Department of Physiology, Kochi Medical School, Kochi University, Kochi, Japan.
Front Neural Circuits. 2024 Nov 7;18:1473403. doi: 10.3389/fncir.2024.1473403. eCollection 2024.
Olfactory behavior is highly plastic, and the olfactory tubercle (OT), a component of the olfactory cortex and ventral striatum, includes anteromedial (amOT) and lateral (lOT) domains with roles in attractive and aversive olfactory behavioral learning, respectively. However, the underlying properties of synaptic plasticity in these domains are incompletely understood. Synaptic plasticity is regulated by multiple signals including synaptic inputs and neuromodulators. Interestingly, the amOT domain exhibits high expression of various receptors for neuromodulators. We investigated synaptic plasticity in mouse OT slices by combining electrical stimulation and treatment with the appetite-promoting neuropeptide orexin, the receptors of which are highly expressed in the amOT. In both the amOT and lOT, one round of 2-Hz burst stimulation elicited short-term potentiation of the field excitatory postsynaptic potential, whereas three rounds of stimulation induced long-term potentiation (LTP) that persisted for 150 min. In the amOT, orexin-A induced LTP was blocked by the orexin receptor type 1 antagonist SB334867. Orexin-A also facilitated LTP induction in the amOT by one round of 2-Hz burst stimulation. By contrast, these effects were not observed in the lOT. These results highlighted the similarity and difference in synaptic plasticity between the OT domains and suggested that orexin facilitates synaptic plasticity in the amOT during olfactory learning processes such as food odor learning.
嗅觉行为具有高度可塑性，而嗅球（OT）作为嗅觉皮层和腹侧纹状体的一部分，包括前内侧（amOT）和外侧（lOT）两个区域，分别在吸引性和厌恶性嗅觉行为学习中发挥作用。然而，这些区域中突触可塑性的潜在特性尚不完全清楚。突触可塑性受多种信号调节，包括突触输入和神经调质。有趣的是，amOT 区域表现出对各种神经调质受体的高表达。我们通过结合电刺激和食欲促进神经肽食欲素的处理，研究了小鼠 OT 切片中的突触可塑性，其受体在 amOT 中高度表达。在 amOT 和 lOT 中，一轮 2-Hz 爆发刺激引发了场兴奋性突触后电位的短期增强，而三轮刺激则诱导了持续 150 分钟的长期增强（LTP）。在 amOT 中，食欲素 A 诱导的 LTP 被食欲素受体 1 拮抗剂 SB334867 阻断。食欲素 A 还通过一轮 2-Hz 爆发刺激促进了 amOT 中的 LTP 诱导。相比之下，这些效应在 lOT 中没有观察到。这些结果突出了 OT 区域之间突触可塑性的相似性和差异，并表明食欲素在食物气味学习等嗅觉学习过程中促进了 amOT 中的突触可塑性。
