出生前氚水照射对仔代大鼠生长发育及神经行为的影响

利用多项指标研究出生前氚水照射对仔代大鼠生长发育及神经行为的影响。方法妊娠１３天的成年Ｗｉｓｔａｒ大鼠腹腔单次分别注入不同活度氚水，各组仔鼠氚累积吸收剂量分别为０，０．０４４，０．０８８和０．２６４Ｇｙ。观察氚β射线对仔鼠出生后生长发育及神经行为的影响。结果在０．０４４Ｇｙ组即可使仔鼠连续通道转弯数减少，Ｙ迷宫刺激回避反射逃避时间延长；在０．０８８Ｇｙ组即可使出牙发育延迟，平面翻正，负趋地性及听觉惊愕等新生反射和感觉功能出现的天龄延迟，Ｙ迷宫刺激单向回避反射无误率降低，条件反射达标率降低；０．２６４Ｇｙ组张耳、开眼发育延迟，前肢悬挂时间缩短，Ｙ迷宫刺激回避反射阳性率降低；绝大部分指标表现与剂量相关。结论出生前一定剂量的氚水照射可导致仔代大鼠生长发育的延缓及学习记忆功能的降低等神经行为的异常。     

山莨菪碱对大鼠颈总动脉吻合术后血流动力学的影响

目的研究山莨菪碱对血管吻合后血流动力学的影响。方法取ＳＤ大鼠９６只，切断左侧颈总动脉作端端吻合后，随机分成术后６、１２、２４、４８、７２和１２０小时共６个时间组。各时间组再分成实验组和对照组，每组８只大鼠。实验组用２％氢溴酸山莨菪碱（３０ｍｇ／ｋｇ）作腹腔注射，对照组则注射等体积生理盐水，给药１０分钟后用彩色多普勒血流仪检测颈总动脉吻合口前、吻合口、吻合口后动脉收缩期平均最高血流速度，并计算吻合口横截面积。结果术后１２、２４、４８、７２和１２０小时组，颈总动脉吻合口前的血流速度比对照组明显增加（Ｐ＜０．０５），平均增加３１．５％。术后６和２４小时组，实验组吻合口狭窄程度比对照组明显减轻（Ｐ＜０．０１，０．０５）。术后１２０小时组，山莨菪碱能够明显增加吻合口后的血流速度，实验组和对照组相比有显著性差异（Ｐ＜０．０５）。结论山莨菪碱能够提高大鼠颈总动脉吻合后，血管吻合口前及吻合口的血流速度，术后２４小时内用药能够减少吻合口的狭窄程度。     

铁心甘草对大鼠离体回肠的作用研究

实验证明：铁心甘草对大鼠离体回肠的正常收缩运动有明显抑制作用；对由ＭＰＧＦ２α所致的大鼠离体回肠强烈收缩有明显抑制作用。为临床运用铁心甘草治疗妇科痛经并发症恶心、呕吐、腹泻等胃肠道反应，提供了实验依据     

Emotional and footshock stimuli induce differential long-lasting behavioural effects in rats; involvement of opioids

Rats were exposed to either a footshock stimulus (FS) or emotional stimulus (ES, forced perception of another rat receiving footshocks) during a daily 10-min session for 5 consecutive days. The consequences of FS and ES on their behavioural responsiveness were assessed at different post-stress intervals using a small open-field. FS induced a decrease in ambulation, rearing and sniffing and an increased immobility in the small open field. These effects were present in rats tested immediately after the last session and remained present for at least 15 days. In contrast, ES induced a transient decrease in ambulation and rearing immediately after the last session, but in the period from half an hour until at least 15 days after the stimulus experience, an increase in ambulation, rearing and sniffing was observed. Exposure to one footshock per session for 5 consecutive days or to 10 footshocks in a single session also resulted in a long-lasting reduction in ambulation and sniffing and an increase in immobility. The former regime did not influence the behavioural response of ES rats, but the latter resulted in an increase in ambulation, rearing and sniffing in ES rats. Naloxone (1 mg/kg s.c.) pretreatment antagonized the increased behavioural activity of the ES rats whereas the activity of control and FS animals was not affected, suggesting an involvement of endogenous opioid systems in the behavioural responses observed in ES rats. It is suggested that the behavioural responses of the ES and FS animals are regulated by different mechanisms.     

