Ciriello John, Caverson Monica M
Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, N6A 5C1 Canada.
Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, N6A 5C1 Canada.
Brain Res. 2016 Apr 1;1636:21-42. doi: 10.1016/j.brainres.2016.01.041. Epub 2016 Feb 1.
The effects of 17β-estradiol (E) on the distribution and density of brainstem projections of small or large diameter primary vagal afferents were investigated in Wistar rats using transganglionic transport of wheat germ agglutinin- (WGA; preferentially transported by non-myelinated afferent C-fibers; 2%), or cholera toxin B-subunit- (CTB, 5%; preferentially transported by large myelinated afferent A-fibers) conjugated horseradish peroxidase (HRP) in combination with the tetramethylbenzidine method in age matched ovariectomized (OVX) only or OVX and treated with E (OVX+E; 30 pg/ml plasma) females for 12 weeks. Additionally, these projections were compared to aged matched males. Unilateral microinjection of WGA-HRP into the nodose ganglion resulted in dense anterograde labeling bilaterally, with an ipsilateral predominance in several subnuclei of the nucleus of the solitary tract (NTS) and in area postrema that was greatest in OVX+E animals compared to OVX only and males. Moderately dense anterograde labeling was also observed in paratrigeminal nucleus (PAT) of the OVX+E animals. CTB-HRP produced less dense anterograde labeling in the NTS complex, but had a wider distribution within the brainstem including the area postrema, dorsal motor nucleus of the vagus, PAT, the nucleus ambiguus complex and ventrolateral medulla in all groups. The distribution of CTB-HRP anterograde labeling was densest in OVX+E, less dense in OVX only females and least dense in male rats. Little, if any, labeling was found within PAT in males using either WGA-or CTB-HRP. Taken together, these data suggest that small, non-myelinated (WGA-labeled) and large myelinated (CTB-labeled) diameter vagal afferents projecting to brainstem autonomic areas are differentially affected by circulating levels of estrogen. These effects of estrogen on connectivity may contribute to the sex differences observed in central autonomic mechanisms between gender, and in females with and without estrogen.
在Wistar大鼠中，采用结合了四甲基联苯胺法的小麦胚芽凝集素（WGA；优先被无髓传入C纤维转运；2%）或霍乱毒素B亚基（CTB，5%；优先被有髓大传入A纤维转运）偶联辣根过氧化物酶（HRP）的跨神经节运输方法，研究了17β - 雌二醇（E）对小直径或大直径初级迷走传入神经脑干投射的分布和密度的影响，实验对象为年龄匹配的仅切除卵巢（OVX）或切除卵巢并接受E治疗（OVX + E；血浆中浓度为30 pg/ml）的雌性大鼠，为期12周。此外，还将这些投射与年龄匹配的雄性大鼠进行了比较。将WGA - HRP单侧微量注射到结状神经节中，导致双侧出现密集的顺行标记，在孤束核（NTS）的几个亚核以及最后区中同侧优势明显，与仅OVX组和雄性大鼠相比，在OVX + E动物中最为显著。在OVX + E动物的三叉旁核（PAT）中也观察到中等密度的顺行标记。CTB - HRP在NTS复合体中产生的顺行标记较稀疏，但在脑干内分布更广，包括所有组的最后区、迷走神经背运动核、PAT、疑核复合体和延髓腹外侧。CTB - HRP顺行标记的分布在OVX + E中最密集，在仅OVX的雌性中较稀疏，在雄性大鼠中最稀疏。使用WGA - 或CTB - HRP在雄性大鼠的PAT中几乎未发现标记。综上所述，这些数据表明，投射到脑干自主区域的小直径无髓（WGA标记）和大直径有髓（CTB标记）迷走传入神经受到循环雌激素水平的不同影响。雌激素对连接性的这些影响可能导致在性别之间以及有或无雌激素的女性的中枢自主机制中观察到的性别差异。
