Tseng J Y, Kolb P E, Raskind M A, Miller M A
Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle 98195, USA.
Brain Res Mol Brain Res. 1997 Oct 15;50(1-2):100-6. doi: 10.1016/s0169-328x(97)00164-2.
The neuropeptide galanin (GAL) is coexpressed by the majority of noradrenergic neurons in the rat locus ceruleus (LC) and may function as an inhibitory modulator of noradrenergic transmission. Because estrogen has been shown to induce GAL expression in other brain regions and modulate noradrenergic transmission, we used in situ hybridization histochemistry to assess the effects of chronic estrogen treatment on GAL and tyrosine hydroxylase (TH) gene expression in the LC of ovariectomized female rats. We found that GAL mRNA levels were significantly elevated in rats implanted with a Silastic capsule containing estradiol compared to sham-implanted controls. Both the average optical density (P < or = 0.05) and the labelling area (P < or = 0.007) differed significantly between the groups. In contrast, TH gene expression measured in alternate brain sections did not differ between the groups. If GAL functions as an inhibitory modulator of noradrenergic transmission as postulated, these findings suggest that chronic estrogen treatment could reduce the noradrenergic tone of the brain in the absence of significant alterations in TH expression by enhancing the level of cosecreted GAL.
神经肽甘丙肽（GAL）与大鼠蓝斑（LC）中的大多数去甲肾上腺素能神经元共同表达，并可能作为去甲肾上腺素能传递的抑制性调节剂发挥作用。由于雌激素已被证明可在其他脑区诱导GAL表达并调节去甲肾上腺素能传递，我们采用原位杂交组织化学方法来评估慢性雌激素处理对去卵巢雌性大鼠LC中GAL和酪氨酸羟化酶（TH）基因表达的影响。我们发现，与假手术对照组相比，植入含雌二醇硅橡胶胶囊的大鼠中GAL mRNA水平显著升高。两组之间的平均光密度（P≤0.05）和标记面积（P≤0.007）均存在显著差异。相比之下，在相邻脑切片中测量的TH基因表达在两组之间没有差异。如果GAL如假设的那样作为去甲肾上腺素能传递的抑制性调节剂发挥作用，这些发现表明慢性雌激素处理可通过提高共分泌的GAL水平，在TH表达无显著改变的情况下降低大脑的去甲肾上腺素能张力。
