ABSTRACT
The open field test is one of the most popular ethological tests to assess anxiety-like behavior in rodents. In the present study, we examined the effect of early deprivation (ED), a model of early life stress, on anxiety-like behavior in rats. In ED animals, we failed to find significant changes in the time spent in the center or thigmotaxis area of the open field, the common indexes of anxiety-like behavior. However, we found a significant increase in high-leaning behavior in which animals lean against the wall standing on their hindlimbs while touching the wall with their forepaws at a high position. The high-leaning behavior was decreased by treatment with an anxiolytic, diazepam, and it was increased under intense illumination as observed in the center activity. In addition, we compared the high-leaning behavior and center activity under various illumination intensities and found that the high-leaning behavior is more sensitive to illumination intensity than the center activity in the particular illumination range. These results suggest that the high-leaning behavior is a novel anxiety-like behavior in the open field test that can complement the center activity to assess the anxiety state of rats.
Subject(s)
Anxiety/etiology , Exploratory Behavior/physiology , Learning/physiology , Stress, Psychological/complications , Animals , Anti-Anxiety Agents/therapeutic use , Anxiety/drug therapy , Diazepam/therapeutic use , Disease Models, Animal , Exploratory Behavior/drug effects , Female , Male , Motor Activity/physiology , Random Allocation , Rats , Rats, Sprague-Dawley , Statistics, NonparametricABSTRACT
As increasing evidence suggest that oxidative stress plays an important role in the developing angiopathy in diabetes, we studied the effects of taurine, a free radical scavenger, on diabetes induced angiopathy in the rat aorta. Six-week-old male Wistar rats were randomly divided into three groups; control group (Cont), diabetes group (DM) and diabetes group treated with taurine for four weeks, 500 mg/kg/day, intraperitoneally (i.p.) (DM+T). Diabetes was induced by streptozotocin (50 mg/kg i.p.). Four weeks after the induction of diabetes, serum glucose and malondialdehyde concentrations were measured. Additionally, organ bath studies and real-time PCR on muscarinic M(3) receptor and eNOS were performed. Although taurine treatment failed to decrease serum glucose levels, the increased serum malondialdehyde levels in diabetic rats were significantly decreased after taurine treatment. Norepinephrine-induced hyper-contractility as well as acetylcholine-induced, endothelium-dependent hypo-relaxation in diabetes were significantly prevented after taurine treatment. The differences in the expressions of muscarinic M(3) receptor mRNAs were statistically non-significant between groups. Moreover, diabetes-induced up-regulation of eNOS mRNAs was slightly prevented after taurine treatment. These data suggest that taurine acts beneficially against the diabetes-induced vascular dysfunction. Its potential action as a radical scavenger ameliorates the vascular disorders in diabetes.