消炎痛宫内节育器对大鼠和兔子宫内膜影响的形态学观察

为了探讨消炎痛宫内节育器（ＩＵＤ）对子宫内膜的影响，给ＳＤ大鼠和新西兰兔经腹放置消炎痛－Ｃｕ－ＩＵＤ、Ｃｕ－ＩＵＤ、消炎痛－ＩＵＤ或硅橡胶ＩＵＤ，分别于置器后１、３、６个月解剖取子宫，行光镜和电镜观察，并与不放ＩＵＤ动物作对照。结果：消炎痛－Ｃｕ－ＩＵＤ放置１～６个月后子宫内膜无明显病理改变，与对照组相似，消炎痛及硅橡胶ＩＵＤ也都未引起子宫内膜病理改变，Ｃｕ－ＩＵＤ组可见组织水肿、纤维组织增生及散在白细胞等轻度病理变化。血管分布状态有一些变化，消炎痛－ＩＵＤ微血管以正常和收缩状态为主，Ｃｕ－ＩＵＤ则见微循环扩张，以微血管舒张状态为主（７０％），与消炎痛－Ｃｕ－ＩＵＤ组及对照组比较，有显著性差异（Ｐ＜０．０１）。结论：消炎痛对子宫内膜无不良影响     

Dose-Dependent Brainstem Neuropathology Following Repeated Arteether Administration in Rats

Histopathological effects of the artemisinin antimalarial, β-arteether, were evaluated in rats. Arteether (3.125–12.5 mg/kg/day, IM, in sesame oil) was administered for 7 consecutive days. Seven days following the last injection, histological evaluation of the brainstem was performed. Rats treated with 12.5 mg/kg showed significant neuropathology, including chromatolysis, in the nucleus trapezoideus and nucleus superior olive. To a lesser extent, neuropathology was present in the nucleus ruber. Mild neuropathology was also detected in other brainstem regions examined. Although no statistically significant neuropathology was found for the groups treated with 6.25 mg/kg/day and 3.125 mg/kg/day, substantial neuropathology was observed in a single rat in each of these treatment conditions. These results confirm and extend previous studies demonstrating brainstem neurotoxicity from artemisinin antimalarials. Furthermore, these results suggest that, in rats, brainstem auditory pathways may be particularly vulnerable. Early detection of arteether neuropathology may, therefore, require examination of auditory functions.     

Distribution of 1,25-dihydroxyvitamin D3[22-oxa] in vivo receptor binding in adult and developing skin

Because of the therapeutic potential of oxacalcitriol (OCT, 22-oxa-dihydroxyvitamin D₃), in vivo studies were conducted in adult and neonatal rats to identify the nuclear receptor sites of action in different tissues of the skin. Results were compared with those for 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃) and oestradiol from previous studies. Autoradiograms were prepared from the dorsal skin of adult rats and the skin of the leg and head regions of neonatal rats 1 or 2 h after the injection of³H-OCT. Specific nuclear concentrations of radioactivity, eliminated by competition with unlabelled OCT or 1,25(OH)₂D₃, were found in cells of the epidermis, outer hair sheath, hair bulb and sebaceous glands, but were absent or low in most fibroblasts of the dermis and hypodermis. The strongest nuclear binding of OCT was conspicuous in outer hair sheaths, where it was 1.5 to 3.2 times higher than in keratinocytes of the epidermis. The distribution of nuclear receptors for OCT was similar to that for 1,25(OH)₂D₃ but in part dissimilar to that for oestradiol. Oestradiol binding was found in the epidermis and hair sheaths, and also predominantly in fibroblasts of the dermis and hair dermal papillae. The results suggest genomic regulatory effects of OCT, similar to the effects of vitamin D, on proliferation, differentiation and activity of keratinocytes, growth and maintenance of hair, and proliferation and secretion of sebaceous glands. This may be utilized therapeutically, since OCT has a lower calcaemic effect than 1,25(OH)₂D₃.     

