Involvement of central α1-adrenoceptors on renal responses to central moxonidine and α-methylnoradrenaline

Renoprotective effects of prazosin on ischemia-reperfusion injury in rats

BACKGROUND

Renal ischemia-reperfusion (IR) injury is one of the main leading causes of acute kidney injury associated with inflammation, oxidative stress and cell apoptosis. We studied the effects of prazosin, as a specific blocker of α1-AR, on renal IR injury.

METHODS

Rats were divided into normal control; untreated IR and prazosin-treated IR (1 mg/kg body weight). Prazosin was administered by intraperitoneal injection 30 min prior to IR induction. The level of urea/creatinine and oxidative factors were detected by colorimetric methods. Apoptosis-associated factors, inflammatory, and signaling proteins were analyzed in renal tissue. The abnormalities of renal histopathology were detected by immunohistochemistry.

RESULTS

Administration of prazosin to IR rats ameliorated serum urea and creatinine and IR-induced histopathological damages. Lipid peroxidation was significantly improved after treatment by prazosin in IR injury rats, however, antioxidant status was not affected. Rats subjected to IR injury activated Bax protein and NF-κB mediated inflammatory response. Moreover, treatment with prazosin inhibited renal NF-κB activation, resulting in a significant decline in pro-inflammatory cytokine of IL-6.

CONCLUSION

These findings suggest that prazosin could be a good candidate to attenuate renal IR injury due to its ability to modulate renal function, apoptosis and inflammation.

Induction of renal artery hyperresponsiveness by alpha1-adrenoceptor in hepatorenal syndrome

Objective

To investigate the potential role of alpha1-adrenoceptor (α1-AR) in the pathogenesis of hepatorenal syndrome.

Methods

Hepatorenal syndrome was induced in male rats by intraperitoneal injection of D-galactosamine and orally treatment with α1-AR antagonist tamsulosin. Hyperresponsiveness of the renal artery contraction was evaluated by the laser-Doppler flowmetry and multimyograph system, while renal blood flow (cortical and medullary perfusion) was simultaneously measured. Renal artery ring segment tone was recorded with the myograph system, and concentration-response curves were obtained by cumulative administration of agonists.

Results

This model developed acute renal and liver failure without renal damage in pathology, accompanied by significant hyperresponsiveness of renal artery contraction. After hepatorenal syndrome, plasma concentrations of tumor necrosis factor-α increased by two-fold, and α1-AR was significantly activated in the renal artery. Concentration-dependent vasoconstriction induced by noradrenaline was significantly decreased in the renal arteries of hepatorenal syndrome rat because of gradually decreased renal blood flow. Administration of tamsulosin prevented renal failure when given before the onset of liver injury, but it had no effect on liver injury by itself.

Conclusion

α1-AR expression is positively associated with renal vasoconstriction induced by renal artery hyperresponsiveness in HRS. Therefore, α1-AR may be a potential target in the treatment of HRS.

How impaired efficacy happened between Gancao and Yuanhua: Compounds, targets and pathways

As recorded in Traditional Chinese Medicine (TCM) theory, Gancao (Glycyrrhizae Radix et Rhizoma) could weaken the pharmacological effect or increase the toxicity of Yuanhua (Genkwa Flos). However, the theory has been suspected due to lack of evidence. Here, we investigate whether Gancao could weaken Yuanhua’s diuretic effect, if so, which chemicals and which targets may be involved. Results showed that Yuanhua exerted diuretic effect through down-regulating renal AQP 2, without electrolyte disturbances such as K⁺ loss which has been observed as side-effect of most diuretics. Gancao had no diuretic effect, but could impair Yuanhua’s diuretic effect through up-regulating renal AQP 2. Glycyrrhetinic acid (GRA) in Gancao could up-regulate AQP 2 and counteract the AQP 2 regulation effect of Yuanhuacine (YHC) and Ginkwanin (GKW) in Yuanhua. Network pharmacology method suggested that YHC, GKW and GRA could bind to MEK1/FGFR1 protein and influence ERK-MAPK pathway, which was verified by Western blotting. This study supports TCM theory and reminds that more attention should be paid to the safety and efficacy problems induced by improper combination between herbs. Moreover, we suggested that promising diuretics with less side effects can be developed from Chinese Medicines such as Yuanhua.

Strain-Specific Single-Nucleotide Polymorphisms in Hypertensive ISIAH Rats

Single-nucleotide polymorphisms (SNPs) in the coding and regulatory regions of genes can affect transcription rate and translation efficiency, modify protein function, and, in some cases, cause the development of diseases. In the current study, the RNA-Seq approach has been used to discover strain-specific SNPs in ISIAH (inherited stress-induced arterial hypertension) rats, which are known as a model of stress-induced arterial hypertension. The comparison of the ISIAH SNPs with genome sequencing data available for another 42 rat strains and substrains, 11 of them known as hypertensive, showed a considerable genetic distance between the genotypes of ISIAH and all other rat strains and substrains. The study revealed 1849 novel SNPs specific for ISIAH rats and 158 SNPs present only in the genotypes of hypertensive rats. Amino acid substitutions with possible deleterious effect on protein function were detected. Several of them were found in the genes associated with hypertension. These SNPs may be considered as novel molecular targets for further studies aimed at assessing their potential in the therapy of stress-induced hypertension.