No abstract available.
Colon* ; Rats, Sprague-Dawley* ; Rectum*

BACKGROUND: Several studies have demonstrated that the transient administration of oxygen improves cognitive performance. However, the effect of long-term oxygen administration remains unknown. This study investigated the impact of long-term oxygen administration on cognitive enhancement. METHODS: Six week old Sprague-Dawley rats (n = 46) were randomly allocated to one of three groups: the control (Control; n = 15), 30 min/day oxygen administration (Oxy30min; n = 16) and 60 min/day oxygen administration groups (Oxy60min; n = 15). The rats in all three groups were administered air or oxygen for 10 weeks. The Morris water maze test was employed to assess the latency (L & Lt), dwelling time (DT) and the total fraction above the mean dwelling time (FmDT) for cognitive performance. RESULTS: Compared to the control group, the Oxy30min and Oxy60min groups showed no differences in their L and Lt. There was a dose-response trend due to oxygen administration. Compared to the control group, the Oxy60min group had a significantly improved DT (P< 0.05). The FmDT also significantly increased in both of the oxygen administration groups, which also showed a dose-response trend (P<0.05). CONCLUSIONS: The present results suggest that long-term (10 weeks) oxygen administration can dose-dependently enhance cognitive performance.
Animals ; Oxygen* ; Rats* ; Rats, Sprague-Dawley

Several microvascular anastomotic techniques have been described with methodical effectiveness, patency rates, healing state of microscopic findings. This experimental study presents the comparison of three types of arterial microvascular anastomotic techniques: end-to-end(ETE) anastomosis, end-in-end(EIE) anastomosis, and continuous technique. Sixty male Sprague-Dawley rats, 60 femoral arteries were used for this study. Twenty rats per each technique were used and sacrificed at post-operation 1 day, 3 days, a week, 2 weeks for scanning electromicroscopic findings. The patency was monitored by miniDoppler throughout total experimental periods. The anastomotic time on each method was measured to compare the technical effectiveness. The final results were as follows: 1. The anastomotic time for the end-in-end technique was significantly shorter than another techniques. The average time for each technique was measured as 15 minutes on EIE technique, 20 minutes on continuous technique and 25 minutes on ETE technique. 2. The patency rate for the end-in-end technique at 2 weeks also was superior to another techniques. The patency rate for each technique was demonstrated as 90 % on EIE technique, 85 % on ETE technique and 80 % on continuous technique. 3. The scanning electromicroscopic findings on healing condition of vessel endothelium during the observation period showed that the end results of EIE technique, ETE technique and continuous technique in sequence were good. The end-in-end technique proved to be the superior with regard to anastomotic time and patency rate when compared to end-to-end technuqe, so EIE techniqe might be well available for the case of large discrepancy of vessel size. The patency rate, microscopic healing findings in continuous technique were seen as the lowest level among the three anastomotic techniques, therefore the application of continuous technique was recommended only on the inevitable case.
Animals ; Endothelium ; Femoral Artery ; Humans ; Male ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo study the teratogenicity of new high-energy compounds, 3, 4 two furazan-based oxidation furazan (DNTF) and the impact on human health, occupational exposure limits were provided for the following research.

METHODSPregnant SD rats were randomly divided into five groups by Standard teratogenicity test, including three dose groups (5.0, 15.8, 50.0 mg/kg), the negative control (vegetable oil), and the positive control group (CP 10.0 mg/kg). Each 10 to 15 rats were in one group. Gavage was consecutive for rats during pregnancy 7 ∼ 12 d and then sacrifice after 20 d.

RESULTSThere were no significantly difference between the three dose groups and negative controls in the pregnancy rate, the weight of pregnant rats, fetal weight, fetal growth, fetal malformation rate and internal organs,

CONCLUSIONThere were no maternal toxicity, embryo toxicity and teratogenicity for rats when DNTF in the range 5.0 ∼ 50.0 mg/kg.

OBJECTIVETo study the influence of 14- day simulated weightlessness on emotional behaviour in rats.

METHODSSixteen from twenty male SD rats were selected and assigned to a 2-group design: the control group and the tail suspension (TS) group (n = 8). The essay deployed typical methods for assessing emotional activity in the current, including food-intake and body weight variation, open field testing, sucrose preference testing and the evaluation of emotional arousal level to test emotional behavior.

RESULTS1. After 14- day simulated weightlessness for rats, their food-intake and body weight increase were less than those in the control group. 2. The ability of movement reduced in rats, the number of locomotion was significantly lower than that in the control group (P < 0.05) and the frequency of self-grooming was significantly higher than that in the control group(P <0.01. 3. A higher level of emotionality in TS group was recorded. 4. Sucrose preference was not observed in TS group.

CONCLUSIONIt demonstrated depression, anxiety and nervous symptom occurred in the TS rats with a certain degree of nervous reaction but no anhedonia.

OBJECTIVEThere are a great number of modified models based on the four-vessel occlusion (4VO) model of Pulsinelli and Brierley which has been used worldwide for brain ischemia research. However, up to now the problems of collateral circulations of 4VO and the difficulty in arranging a surgery to occlude the basilar artery in other models are not satisfactorily solved yet. In this study, an improved 4-vessel occlusion (I4VO) rat model which is easy to handle and able to decrease the effect of collateral circulation is reported.

