Kulkarni-Narla A, Getchell T V, Getchell M L
Department of Physiology, University of Kentucky College of Medicine, Lexington, 40536, USA.
J Comp Neurol. 1997 Apr 28;381(1):31-40. doi: 10.1002/(sici)1096-9861(19970428)381:1<31::aid-cne3>3.0.co;2-l.
Superoxide dismutases (SODs) protect cells from damage by oxygen free radicals. Manganese (Mn) SOD is preferentially induced in terminally differentiating cells; induction of copper-zinc (CuZn) SOD is more closely associated with postnatal exposure to environmental sources of oxygen free radicals. The purpose of this study was to investigate ontogenetic changes in immunoreactivity for MnSOD and CuZnSOD relative to the expression of markers of neuronal and chemosensory differentiation in olfactory and vomeronasal receptor neurons (ORNs and VRNs, respectively), which mature with different time courses. Immunoreactivity for both SODs was detected in rat ORNs at embryonic day (E) 14, the earliest time point investigated, but not until E16 in vomeronasal neuroblasts. ORNs also expressed the neuronal marker protein gene product (PGP) 9.5 and the chemosensory cell marker olfactory marker protein (OMP) at E14; vomeronasal neuroblasts expressed PGP 9.5 at E16 but were not immunoreactive for OMP until postnatal day (P) 2. Immunoreactivity for MnSOD in ORNs and VRNs generally increased pre- and postnatally to a maximum at P11. Immunoreactivity for CuZnSOD did not increase markedly until after birth, reaching maximal levels at P11-P24. Within ORNs and VRNs, the most intense immunoreactivity was localized in the dendritic and supranuclear regions. The results indicate that in ORNs and VRNs, increases in MnSOD immunoreactivity during ontogeny parallel the ongoing differentiation and maturation of chemosensory receptor neurons; in contrast, the induction of immunoreactivity for CuZnSOD is associated with postnatal exposure to the ambient oxygen and xenobiotic environment.
超氧化物歧化酶（SOD）可保护细胞免受氧自由基的损伤。锰（Mn）超氧化物歧化酶在终末分化细胞中优先被诱导；铜锌（CuZn）超氧化物歧化酶的诱导与出生后暴露于环境氧自由基源的关系更为密切。本研究的目的是调查相对于嗅觉和犁鼻器受体神经元（分别为ORN和VRN）中神经元和化学感觉分化标志物的表达，MnSOD和CuZnSOD免疫反应性的个体发生变化，这两种神经元以不同的时间进程成熟。在胚胎第14天（E14），即所研究的最早时间点，在大鼠ORN中检测到两种SOD的免疫反应性，但在犁鼻器神经母细胞中直到E16才检测到。ORN在E14时也表达神经元标志物蛋白基因产物（PGP）9.5和化学感觉细胞标志物嗅觉标志物蛋白（OMP）；犁鼻器神经母细胞在E16时表达PGP 9.5，但直到出生后第2天（P2）才对OMP呈免疫反应性。ORN和VRN中MnSOD的免疫反应性在出生前和出生后总体上增加，在P11时达到最大值。CuZnSOD的免疫反应性直到出生后才显著增加，在P11 - P24时达到最高水平。在ORN和VRN内，最强的免疫反应性定位于树突和核上区域。结果表明，在ORN和VRN中，个体发生过程中MnSOD免疫反应性的增加与化学感觉受体神经元的持续分化和成熟平行；相比之下，CuZnSOD免疫反应性的诱导与出生后暴露于环境氧和异源生物环境有关。
