Harrell L E, Peagler A, Parsons D S, Litersky J, Barlow T S
Department of Neurology, Veterans Administration, Birmingham, AL.
Behav Brain Res. 1993 May 31;55(1):29-38. doi: 10.1016/0166-4328(93)90004-a.
Following cholinergic denervation of the hippocampal formation, via medial septal (MS) lesions, sympathetic fibers, originating from the superior cervical ganglia, growth into the hippocampus. Previous studies have demonstrated a sexually dimorphic effect of this neuronal rearrangement on recovery of a spatial-learning task, with this rearrangement being detrimental in male but protective in female rats. Circulating male sex hormones were found to interact with this effect in male animals. In this study we assessed the role of circulating female sex hormones on the behavioral and biochemical effects of hippocampal sympathetic ingrowth (HSI). For the behavioral studies female rats underwent either sham ovariectomy (sham OVARX) or OVARX and were taught a standard radial-8-arm maze task. Following attainment of criterion, animals underwent one of three surgical procedures: sham surgery; MS lesions+sham ganglionectomy (MS); HSI group; MS lesions+ganglionectomy (MSGx). As in our previous study, animals with HSI (i.e. MS group) were found to recover learning faster (in fact, these animals did not differ from controls) than animals with MS lesions without HSI. Gonadal status did not affect this behavioral recovery. For the biochemical studies hippocampal norepinephrine (NE) and choline acetyltransferase (ChAT) were measured in animals sham OVARX and OVARX, 8-12 weeks after the neurosurgical procedure. MS lesions (i.e. MSGx; MS) were found to reduce ChAT activity, regardless of circulating sex hormones. In controls NE levels were similar between OVARX and sham OVARX. NE levels were markedly elevated in the OVARX MS group compared to all other groups including sham OVARX. In the MSGx groups, NE levels were reduced compared to controls, while comparisons between these groups revealed a significant reduction in NE levels in the OVARX MSGx group compared to sham OVARX MSGx group. These studies suggest that female circulating sex hormones interact with brain injury in a very complex manner. However, this interaction does not appear to mediate the changes in behavior observed after HSI.
通过内侧隔区（MS）损伤对海马结构进行胆碱能去神经支配后，源自颈上神经节的交感神经纤维长入海马。先前的研究已经证明，这种神经元重排对空间学习任务恢复具有性别二态性效应，这种重排在雄性大鼠中是有害的，但在雌性大鼠中具有保护作用。发现循环中的雄性性激素在雄性动物中与这种效应相互作用。在本研究中，我们评估了循环中的雌性性激素对海马交感神经长入（HSI）的行为和生化效应的作用。对于行为学研究，雌性大鼠接受假卵巢切除术（假OVARX）或卵巢切除术（OVARX），并学习标准的放射状八臂迷宫任务。达到标准后，动物接受三种手术程序之一：假手术；MS损伤+假神经节切除术（MS）；HSI组；MS损伤+神经节切除术（MSGx）。与我们之前的研究一样，发现具有HSI的动物（即MS组）比没有HSI的MS损伤动物恢复学习更快（实际上，这些动物与对照组没有差异）。性腺状态不影响这种行为恢复。对于生化研究，在神经外科手术后8-12周，测量假OVARX和OVARX动物海马中的去甲肾上腺素（NE）和胆碱乙酰转移酶（ChAT）。发现MS损伤（即MSGx；MS）会降低ChAT活性，无论循环性激素如何。在对照组中，OVARX和假OVARX之间的NE水平相似。与包括假OVARX在内的所有其他组相比，OVARX MS组的NE水平明显升高。在MSGx组中，与对照组相比NE水平降低，而这些组之间的比较显示，与假OVARX MSGx组相比，OVARX MSGx组的NE水平显著降低。这些研究表明，雌性循环性激素与脑损伤以非常复杂的方式相互作用。然而，这种相互作用似乎并未介导HSI后观察到的行为变化。
