The monoamine neurotransmitter serotonin (5-HT) modulates anxiety by its activity on 5-HT receptors (5-HTR) expressed in the dorsal periaqueductal gray (dPAG). Here, we investigated the presence of 5-HT receptors (5-HTR) in the dPAG, and the interplay between 5-HTR and 5-HTR in the dPAG in mediating anxiety-like behavior in mice. We found that 5-HTR is expressed in the dPAG and the blockade of these receptors using intra-dPAG infusion of ondansetron (5-HTR antagonist; 3.0 nmol) induced an anxiogenic-like effect. The activation of 5-HTR by the infusion of mCPBG [1-(m-Chlorophenyl)-biguanide; 5-HTR agonist] did not alter anxiety-like behaviors. In addition, blockade of 5-HTR (1.0 nmol) prevented the anxiolytic-like effect induced by the infusion of the 5-HTR agonist mCPP (1-(3-chlorophenyl) piperazine; 0.03 nmol). None of the treatment effects on anxiety-like behaviors altered the locomotor activity levels. The present results suggest that the anxiolytic-like effect exerted by serotonin activity on 5-HTR in the dPAG is modulated by 5-HTR expressed in same region.

中文翻译：

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导水管周围灰质背侧 5-HT2C 和 5-HT3A 受体之间的相互作用介导小鼠的焦虑样行为


单胺神经递质血清素 (5-HT) 通过其对导水管周围灰质背侧 (dPAG) 表达的 5-HT 受体 (5-HTR) 的活性来调节焦虑。在这里，我们研究了 dPAG 中 5-HT 受体 (5-HTR) 的存在，以及 dPAG 中 5-HTR 和 5-HTR 之间的相互作用在介导小鼠焦虑样行为中的相互作用。我们发现 5-HTR 在 dPAG 中表达，并且使用 dPAG 内输注昂丹司琼（5-HTR 拮抗剂；3.0 nmol）来阻断这些受体可诱导产生焦虑样作用。通过输注 mCPBG [1-(间氯苯基)-双胍来激活 5-HTR； 5-HTR激动剂]不会改变焦虑样行为。此外，阻断5-HTR（1.0 nmol）可防止输注5-HTR激动剂mCPP（1-（3-氯苯基）哌嗪；0.03 nmol）诱导的抗焦虑样作用。对焦虑样行为的治疗效果均不会改变运动活动水平。目前的结果表明，dPAG 中 5-羟色胺活性对 5-HTR 产生的抗焦虑样作用受到同一区域中表达的 5-HTR 的调节。