Stress fear conditioning

Pawlyk, A. C., Jha, S. K., Brennan, F. X., Morrison, A. R. Ross, R. J. (2005). A rodent model of sleep disturbances in posttraumatic stress disorder the role of context after fear conditioning. Biol. Psychiatry 57, 268-77. 

Inhibitory NE/p-adrenergic Mediai prefrontai cortex, baso- Excessive stress-mediated release of CRH, cortisol, and NE will facilitate development of indelible fear memories. Chronic anxiety and phobic symptoms may result from excessive contextual fear conditioning CRH antagonists and p-adrenergic recep-... 

Stressful stimuli of many types produce marked increases in brain noradrenergic function. Stress produces regional selective increases in NE turnover in the locus coeruleus (LC), limbic regions (hypothalamus, hippocampus, and amygdala), and cerebral cortex. These changes can be elicited with immobilization stress, foot-shock stress, tail-pinch stress, and conditioned fear. Exposure to stressors from which the animal cannot escape results in behavioral deficits termed learned helplessness. The learned helplessness state is associated with depletion of NE, probably reflecting the point where synthesis cannot keep up with demand. These studies have been reviewed elsewhere in detail (Bremner et al. 1996a,b). 

Silvestre J, Fernandez AG, Palacios JN (1999) Effects of rolipram on the elevated plus-maze test in rats a preliminary study. J Psychopharmacol 13 274-277 Sousa N, Lukoyanov NV, Madeira MD, Almeida OF, Paula-Barbosa MM (2000) Reorganization of the morphology of hippocampal neurites and synapsed after stress-induced damage correlates with behavioral improvements. Neuroscience 97 253-266 Stanciu M, Radulovic J, Spiess J (2001) Phosphorylated cAMP response element binding protein in the mouse brain after fear conditioning relationship to Fos production. Mol Brain Res 94 15-24... 

Watanabe Y, Gould E, McEwen BS (1992a) Stress induces atrophy of apical dendrites of hippocampal CA3 pyramidal neurons. Brain Res 588 341-345 Weeber E, Atkins CM, Selcher JC, Varga AW, Mirnikjoo B, Paylor R, Leitges M, Sweatt JD (2000) A role for the p isoform of protein kinase C in fear conditioning. J Neurosci 20 5906-5914... 

Several studies postulate that NE plays a central role in consolidation and retrieval of stress-related memory (Hurlemann et al., 2005 Mueller et al., 2008a Ouyang and Thomas 2005 van Stegeren, 2008b). The role of this activity is fear conditioning and extinction. These behavioral effects of NE are probably mediated via hippocampal p2 and a2 receptors, respectively (Davies et al., 2004 Garelick and Storm 2005). NE pathways and their role in nociception, emotions, cognition and behavior are summarized in table 2. 

Toledo-Rodriguez, M., and Sandi, C. (2007). Stress before puberty exerts a sex- and age-related impact on auditory and contextual fear conditioning in the rat. Neural Blast. 2007, 1-12. 

Animal models can complement clinical studies of PTSD in that prospective studies can more readily be conducted, exposure and physiologic stress conditions can be more tightly controlled, and biochemical and neuroanatomical measures can be evaluated. A variety of animal models, including conditioned defeat, fear conditioning, and predator stress models have been developed to mimic ASD and features of PTSD. Animal measures that are considered useful and parallel symptoms of PTSD include fear, avoidant and hypervigilant responses. We will briefly discuss a few representative animal models of ASD and PTSD. 

An increased lactate concentration in CSF is an important indicator for CNS involvement. Increased lactate concentrations in blood are also indicative, but can easily be caused by stress (fear of venapuncture), excessive muscle contractions (status epilepticus), anoxia and other conditions. A reliable value is only obtained from two or more blood lactate determinations. Some patients with a proven mitochondrial defect do not show lactate accumulation in blood or urine, but CSF lactate is frequently increased. Urinary lactate excretion can be secondarily increased in some types of organic aciduria [2]. 

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