大鼠性别及去势对基底前脑一氧化氮合酶阳性神经元形态与数量及学习记忆功能的影响

Effects of sex and castration on the learning memory function and the form and quantity of nitricoxide synthase positive neurons in basal forebrain of rats

目的:比较正常雌、雄大鼠以及去势大鼠基底前脑一氧化氮合酶阳性神经元的变化,为阐明学习记忆的神经内分泌学特点提供形态学资料。方法:实验于2001-03/2002-03在广州中山大学基础医学院人体解剖教研室脑研究室完成。将60只成年健康SD大鼠随机分为6组,正常雌性组、去卵巢2周组、去卵巢4周组、正常雄性组、去睾丸2周组、去睾丸4周组,每组10只。应用组织化学染色法观察各组大鼠基底前脑的内侧隔核、斜角带垂直支及斜角带水平支的一氧化氮合酶阳性神经元形态和数目。结果:60只大鼠全部进入结果分析。①各组大鼠基底前脑一氧化氮合酶阳性神经元形态变化:组织化学染色法显示一氧化氮合酶阳性神经元的胞体和突起均呈紫蓝色,胞体多为圆形、椭圆形、双极形或多极形,常由胞体发出1～3支初级树突,但轴突未被染色。各组大鼠一氧化氮合酶阳性神经元的胞体和树突均相似。②各组大鼠基底前脑的内侧隔核、斜角带垂直支及斜角带水平支的一氧化氮合酶阳性神经元数目:经组织化学染色法观察,正常雄性、雌性大鼠内侧隔核、斜角带垂直支及水平支的一氧化氮合酶阳性神经元数基本一致犤(38.5±4.0)个/切片,(33.0±3.1)个/切片;(45.5±6.0)个/切片,(42.8±4.9)个/切片;(63.8±8.1)个/切片,(58.9±7.8)个/切片,(P>0.05)犦。去睾丸2周组内侧隔核、斜角带垂直支的一氧化氮合酶阳性神经元数明显高于去卵巢2周组犤(45.8±5.8)个/切片,(18.9±3.8)个/切片;(58.4±7.2)个/切片,(28.3±5.0)个/切片,(P<0.01)犦;而去睾丸2周组斜角带水平支的一氧化氮合酶阳性神经元数高于去卵巢2周组犤(60.3±8.5)个/切片,(45.8±6.2)个/切片,(P<0.05)犦。去睾丸4周组内侧隔核、斜角带垂直支及水平支的一氧化氮合酶阳性神经元数依然高于去卵巢4周组犤(35.1±5.5)个/切片,(23.1±4.2)个/切片;(45.7±8.0)个/切片,(27.8±6.5)个/切片;(53.5±6.3)个/切片,(40.2±7.2)个/切片,(P<0.05)犦。结论:不论去势与否,一氧化氮合酶阳性神经元脑体和树突的形态变化不存在性别差异。正常雌雄大鼠基底前脑一氧化氮合酶阳性神经元数不存在性别差异,但去势后一氧化氮合酶阳性神经元数则出现性别差异。这种差异不仅与卵巢雌激素和睾丸雄激素在雌雄个体中所发挥的不同作用密切相关,而且还有可能是促使雌雄个体表现出特征性的学习记忆功能性别差异的形态学基础。

AIM： To provide new morphological data for clarifying the neuroendocrine mechanisms of learning and memory, comparison of changes of nitric oxide synthase （NOS） positive neurons of basal forebrain among female, male and castrated rats is performed.METHODS： The experiment was done in Department of Anatomy and Brain Research, Basic Medical College, Sun Yat-sen University from March 2001 to March 2002. The adult heahhy Sprague-Dawley rats were randomly divided into 6 groups； normal female group, ovariectomized rats for 2 weeks .group and ovariectomized rats for 4 weeks group, normal male group, castrated rats for 2 weeks group and castrated rats for 4 weeks group with 10 in each group. The form and number of NOS-HR neurons in the medial septum （MS）,vertical （vDB） and horizontal （hDB） limbs of the diagonal band of Broca in basal forebrain were investigated among six groups by means of histochemical staining technigue.RESULTS： Sixty rats were all involved in results analysis. ① Positive neural morphologic changes of NOS of basal forehead in rats； histochemical staining technique showed that neuronal soma and apophysis of NOS Presented royal blue, and soma was round, ellipse, diplo-pole or multi-pole.From one to three primary dendrites was sent out by soma, but axiscylinder was not stained. Soma and dendrite of NOS neurons were similar in each group. ② Number of NOS neurons in the MS, vDB and hDB limbs：After observed by histochemical staining technique, NOS neurons in normal male and female rats of MS, vDB and hDB limbs were coincidence basically [（38.5±4.0）,（33.0±3.1）; （453±6.0）,（42.8±4.9）; （63.8±8.1）,（58.9±7.8） per slice,（P 〉 0.05）]. The number of NOS neurons in MS ,vDB and hDB of castrated male rats for 2 or 4 weeks was significantly higher than that of ovariectomized female rats for 2 or 4 weeks[（45.8±5.8）,（18.9±3.8）; （58.4±7.2）,（28.3±5.0） per slice,（P 〈 0.01 ）].Number of NOS neurons in the hDB limb of castrated male rats for 2 weeks was higher than that of ovariectomized female rats for 2 weeks [（60.3±8.5）,（45.8±6.2） per section,（P 〈 0.05）].Number of NOS neurons in the hDB limb of castrated male rats for 4 weeks was higher than that of ovariectomized female rats for 4 weeks[（35.1±5.5）, （23.1±4.2）; （45.7±8.0）. （27.8 ±6.5）; （53.5±6.3）, （40.2±7.2） perslice, （P 〈 0.05）]CONCLUSION： Whether castration exists or not, the morphologic change of soma and dendrite of NOS neuron does not have sex difference.There are no sex differences in the number of NOS neurons in basal forebrain between intact female and male rats. However, sex differences in the number of NOS neurons in the basal forebrain exist between ovariectomized female rats and castrated male rats, which not only are closely related to the functional differences between ovarian estrogen and testicular androgen in female and male individuals, respectively; but also are the morphological foundations of the characteristic learning and memory shown in female and male individuals.