Overexpression of dimethylarginine dimethylaminohydrolase 1 protects from angiotensin II-induced cardiac hypertrophy and vascular remodeling

Development of a HPLC-MS/MS Method to Assess the Pharmacokinetics and Tumour Distribution of the Dimethylarginine Dimethylaminohydrolase 1 Inhibitors ZST316 and L-257 in a Xenograft Model of Triple-Negative Breast Cancer in Mice

We describe the development and validation of an HPLC-MS/MS method to assess the pharmacokinetics and tumour distribution of ZST316, an arginine analogue with inhibitory activity towards dimethylarginine dimethylaminohydrolase 1 (DDAH1) and vasculogenic mimicry, and its active metabolite L-257 in a xenograft model of triple-negative breast cancer (TNBC). The method proved to be reproducible, precise, and highly accurate for the measurement of both compounds in plasma and tumour tissue following acute and chronic (five days) intraperitoneal administration of ZST316 (30 mg/Kg daily) in six-week-old severe combined immunodeficiency disease (SCID) mice inoculated with MDA-MB-231 TNBC cells. ZST316 was detected in tumour tissue and plasma after 1 h (6.47 and 9.01 μM, respectively) and 24 h (0.13 and 0.16 μM, respectively) following acute administration, without accumulation during chronic treatment. Similarly, the metabolite L-257 was found in tumour tissue and plasma after 1 h (15.06 and 8.72 μM, respectively) and 24 h (0.17 and 0.17 μM, respectively) following acute administration of ZST316, without accumulation during chronic treatment. The half-life after acute and chronic treatment ranged between 4.4-7.1 h (plasma) and 4.5-5.0 h (tumour) for ZST316, and 4.2-5.3 h (plasma) and 3.6-4.9 h (tumour) for L-257. The results of our study demonstrate the (a) capacity to accurately measure ZST316 and L-257 concentrations in plasma and tumour tissue in mice using the newly developed HPLC-MS/MS method, (b) rapid conversion of ZST316 into L-257, (c) good intra-tumour penetration of both compounds, and (d) lack of accumulation of both ZST316 and L-257 in plasma and tumour tissue during chronic administration. Compared to a previous method developed by our group to investigate ZST316 in plasma, the main advantages of the new method include a wider range of linearity which reduces the need for dilutions and the combined assessment of ZST316 and L-257 in plasma and tumour tissue which limits the required amount of matrix. The new HPLC-MS/MS method is useful to investigate the in vivo effects of ZST316 and L-257 on vasculogenic mimicry, tumour mass, and metastatic burden in xenograft models of TNBC.

Circulating arginine metabolites in Alzheimer's disease and vascular dementia: A systematic review and meta-analysis

BACKGROUND

Alterations in nitric oxide (NO) synthesis have been reported in Alzheimer's disease and vascular dementia. However, as the measurement of NO in biological samples is analytically challenging, alternative, stable circulatory biomarkers of NO synthesis may be useful to unravel new pathophysiological mechanisms and treatment targets in dementia.

METHODS

We conducted a systematic review and meta-analysis of the circulating concentrations of arginine metabolites linked to NO synthesis, arginine, citrulline, asymmetric (ADMA) and symmetric (SDMA) dimethylarginine, and ornithine, in Alzheimer's disease and vascular dementia. We searched for relevant studies in PubMed, Scopus, and Web of Science from inception to the 31st of May 2023. The JBI checklist and GRADE were used to assess the risk of bias and the certainty of evidence, respectively.

RESULTS

In 14 selected studies, there were no significant between-group differences in arginine and ornithine concentrations. By contrast, compared to controls, patients with dementia had significantly higher ADMA (standard mean difference, SMD=0.62, 95% CI 0.06-1.19, p = 0.029), SDMA (SMD=0.70, 95% CI 0.34-1.35, p<0.001), and citrulline concentrations (SMD=0.50, 95% CI 0.08-0.91, p = 0.018). In subgroup analysis, the effect size was significantly associated with treatment with cholinesterase inhibitors and/or antipsychotics for ADMA, and underlying disorder (Alzheimer's disease), study continent, and analytical method for citrulline.

CONCLUSION

Alterations in ADMA, SDMA, and citrulline, biomarkers of NO synthesis, may be useful to investigate the pathophysiology of different forms of dementia and identify novel therapeutic strategies. (PROSPERO registration number: CRD42023439528).

Knock-out of the critical nitric oxide synthase regulator DDAH1 in mice impacts amphetamine sensitivity and dopamine metabolism

The enzyme dimethylarginine dimethylaminohydrolase 1 (DDAH1) plays a pivotal role in the regulation of nitric oxide levels by degrading the main endogenous nitric oxide synthase inhibitor asymmetric dimethylarginine (ADMA). Growing evidence highlight the potential implication of DDAH/ADMA axis in the etiopathogenesis of several neuropsychiatric and neurological disorders, yet the underlying molecular mechanisms remain elusive. In this study, we sought to investigate the role of DDAH1 in behavioral endophenotypes with neuropsychiatric relevance. To achieve this, a global DDAH1 knock-out (DDAH1-ko) mouse strain was employed. Behavioral testing and brain region-specific neurotransmitter profiling have been conducted to assess the effect of both genotype and sex. DDAH1-ko mice exhibited increased exploratory behavior toward novel objects, altered amphetamine response kinetics and decreased dopamine metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) level in the piriform cortex and striatum. Females of both genotypes showed the most robust amphetamine response. These results support the potential implication of the DDAH/ADMA pathway in central nervous system processes shaping the behavioral outcome. Yet, further experiments are required to complement the picture and define the specific brain-regions and mechanisms involved.

A Heart Failure Model Established by Pressure Overload Caused by Abdominal Aortic Contraction in Rat

Heart failure is a complex clinical syndrome in which ventricular filling or ejection capacity is impaired due to structural or functional diseases of the heart. In order to establish a stable heart failure model, we investigated cardiac parameters in rats with abdominal aortic contraction and normal rats, including the left ventricular posterior wall diameter (LVPWd), the interventricular septum thickness of end-diastolic (IVSd), the left ventricular end-diastolic diameter (LVEDd), the left ventricular ejection fraction (LVEF), and left ventricular fractional shortening (LVFS). Rats were randomly divided into experimental group (n = 20) and control group (n = 20). The experimental group underwent modified abdominal aortic constriction, while the control group only isolated the abdominal aorta without constriction. The results showed that the survival rate of rats in the experimental group was 85% after one week of operation, while the survival rate of rats in the control group was 100%. Five weeks after operation, the left ventricular posterior wall diameter (LVPWd) and the interventricular septum thickness of end-diastolic (IVSd) in the experimental group were all increased compared with those in the control group, and the differences were statistically significant (p < 0.05); the left ventricular end-diastolic diameter (LVEDd) in the experimental group showed an increasing trend compared with the control group, but p > 0.05; compared with the control group, the left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS) in the experimental group showed downward trend, but p > 0.05. 10 weeks after operation, the LVPWd, IVSd, and LVEDd of the experimental group were increased compared with the control group, p < 0.05, and the LVEF and LVFS of the experimental group were decreased compared with the control group, p < 0.05. Compared with the control group, the BNP of the experimental group increased significantly, p < 0.05. The heart weight index and left ventricular weight index of rats in the experimental group were significantly higher than those in the control group, p < 0.05. HE staining showed that the myocardial cells in the experimental group increased in volume, disordered cell arrangement, widened gaps, increased nuclear hyperchromia, and uneven staining. This paper provides a theoretical basis for the study of heart failure.