Renin-Angiotensin-Aldosterone Signaling Inhibitors-Losartan, Enalapril, and Cardosten-Prevent Infarction-induced Heart Failure Development in Rats.

CONTEXT: The activation of the renin-angiotensin-aldosterone system (RAAS) plays an important role in the pathophysiology of congestive heart failure, which is the reason that angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin 2 receptor blockers (ARBs) have become established therapies for heart failure. However, it is still not known whether preventive treatment with losartan or enalapril can reduce symptoms of infarction-induced heart failure. Ultra-low dose (ULD) drug therapy is thought to exert specific activity, with a lower chance of side effects. OBJECTIVES • The research team had hypothesized that preventive treatment with inhibitors of RAAS signaling-losartan, enalapril, and a preparation of a ULD antibody (ie, cardosten), which target the angiotensin type 1 (AT1) receptor-might alleviate pathological hypertrophy and/or functional decline in infarction-induced heart failure. METHODS: The research team treated male Wistar rats orally for 30 d with 20 mg/kg of losartan, 10 mg/kg enalapril, 5 or 7.5 mL/kg of cardosten, or a control solution, started 1 d prior to permanent coronary occlusion. A sham-operated group functioned as a second control group. SETTINGS: The study was conducted at the Department of Biochemistry of the Faculty of Medicine at the University of Szeged in Szeged, Hungary, in cooperation with the Pharmahungary Group, also in Szeged, Hungary, and with OOO "NPF" Materia Medica Holding Ltd in Moscow, Russia. OUTCOME MEASURES: To determine cardiac functional parameters in vivo, the research team inserted a catheter into the left ventricle of the rats and measured the parameters of ventricular pressure, and cardiac output was determined by thermodilution. Morphological parameters were measured after heart isolation in transverse sections by a digital caliper. RESULTS: A total of 30 d after permanent coronary ligation, both losartan and enalapril, significantly decreased mean arterial blood pressure (MABP), attenuated the development of the left-ventricular anterior-wall and septum hypertrophy, and reduced scar thickness compared with the vehicle control group. The deterioration of cardiac output and the increase in total peripheral resistance (TPR) due to coronary ligation were significantly inhibited by both losartan and enalapril. The effects of cardosten were comparable with those of losartan and enalapril on cardiac morphology, left ventricular function, and TPR; however, it did not influence MABP. Moreover, in contrast to losartan and enalapril, cardosten did not decrease the rate of survival. CONCLUSIONS: The study was the first to have demonstrated that preventive treatment with losartan, enalapril, or cardosten can attenuate pathological hypertrophy in infarction-induced heart failure in rats.

Sildenafil and a compound stimulating endothelial NO synthase modify sexual incentive motivation and copulatory behavior in male Wistar and Fisher 344 rats.

INTRODUCTION: Earlier studies have shown that sildenafil may modify some aspects of male rat sexual behavior and sexual incentive motivation. Stimulation of endothelial nitric oxide synthase (eNOS) has also been reported to affect sexual motivation in old rats. AIM: To determine the effects of sildenafil and a compound stimulating eNOS on copulatory behavior and sexual incentive motivation in young adult Fisher 344 and Wistar male rats. METHODS: The rats were selected for a low intromission ratio, and then treated with Impaza (stimulator of eNOS), sildenafil, or Impaza + sildenafil for 28 days. Tests for copulatory behavior and sexual incentive motivation were performed before the beginning of treatment and at days 7, 14, and 28 of treatment. MAIN OUTCOME MEASURES: Standard parameters of copulatory behavior and sexual incentive motivation. Measurements of penis length at mount, intromission, and ejaculation. RESULTS: The Fisher 344 rats displayed a higher level of sexual incentive motivation than the Wistar rats, while the copulatory behavior was similar in both strains. Impaza and sildenafil enhanced the sexual incentive motivation after 28 days of treatment in the Wistar rats, but failed to do so in the Fisher 344 rats. The copulatory behavior was unaffected in the Wistar strain, while the Fisher 344 males had an enhanced intromission ratio after treatment with Impaza and sildenafil for 28 days. CONCLUSIONS: The nitric oxide-guanylyl cyclase pathway seems to be of importance for sexual incentive motivation in animals with a modest baseline level. The different drug effects in the Wistar and Fisher 344 rats can be attributed to baseline differences. The importance of eNOS for sexual functions should not be overlooked.

Antibodies to S100 proteins have anxiolytic-like activity at ultra-low doses in the adult rat.

S100 proteins are small calcium-binding proteins interacting with numerous intra- and extra cellular targets involved in diverse physiological functions. In particular, S100 proteins may be involved in the regulation of anxiety-related behaviour. In the present study, the effects of affinity-purified antibodies to S100 proteins administered orally at ultra-low doses were evaluated in pre-clinical tests for anxiolytic-like activity in the adult rat. In the Vogel conflict test in the rat, antibodies to S100 proteins increased punished drinking (anti-conflict effect) at 5 and 7.5 mL kg(-1), but not at 2.5 or 10 mL kg(-1). Antibodies to S100 proteins increased the percentage of entries into the open arms of an elevated plus-maze at 10 mL kg(-1), but not at lower doses. Taken together, these results indicate the presence of anxiolytic-like activity for antibodies to S100 proteins over the dose range 5-10 mL kg(-1) in the adult rat.