0.01) , while at 14 days, neither showed any remarkable differences between the two groups (P > 0.05). No obvious histopathological change was observed in the testis tissue of group A. At 3 and 7 days, pathological examination of the testis tissue revealed significant differences in the number of seminiferous epithelial layers, testicular histological score, and seminiferous tubule diameter in group B (P < 0.01), but the three indexes at 14 days in group B and at 7 days in group C exhibited no remarkable differences from those at 14 days in group A. CONCLUSION: Tadalafil can alleviate testicular ischemia-reperfusion injury following testis torsion/detorsion in a time- and dose-dependent manner.

Detection of a tadalafil analogue as an adulterant in a dietary supplement for erectile dysfunction.

INTRODUCTION: Several cases of adulteration of dietary supplements with tadalafil, sildenafil, and vardenafil, or their unapproved analogues have been reported worldwide. Mainly, the presence of the latter represents a serious health risk to consumers as their efficacy and toxic effects have not been assessed and may result in unpredictable adverse effects. AIM: To investigate the suspected adulteration with synthetic phosphodiesterase type 5 (PDE-5) inhibitors in a dietary supplement marketed in Argentina for the treatment of erectile dysfunction (ED). METHODS: The content of the capsules of the dietary supplement (sample A) was analyzed by thin layer chromatography (TLC) and high-performance liquid chromatography (HPLC) diode-array detection. From the organic extract of sample A, a major compound was purified by column chromatography (CC). The isolated compound was identified by proton nuclear magnetic resonance (1H NMR) and carbon NMR (13C NMR), heteronuclear single quantum coherence, distortionless enhancement by polarization transfer (DEPT 135), electrospray ionization mass spectrometry, and ultraviolet, and infrared (Fourier transform infrared spectroscopy) spectroscopy. MAIN OUTCOME MEASURE: Proof of adulteration of herbal products with synthetic PDE-5 inhibitors. RESULTS: By TLC and HPLC analysis, a major compound was detected in sample A organic extract. The purification of this extract by CC led to the isolation of a pure compound which was identified according to its spectral data as (6R,12aR)-2-amino-6-(1,3-benzodioxol-5-yl)-2,3,6,7,12,12a-hexahydropyrazino [1',2':1,6] pyrido [3,4-b] indole-1,4-dione or aminotadalafil. CONCLUSIONS: An unapproved PDE-5 inhibitor analogue, which was identified as aminotadalafil, has been detected in a dietary supplement. This study represents the first report in Latin America and one of the few independent studies of an adulteration with an unapproved PDE-5 inhibitor of an herbal product for ED treatment.

[Low-dose tadalafil combined with Shuganyiyang capsules for mild-to-moderate erectile dysfunction].

OBJECTIVE: To observe the clinical effect of low-dose once-daily tadalafil combined with Shuganyiyang Capsules in the treatment of mild-to-moderate erectile dysfunction (ED). METHODS: Ninety patients with mild-to-moderate ED were equally randomized to groups A, B and C to receive Shuganyiyang Capsules, tadalafil, and tadalafil + Shuganyiyang Capsules, respectively. The scores of the patients on IIEF-5 and SF-PAIRS (15-Item Short Form of Psychological Interpersonal Relationship Scales) were recorded before and at 1 and 3 months after treatment. RESULTS: The IIEF-5 scores of groups A, B and C were 10.13 +/- 1.55, 11.00 + 1.60 and 10.73 +/- 1.91 before treatment, and 13.77 +/- 2.11, 17.77 +/- 2.13 and 17.17 +/- 3.84 at 1 month after treatment, significantly higher in B and C than in A (P <0. 001) , but with no remarkable difference between B and C (P =0. 411). At 3 months after treatment, the IIEF-5 scores were 15.77 +/- 2.05, 18.07 +/- 2.24 and 19.37 +/- 3.76 in the three groups, dramatically higher in B and C than in A (P <0.001) as well as in C than in B (P<0.05). The scores on sexual self-confidence, sexual spontaneity and time concerns in SF-PAIRS were 3.90 +/-0.80, 8.67 +/- 1.94 and 14.43 +/- 1.92 before medication, 5.83 +/- 1.02, 9.90 +/- 1.75 and 11.17 +/- 1.68 at 1 month and 6.73 +/- 0.98, 11.07 +/- 2.08 and 10.67 +/-1.60 at 3 months after medication in group A; 4.17 +/- 0.87, 9.37 +/-1.43 and 14.47 +/-1.57 before medication, 6.47 +/-0.78, 10.83 +/- 2.18 and 10.20 +/-1.56 at 1 month and 6.83 +/-0.91, 11.30 +/- 1.88 and 9.47 +/- 1.57 at 3 months in group B; and 4.23 +/-0. 94, 9.50 +/- 1.89 and 14.67 +/- 2.91 before medication, 8.03 +/- 1.67, 13.43 +/-1.10 and 9.70 +/-1.21 at 1 month and 8.93 +/- 1.78, 14.70 +/- 1.26 and 8. 87 +/- 0. 97 at 3 months in group C. Compared with the baseline, the SF-PAIRS scores of the three groups were all significantly improved after treatment (P <0. 05) , and markedly higher in C than in the other two groups (P <0.05). CONCLUSION: Low-dose once-daily tadalafil combined with Shuganyiyang Capsules is obviously effective in the treatment of mild-to-moderate ED, which not only improves the patients'erectile function, sexual self-confidence and sexual spontaneity, but also reduces their time concerns.

