Modulation of haemodynamics, endogeneous antioxidant enzymes, and pathophysiological changes by selective inhibition of angiotensin II type 1 receptors in pressureoverload rats

Background

Constriction of the thoracic or abdominal aorta provides an experimental model of pressure-overload cardiac hypertrophy. Blockade of AT₁ receptors is beneficial in preventing target-organ damage in hypertension.

Objective

To examine the effect of angiotensin II receptor antagonists on blood pressure, endogenous antioxidant enzyme and histopathological changes in pressure-overload rats.

Methods

Pressure overload was produced by abdominal aortic banding (AAB) using a blunt 22-guage needle in male rats as a model of cardiac hypertrophy. After surgery, the AAB-induced hypertension (AABIH) rats were treated with losartan 40 mg/kg/day, candesartan 10 mg/kg/day, irbesartan 10 mg/kg/day per os for 16 weeks. At 16 weeks of surgery, the rats were observed for general characteristics and mortality, and we determined non-invasive blood pressure (NIBP), endogenous antioxidant enzyme catalase and superoxide dismutase (SOD) activities, and histology of the target organs.

Results

In the AABIH group, significant increase in systolic blood pressure was observed from weeks 3 to 16 compared with the control group, along with reduced serum catalase and SOD activities. The treated groups showed significant reduction in systolic BP and increase in serum SOD and catalase activities. The histological changes induced in the target organs, namely heart, liver, kidneys and thoracic aorta in the AABIH rats were attenuated in the treated rats.

Conclusion

Blockade of the AT₁ receptor caused an improvement in the myocardial antioxidant reserve and decreased oxidative stress in the hypertensive rats, which was evidenced by the protection observed in the treatment groups.

Evaluation of the anti-depressant activity of Myristica fragrans (Nutmeg) in male rats

OBJECTIVE

The present study was undertaken to evaluate anti-depressant activity of Myristica fragrans (MS).

MATERIALS AND METHODS

Male Wistar rats were subjected to imipramine and herbal extract of MS for their antidepressant activity using Forced Swimming Test (FST), Reserpine Reversal Test (RRT), Haloperidol-Induced Catalepsy (HIC), and Pentobarbitone Sleeping Time (PST).

RESULTS

Administration of MS and imipramine revealed a statistically significant reduction in immobility time in FST, RRT, and protection against HIC, compared to the control group. However, there was no significant potentiation of PST.

CONCLUSION

Our study demonstrated the potential antidepressant activity of MS.

Modulation of hemodynamics, endogenous antioxidant enzymes, and pathophysiological changes by Angiotensin-converting enzyme inhibitors in pressure-overload rats

INTRODUCTION

We sought to assess the role of angiotensin-converting enzyme (ACE) inhibitors on systolic blood pressure (BP), endogenous antioxidant enzymes and histopathological changes in pressure-overload rats.

METHODS

Pressure overload was produced in male rats by abdominal aortic banding (AAB) using a blunt 22-gauge needle, as a model of cardiac hypertrophy. After surgery, AAB-induced hypertensive (AABIH) groups were treated with captopril 4 mg and ramipril 10 mg/kg per day p.o. for 16 weeks. At 16 weeks, rats were observed for general characteristics and mortality, non-invasive blood pressure (NIBP) and endogenous antioxidant enzyme catalase and superoxide dismutase (SOD) activity and histological evaluation of target organs.

RESULTS

In the AABIH group a significant increase in systolic BP was observed in week 3 (149.3 ± 0.821) and persisted until week 16, along with lower levels of serum catalase (144.7 ± 2.204) and SOD (12.92 ± 0.4601) activity compared to the control group. Captopril and ramipril treated groups showed a significantly smaller increase in systolic BP (25.47 ± 3.685, 20.21 ± 3.306) and greater serum SOD (27.33 ± 2.338, 28.95 ± 1.143) and catalase (181.7 ± 8.407, 187.9 ± 8.497) activity, respectively, than the hypertensive rats. The histological changes induced in target organs (heart, liver, kidneys and thoracic aorta) in AABIH rats were attenuated in treated rats.

CONCLUSIONS

ACE-inhibition causes an improvement in myocardial antioxidant reserve, reduces oxidative stress, and prevents pathophysiological alterations, while showing a trend for potential target organ protection in hypertensive rats.