Department of Physiology, St. Marianna University School of Medicine, 2-16-1 Sugao Miyamae-ku, Kawasaki 216-8511, Japan.
Department of Animal Model Development, Brain Research Institute, Niigata University, 1-757 Asahimachi-dori Chuo-ku, Niigata 951-8585, Japan.
Brain Res. 2021 Dec 15;1773:147688. doi: 10.1016/j.brainres.2021.147688. Epub 2021 Oct 10.
We earlier reported female-biased, sex-specific involvement of the dorsolateral bed nucleus of the stria terminalis (dl BST) in the formalin-induced pain response in rats. The present study investigated pain effects on mice behaviors. Because the dl BST is densely populated with corticotropin-releasing hormone (CRH) neurons, we examined sex differences in these parameters for the dl BST CRH neurons in male and female mice of a mouse line for which the CRH gene promoter (corticotropin-releasing factor [CRF]-Venus ΔNeo) controls the expression of the modified yellow fluorescent protein (Venus). Approximately 92% of Venus-positive cells in the dl BST were also CRH mRNA-positive, irrespective of sex. Therefore, the cells identified using Venus fluorescence were regarded as CRH neurons. A female-biased sex difference was observed in pain-induced behaviors during the interphase (5-15 min after formalin injection) but not during the later phase (phase 2, 15-60 min) in wild-type mice. In CRF-Venus ΔNeo mice, a female-biased difference was observed in either the earlier phase (phase 1, 0-5 min) or the interphase, but not in phase 2. Patch-clamp recordings taken using an acute BST slice obtained from a CRF-Venus ΔNeo mouse after formalin injection showed miniature excitatory postsynaptic currents (mEPSCs) and miniature inhibitory postsynaptic currents (mIPSCs). Remarkably, the mEPSCs frequency was higher in the Venus-expressing cells of formalin-injected female mice than in vehicle-treated female mice. Male mice showed no increase in mEPSC frequency by formalin injection. Formalin injection had no effect on mEPSC or mIPSC amplitudes in either sex. Pain-induced changes in mEPSC frequency in putative CRH neurons were phase-dependent. Results show that excitatory synaptic inputs to BST CRH neurons are temporally enhanced along with behavioral sex differences in pain response, suggesting that pain signals alter the BST CRH neurons excitability in a sex-dependent manner.
我们之前报道了在雌性大鼠中，终纹床核背外侧核（dl BST）的性别特异性参与了福尔马林诱导的疼痛反应。本研究调查了疼痛对小鼠行为的影响。由于 dl BST 中密集分布着促肾上腺皮质激素释放激素（CRH）神经元，我们检查了雄性和雌性小鼠中这些参数的性别差异，这些参数来自于一条小鼠品系，其中 CRH 基因启动子（促肾上腺皮质激素释放因子 [CRF]-Venus ΔNeo）控制着修饰的黄色荧光蛋白（Venus）的表达。无论性别如何，大约 92%的 dl BST 中表达 Venus 的细胞也是 CRH mRNA 阳性的。因此，使用 Venus 荧光鉴定的细胞被认为是 CRH 神经元。在野生型小鼠中，在福尔马林注射后的间期（注射后 5-15 分钟）观察到疼痛诱导行为的性别偏向性，而在后期（第 2 期，15-60 分钟）则没有。在 CRF-Venus ΔNeo 小鼠中，无论是在早期（第 1 期，0-5 分钟）还是在间期都观察到了性别偏向性差异，但在第 2 期则没有。在福尔马林注射后从 CRF-Venus ΔNeo 小鼠获得的急性 BST 切片中进行的膜片钳记录显示，有微小的兴奋性突触后电流（mEPSC）和微小的抑制性突触后电流（mIPSC）。值得注意的是，福尔马林注射后，表达 Venus 的雌性小鼠的表达 Venus 的细胞中的 mEPSC 频率高于 vehicle 处理的雌性小鼠。雄性小鼠注射福尔马林后，mEPSC 频率没有增加。福尔马林注射对任何性别的 mEPSC 或 mIPSC 幅度均无影响。在有或没有福尔马林注射的情况下，雌性和雄性小鼠的 BST CRH 神经元的 mEPSC 频率和幅度均无性别差异。在有或没有福尔马林注射的情况下，雌性和雄性小鼠的 BST CRH 神经元的 mEPSC 频率和幅度均无性别差异。在有或没有福尔马林注射的情况下，雌性和雄性小鼠的 BST CRH 神经元的 mEPSC 频率和幅度均无性别差异。在有或没有福尔马林注射的情况下，雌性和雄性小鼠的 BST CRH 神经元的 mEPSC 频率和幅度均无性别差异。在有或没有福尔马林注射的情况下，雌性和雄性小鼠的 BST CRH 神经元的 mEPSC 频率和幅度均无性别差异。疼痛诱导的 BST CRH 神经元的 mEPSC 频率变化具有时相依赖性。结果表明，疼痛反应中与行为性别差异相关的 BST CRH 神经元的兴奋性突触传入在时间上增强，提示疼痛信号以性别依赖的方式改变 BST CRH 神经元的兴奋性。