Antenatal maternally-administered phosphodiesterase type 5 inhibitors normalize eNOS expression in the fetal lamb model of congenital diaphragmatic hernia.

PURPOSE: Pulmonary hypertension (pHTN), a main determinant of survival in congenital diaphragmatic hernia (CDH), results from in utero vascular remodeling. Phosphodiesterase type 5 (PDE5) inhibitors have never been used antenatally to treat pHTN. The purpose of this study is to determine if antenatal PDE5 inhibitors can prevent pHTN in the fetal lamb model of CDH. METHODS: CDH was created in pregnant ewes. Postoperatively, pregnant ewes received oral placebo or tadalafil, a PDE5 inhibitor, until delivery. Near term gestation, lambs underwent resuscitations, and lung tissue was snap frozen for protein analysis. RESULTS: Mean cGMP levels were 0.53±0.11 in placebo-treated fetal lambs and 1.73±0.21 in tadalafil-treated fetal lambs (p=0.002). Normalized expression of eNOS was 82%±12% in Normal-Placebo, 61%±5% in CDH-Placebo, 116%±6% in Normal-Tadalafil, and 86%±8% in CDH-Tadalafil lambs. Normalized expression of ß-sGC was 105%±15% in Normal-Placebo, 82%±3% in CDH-Placebo, 158%±16% in Normal-Tadalafil, and 86%±8% in CDH-Tadalafil lambs. Endothelial NOS and ß-sGC were significantly decreased in CDH (p=0.0007 and 0.01 for eNOS and ß-sGC, respectively), and tadalafil significantly increased eNOS expression (p=0.0002). CONCLUSIONS: PDE5 inhibitors can cross the placental barrier. ß-sGC and eNOS are downregulated in fetal lambs with CDH. Antenatal PDE5 inhibitors normalize eNOS and may prevent in utero vascular remodeling in CDH.

Determination of dimethyltryptamine and ß-carbolines (ayahuasca alkaloids) in plasma samples by LC-MS/MS.

BACKGROUND: Ayahuasca is a psychoactive plant beverage originally used by indigenous people throughout the Amazon Basin, long before its modern use by syncretic religious groups established in Brazil, the USA and European countries. The objective of this study was to develop a method for quantification of dimethyltryptamine and ß-carbolines in human plasma samples. RESULTS: The analytes were extracted by means of C18 cartridges and injected into LC-MS/MS, operated in positive ion mode and multiple reaction monitoring. The LOQs obtained for all analytes were below 0.5 ng/ml. By using the weighted least squares linear regression, the accuracy of the analytical method was improved at the lower end of the calibration curve (from 0.5 to 100 ng/ml; r(2)> 0.98). CONCLUSION: The method proved to be simple, rapid and useful to estimate administered doses for further pharmacological and toxicological investigations of ayahuasca exposure.

Strictosidinic acid, isolated from Psychotria myriantha Mull. Arg. (Rubiaceae), decreases serotonin levels in rat hippocampus.

