Animal models to study cognitive impairment of chronic kidney disease

Mild cognitive impairment (MCI) is common in people with chronic kidney disease (CKD) and its prevalence increases with progressive loss of kidney function. MCI is characterized by a decline in cognitive performance greater than expected for an individual age and education level but with minimal impairment of instrumental activities of daily living. Deterioration can affect one or several cognitive domains (attention, memory, executive functions, language, and perceptual motor or social cognition). Given the increasing prevalence of kidney disease, more and more people with CKD will also develop MCI causing an enormous disease burden for these individuals, their relatives and society. However, the underlying pathomechanisms are poorly understood and current therapies mostly aim at supporting patients in their daily life. This illustrates the urgent need to elucidate the pathogenesis, and potential therapeutic targets and test novel therapies in appropriate preclinical models. Here, we will outline the necessary criteria for experimental modelling of cognitive disorders in CKD. We discuss the use of mice, rats and zebrafish as model systems and present valuable techniques through which kidney function and cognitive impairment can be assessed in this setting. Our objective is to enable researchers to overcome hurdles and accelerate preclinical research aimed at improving therapy of people with CKD and MCI.

Cardioprotective effect of postconditioning against ischemia-reperfusion injury is lost in heart of 8-week diabetic rat

Although ischemic preconditioning (IPC) and ischemic postconditioning (IPost) result in protection against ischemia-reperfusion (I/R) injury in healthy hearts, pathological conditions such as diabetes can modify the protective effects of IPC and IPost. There are a few studies concerning the effect of IPost only in diabetic hearts which have similar or decreased tolerance to I/R injury. In the present study we investigated the effects of IPost in diabetic hearts which had increased tolerance to I/R injury. Isolated hearts from control and diabetic rats were subjected to global ischemia (40 min) followed by reperfusion (40 min). IPost was induced by six cycles (10 s) of reperfusion and ischemia after the global ischemia. After I/R, cardiac recovery in diabetic hearts was better than that in control hearts. IPost did not produce any further protection in the diabetic hearts whereas it resulted in a significant recovery in the control hearts. Similarly, the decreased troponin I (TnI) levels of diabetic hearts did not change after IPost. However, IPost significantly lowered the increase in TnI levels of control hearts. In conclusion, these results show that IPost can not produce a further protection in the hearts of 8-week diabetic rats which have increased tolerance to I/R injury.

The role of mitochondrial ATP-sensitive potassium channels on cardiovascular effects of thiopental and ketamine in rats

OBJECTIVE

We aimed to investigate whether mitochondrial ATP-sensitive potassium (mitoKATP) channels play any role on cardiovascular effects of thiopental (TP) or ketamine (K) anesthesia in rats.

BACKGROUND

mitoKATP channels are the end-effectors of cardioprotection induced by some anesthetics. TP and K are the most frequently used anesthetics with their own cardiovascular effects in experimental studies. To the best of our knowledge, there is no study investigating the cardiovascular effects of TP and K associated with mitoKATP channels.

MATERIALS AND METHODS

The experimental groups: TP control, K/Xylazine (X) control, TP+5-hydroxydecanoate (5-HD; mitoKATP channel blocker) and K/X+5-HD. Mean arterial blood pressure (MABP), heart rate (HR) and standard limb lead II ECG were recorded and arrhythmia parameters were evaluated.

RESULTS

Blockage of mitoKATP channels by 5-HD increased MABP and decreased HR in the TP+5-HD and K/X+5-HD groups, respectively. 5-HD caused an increase in ventricular ectopic beat (VEB) incidence. Moreover, VEB incidence was significantly different in TP+5-HD (100%) than K/X+5-HDgroup (66.6%) and ventricular tachycardia was only seen in TP+5-HD (incidence was 88.3%).

CONCLUSION

mitoKATP channels play different roles in influencing cardiovascular effects of K/X and TP anesthesia in rats. The differences in hemodynamic parameters and arrhythmia scores of these anesthetics should be considered when they are used in an experimental study associated with mitoKATP channels (Fig. 3, Ref. 35).