Pituitary adenylate cyclase-activating polypeptide (PACAP) is known to broadly regulate the cellular stress response. In contrast, it is unclear if the PACAP/PAC1 receptor pathway has a role in human psychological stress responses, such as posttraumatic stress disorder (PTSD). In heavily traumatized subjects, we find a sex-specific association of PACAP blood levels with fear physiology, PTSD diagnosis and symptoms in females (N=64, replication N=74, p<0.005). Using a tag-SNP genetic approach (44 single nucleotide polymorphisms, SNPs) spanning the PACAP (ADCYAP1) and PAC1 (ADCYAP1R1) genes, we find a sex-specific association with PTSD. rs2267735, a SNP in a putative estrogen response element within ADCYAP1R1, predicts PTSD diagnosis and symptoms in females only (combined initial and replication samples: N=1237; p<2x10−5). This SNP also associates with fear discrimination and with ADCYAP1R1 mRNA expression. Methylation of ADCYAP1R1 is also associated with PTSD (p < 0.001). Complementing these human data, ADCYAP1R1 mRNA is induced with fear conditioning or estrogen replacement in rodent models. These data suggest that perturbations in the PACAP/PAC1 pathway are involved in abnormal stress responses underlying PTSD. These sex-specific effects may occur via estrogen regulation of ADCYAP1R1. PACAP levels and ADCYAP1R1 SNPs may serve as useful biomarkers to further our mechanistic understanding of PTSD.

Posttraumatic stress disorder (PTSD) is an anxiety disorder that can develop after a traumatic experience such as domestic violence, natural disasters or combat-related trauma. The cost of such disorders on society and the individual can be tremendous. In this article we will review how the neural circuitry implicated in PTSD in humans is related to the neural circuitry of fear. We then discuss how fear conditioning is a suitable model for studying the molecular mechanisms of the fear components which underlie PTSD, and the biology of fear conditioning with a particular focus on the brain derived neurotropic factor (BDNF)-TrkB, GABAergic and glutamatergic ligand-receptor systems. We then summarize how such approaches may help to inform our understanding of PTSD and other stress-related disorders and provide insight to new pharmacological avenues of treatment of PTSD.

Half of the data points were inadvertently omitted from the published version of Fig. 4a; the statistical analyses in the text and figure legend, however, do refer to the complete data set. The corrected figure is shown here and has been corrected in the online versions of the paper.In addition, we present additional information to clarify two results reported in the Article regarding plasma pituitary adenylate cyclaseactivating polypeptide (PACAP) levels and post-traumatic stress disorder (PTSD) symptom associations. In the Article, we reported replication of the association between PACAP levels and hyperarousal subscale, because this was the most robust association in the initial cohort. We now present the analyses separately for initial, replication and combined cohorts in Table 1. All associations but one are significant in the replication cohort. The second issue concerns potential medical confounds that could underlie the reported association. Although we do not have medical chart data on most patients, we do have responses from a health questionnaire administered during collection of trauma history and other data. We have now reanalysed the associations for the PTSD symptom scale (PSS) hyperarousal and total symptoms using subjective reports of health condition from the questionnaires as covariates. These data are presented in Table 2 and do not show any effect of health-and illness-related questions on the relationship between PACAP and PTSD symptoms. None of these additions affect the results and conclusions of the original Article.

Activin and myostatin are related members of the TGF-␤ growth factor superfamily. FSTL3 (Follistatin-like 3) is an activin and myostatin antagonist whose physiological role in adults remains to be determined. We found that homozygous FSTL3 knockout adults developed a distinct group of metabolic phenotypes, including increased pancreatic islet number and size, ␤ cell hyperplasia, decreased visceral fat mass, improved glucose tolerance, and enhanced insulin sensitivity, changes that might benefit obese, insulin-resistant patients. The mice also developed hepatic steatosis and mild hypertension but exhibited no alteration of muscle or body weight. This combination of phenotypes appears to arise from increased activin and myostatin bioactivity in specific tissues resulting from the absence of the FSTL3 antagonist. Thus, the enlarged islets and ␤ cell number likely result from increased activin action. Reduced visceral fat is consistent with a role for increased myostatin action in regulating fat deposition, which, in turn, may be partly responsible for the enhanced glucose tolerance and insulin sensitivity. Our results demonstrate that FSTL3 regulation of activin and myostatin is critical for normal adult metabolic homeostasis, suggesting that pharmacological manipulation of FSTL3 activity might simultaneously reduce visceral adiposity, increase ␤ cell mass, and improve insulin sensitivity.embers of the TGF-␤ superfamily of growth factors play diverse roles in embryonic development as well as in organ homeostasis and injury/pathogen response in adults (1). Activin and myostatin form one structurally related branch of the TGF-␤ family that utilizes common cell-surface receptors and Smad second messengers (2-4). Activin is a critical regulator of embryonic cell fate determination and organ development as well as adult organ homeostasis (5). Activin deletion in mice results in developmental defects and early neonatal death (6), whereas activin overexpression results in cancer, cachexia, and liver necrosis (3,7,8). Loss of myostatin expression results in increased muscle mass and reduced adiposity (9-11), whereas overexpression of myostatin leads to a severe reduction of both muscle and adipose tissue mass, along with cachexia (12, 13). These findings demonstrate the requirement for tight regulation of activin and myostatin activity to maintain normal adult physiology.Regulation of activin and myostatin activity occurs at multiple levels. Among the extracellular regulators, FSTL3 (follistatin like-3) and FST (follistatin) are structurally and functionally related glycoproteins that bind and antagonize actions of both activin and myostatin (14, 15). FSTL3 expression is highest in placenta, followed by testis, pancreas, and heart, whereas FST expression is high in ovary, testis, and kidney, suggesting that they may have nonoverlapping actions in different organs (16). Circulating FST was largely bound to activin (17), whereas FSTL3 was isolated from human and mouse serum as a complex with myostatin (18), indicating that F...

The consolidation of conditioned fear involves upregulation of genes necessary for long-term memory formation. An important question remains as to whether this results in part from epigenetic regulation and chromatin modulation. We examined whether homer1a, which is required for memory formation, is necessary for Pavlovian cued fear conditioning, whether it is downstream of BDNF - TrkB activation, and whether this pathway utilizes histone modifications for activity-dependent transcriptional regulation. We initially found that Homer1a ko mice exhibited deficits in cued fear conditioning (5 tone-shock presentations with 70 dB, 6kHz tones and 0.5s, 0.6mA footshocks). We then demonstrate that homer1a mRNA 1) increases after fear conditioning in vivo within both amygdala and hippocampus of wild type mice, 2) increases after BDNF application to primary hippocampal and amygdala cultures in vitro, and 3) these increases are dependent on transcription and MAPK signaling. Furthermore, using chromatin immunoprecipitation we found that both in vitro and in vivo manipulations result in decreases in homer1 promoter H3K9 methylation in amygdala cells but increases in homer1 promoter H3 acetylation in hippocampal cells. However no changes were observed in H4 acetylation or H3K27 dimethylation. Inhibition of H3 acetylation by sodium butyrate enhanced contextual but not cued fear conditioning and enhanced homer1 H3 acetylation in the hippocampus. These data provide evidence for dynamic epigenetic regulation of homer1a following BDNF-induced plasticity and during a BDNF-dependent learning process. Furthermore, upregulation of this gene may be regulated through distinct epigenetic modifications in the hippocampus and amygdala.