Psychotria is a complex genus whose neotropical species are known by the presence of glucosidic monoterpene indole alkaloids. These compounds are able to display a large range of effects on the central nervous system, such as anxiolytic, antidepressant, analgesic, and impairment of learning and memory acquisition. The aims of this study were to investigate the effects displayed by strictosidinic acid, isolated from Psychotria myriantha Mull. Arg. (Rubiaceae) leaves, on monoamine levels in rat hippocampus and on monoamine oxidase activity. A significance (p<0.01) of 83.5% reduction in 5-HT levels was observed after intra-hippocampal injection (20 µg/µl). After treatment by intraperitoneal route (10 mg/kg), a 63.4% reduction in 5-HT levels and a 67.4% reduction in DOPAC values were observed. The results indicate that strictosidinic acid seems to act on 5-HT system in rat hippocampus, possibly inhibiting precursor enzymes of 5-HT biosynthesis. The decrease verified in DOPAC levels suggests a role of strictosidinic acid in the dopaminergic transmission, probably due to an inhibition of monoamine oxidase activity, confirmed by the enzymatic assay, which demonstrated an inhibitory effect on MAO A in rat brain mitochondria.

[Yangjing capsule plus low-dose tadalafil for functional anejaculation].

OBJECTIVE: To search for an effective therapy for functional anejaculation (AE). METHODS: Fifty-five AE patients were randomized into a treatment group (n = 30) and a control group (n = 25), the former treated with Yangjing Capsule (once 5 pills, tid) and low-dose tadalafil (5 mg, qd alt, 1 h before bedtime), while the latter with oral ephedrine (25 mg before bedtime). Meanwhile, the patients were advised to expose themselves to sexual stimulation, reduce the frequency of sexual intercourses and quit masturbation. The medication lasted 1-3 months, followed by observation of the therapeutic effects. RESULTS: The total effectiveness rate was 83.34% in the treatment group, 11 cases cured, 8 obviously improved, 6 improved and 5 unimproved, significantly higher than 40.00% in the control group, 4 cases cured, 3 obviously improved, 3 improved and 15 unimproved (P < 0.05). CONCLUSION: Yangiing Capsule plus low-dose tadalafil is safe and effective for the treatment of functional anejaculation.

Neuropathy in a rat model of mild diabetes induced by multiple low doses of streptozotocin: effects of the antioxidant stobadine in comparison with a high-dose alpha-lipoic acid treatment.

Hyperglycaemia-induced oxidative stress makes an important contribution to the aetiology of diabetic neuropathy. The aim of our study was to evaluate the effect of the antioxidant stobadine (STB) in comparison with a treatment by a high-dose of alpha-lipoic acid (ALA), on the neurological consequences of chronic hyperglycaemia in an animal model of diabetes in Wistar rats (16 weeks old), made diabetic by streptozotocin (STZ 3 x 20 mg i.v.). Neuropathy was evaluated electrophysiologically by measuring motor nerve conduction velocity (NCV) in the 4th and 8th week in vivo and motor NCV and resistance to ischaemic conduction failure (RICF) of the sciatic nerve in the 10th week of the experiment in vitro. The therapy with ALA (100 mg/kg i.p., 5 times a week) and STB (25 mg/kg i.p., 5 times a week) had a significant effect on NCV in vivo in the 8th week of the experiment and no effect in the 10th week in vitro. The RICF elevated in diabetic animals was significantly modified by ALA. The effect of the antioxidant STB on NCV was comparable with that of ALA, while RICF was affected only by ALA. We conclude that treatment with appropriate antioxidants might partially prevent nerve dysfunction in diabetic rats.

Effects of beta-carboline alkaloids on the object recognition task in mice.

beta-carboline alkaloids are found in several medicinal plants and display a variety of actions on the central nervous, muscular and cardiovascular systems. The aim of the present study was to evaluate the effects of systemic administration of beta-carboline alkaloids on object recognition in mice. Adult Swiss mice received an intra-peritoneal injection (i.p.) of alkaloids (1.0, 2.5 or 5.0 mg/kg) 30 min before training in an object recognition task. The fully aromatic beta-carbolines, harmine and harmol, induced an enhancement of short-term memory (STM) at all doses tested when compared to controls. Harmaline, a dihydro beta-carboline and inverse agonist of the MK-801 binding site on the N-methyl-d-aspartate (NMDA) receptor, also induced an enhancement of both short-term memory (STM) and long-term memory (LTM). These results demonstrate that systemic administration of beta-carboline alkaloids can improve object recognition memory in mice.

