EFFECTS OF “NEPHROPHYTE” ON CASPASE-3 ACTIVITY AND PRESERVATION OF TISSUE ATP IN RENAL ISCHEMIA/REPERFUSION / Монголын эм зүй, эм судлал

ABSTRACT

This paper describes the effects of a multicomponent plant preparation developed on the basis of Tibetan prescriptions, including ethanolic extracts of Arctostaphylos uva- ursi (L.) Spreng, Orthosiphon stamineus (L.), Polygonum aviculare (L.), on caspase-3 activity and recovery of tissue ATP content in ischemic renal cells of albino Wistar rats. It has been shown that after “Nephrophyte” administration at a dose of 150 mg/kg body wt. (overnight and 1 hour before ischemia) the activity of caspase-3 significantly decreased and the recovery of tissue ATP was significantly enhanced. These results suggest that “Nephrophyte” may protect the kidney against ischemia/ reperfusion injuries, at least, by ameliorating apoptotic process and preserving tissue ATP content. KEY WORDS kidney, ischemia/reperfusion, caspase-3, ATP, “Nephrophyte” INTRODUCTION Acute renal failure (ARF) as a result of ischemia/reperfusion (I/R) is of great clinical significance because of its frequent occurrence, high morbidity and mortality. It is important to improve the ability of kidney to tolerate ischemic damages. ATP depletion and apoptosis are widely recognized to be implicated in ischemic renal injury. Hence, research efforts designed to prevent or ameliorate I/R injury have focused on the pharmacological inhibition of apoptotic process, preservation and recovery of intracellular ATP. However, the above approaches remain to be fully explored. It is now widely recognized that several pathological processes of biological tissues are caused by ischemia-reperfusion processes. Acute renal failure (ARF) is a clinical syndrome characterized by an abrupt loss of kidney function resulted from different forms of renal injury including ischemic and toxic stimuli. Tubular cell death through apoptosis is supposed to play a significant role in the genesis of ARF that has been confirmed by studies both in animal models and in clinical kidney diseases [12; 16]. Therefore, the control of apoptosis could be a potential target for therapeutic interventions with the aim to prevent or at least to alleviate the severity of ARF. Among the biochemical events leading to apoptotic changes, activation of caspases is of great importance since they are responsible for almost all the biochemical and morphological features of apoptosis, caspase-3 being a key mediator of apoptotic death in different cell types. Earlier, it has been shown that protease inhibitors, especially peptide-based inhibitors are highly effective in preventing programmed cell death in both in vitro and in vivo models [8; 10]. Recently, natural compounds of plant origin became a focus of interest in regulating cell survival. The induction of apoptosis by plant extracts largely through caspase-3 activation has been reported in a number of studies. For example, solamargine, a steroidal alkaloid glycoside from Solanum incunum triggers apoptosis in human hepatoma cells [9]; triterpenoid saponins from Acacia victoriae induce apoptosis in Jurkat cells [6]; Tylophora alkaloids were shown to induce apoptosis in human erythroleukemic cells involving cytochrome c release and caspase-3 activation [3]. As to the data on the natural inhibitors of apoptosis, there are few reports in the present-day literature. Luo et al. [11] have found that the standardized Ginkgo biloba extract EGb761 significantly attenuates mitochondrion- initiated apoptosis and decreases caspase-3 activity in neuroblastoma cells [19]. The inhibitory effect of caffeic acid on the activity of caspase-3 in cultured cerebellar granule neurons subjected to apoptosis has been shown in a more recent study [18], as well as protective effect of tirofuban on ischemia-induced renal apoptosis [5]. Here, we report the inhibition of caspase-3 activity and significant recovery of tissue ATP by “Nephrophyte”, a multicomponent plant preparation developed on the Tibetan prescriptions, in rat ischemic kidney cells. Our previous studies showed antioxidant, anti- inflammatory and nephroprotective activity of the phytopreparation in question due to its phytoconstituents (flavonoids, phenolic acids and free amino acids) that was the rationale for the present research [13; 15]. MATERIALS AND METHODS ANIMALS Albino Wistar rats, weighing 180-200 g each of either sex were used. The animals were maintained under a standard light cycle (12 h light, 12 h dark) and temperature (20˚C), with free access to food and water. The research was approved by the animal study committee of the local institutional review board and conducted according to the guide for the care and use of laboratory animals.