Favorable effects of egg white protein on lipid metabolism in rats and mice

Egg is a cholesterol-rich food and has a strong hyper-cholesterolemic action. However, all the cholesterol is in egg yolk and egg white is cholesterol-free. The effect of egg white protein and its hydrolysates on the serum lipids were compared with casein and soybean protein in rats and mice. The animals were given 30% casein diet (Ca group) or diets of 15% casein plus 15% soybean protein isolate (SPI group), egg white protein (EW group) or egg white protein hydrolysates (EW-P group) for 3 (rats) or 2 (mice) weeks. Food intake and growth were very similar among the different dietary groups. Hypocholesterolemic effect was observed in SP, EW and EW-P groups in rats and EW group in mice. Prevention of the reduction of HDL-cholesterol was found in EW and EW-P groups in rats and EW-P group in mice. The result suggests the possibility of the use of egg white for the prevention and treatment of hyper-cholesteremia.     

Dopamine efflux during withdrawal from continuous or intermittent cocaine

Daily, intermittent, subcutaneous cocaine injections produce sensitization, while the continuous administration of cocaine produces tolerance to the behavioral effects of subsequent cocaine injections. The present experiments examined whether these behavioral differences are related to differences in the ability of cocaine to increase extracellular dopamine. Increases in perfusate DA, in response to different concentrations of cocaine, were measured in caudate-putamen slices obtained from rats withdrawn for 7 days from a 14-day treatment of either continuous or daily subcutaneous cocaine injections. Compared to saline controls, cocaine-induced DA efflux was increased in subjects receiving daily injections and markedly decreased in subjects receiving continuous cocaine. Thus, different temporal patterns of cocaine administration produce dramatically different alterations in DA neurotransmission. Such changes in dopamine release may be related to the withdrawal symptoms experienced by human cocaine abusers.     

Tyrosine ameliorates a cold-induced delayed matching-to-sample performance decrement in rats

Exposure to cold stress has been shown to impair short-term, or working, memory which may be related to a reduction in brain catecholamines. Administration of the catecholamine precursor tyrosine may alleviate a cold-stress-induced memory impairment by preventing a deficit in brain catecholamine levels. To test this hypothesis, eight rats performed a delayed matching-to-sample (DMTS) task at an ambient temperature of either 2°C (cold) or 22°C, following intraperitoneal administration of saline or tyrosine (50, 100 or 200 mg/kg). Rats administered saline prior to 22°C exposure demonstrated a characteristic delay gradient in which accuracy decreased as the delay interval between sample and comparison stimuli increased from 1 to 16 s. Consistent with previous research, and relative to 22°C exposure sessions, matching accuracy during 2°C exposure sessions was reduced, which is attributed to the effect of cold on short-term, or working, memory. In particular, during cold exposure sessions matching accuracy was significantly reduced at the longer delay intervals, relative to matching accuracy at 22°C. Additional analysis of cumulative matching errors within sessions showed that during exposure to cold, errors occurred at a constant rate throughout the session, indicating rats' performance was equally debilitated by the stressor over the entire session. During cold exposure sessions, the higher doses of 100 and 200 mg/kg tyrosine significantly improved overall matching accuracy relative to saline, but did not completely reverse the effect of cold exposure, as overall matching accuracy did not increase entirely to levels obtained at 22°C. A linear slope analysis of cumulative errors within cold sessions indicated that, relative to saline, the higher doses of tyrosine also significantly reduced errors, but did not reduce these errors to levels obtained during exposure to 22°C. It appears that supplemental tyrosine was effective in partially ameliorating the effects of cold stress on DMTS performance, possibly by preventing a cold-stress-induced reduction in brain catecholamine levels.Experiments reported herein were conducted according to the principles set forth in the Guide for the Care and Use of Laboratory Animal Resources, National Research Council, DHHS Publication (NIH) 86-23, (1985). The opinions and assertions contained herein are those of the authors and are not to be construed as official or reflecting the views of the Navy Department or the Naval Service at large. The research was supported by Naval Medical Research and Development Command research and technology work units 61152N.MR04120.00D.1383 and 62233 N.MR03C30.004-1002.This research was conducted while the first author held a National Research Council-NMRI Research Associateship