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

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

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

To analyze the developmental changes in soma diameters of digastric motoneurons, wheat-germ agglutinin conjugated horseradish peroxidase (WGA-HRP) was injected into the digastric muscle and visualized the retrogradely HRP-labeled motoneurons through tungstate/tetramethylbenzidine (TMB) and following diaminobenzidine (DAB) reactions. The results obtained from Sprague-Dawley rats at postnatal days 1 (P1), 10 (P10) and 30 (P30) indicated as follows: firstly, soma diameters of digastric motoneurons showed unimodal distribution in all postnatal days examined; secondly, the period of P1 to P10 (period 1) showed about 2 times faster growth rate than that of P10 to P30 (period 2); thirdly, the smallest soma examined in each postnatal day exhibited slower growth rate with that of the largest one (increase ratio in soma diameters from P1 to P30, smallest vs. largest =1.62 : 1.93); Finally, relative growth rates a day showed again that period 1 had faster growth rate than that of period 2. Consequently, developmental changes in soma diameters of digastric motoneurons resulted in very different growth rates between both periods. This implies that the growth of the soma is almost completing within P10 and thereafter growing slowly. The period 1 and 2 are corresponding to sucking and sucking/masticatory period, respectively. Therefore present study providing morphological changes in soma diameters of digastric motoneurons suggests that both periods and their different growth rates of the motoneurons in each period may closely be related with each other.
Animals ; Carisoprodol* ; Horseradish Peroxidase ; 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

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 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.

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.