Laboratory of Neuroanatomy & Neuropsychobiology, Department of Pharmacology, Ribeirão Preto Medical School of the University of São Paulo (FMRP-USP), Av. Bandeirantes, 3900, Ribeirão Preto, São Paulo, 14049-900, Brazil.
Department of Zoology, Islamia College Peshawar, Grand trunk Rd, Rahat Abad, Peshawar, 25120, Pakistan.
Pflugers Arch. 2022 Apr;474(4):469-480. doi: 10.1007/s00424-022-02672-0. Epub 2022 Feb 24.
Defensive responses are neurophysiological processes crucial for survival during threatening situations. Defensive immobility is a common adaptive response, in rodents, elaborated by ventrolateral periaqueductal gray matter (vlPAG) when threat is unavoidable. It is associated with somatosensory and autonomic reactions such as alteration in the sensation of pain and rate of respiration. In this study, defensive immobility was assessed by chemical stimulation of vlPAG with different doses of NMDA (0.1, 0.3, and 0.6 nmol). After elicitation of defensive immobility, antinociceptive and respiratory response tests were also performed. Results revealed that defensive immobility was followed by a decrease in the nociceptive perception. Furthermore, the lowest dose of NMDA induced antinociceptive response without eliciting defensive immobility. During defensive immobility, respiratory responses were also disturbed. Interestingly, respiratory rate was increased and interspersed with prolonged expiratory phase of breathing. These findings suggest that vlPAG integrates three different defensive behavioral responses, contributing to the most effective defensive strategies during threatening situations.
防御反应是神经生理过程，对于在威胁情况下的生存至关重要。防御性不动是一种常见的适应性反应，在啮齿动物中，当威胁不可避免时，腹外侧导水管周围灰质（vlPAG）会引发这种反应。它与感觉和自主反应有关，例如疼痛感觉和呼吸率的改变。在这项研究中，通过用不同剂量的 NMDA（0.1、0.3 和 0.6 nmol）对 vlPAG 进行化学刺激来评估防御性不动。在引发防御性不动之后，还进行了抗伤害和呼吸反应测试。结果表明，防御性不动后疼痛感知会下降。此外，最低剂量的 NMDA 诱导出抗伤害反应而不会引发防御性不动。在防御性不动期间，呼吸反应也受到干扰。有趣的是，呼吸频率增加，并伴有呼气阶段延长。这些发现表明，vlPAG 整合了三种不同的防御性行为反应，有助于在威胁情况下采取最有效的防御策略。
