Neuropeptide Y Impairs Retrieval of Extinguished Fear and Modulates Excitability of Neurons in the Infralimbic Prefrontal Cortex.

Unlabelled: Neuropeptide Y (NPY), a 36 aa peptide, regulates stress and emotional behaviors. Preclinical and clinical studies support an association of NPY with trauma-evoked syndromes such as posttraumatic stress disorder (PTSD), although the exact contribution of NPY is not clear. In the current study, we examined functional attributes of NPY in the infralimbic (IL) cortex, an area that regulates fear memories and is reported to be hypoactive in PTSD.

History of chronic stress modifies acute stress-evoked fear memory and acoustic startle in male rats.

Chronicity of trauma exposure plays an important role in the pathophysiology of posttraumatic stress disorder (PTSD). Thus, exposure to multiple traumas on a chronic scale leads to worse outcomes than acute events. The rationale for the current study was to investigate the effects of a single adverse event versus the same event on a background of chronic stress.

The medial prefrontal cortex differentially regulates stress-induced c-fos expression in the forebrain depending on type of stressor.

The medial prefrontal cortex (mPFC) plays an important inhibitory role in the hypothalamic-pituitary-adrenal (HPA) axis response. The involvement of the mPFC appears to depend on the type of stressor, preferentially affecting 'psychogenic' stimuli. In this study, we mapped expression of c-fos mRNA to assess the neural circuitry underlying stressor-specific actions of the mPFC on HPA reactivity.

Stress activation of cortex and hippocampus is modulated by sex and stage of estrus.

Sex plays a major role in stress integration and stress-related affective disease states. Notably, neurocircuits regulating organismic responses to stress are prime targets for central gonadal steroid action. To assess the roles of sex and estrous cycle in central stress integration, we analyzed c-fos mRNA expression in hypothalamic-pituitary-adrenocortical-related regions of stressed male and cycling female (proestrous, estrous, and diestrous) rats.