METHODSThe common carotid arteries and the beginning of the subclavical arteries of rats were occluded for different time by one-stage apertura thoracis superior approach. Neurological deficit scores defined by the modified Garcia scoring system and histopathological method were used to evaluate the effects of this model up to 7 days after reperfusion.

RESULTSThe neurological scores in the 15-min and 25-min groups decreased significantly at 24, 48 and 72 hours after reperfusion (P less than 0.05), and the histopathologic study showed that there were stable, symmetrical changes of lesions in bilateral hippocampus in all the ischemia samples from two ischemia groups compared with sham operated group (P less than 0.05).

CONCLUSIONThis modified model is safe, easy, reliable, stable, mini-invasive as well as time-saving in making bilateral hemispheric ischemia, which can effectively decrease collateral circulations and meanwhile lead to stable lesions in hippocampus and cortex.

AIMOur previous studies showed that electroacupuncture (EA) could inhibited radiant heat induced pain and acute or chronic inflammatory pain in rats. In the present study, we observed whether EA with different frequencies could suppress neuropathic pain.

METHODSL5/L6 nerve ligation model was used to assess the effect of EA on neuropathic pain. Mechanical allodynia was represented by 50% withdrawal threshold, while cold-induced ongoing pain was detected by the number of paw lift in 5 min when the rat was put on a 5 degrees cold plate. Han's acupoint nerve stimulator (HANS) was connected to needles inserted into acupoints "jiaji" and "Zusanli" in both sides. The parameters were: (intensity: 0.5-1-2 mA, 10 min each; frequency 2 Hz or 100 Hz; pulse width: 0.6 ms for 2 Hz, 0.2 ms for 100 Hz).

RESULTSEA of both 2 Hz and 100 Hz could relieve the mechanical allodynia, where 2 Hz could induce the effect with shorter latency; they could also relieve the cold-induced ongoing pain, where the effect of 2 Hz outlasted the EA session by up to 48 h after repetitive stimulations over several weeks; a significant relieving effect on cold-induced ongoing pain could also be induced by needle insertion without stimulation.

CONCLUSIONEA could relieve neuropathic pain, the analgesic effect of 2 Hz EA is higher than 100 Hz EA.

One, two, six and ten week old Sprague-Dawley rats were exposed to carbon monoxide at 3,700 ppm for 30 minutes, and carboxyhemoglobin was measured immediateley, 5, 30, 60, 90, 120 minutes after the exposure. In each time after the exposure, the means of the carboxyhemoglobin levels were "compared among the week age groups. The regression analysis was done using the natural logarithm. of the carboxyhemoglobin concentration as a dependent variable and the time after the exposure. as an independent vaiable. From the regression equation, the half lives of the carboxyhemoglobin were calculated. The one week old rats showed significantly higher carboxyhemoglobin level than other week age rats in the entire time after the exposure. The corrected carboxyhemoglobin concentration calculated by subtracting the normal carboxyhemoglobin level from the me cured carboxyhemoglobin at each age group, showed no uniform differences.
Animals ; Carbon Monoxide ; Carboxyhemoglobin* ; Humans ; Rats* ; Rats, Sprague-Dawley

OBJECTIVETo investigate the effect of low-frequency ultrasound in promoting milk secretion in rats during lactation.

METHODSTwenty-four lactating SD rats feeding 10 suckling rats each were randomly allocated into 3 groups, namely the control group (with sham irradiation), 5 min group (with ultrasonic irradiation of the breast for 5 min daily), and 10 min group (irradiation for 10 min daily). The mammary glands of the rats were consistently irradiated by low-frequency ultrasound (40 kHz, 0.26 W/cm(2)) for 7 days since the 2nd day after delivery. The milk yield, average body weight gain of the offspring, mammary gland index, serum prolactin (PRL) and breast histology were examined.

RESULTSThe milk yield, body weight gain of offspring, mammary gland index and serum PRL concentration in 10 min group were significantly greater than those in the control group and 5 min group (P<0.05). Compared with the other two groups, the 10 min group showed significantly increased acinar gland expansion and acinar number.

CONCLUSIONLow-frequency ultrasound can promote milk secretion in lactating rats, suggesting its potential as a new approach of physical therapy for promoting milk secretion.

OBJECTIVETo study the influence of emotion stress on mechanical hyperalgesia of masseter muscles in rats through the equipment of communication box.

METHODS50 Sprague-Dawley rats were randomly divided into 5 groups: Control group, emotion stress (ES) group, drug control group, saline treated control group and footshock (FS) group, 10 rats each group. Footshock group only induced emotion stress and was not concerned with the result of the experiment. The last four groups of the rats were placed in communication box and bred under the same conditions during the experiment time. According to Rens' method, von Frey filaments were used to assess the muscle mechanical threshold, head withdrawal, leg raising and crying were observed as pain action.

RESULTS1) During the adaptive period of 7 days before the emotion stress experiment, mechanical pain values of bilateral masseter muscles were descent and were stabilized in the 5 th to 7 th day. In emotion stress period, hyperalgesia of emotion stress group was induced in bilateral masseter muscles, and the peak time was the 7 th day, then it alleviated in the following days and was stabilized in the 12 th to 14 th day, but its pain threshold was lower than blank control group. 2)During the emotion stress period, the change of drug control group was similar to stress group but its pain threshold was higher.

CONCLUSIONIt is suggested that emotion stress can lead to the hyperalgesia of masseter muscles and antidepressant drug can lower the hyperalgsia resulted of emotion stress.