Role of locus coeruleus in foot shock-evoked fos expression in rat brain
Section snippets
Animals and surgical procedures
Adult, male Sprague–Dawley rats (281–430 g; Zivic Miller, Zelienople, PA, USA) were individually housed in stainless steel cages. Rats were maintained on a 12-h light/dark cycle with food and water available ad libitum. All procedures conformed to NIH guidelines and were approved by the Institutional Animal Care and Use Committee at The University of Pittsburgh. Two to five days after arrival, rats were anesthetized with halothane and stereotaxic procedures were used to implant bilateral guide
Injection sites
Histological examination of tissue was used to document cannula placement. A typical LC microinjection site in a non-shocked rat in which aCSF was infused directly into the LC is shown in Fig. 1. The high level of Fos expression in the area immediately surrounding the cannula tracts was noted in all rats that received microinjections of either aCSF or muscimol and occurred when microinjections were made into the LC or into areas adjacent to the LC. Therefore, Fos expression in the LC was
DISCUSSION
In an effort to elucidate the role of the LC in stress-evoked responses, the present study sought to determine the effect of acute inhibition of the LC on foot shock-induced Fos expression throughout the rat brain. The key finding of the present study is that injection of the GABA agonist, muscimol, into the LC prevented or attenuated shock-induced Fos expression in many brain sites that express Fos in response to foot shock. These findings suggest that the LC may be an important component of
Conclusion
The present study has demonstrated that functional blockade of the LC prevented or attenuated foot shock-evoked Fos expression in several discrete brain areas previously shown to be activated in response to stress. Importantly, direct inhibition of the LC did not alter the response of all brain sites to foot shock stress, thereby demonstrating that this response to LC inhibition was not global. Thus, it seems that stress-evoked activation of LC neurons is necessary for the full activation of
Acknowledgements
This work was supported by PHS grants MH43411 and MH29670, and NIH Postdoctoral Training Award MH18903.
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2016, Behavioural Brain ResearchCitation Excerpt :However, two higher doses of clonidine or the highest dose of yohimbine increased % grooming, while two middle doses of clonidine or yohimbine increased % rearing in the auditory fear conditioning. It has been reported that stressors such as electric shock, loud noise, tail-pinch, and immobilization as well as stress hormones activate noradrenergic input to the basolateral amygdala (BLA) from locus coeruleus (LC) [22–27]. In addition, some papers have confirmed the role of the noradrenergic projection to the BLA in memory processing [28].
CRH Engagement of the Locus Coeruleus Noradrenergic System Mediates Stress-Induced Anxiety
2015, NeuronCitation Excerpt :Numerous groups have reported that tonic activity of LC-NE neurons increases in response to stress (Bingham et al., 2011; Cassens et al., 1981; Curtis et al., 1997, 2012; Francis et al., 1999; Reyes et al., 2008; Valentino and Van Bockstaele, 2008; Valentino et al., 1991). Others have demonstrated that non-selective pharmacological inactivation or lesions to the LC lessen morphine withdrawal symptoms, prevent footshock-evoked c-fos expression throughout the brain, and disrupt both unconditioned and conditioned aversive responses (Mirzaii-Dizgah et al., 2008; Neophytou et al., 2001; Passerin et al., 2000), but it has previously been untenable to selectively inhibit the activity of only these NE neurons and assess their role in stress-induced behaviors. To examine the role of LC-NE neurons in stress-induced anxiety-like behavior, we implemented a restraint stress paradigm, immediately followed by anxiety testing in the open field test (OFT) (Figure 1A).
Amygdalar orexinergic-GABAergic interactions regulate anxiety behaviors of the Syrian golden hamster
2011, Behavioural Brain ResearchCitation Excerpt :This telencephalic region is composed of different anatomically interconnected amygdaloid nuclei that include basolateral (BLA), cortico-medial and centromedial nuclear groups, [44,48] which are capable of influencing emotional and mnemonic functions [17], vary likely through extensive visceral (hypothalamus and olfactory lobes) and autonomic-somatomotor connections [50]. Even the central AMY nucleus (Ce) that is involved with aversive learning, escaping responses and mnemonic capabilities of stressful experiences [3,32] has been identified as a critical site for the mediation of responses to anxiogenic stimuli or stress-related behaviors [41,52] deriving from elevated-plus maze (EPM), shock probe burying, and social anxiety tests [53]. Curiously, numerous evidences have demonstrated that Ce is mostly innervated by ORX neurons as displayed by dense levels of ORX1R and ORX2R fibers throughout this AMY nucleus [60].