Kream R M, Davis B J, Kawano T, Margolis F L, Macrides F
J Comp Neurol. 1984 Jan 1;222(1):140-54. doi: 10.1002/cne.902220112.
A coordinated series of immunohistochemical and biochemical analyses have been conducted in the hamster to examine the dependence of substance P and tyrosine hydroxylase (TH) expression by second-order olfactory neurons, and the level of dopamine in the main olfactory bulb (MOB), on the integrity of carnosine- and olfactory marker protein (OMP)-containing primary afferent neurons. Substance P-like immunoreactivity (SPLI) is localized in external tufted cells and centrifugal afferents of the MOB; TH immunoreactivity has a wider distribution, in external tufted, middle tufted, periglomerular, and deep short-axon cells as well as in centrifugal afferents. To characterize the SPLI, this material was isolated by guanidine-HCl extraction and passage over a C18 SEP-PAK. The SPLI coelutes on HPLC with authentic substance P and, following oxidation, coelutes with substance P sulfoxide. It is sensitive to alpha-chymotrypsin and is resistant to trypsin. Thus, the SPLI in the MOB behaves as authentic substance P. Intranasal irrigation with 0.17 M ZnSO4 results in peripheral deafferentiation of the MOB for up to 8 months as evidenced by a persistent loss of OMP immunoreactivity and shrinkage of the olfactory nerve layer and glomeruli. By these criteria, the vomeronasal inputs to the accessory olfactory bulb are not destroyed and the spared vomeronasal receptor neurons do not innervate the vacated peripheral projection field in the MOB. The loss of peripheral inputs to the MOB is accompanied by marked and parallel reductions in the incidences of SPLI- and TH-positive second-order neurons despite an increase in the density of neuronal somata in the glomerular layer. Biochemical quantifications following peripheral deafferentation also demonstrate significant decreases of both substance P and dopamine, together with the expected decrease of carnosine. In contrast, the SPLI and the TH and serotoninlike immunoreactivities in centrifugal afferents as well as the TH immunoreactivity in deep interneurons do not appear to be reduced, and the MOB content of norepinephrine in centrifugal afferents is unaffected. These results collectively indicate that the loss of inputs from the primary olfactory receptor neurons can reduce the levels of at least two different, putatively neuroactive compounds (substance P and dopamine) in at least three classes of second-order neurons (external tufted, middle tufted, and periglomerular cells). The control of central neuron phenotype by the peripheral olfactory neurons thus appears to be a phenomenon of broad influence. It may play a role in processing chemosensory information as well as offering a system in which to study neuronal plasticit
在仓鼠中进行了一系列协调的免疫组织化学和生化分析，以研究含肌肽和嗅觉标记蛋白（OMP）的初级传入神经元的完整性对二级嗅觉神经元中P物质和酪氨酸羟化酶（TH）表达以及主嗅球（MOB）中多巴胺水平的依赖性。P物质样免疫反应性（SPLI）定位于MOB的外侧簇状细胞和离心传入纤维；TH免疫反应性分布更广，存在于外侧簇状、中间簇状、球周和深层短轴突细胞以及离心传入纤维中。为了表征SPLI，该物质通过盐酸胍提取并通过C18 SEP-PAK柱进行分离。SPLI在高效液相色谱（HPLC）上与 authentic P物质共洗脱，氧化后与P物质亚砜共洗脱。它对α-糜蛋白酶敏感，对胰蛋白酶有抗性。因此，MOB中的SPLI表现为 authentic P物质。用0.17 M硫酸锌进行鼻内冲洗可导致MOB外周去传入长达8个月，这可通过OMP免疫反应性的持续丧失以及嗅神经层和肾小球的萎缩来证明。根据这些标准，副嗅球的犁鼻器输入未被破坏，剩余的犁鼻器受体神经元不会支配MOB中空出的外周投射区域。MOB外周输入的丧失伴随着SPLI和TH阳性二级神经元发生率的显著且平行降低，尽管肾小球层中神经元胞体的密度增加。外周去传入后的生化定量分析还表明P物质和多巴胺均显著减少，同时肌肽也出现预期的减少。相比之下，离心传入纤维中的SPLI、TH和5-羟色胺样免疫反应性以及深层中间神经元中的TH免疫反应性似乎并未降低，离心传入纤维中去甲肾上腺素的MOB含量也未受影响。这些结果共同表明，初级嗅觉受体神经元输入的丧失可降低至少三类二级神经元（外侧簇状、中间簇状和球周细胞）中至少两种不同的、推测具有神经活性的化合物（P物质和多巴胺）的水平。因此，外周嗅觉神经元对中枢神经元表型的控制似乎是一种具有广泛影响的现象。它可能在处理化学感觉信息中起作用，并提供了一个研究神经元可塑性的系统。
