孤束核内鼓索传入味觉神经元的形态与功能的关系

MORPHOLOGIC AND FUNCTIONAL RELATIONSHIP OF THE GUSTATORY NEURONS IN THE ROSTRAL NUCLEUS OF THE SOLITARY TRACT IN THE RAT

雄性SD大鼠54只，体重250～300g，用细胞内记录和细胞内注射的方法，将灌注的（2％NB溶于0.1mol／LKCl，pH7．4）记录电极（尖端直径80～100nm，电阻60～100MΩ）置于孤束核吻侧部，同时用味素（盐，酸，糖，苦）灌洗舌。在完成生理学记录、确认其至少对一种味素起反应后，进行细胞内注射．成色反应证明71个吻例孤束核味觉神经元被标记．标记神经元经三维重组系统重组后，依据细胞体积、胞体面积、树突节段平均长度、膨体密度、树突棘密度和初级树突数量等六个形态学特征，进行统计学（ANOVA）定量分析，将标记细胞分为A，B，C，D，E，F六类．每类细胞至少有一个形态学特征与其它五类有显著的不同．本研究还发现味谱值与标记细胞的大小及树突分校点的数量呈正相关而与树突棘密度呈负相关；对四种基本味素反应的标记细胞数量依次为盐＞酸＞甜＞苦；C类神经元的味谱值较小；单纯对苦（Quinine）反应的神经元与单纯对其它三种味素反应的神经元相比，具有胞体小、树突在冠状和矢状切面上的扩展范围小、树突整体接受面积也小的特征；在对盐类反应的神经元中，单纯氯化钠反应神经元与对所有盐类都反应的神经元相比，具有胞体表面积大、树突接受区域大、树突总长度长及在水平切面上吻尾扩展长的特点。此结果为?

Intracellular recording and injection techniques were used to study the relationships between function and struc-ture of the gustatory neurons in the rNST, 71 neurons in the rNST were successfully characterized by their physiologic fea-tures and labeled by Nb(neurobiotin). The statistic results showed that the labeled neurons can be divided into 6 groups (A～F) according to their morphological features and the positive correlations between the breadth of tuning (taste spectrum)and the number of branch points and between the breadth of tuning and the dendritic spine density were found. The neuronswith wideer-tuning have more branch points and with narrower tuning possess more spines. When we focused on the four ba-sic tastants, the number of the cells that responded to the four basic tastants were salt>acid>sweet>bitter. We demon-strated that the quinine-only neurons were smaller in cell body, rostrocaudal and ventrodorsal spreads, and dendritic recep-tive area than NaCl-, HCl- and sucrose-only neurons. We also found that the neurons responded to NaCl, but not to NH4Cland KCl, have larger cell body and bigger dendritic receptive area, longer total dendritic length and widely spread in rostro-caudal extent than the neurons that responded to all three salts. The neurons of group E were more narrowly-tuned thangroup C and D. These results suggested that there were function-structure relationships in the neurons of the rostral nucleusof the solitary tract.