@article {2426, title = {A salience hypothesis of stress in PTSD.}, journal = {Eur J Neurosci}, volume = {54}, year = {2021}, month = {2021 12}, pages = {8029-8051}, abstract = {

Attention to key features of contexts and things is a necessary tool for all organisms. Detecting these salient features of cues, or simply, salience, can also be affected by exposure to traumatic stress, as has been widely reported in individuals suffering from post-traumatic stress disorder (PTSD). Interestingly, similar observations have been robustly replicated across many animal models of stress as well. By using evidence from such rodent stress paradigms, in the present review, we explore PTSD through the lens of salience processing. In this context, we propose that interaction between the neurotrophin brain-derived neurotrophic factor (BDNF) and glucocorticoids determines the long lasting cellular and behavioural consequences of stress salience. We also describe the dual effect of glucocorticoid therapy in the amelioration of PTSD symptoms. Finally, by integrating in vivo observations at multiple scales of plasticity, we propose a unifying hypothesis that pivots on a crucial role of glucocorticoid signalling in dynamically orchestrating stress salience.

}, keywords = {Animals, Brain-Derived Neurotrophic Factor, Glucocorticoids, Stress Disorders, Post-Traumatic}, issn = {1460-9568}, doi = {10.1111/ejn.15526}, author = {Chakraborty, Prabahan and Chattarji, Sumantra and Jeanneteau, Freddy} } @article {2291, title = {The same stress has divergent effects on social versus asocial manifestations of anxiety-like behavior over time.}, journal = {Stress}, volume = {24}, year = {2021}, month = {2021 07}, pages = {474-480}, abstract = {

Stress may lead to augmented anxiety, which may, with time culminate in some form of anxiety disorder. Behavioral alterations related to increased anxiety can be broadly classified into two types-social, affecting interactions between individuals, and self-oriented, affecting the anxious individual only. While a growing body of literature now exists describing the effects of stress-induced anxiety on self-oriented behavior in animal models of anxiety disorders, the effects of such aberrant anxiety on social behavior has largely remained uncharacterized in these models. This study aims to fill this gap in our understanding by examining changes in social behavior following a single 2-hour episode of immobilization stress, which has been shown to cause delayed structural and functional changes in the amygdala. To this end, we examined social behavior, measured as active social interactions, anogenital sniffing, nose-to-nose contacts, allogrooming, actively following and crawling under, as well as self-oriented asocial behavior, manifested as self-grooming and rearing, in adult male rats. Stressed animals showed reduced social interaction 1 day after immobilization stress and this decrease was persistent for at least 10 days after stress. In contrast, individualistic behaviors were impaired only 10 days, but not 1 day later. Together, these results not only show that the same single episode of stress can elicit divergent effects on social and asocial measures of anxiety in the same animal, but also suggest that enhanced social anxiety soon after stress may also serve as an early indicator of its delayed behavioral effects.

}, keywords = {Amygdala, Animals, Anxiety, Anxiety Disorders, Behavior, Animal, Disease Models, Animal, Male, Rats, Social Behavior, Stress, Psychological}, issn = {1607-8888}, doi = {10.1080/10253890.2020.1855421}, author = {Saxena, Kapil and Chakraborty, Prabahan and Chattarji, Sumantra} } @article {2111, title = {Stress-induced modulation of endocannabinoid signaling leads to delayed strengthening of synaptic connectivity in the amygdala.}, journal = {Proc Natl Acad Sci U S A}, volume = {117}, year = {2020}, month = {2020 01 07}, pages = {650-655}, abstract = {

Even a brief exposure to severe stress strengthens synaptic connectivity days later in the amygdala, a brain area implicated in the affective symptoms of stress-related psychiatric disorders. However, little is known about the synaptic signaling mechanisms during stress that eventually culminate in its delayed impact on the amygdala. Hence, we investigated early stress-induced changes in amygdalar synaptic signaling in order to prevent its delayed effects. Whole-cell recordings in basolateral amygdala (BLA) slices from rats revealed higher frequency of miniature excitatory postsynaptic currents (mEPSCs) immediately after 2-h immobilization stress. This was replicated by inhibition of cannabinoid receptors (CBR), suggesting a role for endocannabinoid (eCB) signaling. Stress also reduced -arachidonoylethanolamine (AEA), an endogenous ligand of CBR. Since stress-induced activation of fatty acid amide hydrolase (FAAH) reduces AEA, we confirmed that oral administration of an FAAH inhibitor during stress prevents the increase in synaptic excitation in the BLA soon after stress. Although stress also caused an immediate reduction in synaptic inhibition, this was not prevented by FAAH inhibition. Strikingly, FAAH inhibition during the traumatic stressor was also effective 10 d later on the delayed manifestation of synaptic strengthening in BLA neurons, preventing both enhanced mEPSC frequency and increased dendritic spine-density. Thus, oral administration of an FAAH inhibitor during a brief stress prevents the early synaptic changes that eventually build up to hyperexcitability in the amygdala. This framework is of therapeutic relevance because of growing interest in targeting eCB signaling to prevent the gradual development of emotional symptoms and underlying amygdalar dysfunction triggered by traumatic stress.

}, keywords = {Administration, Oral, Amidohydrolases, Animals, Basolateral Nuclear Complex, Cannabinoid Receptor Antagonists, Disease Models, Animal, Emotions, Endocannabinoids, Enzyme Inhibitors, Excitatory Postsynaptic Potentials, Humans, Male, Rats, Receptor, Cannabinoid, CB1, Signal Transduction, Stress, Psychological}, issn = {1091-6490}, doi = {10.1073/pnas.1910322116}, author = {Yasmin, Farhana and Colangeli, Roberto and Morena, Maria and Filipski, Sarah and van der Stelt, Mario and Pittman, Quentin J and Hillard, Cecilia J and Teskey, G Campbell and McEwen, Bruce S and Hill, Matthew N and Chattarji, Sumantra} } @article {1584, title = {Extinction recall of fear memories formed before stress is not affected despite higher theta activity in the amygdala.}, journal = {Elife}, volume = {7}, year = {2018}, month = {2018 08 13}, abstract = {

Stress is known to exert its detrimental effects not only by enhancing fear, but also by impairing its extinction. However, in earlier studies stress exposure preceded both processes. Thus, compared to unstressed animals, stressed animals had to extinguish fear memories that were strengthened by prior exposure to stress. Here, we dissociate the two processes to examine if stress specifically impairs the acquisition and recall of fear extinction. Strikingly, when fear memories were formed before stress exposure, thereby allowing animals to initiate extinction from comparable levels of fear, recall of fear extinction was unaffected. Despite this, we observed a persistent increase in theta activity in the BLA. Theta activity in the mPFC, by contrast, was normal. Stress also disrupted mPFC-BLA theta-frequency synchrony and directional coupling. Thus, in the absence of the fear-enhancing effects of stress, the expression of fear during and after extinction reflects normal regulation of theta activity in the mPFC, not theta hyperactivity in the amygdala.

}, keywords = {Amygdala, Animals, Extinction, Psychological, Fear, Male, Memory, Mental Recall, Prefrontal Cortex, Rats, Sprague-Dawley, Stress, Physiological, Theta Rhythm}, issn = {2050-084X}, doi = {10.7554/eLife.35450}, author = {Rahman, Mohammed Mostafizur and Shukla, Ashutosh and Chattarji, Sumantra} }