Preclinical assessment of the feasibility of applying controlled release oral drug delivery to a lead series of atypical antipsychotics.

In this paper, we present a preclinical approach for evaluating the feasibility of applying controlled-release (CR) oral drug delivery to increase the duration of exposure and lower the C(max) of compounds in a lead series of short half-life atypical antipsychotics. Three lead compounds in the series had demonstrated potential pharmacological benefits for the treatment of psychosis, in preclinical studies. However, the compounds showed evidence of insufficient half-lives to enable a once-a-day (QD) product using immediate-release (IR) oral delivery. To evaluate and compare the potential for oral CR delivery to extend the duration of action and thereby enable QD administration, the in vitro solubility and permeability, and the duodenal and colonic absorption of three compounds in the series were measured. Based on the results, one candidate was selected for advancement that showed moderate in vitro solubility, but had the highest in vitro permeability and ratio of colonic to duodenal bioavailability (0.9) in the rat. The results from this study provided evidence that a CR drug delivery system could be used to extend the duration of exposure of the compounds in the series and a scientific basis for selecting one of the three compounds as a candidate.

Evidence for contamination of herbal erectile dysfunction products with phosphodiesterase type 5 inhibitors.

PURPOSE: We determined if pharmacological dosages of phosphodiesterase type 5 inhibitors (PDE5) inhibitors were present within a group of natural products marketed for the treatment of erectile dysfunction. MATERIALS AND METHODS: Seven herbal products marketed for the treatment of erectile dysfunction were purchased via the Internet or at local health food stores. Specimens were batched, relabeled and blindly analyzed for contamination with PDE5 inhibitors. High performance liquid chromatography and mass spectrometry were used to detect evidence of contamination with sildenafil, tadalafil or vardenafil. RESULTS: Of the 7 tested products 2 contained pharmacological dosages of sildenafil and tadalafil. Contamination with vardenafil was not identified. Mean dosages of sildenafil and tadalafil were 30.2 and 19.7 mg, respectively. CONCLUSIONS: A significant proportion of natural products marketed for erectile dysfunction contains PDE5 inhibitors. Although marketed as natural products devoid of adverse effects, these agents are known to have potentially fatal drug interactions with nitrates. Better regulation of the natural health products industry is urged.

Effect of the pyridoindole antioxidant stobadine on development of experimental diabetic cataract and on lens protein oxidation in rats: comparison with vitamin E and BHT.

PURPOSE: The aim of this study was to investigate the effect of dietary supplementation with the pyridoindole antioxidant stobadine on the development of diabetic cataract in rats. The findings were compared with the effect of the natural antioxidant vitamin E and the well known phenolic synthetic antioxidant butylated hydroxytoluene. METHODS: Streptozotocin induced diabetic male Wistars rats were fed for 18 weeks a standard diet or a diet supplemented with stobadine (0.05% w/w), vitamin E (0.1% w/w), butylated hydroxytoluene (BHT, 0.4% w/w), or a mixture of stobadine (0.05% w/w) and vitamin E (0.1% w/w). The progress of cataract was monitored biweekly by ophthalmoscopic inspection. Plasma glucose and body weight were recorded regularly. At the end of the experiment, the content of free sulfhydryl and carbonyl was determined in total lens proteins and in the stobadine group plasma levels of malondialdehyde were also measured. RESULTS: Long term treatment of diabetic animals with stobadine (STB), vitamin E, or BHT led to a marked delay in the development of advanced stages of cataract. At the end of the experiment, the visual cataract score was significantly decreased in the diabetic groups treated with stobadine or BHT, while vitamin E had no significant effect. Unexpectedly, combined treatment with STB+vitamin E advanced the progression of the higher stages of cataract, though without affecting the overall visual cataract score. Neither of the antioxidants exerted an effect on the glycemic state or body weight of the animals. Biochemical analyses of eye lens proteins showed significant diminution of sulfhydryl groups and elevation of carbonyl groups in diabetic animals in comparison to healthy controls. Dietary supplementation with any of the antioxidants studied did not influence the levels of these biomarkers significantly. Nevertheless, in diabetic animals, stobadine supplementation significantly attenuated plasma levels of malondialdehyde, an index of systemic oxidative damage. CONCLUSIONS: The results are in accordance with the postulated pro-oxidant role of chronic hyperglycemia, however, the direct oxidative free radical damage of eye lens proteins does not seem to be the key mechanism effective in the development of diabetic cataract. Sugar cataractogenesis appears to be a complex process, in which multiple mechanisms may be involved, including consequences of the overt oxidative stress in diabetes (e.g., protein modifying potential of toxic aldehydes generated as byproducts of carbohydrate autoxidation and lipid peroxidation). The ability of stobadine to attenuate lipoxidation reactions in diabetes may account, at least partly, for its observed anticataract action. Mechanisms involving reduction of mitochondrial damage by stobadine are also discussed.

