In various areas of the bio-medical, pharmacological and psychological research a multitude of behavioural tests have been used to investigate the effects of environmental, genetic and epi-genetic factors as well as pharmacological substances or diseased states on behaviour and thus on the physiological and psycho-social status of experimental subjects. This article is reviewing the most frequently used behavioural tests in animal research (open field, elevated plus maze, zero maze, and black and white box). It provides a summary of common characteristics as well as differences in the methods used in various studies to determine motor activity, anxiety and emotionality. Additionally to methodological aspects, strain, sex and stress-related differences as well as the involvement of nitric oxide in modulation of motor activity and anxiety of rodents were briefly reviewed.

Studies in humans have found consumption of certain flavanoid-containing foods to be associated with improvement in endothelial function and with reduction of blood pressure (BP). (-)-Epicatechin is a compound representative of the flavanols (a subfamily of flavonoids), abundant in cocoa seeds, which is preserved during the industrialization process to chocolate. The antihypertensive effect of dietary (-)-epicatechin was investigated on spontaneously hypertensive rats (SHRs). Consumption of (-)-epicatechin-supplemented diet (3 g (-)-epicatechin/kg diet) decreased BP in SHR by 27 and 23 mm Hg on days 2 and 6, respectively. On day 6, a 173% increase of nitric oxide synthase (NOS) activity was observed in the aorta of EPI-SHR as compared to nonsupplemented SHR (P < 0.05). Responses to acetylcholine (ACh) were then examined in femoral arteries in the absence and the presence of L-NAME, a nonselective NOS inhibitor, to assess the AChmediated relaxation ascribed to NO-dependent and -independent mechanisms. Acetylcholine-induced endothelium-dependent relaxation in the femoral artery was significantly higher in EPI-SHR than in SHR, with a predominance of the NO-dependent component of this relaxation. The endothelium-independent relaxation, assayed by using the NO donor sodium nitroprusside, resulted in nonsignificant difference in the three experimental groups, demonstrating an unaffected function of vascular smooth muscle cells. These results give further support to the concept that (-)-epicatechin can modulate BP in hypertension by increasing NO levels in the vasculature.V C 2013 IUBMB Life, 65(8):710-715, 2013

L-arginine analogues are widely used inhibitors of nitric oxide synthase (NOS) activity both in vitro and in vivo, with N(ω)-nitro-L-arginine methyl ester (L-NAME) being at the head. On the one hand, acute and chronic L-NAME treatment leads to changes in blood pressure and vascular reactivity due to decreased nitric oxide (NO) bioavailability. However, lower doses of L-NAME may also activate NO production via feedback regulatory mechanisms if administered for longer time. Such L-NAME-induced activation has been observed in both NOS expression and activity and revealed considerable differences in regulatory mechanisms of NO production between particular tissues depending on the amount of L-NAME. Moreover, feedback activation of NO production by L-NAME seems to be regulated diversely under conditions of hypertension. This review summarizes the mechanisms of NOS regulation in order to better understand the apparent discrepancies found in the current literature.