Brain-derived neurotrophic factor (BDNF) in the paraventricular nucleus of the hypothalamus (PVN) can regulate food intake and energy expenditure. However, the regulatory mediator of BDNF-positive neurons in the PVN remains unclear. Recently, widespread expression of the dopamine D1 receptor (DRD1) and D2 receptor (DRD2) has been observed in PVN neurons. We hypothesized that dopamine receptors (DRs) are also expressed in BDNF-positive neurons and mediate the function of BDNF in the PVN. Using multiple immunofluorescence assays combined with confocal microscopy, we found that BDNF-immunoreactive (IR) neurons were widely distributed throughout the PVN in both the magnocellular and parvocellular regions. The BDNF protein was mainly expressed in the somas of neurons. The distribution of DR-IR neurons exhibited a pattern similar to that of BDNF. Nearly all DRD1 and DRD2 expression occurred within BDNF-IR neurons. A large number of tyrosine hydroxylase (TH)-IR fibers innervated the entire PVN. The BDNF-IR neurons were surrounded by TH-IR nerve fibers that were punctiform or shaped like short bars. Additionally, BDNF colocalized with vasopressin-, oxytocin- and corticotrophin releasing hormone-positive neurons in the PVN. The present study suggests that DRs have a potential role in mediating the function of the PVN BDNF neurons. This finding is important for elucidating the central circuitry involved in energy balance.

中文翻译：

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大鼠室旁核表达BDNF的肽能神经元中多巴胺受体的共定位

下丘脑室旁核 (PVN) 中的脑源性神经营养因子 (BDNF) 可以调节食物摄入和能量消耗。然而，PVN 中 BDNF 阳性神经元的调节介质仍不清楚。最近，在 PVN 神经元中观察到多巴胺 D1 受体 (DRD1) 和 D2 受体 (DRD2) 的广泛表达。我们假设多巴胺受体 (DR) 也在 BDNF 阳性神经元中表达并介导 BDNF 在 PVN 中的功能。使用多个免疫荧光测定结合共聚焦显微镜，我们发现 BDNF 免疫反应 (IR) 神经元广泛分布在整个 PVN 中的大细胞和细小细胞区域。BDNF蛋白主要在神经元胞体中表达。DR-IR 神经元的分布表现出与 BDNF 相似的模式。几乎所有的 DRD1 和 DRD2 表达都发生在 BDNF-IR 神经元内。大量酪氨酸羟化酶 (TH)-IR 纤维支配整个 PVN。BDNF-IR 神经元被 TH-IR 神经纤维包围，这些神经纤维呈点状或短条状。此外，BDNF 与 PVN 中的血管加压素、催产素和促肾上腺皮质激素释放激素阳性神经元共定位。本研究表明，DRs 在介导 PVN BDNF 神经元的功能方面具有潜在作用。这一发现对于阐明参与能量平衡的中央电路很重要。BDNF 与 PVN 中的血管加压素、催产素和促肾上腺皮质激素释放激素阳性神经元共定位。本研究表明，DRs 在介导 PVN BDNF 神经元的功能方面具有潜在作用。这一发现对于阐明参与能量平衡的中央电路很重要。BDNF 与 PVN 中的血管加压素、催产素和促肾上腺皮质激素释放激素阳性神经元共定位。本研究表明，DRs 在介导 PVN BDNF 神经元的功能方面具有潜在作用。这一发现对于阐明参与能量平衡的中央电路很重要。