Dissociation in Effective Treatment and Behavioral Phenotype Between Stress-Enhanced Fear Learning and Learned Helplessness

Post-traumatic stress disorder (PTSD) is a debilitating disease with relatively high lifetime prevalence. It is marked by a high diversity of symptoms and comorbidity with other psychiatric disease. Furthermore, PTSD has a high level of origin and symptom heterogeneity within the population. These characteristics taken together make it one of the most challenging diseases to effectively model in animals. However, with relatively little headway made in developing effective disease interventions, PTSD remains as a high priority target for animal model study. Learned Helplessness (LH) is a procedure classically used to model depression, but has in recent years transitioned to use as a model of PTSD. Animals in this procedure receive 100 inescapable and unpredictable tailshocks or simple restraint without shock. The following day, the animals are tested in a shuttle box, where inescapably-shocked subjects exhibit exaggerated fear and profound deficit in escape performance. Stress-enhanced fear learning (SEFL) also uses an acute (single session) stressor for modeling PTSD in rodents. The SEFL procedure begins with exposure to 15 footshocks or simple context exposure without shock. Animals that initially received the 15 footshocks exhibit future enhanced fear learning. In this review, we will compare the behavior, physiology, and interventions of these two animal models of PTSD. Despite considerable similarity (a single session containing inescapable and uncontrollable shock) the two procedures produce a very divergent set of behavioral consequences

Dissociation in Effective Treatment and Behavioral Phenotype Between Stress-Enhanced Fear Learning and Learned Helplessness.

Post-traumatic stress disorder (PTSD) is a debilitating disease with relatively high lifetime prevalence. It is marked by a high diversity of symptoms and comorbidity with other psychiatric disease. Furthermore, PTSD has a high level of origin and symptom heterogeneity within the population. These characteristics taken together make it one of the most challenging diseases to effectively model in animals. However, with relatively little headway made in developing effective disease interventions, PTSD remains as a high priority target for animal model study. Learned Helplessness (LH) is a procedure classically used to model depression, but has in recent years transitioned to use as a model of PTSD. Animals in this procedure receive 100 inescapable and unpredictable tailshocks or simple restraint without shock. The following day, the animals are tested in a shuttle box, where inescapably-shocked subjects exhibit exaggerated fear and profound deficit in escape performance. Stress-enhanced fear learning (SEFL) also uses an acute (single session) stressor for modeling PTSD in rodents. The SEFL procedure begins with exposure to 15 footshocks or simple context exposure without shock. Animals that initially received the 15 footshocks exhibit future enhanced fear learning. In this review, we will compare the behavior, physiology, and interventions of these two animal models of PTSD. Despite considerable similarity (a single session containing inescapable and uncontrollable shock) the two procedures produce a very divergent set of behavioral consequences

Isolation of the differential effects of chronic and acute stress in a manner that is not confounded by stress severity

Firm conclusions regarding the differential effects of the maladaptive consequences of acute versus chronic stress on the etiology and symptomatology of stress disorders await a model that isolates chronicity as a variable for studying the differential effects of acute versus chronic stress. This is because most previous studies have confounded chronicity with the total amount of stress. Here, we have modified the stress-enhanced fear learning (SEFL) protocol, which models some aspects of posttraumatic stress disorder (PTSD) following an acute stressor, to create a chronic variant that does not have this confound. Comparing results from this new protocol to the acute protocol, we found that chronic stress further potentiates enhanced fear-learning beyond the nonassociative enhancement induced by acute stress. This additional component is not observed when the unconditional stimulus (US) used during subsequent fear learning is distinct from the US used as the stressor, and is enhanced when glucose is administered following stressor exposure, suggesting that it is associative in nature. Furthermore, extinction of stressor-context fear blocks this additional associative component of SEFL as well as reinstatement of generalized fear, suggesting reinstatement of generalized fear may underlie this additional SEFL component

Post-Stress Fructose and Glucose Ingestion Exhibit Dissociable Behavioral and Physiological Effects

An acute traumatic event can lead to lifelong changes in stress susceptibility and result in psychiatric disease such as Post-Traumatic Stress Disorder (PTSD). We have previously shown that access to a concentrated glucose solution for 24 h beginning immediately after trauma decreased stress-related pathology in the learned helplessness model of PTSD and comorbid major depression. The current study sought to investigate the peripheral physiological effects of post-stress glucose consumption. We exposed 128 male Sprague-Dawley rats to inescapable and unpredictable 1-milliamp electric tail shocks or simple restraint in the learned helplessness procedure. Rats in each stress condition had access to a 40% glucose solution, 40% fructose solution, or water. Blood and liver tissue were extracted and processed for assay. We assessed corticosterone, corticosteroid-binding globulin (CBG), glucose, and liver glycogen concentrations at various time points following stress. We found that rats given access to glucose following exposure to traumatic shock showed a transient rise in blood glucose and an increase in liver glycogen repletion compared to those that received water or fructose following exposure to electric shock. We also found that animals given glucose following shock exhibited reduced free corticosterone and increased CBG compared to their water-drinking counterparts. However, this difference was not apparent when glucose was compared to fructose. These data suggest that post-stress glucose prophylaxis is likely not working via modulation of the HPA axis, but rather may provide its benefit by mitigating the metabolic challenges of trauma exposure

Data Mining Technique (Maximum Entropy Model) for Mapping Gully Erosion Susceptibility in the Gorganrood Watershed, Iran

Soil erosion is a serious problem affecting most of the countries. This study was carried out in Gorganrood Watershed (Iran), which extends for 10,197 km2 and is severely affected by gully erosion. A gully headcut inven- tory map consisting of 307 gully headcut points was provided by Google Earth images, field surveys, and national reports. Gully conditioning factors including sig- nificant geo-environmental and morphometric variables were selected as predictors. Maximum entropy (ME) model was exploited to model gully susceptibility, whereas the area under the ROC curve (AUC) and draw- ing receiver operating characteristic (ROC) curves were employed to evaluate the performance of the model. The highly acceptable predictive skill of the ME model confirms the reliability of the procedure adopted to using this model in other gully erosion studies, as they are qualified to rapidly producing accurate and robust GESMs (gully erosion susceptibility maps) for making decisions and management of soil and water. The result is useful for local administrators to recognize the areas that are most susceptible to gully erosion and to best allocate resources for soil conservation approaches. Three different sample datasets including 70% for training and 30% for validation were randomly prepared to evaluate the robustness of the model for gully erosion. The accuracy of the predictive model was evaluated by drawing ROC curves and by calculating the area under the ROC curve (AUC). The ME model performed excellently both in the degree of fitting and in predictive performance (AUC values well above 0.8), which resulted in accurate predictions