镧对仔鼠嗅感觉神经元超微结构和嗅功能的影响

Effects of Lanthanum on Olfactory Sensory Neuron Ultra-structure and Olfactory Function in Offspring Rats

目的观察发育期氯化镧暴露对仔鼠嗅感觉神经元超微结构及嗅功能的影响。方法将24只健康8周龄清洁级妊娠2 d的Wistar大鼠按体重随机分为3组,分别为对照(蒸馏水)组和低(2.5 g/L)、高浓度(5.0 g/L)氯化镧染毒组,每组8只。采用自由饮水方式进行染毒,连续染毒50 d。仔鼠出生4 d后,统计仔鼠存活数和性别情况,并计算生存率和雌雄比;并开始观察并记录仔鼠体重。仔鼠出生后25～27 d,采用嗅觉行为学方法(埋藏食物小球试验)检测嗅觉功能;于出生后28 d,采用透射电镜技术观察仔鼠嗅上皮嗅感觉神经元超微结构并测定嗅球镧含量。结果各组仔鼠体重、生存率、性别比间比较,差异均无统计学意义。与对照组比较,各氯化镧染毒组仔鼠寻找食物所需时间较长,嗅球镧含量较高,差异均有统计学意义(P<0.05);且随着氯化镧染毒浓度的升高,仔鼠寻找食物所需时间均呈延长趋势,嗅球镧含量呈上升趋势。但所有测试均未出现超出400 s以上的情况。另外,随着测试天数的增加,仔鼠寻找食物的时间均呈逐渐缩短的趋势。病理学观察结果显示,氯化镧染毒可造成仔鼠出生后嗅感觉神经元隆起增大,形状不规则,部分与嗅上皮表面分离,且顶端的纤毛数减少。结论氯化镧可损伤子代大鼠的嗅觉功能,这可能与镧损害嗅上皮嗅感觉神经元的超微结构有关。

Objective To observe the effects of lanthanum （La） on ultra-structure of olfactory sensory neuron in olfactory epithelium and olfactory function in offspring rats. Methods Twenty-four clean pregnant rats aged 8 weeks were randomly divided into three groups,8 in each, control,0.25% LaCl3,0.5% LaCl3 on gestational day 2.In the control group,the clams drank distilled water and in the exposed groups, the dams respectively drank for fifty consecutive days. On postnatal clay 4, the number of viable puppies,pup sex,survival and sex ratio were measured. Body weights of puppies were recorded. On postnatal day 25, pups were tested about olfactory function by buried food pellet test. On postnatal day 28,pups were observed about ultra- structural features of olfactory sensory neuron in olfactory epithelium with a transmission electron microscope and determination of La content. Results Compared with the control group, the offspring exposed to LaCl3 showed a significantly increased latency time on each of the trial days,and exhibited significantly elevated levels of La （P〈0.05）. Moreover, there were an increased tendency of latency time and La content with the increasing of LaCl3 concentrations. But all of the latency time did not exceed 400 s. In addition, with the increasing of test day,there was the abbreviated tendency of latency time in pups looking for food. Pathological results showed that LaCl3-exposure induced enlarged ORN knobs, some of which exhibited irregular shapes, with knobs frequently appearing to be detached from the OE surface, and a decreased number of cilia. Conclusion LaCl3 may damage offspring olfactory function by altering ultra-structure of olfactory sensory neuron.