Effects of age and sex differences on conditioned and unconditioned fear in anxiety developed animals

Elevated T-maze is an animal model of anxiety to separate, in the same animal, conditioned from unconditioned fear. The aim of this research was to assess the effects of age and sex differences on two types of fear in the elevated T-maze both in mice [Balb-c] and rats [Wistar Albino]. 40 mice and 40 rats [10 young male, 10 young female, 10 aged male and 10 aged female] were used in this study. Elevated T-maze consists of 3 arms of equal dimensions, elevated from the floor. Animal was placed at the distal end of the enclosed arm and the baseline latency is recorded by the time taken to withdraw from this arm with all four paws. In order to evaluate conditioned fear the same measurement was repeated in two subsequent trials. Then the rats were placed at the distal end of open arm and the escape latency is recorded. The avoidance latencies were analyzed by Repeated Measures and Mann Whitney-U test, the escape latencies were analyzed by One-way ANOVA [Scheffe]. Mice exhibited high latencies in avoidance responses [avoidance 1, avoidance 2] compared with baseline latencies in the 4 groups. However, only young male and aged female mice were significantly different [p<0.05]. Avoidance 1 latencies significantly different in the aged and young male mice [p<0.05]. While escape latencies representing unconditioned fear were decreased in the aged mice, no statistical difference was found in respect to sex distribution. In rats, avoidance responses exhibited high latencies in all groups when compared with baseline latencies. However there were statistically no significant difference in age and sex distributions in conditioned and unconditioned responses [p>0.05]. The fact that mice were effected more than rats suggests that in animal models of anxiety, the differences in age and sex may be changed according to the gender and the model which is used

Effects of high and low doses of Donepezil in female and male mice in staircase test

This study is aimed at investigating if donepezil [DO], which is used in Alzheimer disease, has also an anxiolytic activity or not in the staircase test in mice.To carry out this investigation, male and female mice weighing 20-34 g, were divided in groups of ten. DO was investigated at following doses: 5 mg/kg/day and 10 mg/kg/day, administered PO only once for 4 days and 60 minutes before the test on the 5th day. The effects of acute administrations were also investigated when DO [5 mg/kg/day and 10 mg/kg/day] was administered only once, 60 minutes before the test, to animals which had previously received the same number of administrations of distilled water. Diazepam [2 mg/kg PO], which is administered acutely in the same conditions, was used as a reference compound. The animals in the control group received distilled water at each administration. The behavioural parameter measured was the number of steps climbed during a 3-minute test. Following the measurements, the results obtained were compared statistically. In male mice the number of steps climbed were increased by DO administration, but significant differences were shown at only high doses of DO administration. There are no significant differences in the number of steps climbed by female mice. Our results showed that DO might also have an anxiolytic activity at high doses

respiratory pump

The pump consists of the chest wall, the respiratory muscles that displace it, the centers in the nervous system that control the muscles. The chest wall can be divided into three parts; the diaphragm, the rib cage with its musculature, and the abdomen with its musculature. Diaphragm's primary function is act of breathing, specially the inspiratory phase. The function of the diaphragm as a pump depends on the ability of the muscle fibers to shorten. In this article we discussed the function of diaphragm, its fiber types, innervation, contractile properties, length-tension relationships, and its blood supply