Histaminergic neurons of the tuberomammillary nucleus (TMN) are important regulators of behavioral and homeostatic processes. Previous work suggested that histaminergic neurons exhibit a characteristic electrophysiological signature, allowing for their identification in brain slice preparations. However, these previous investigations focused on neurons in the ventral subregion of the TMN of rats. Consequently, it remains unclear whether such electrophysiological properties extend to mice, including other subregions of the TMN, and the potential for differences between males and females. To further characterize the electrophysiological properties of histaminergic neurons, we performed whole-cell patch-clamp recordings on transgenic mice expressing Cre recombinase in histidine decarboxylase (HDC)-expressing cells; the sole enzyme for histamine synthesis (Hdc-cre::tdTomato). Despite similarities with the electrophysiological properties reported in rats, we observed considerable variability in mouse HDC neuron passive membrane properties, action potential firing, and intrinsic subthreshold active membrane properties. Overall, the electrophysiological properties of HDC neurons appeared similar across subregions of the TMN, consistent with a lack of topographical organization in this nucleus. Moreover, we found no obvious sex differences in the electrical excitability of HDC neurons. However, our data reveal a diversity in the electrophysiological properties of genetically identified histaminergic neurons from mice not previously appreciated from rat studies. Thus, these data highlight the utility of mouse genetics to target the widespread histaminergic neuronal population within the TMN and support the idea that histaminergic neurons are a heterogeneous neuronal population.

结核母核（TMN）的组胺能神经元是行为和体内平衡过程的重要调节剂。先前的工作表明，组胺能神经元表现出特征性的电生理特征，从而可以在脑切片制备中对其进行鉴定。但是，这些先前的研究集中在大鼠TMN腹侧亚区域的神经元。因此，尚不清楚这种电生理特性是否扩展到小鼠，包括TMN的其他子区域，以及雌雄之间存在差异的可能性。为了进一步表征组胺能神经元的电生理特性，我们在表达组氨酸脱羧酶（HDC）的细胞中表达Cre重组酶的转基因小鼠上进行了全细胞膜片钳记录；高压直流-cre :: tdTomato）。尽管与大鼠中报道的电生理特性相似，但我们观察到小鼠HDC神经元被动膜特性，动作电位触发和固有的阈下活性膜特性有相当大的可变性。总体而言，HDC神经元的电生理特性在TMN的各个子区域中表现出相似性，这与该细胞核中缺乏地形组织相一致。此外，我们发现HDC神经元的电兴奋性没有明显的性别差异。但是，我们的数据揭示了从老鼠那里获得的遗传鉴定的组胺能神经元的电生理特性的多样性，而老鼠此前从未对此进行过赞赏。从而，