Basolateral amygdala (BLA) nuclei and their reciprocal connections with prelimbic (PL) and infralimbic (IL) regions of the medial prefrontal cortex (mPFC) are involved in the regulation of fear. 2-Heptanone is released in urine in stressed rats, and the olfactory detection of this odor produces immediate avoidance and alarm reactions and modifies neuronal activity in limbic connections in non-stressed rats. If 2-heptanone acts as a danger signal, then long-lasting actions would be expected. The aim of the present study was to investigate whether the forced inhalation of 2-heptanone modifies the response capacity of the BLA-mPFC circuit in the long term (48 h). Single-unit extracellular recordings were obtained from the PL and IL during electrical stimulation of the BLA (square-wave pulses; 1 ms, 20 µA, 0.3 Hz, 110 stimuli over a total duration of 360 s) in three groups of Wistar rats: control group (no sensory stimulation), unpredictable auditory stimulation group, and 2-heptanone stimulation group. A brief-latency (1 ms), short-duration (5 ms) paucisynaptic response followed BLA stimulation and was unaffected by any sensorial stimulation. The paucisynaptic response was followed by a mostly inhibitory and long-lasting (>750 ms) afterdischarge in the control and auditory stimulation groups. In the 2-heptanone group, the inhibitory afterdischarge shifted to an excitatory afterdischarge after ∼250 ms in the PL and after ∼500 ms in the IL. Importantly, the rats that were included in this study were born in local housing facilities. Thus, these animals were never in contact with predators and instead in contact with only conspecifics. These results indicate that the forced inhalation of 2-heptanone is able to modify BLA-mPFC responsivity in the long term. 2-Heptanone decreases inhibitory control of the amygdala over mPFC activity. Disinhibition of the mPFC may lead to the adaptive expression of defensive behaviors, even in animals that are not in the presence of predators.

基底外侧杏仁核 (BLA) 核及其与内侧前额叶皮层 (mPFC) 的前边缘 (PL) 和下边缘 (IL) 区域的相互联系参与了恐惧的调节。2-庚酮在应激大鼠的尿液中释放，嗅觉检测到这种气味会立即产生回避和警报反应，并改变非应激大鼠边缘连接中的神经元活动。如果 2-庚酮作为危险信号，则预期会产生持久作用。本研究的目的是调查强制吸入 2-庚酮是否会长期（48 小时）改变 BLA-mPFC 电路的响应能力。在对 BLA 进行电刺激（方波脉冲；1 ms、20 µA、0.3 Hz、110 次刺激，总持续时间为 360 秒）在三组 Wistar 大鼠中：对照组（无感觉刺激）、不可预测的听觉刺激组和 2-庚酮刺激组。BLA 刺激后出现短暂的潜伏期 (1 ms)、短时间 (5 ms) 的少突触反应，并且不受任何感觉刺激的影响。在对照组和听觉刺激组中，少突触反应之后是主要抑制和持久（> 750 ms）的后放电。在 2-庚酮组中，PL 约 250 ms 和 IL 约 500 ms 后，抑制性后放电转变为兴奋性后放电。重要的是，本研究中的老鼠出生在当地的住房设施中。因此，这些动物从未与捕食者接触，而是仅与同类接触。这些结果表明，2-庚酮的强制吸入能够长期改变 BLA-mPFC 响应性。2-庚酮降低杏仁核对 mPFC 活性的抑制控制。mPFC 的去抑制可能导致防御行为的适应性表达，即使在没有捕食者存在的动物中也是如此。