In vitro and in vivo antimalarial properties of isostrychnopentamine, an indolomonoterpenic alkaloid from Strychnos usambarensis.

Isostrychnopentamine (ISP) is an asymmetric indolomonoterpenic alkaloid isolated from the leaves of Strychnos usambarensis. The in vitro antiplasmodial activities against five Plasmodium falciparum cell lines were evaluated: ISP possessed an in vitro IC (50) near 0.1 microM against all P. falciparum cell lines tested (chloroquine-resistant and chloroquine-sensitive lines) and showed antiplasmodial selectivity compared to cytotoxicity on human cell lines. The stage-dependent susceptibility to a short exposure of ISP was then investigated. The ring stage was shown to be the most sensitive one, but all stages were affected by ISP treatment. By means of fluorescence microscopy, it was shown that ISP was not accumulated inside the food vacuole of the parasite. Finally, the in vivo antimalarial activities against the P. berghei NK173 and P. vinckei petteri murine strains were determined. The ED (50) in vivo was about 30 mg/kg/day by the intraperitoneal route (after 4 days treatment).

Synthesis and antimycobacterial activity of some beta-carboline alkaloids.

In view of the attributed medicinal properties of beta-carboline alkaloids, some new O-acyl derivatives of beta-carboline alkaloid--harmol, were prepared and tested for possible antimycobacterial activity against Mycobacterium tuberculosis H37Rv.

Effect of the pyridoindole antioxidant stobadine on sodium handling of renal Na,K-ATPase in rats with streptozotocin-induced diabetes.

Overload of reactive oxygen species during diabetes is known to impair cellular homeostasis and to promote deterioration of membrane function in the organism. The aim of the present study was to examine the effect of dietary supplementation with the pyridoindole atioxidant stobadine on functional properties of the renal Na, K-ATPase in diabetic rats. After 16 weeks of streptozotocin-induced diabetes (single intravenous dose of streptozotocin; 55 mg/kg), a significant inhibition (by 35%-42%) of the enzyme was observed throughout the range of NaCl 2-100 mmol/l, probably as an event of altered functional properties of Na,K-ATPase, suggested by the 42% decrease of the V(max) value. Administration of 0.05% (w/w) stobadine in the diet dramatically improved the function of renal Na,K-ATPase in diabetic rats with regard to sodium handling, as suggested by significant stimulation (by 104%-77% in accordance with increasing concentration of NaCl) of the enzyme over the whole NaCl concentration range investigated. This stimulatory effect was accompanied by an increase of V(max) value to the level of nondiabetic rats on standard diet. In conclusion, stobadine was found to antagonise the negative effects of diabetes on the renal Na,K-ATPase, preserving its normal function in regulation of intracellular homeostasis of Na(+) and K(+) ions.

The effects of the benzodiazepine receptor ligand 3-(methoxycarbonyl) amino-beta-carboline on food and water intake in rats.

The effects of the benzodiazepine receptor ligand 3-(methoxycarbonyl) amino-beta-carboline (beta-CMC) were investigated on food intake in rats that had been fasted for 22 h, and on water intake in rats that had been deprived of water for 16 h. beta-CMC (2-8 mg/kg i.p.) produced a dose-related inhibition of food intake. Significant hyperphagia (p < 0.01) was observed with the 8 mg/kg dose. By contrast, the 8 mg/kg dose did not affect water intake in thirsty rats. The data suggests that beta-CMC has properties on food intake similar to those of a benzodiazepine receptor inverse agonist.