Effects And Mechanisms Of Anxiety On Sleep In Rats Of Two Different Strains

The effects and mechanisms of anxiety on sleep in rats of two different strains were investigated with the methods of sterotaxic surgery, polysomnography(PSG), conditioned fear training, immunohistochemical ABC technical and computer assisted image analyzing system, behavioral test such as freezing behavioral test, the elevated plus -maze test, the open field test.Results as follows:1 The establishment and evaluation of anxiety modelAfter 4 consecutive days of conditioned fear training, which was achieved by exposure of rats to tone (1000Hz, 75dB, 5s) as conditioned stimulus paired with an electric footshock (0.5mA, 0.5s) as unconditioned stimulus, rats showed that freezing responses were increased and lowly explorative activities were reduced in freezing behavioral test; the entries to the open arms were reduced and the time stoped in the open arms were reduced in the elevated plus -maze test; the number of squares crossed and the central time stoped were reduced in the open field test.After pretreatment with the anxiolytic drug diazepam (5mg/ml, 5mg/kg), the entries to the open arms and the time stoped in the open arms were increased significantly in the elevated plus -maze test.2 The effects of anxiety on sleep in rats of twodifferent strainsa) Baseline sleep was recorded, the rats were trained to associate tone with footshock on 4 consecutive days.Sleep recorded after training and again 2 days later after presentation of tone alone. Conditioned fear training increased paradoxical sleep (PS) and reduced slow wave sleep (SWS).The change of PS in F₃₄₄ rats as follows: the first day after training among 6h sleep No2 PS was increased,the second day No4, No5and N06 PS were increased,the third day No5 and N06 PS were increased,the fourth day No^ No5 and N06 PS were increased. The change of PS in Wistar rats as follows: the first day after training among 6h sleep no obvious change was seen,the second day No3 PS was increased,the third day No5 PS was increased,the fourth day No3 PS was increased.b) Post-training exposure to the tone alone that have been paired with foot-shock also increased PS,the F344 rats exhibited a relatively greater increase than Wistar rats. 3 The effect of anxiety on the expression of the immediate early gene c-fos in central nervous system.The mean numberal density of FLI in amygdala central :0.13 + 0.13 in control group, 2.71 ±0.32 in test group(vs control group,p<0.001). the mean numberal density of FLI in amygdale basolateral : 0.00 + 0.00 in control group, 1.35 + 0.25 in test group(vs control group,p<0.001). the mean numberal density of FLI in hippocampus: 4.13 + 0.67 in control group, 3.51 + 0.97 in test group(vs control group,p>0.05).These results indicated that:1. After conditioned fear training, the increased anxiety responses , and the decreased locomotion are similar to the symptoms of anxiety disorder in humans.Furthermore,it's useful that treatment with the anxiolytic drug.These results show that conditioned fear training may provide a useful modle for examining anxiety.2. Conditioned fear training decrease SWS and selectively increased PS, the inbred F344 rats exhibited a relatively greater increase than hybrid Wistar rats. Exposure to the tone alone that have been paired with foot-shock, also increased PS that was great in F344 rats than Wistar rats. These results show that there are differences in the effects that anxiety on sleep among strains.