The lateral hypothalamus (LH) is a diencephalic structure that has been considered part of the central circuitry regulating the baroreflex function. However, the local neurochemical mechanisms involved in baroreflex control by this hypothalamic area are poorly understood. Therefore, in the present study we investigated the role of corticotropin-releasing factor (CRF) neurotransmission within the LH acting via local CRF₁ and CRF₂ receptors in cardiac baroreflex responses in unanesthetized rats. For this, the baroreflex activity was assessed using two approaches: i) the pharmacological approach via intravenous infusion of vasoactive agents, and ii) the sequence analysis technique that evaluates reflex responses during spontaneous arterial pressure variations. The sequence analysis technique indicated that LH treatment with the selective CRF₁ receptor antagonist CP376395 decreased the baroreflex effectiveness index, whereas the selective CRF₂ receptor antagonist antisauvagine-30 increased the reflex shortening of pulse interval during spontaneous arterial pressure decreases. However, the pharmacological approach did not indicate effect of the bilateral microinjection of either CP376395 or antisauvagine-30 into the LH in the tachycardia evoked by blood pressure decrease or the reflex bradycardia caused by blood pressure increase. Overall, these findings indicate that CRF neurotransmission within the LH controls baroreflex function during a narrow range of physiological arterial pressure variations. Besides, results provide evidence that CRF₁ and CRF₂ receptors in the LH oppositely modulate the spontaneous baroreflex activity through different mechanisms.

外侧下丘脑 (LH) 是一种间脑结构，被认为是调节压力反射功能的中枢回路的一部分。然而，对该下丘脑区域参与压力反射控制的局部神经化学机制知之甚少。因此，在本研究中，我们研究了促肾上腺皮质激素释放因子 (CRF) 神经传递在 LH 中通过局部 CRF ₁和 CRF ₂起作用的作用未麻醉大鼠心脏压力反射反应中的受体。为此，使用两种方法评估压力反射活动：i) 通过静脉输注血管活性剂的药理学方法，以及 ii) 评估自发动脉压变化期间反射反应的序列分析技术。序列分析技术表明，用选择性 CRF ₁受体拮抗剂 CP376395治疗 LH降低了压力反射有效性指数，而选择性 CRF ₂受体拮抗剂 antisauvagine-30 在自发性动脉压降低期间增加反射性缩短脉搏间隔。然而，药理学方法并未表明双侧微量注射 CP376395 或 antisauvagine-30 到 LH 中对由血压降低引起的心动过速或由血压升高引起的反射性心动过缓的影响。总体而言，这些发现表明 LH 内的 CRF 神经传递在狭窄的生理动脉压变化范围内控制压力反射功能。此外，结果证明LH中的 CRF ₁和 CRF ₂受体通过不同的机制相反地调节自发压力反射活动。