Parker Lindsay M, Le Sheng, Wearne Travis A, Hardwick Kate, Kumar Natasha N, Robinson Katherine J, McMullan Simon, Goodchild Ann K
Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, NSW, 2109, Australia.
ARC Centre of Excellence for Nanoscale Biophotonics, Macquarie University, NSW, 2109, Australia.
J Comp Neurol. 2017 Jun 15;525(9):2249-2264. doi: 10.1002/cne.24203. Epub 2017 Mar 29.
Previous studies have demonstrated that a range of stimuli activate neurons, including catecholaminergic neurons, in the ventrolateral medulla. Not all catecholaminergic neurons are activated and other neurochemical content is largely unknown hence whether stimulus specific populations exist is unclear. Here we determine the neurochemistry (using in situ hybridization) of catecholaminergic and noncatecholaminergic neurons which express c-Fos immunoreactivity throughout the rostrocaudal extent of the ventrolateral medulla, in Sprague Dawley rats treated with hydralazine or saline. Distinct neuronal populations containing PPCART, PPPACAP, and PPNPY mRNAs, which were largely catecholaminergic, were activated by hydralazine but not saline. Both catecholaminergic and noncatecholaminergic neurons containing preprotachykinin and prepro-enkephalin (PPE) mRNAs were also activated, with the noncatecholaminergic population located in the rostral C1 region. Few GlyT2 neurons were activated. A subset of these data was then used to compare the neuronal populations activated by 2-deoxyglucose evoked glucoprivation (Brain Structure and Function (2015) 220:117). Hydralazine activated more neurons than 2-deoxyglucose but similar numbers of catecholaminergic neurons. Commonly activated populations expressing PPNPY and PPE mRNAs were defined. These likely include PPNPY expressing catecholaminergic neurons projecting to vasopressinergic and corticotrophin releasing factor neurons in the paraventricular nucleus, which when activated result in elevated plasma vasopressin and corticosterone. Stimulus specific neurons included noncatecholaminergic neurons and a few PPE positive catecholaminergic neuron but neurochemical codes were largely unidentified. Reasons for the lack of identification of stimulus specific neurons, readily detectable using electrophysiology in anaesthetized preparations and for which neural circuits can be defined, are discussed.
先前的研究表明，一系列刺激可激活延髓腹外侧的神经元，包括儿茶酚胺能神经元。并非所有儿茶酚胺能神经元都会被激活，而且其他神经化学物质的含量大多未知，因此尚不清楚是否存在刺激特异性神经元群体。在此，我们在接受肼屈嗪或生理盐水处理的Sprague Dawley大鼠中，通过原位杂交确定了在延髓腹外侧全长范围内表达c-Fos免疫反应性的儿茶酚胺能和非儿茶酚胺能神经元的神经化学特性。含有PPCART、PPPACAP和PPNPY mRNA的不同神经元群体（大多为儿茶酚胺能神经元）被肼屈嗪激活，但未被生理盐水激活。含有前速激肽原和前脑啡肽原（PPE）mRNA的儿茶酚胺能和非儿茶酚胺能神经元也被激活，非儿茶酚胺能神经元群体位于吻侧C1区域。很少有甘氨酸转运体2（GlyT2）神经元被激活。然后使用这些数据的一个子集来比较由2-脱氧葡萄糖诱发的糖剥夺激活的神经元群体（《脑结构与功能》（2015年）220:117）。肼屈嗪激活的神经元比2-脱氧葡萄糖多，但儿茶酚胺能神经元数量相似。定义了共同激活的表达PPNPY和PPE mRNA的神经元群体。这些可能包括向室旁核中血管加压素能和促肾上腺皮质激素释放因子神经元投射的表达PPNPY的儿茶酚胺能神经元，这些神经元被激活时会导致血浆血管加压素和皮质酮升高。刺激特异性神经元包括非儿茶酚胺能神经元和一些PPE阳性儿茶酚胺能神经元，但神经化学编码大多未被识别。讨论了在麻醉制剂中使用电生理学可轻易检测到且神经回路可被定义的刺激特异性神经元缺乏识别的原因。
