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

In order to study the effects of stereotaxic destruction of distinct epileptogenic focus, the amygdala was destroyed with radiofrequency coagulator. A total of twenty Sprague-Dawley rats were divided into two group : the control group which underwent craniectomy on the biparietal area and was instilled crytal penicillin solution into the right amygdala on the basis of stereotaxic coordinates(n=10), and the amygdalectomy group which was performed selective amygdalectomy with radiofrequency coagulator after confirmation of clinical and electroencephalographic epileptic features after proceeding same methods of control group(n=10). The experimental epileptic models in rats were obtained by selective instillation of crystal penicillin solution into the right amygdala. The effects of amygdalectomy were investigated by observation of the changes in behavior and electroencephalographic recordings. The results were as follows ; 1) A typical behavioral seizure was shown in the control group and epilepticform discharge was prominent in crystal penicillin soultion instilled side, but there was no bilateral synchronous epileptic discharges during ictal stages. 2) In comparision to two groups, the severity and the frequency of behavioral seizure were more decreased in the stereotaxic amygdalectomy group. 3) The amygdalectomy group was shwon a significant decrease in amplitude and frequency of spikes, especially during interictal stages, compared to the control group. From the results of electroencephalographic and behavioral analysis, selective amygdalectomy with radiofrequency coagulator seemed to be an effective method to treat the crystal penicillin soulution induced epileptic rats.
Amygdala ; Animals ; Penicillins ; Rats* ; Rats, Sprague-Dawley ; Seizures

This study was designed to investigate the effective duration of delay period, and to study what changes were induced in the vasculatures of the prefabricated cutaneous flap. Abdominal skin flaps in six groups were fabricated by the subcutaneous implantation of a skeletonized saphenous pedicle using fourty-eight male Sprague-Dawley rats. Forty flaps were elevated at six weeks after fabrication, based solely on the implanted pedicle. Group 1 was used as the control without delay. A surgical delay was carried out at 24, 48, 72 hours, and 7 days prior to flap elevation in the group 2, 3, 4, and 5, respectively. Eight flaps of the group 6 were elevated without delay at 8 weeks after fabrication. Three days later, the flap viability and the numbers of vessels were analyzed quantitatively, and the flap vasculature was evaluated with microangiograms. Flap viabilities of the group 3(95.3+/-7.04) and 4(98.5+/-2.90) were higher than that of the control(83.4+/-11.17, p<0.05). In microangiographic study, the connection between dilated large vessels via choke vessels is dominant finding during the first 24 hours after delay. Dilatations of preexisting small choke vessels started to be appear at 48 hour after delay, and vascular networks of small vessels were progressively developed over the whole flap at 72 hours after delay. The number of vessel, in the flap itself, was increased after 72 hours of delay(p<0.05), but new vessels around the pedicles were more developed at 48 hours after delay(p<0.05). In conclusion, the delay procedure enhances the viability of the prefabricated flap, and the optimal duration is 48 - 72 hours to obtain maximal survival in rats.
Animals ; Dilatation ; Humans ; Male ; Rats ; Rats, Sprague-Dawley ; Skeleton ; Skin

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.

BACKGROUND: Chronic administration of morphine leads to the development of tolerance. We investigated the effects of intrathecal lamotrigine on the spinal morphine tolerance in rats that are undergoing tail flick tests. METHODS: Sprague-Dawley rats were given intrathecal injections of saline 10 microl, lamotrigine 300 microg, morphine 15 microg or lamotrigine plus morphine combinations for 7 days (lamotrigine was given for days 1-7, days 1-3 or days 5-7). The acute and chronic nociceptive sensitivities were assessed using a tail flick test in which the distal 5 cm of the tail was dipped into warm water before and 30 minutes after the drug injection. With successive injections of morphine on day 8, a cumulative antinociceptive dose-response curve was constructed and the 50% effective dose (ED50) was calculated for each study group. RESULTS: The coinjection group of lamotrigine with morphine blocked the development of tolerance, as was shown by the preservation of morphine antinociception over 7 days and the concomitant decrease in the ED50 values on day 8, as compared with the morphine-alone group. Coinjection of lamotrigine blocked the development of morphine tolerance, as shown by the preservation of morphine antinociception over 7 days and the concomitant decrease in the ED50 values on day 8, as compared with the morphine-alone group. CONCLUSIONS: This study suggests that lamotrigine augments the antinociceptive action of both acute and chronic morphine therapy, and it also attenuates the antinociceptive morphine tolerance in rats.
Animals ; Injections, Spinal ; Morphine ; Rats ; Rats, Sprague-Dawley ; Triazines ; Water

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 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.

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.