New Perspectives on β-Adrenergic Mediation of Innate and Learned Fear Responses to Predator Odor
New Perspectives on β-Adrenergic Mediation of Innate and Learned Fear Responses to Predator Odor
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DOI：
10.1523/jneurosci.2843-08.2008
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发表时间：
2008-12-03
影响因子：
5.3
通讯作者：
Carobrez, Antonio P.
中科院分区：
文献类型：
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作者：
Do Monte, Fabricio H. M.;Canteras, Newton Sabino;Carobrez, Antonio P.
在本研究中，我们研究了去甲肾上腺素能传递在非条件性和条件性捕食性威胁反应中的作用。首先，我们研究了全身注射β受体阻滞剂对猫气味的非条件性和背景条件性反应的影响。中枢作用的β-受体阻滞剂（普萘洛尔）能够削弱非条件反应，以及收购的上下文恐惧猫的气味;然而，外周作用（纳多洛尔）是无效的。接下来，我们研究了猫气味防御反应的去甲肾上腺素能调制的神经基质，并集中在背侧乳头体前核（PMD），因为它代表了下丘脑对捕食性威胁最敏感的部位，同时，呈现出密集的去甲肾上腺素能纤维丛。我们能够看到，普萘洛尔显着降低PMd-Fos表达响应猫的气味和β-肾上腺素受体阻滞剂在PMd，猫的气味暴露前，减少防御反应的猫的气味和猫的气味相关的环境。我们还表明，β-肾上腺素受体阻滞剂在PMD，暴露于猫气味相关的背景下，损害了上下文的条件反应。总体而言，目前的研究结果提供了令人信服的证据表明，中央去甲肾上腺素能介导的非条件和上下文条件的antipredatory反应的表达是至关重要的。我们进一步表明，PMd似乎是一个重要的位点，介导这些β-肾上腺素受体的影响。
In the present study, we investigated the role of noradrenergic transmission in unconditioned and conditioned responses to predatory threats. First, we examined the effects of systemically injected beta-blockers on unconditioned and contextual conditioned response to cat odor. The centrally acting beta-blocker (propranolol) was able to impair unconditioned responses, as well as the acquisition of the contextual fear to cat odor; however, the peripherally acting (nadolol) was not effective. Next, we examined the neural substrate underlying the noradrenergic modulation of the defensive response to cat odor and focused on the dorsal premammillary nucleus (PMd), because it represents the hypothalamic site most responsive to predatory threats and, at the same time, presents a dense plexus of noradrenergic fibers. We were able to see that propranolol significantly reduced PMd-Fos expression in response to cat odor and that beta-adrenoceptor blockade in the PMd, before cat odor exposure, reduced defensive responses to the cat odor and to the cat odor-related environment. We have also shown that beta-adrenoceptor blockade in the PMd, before the exposure to cat odor-related context, impaired the contextual conditioned responses. Overall, the present results provide convincing evidence suggesting that central noradrenergic mediation is critical for the expression of unconditioned and contextual conditioned antipredatory responses. We have further shown that the PMd appears to be an important locus to mediate these beta-adrenoceptor effects.