The role of COX-2 in heart pathology.

Cyclooxygenase-2 (COX-2) is a key enzyme in the production of prostaglandins, and an important anti-inflammation drug target. Recent focus has been placed on the role of COX-2 in heart function and pathology, due to the finding that specific COX-2 inhibitors significantly increased the risk of heart disease in chronic users. However, the exact role of COX-2 in cardiac physiology and disease remains controversial due to the conflicting data reported. Roughly equal numbers of reports have shown either a detrimental role or a protective role for COX-2 in heart in experimental models. Here we attempt to provide a background on the more general roles of COX-2 in pathophysiology, as well as molecular mechanisms employed to control COX-2 expression. This background provides a basis for better understanding the functional role of COX-2 in human heart pathologies, based on the results of COX-2 pharmacological inhibitor studies in humans as well as COX-2 expression in human heart disease. Furthermore, we will explore the experimental evidence implicating different intracellular molecular signaling cascades that regulate COX-2 expression in cardiomyocytes. All of this data permits a more mechanistic understanding of the published studies using pharmacological inhibitors of COX-2 in experimental models of heart pathology. Lastly, we will examine the use of genetic manipulation of COX-2 in mice as one of the future avenues in an attempt to resolve the role of COX-2 in cardiac physiology and pathology.

Serotonin-related gene expression in female monkeys with individual sensitivity to stress.

Female cynomolgus monkeys exhibit different degrees of reproductive dysfunction with moderate metabolic and psychosocial stress. In this study, the expression of four genes pivotal to serotonin neural function was assessed in monkeys previously categorized as highly stress resistant (n=3; normal menstrual cyclicity through two stress cycles), medium stress resistant (n=5; ovulatory in the first stress cycle but anovulatory in the second stress cycle), or low stress resistant (i.e. stress-sensitive; n=4; anovulatory as soon as stress is initiated). In situ hybridization and quantitative image analysis was used to measure mRNAs coding for SERT (serotonin transporter), 5HT1A autoreceptor, MAO-A and MAO-B (monoamine oxidases) at six levels of the dorsal raphe nucleus (DRN). Optical density (OD) and positive pixel area were measured with NIH Image software. In addition, serotonin neurons were immunostained and counted at three levels of the DRN. Finally, each animal was genotyped for the serotonin transporter long polymorphic region (5HTTLPR). Stress sensitive animals had lower expression of SERT mRNA in the caudal region of the DRN (P<0.04). SERT mRNA OD in the caudal DRN was positively correlated with serum progesterone during a pre-stress control cycle (P<0.0007). 5HT1A mRNA OD signal tended to decline in the stress-sensitive group, but statistical difference between averages was lacking in analysis of variance. However, 5HT1A mRNA signal was positively correlated with control cycle progesterone (P<0.009). There was significantly less MAO-A mRNA signal in the stress-sensitive group (P<0.007) and MAO-A OD was positively correlated with progesterone from a pre-stress control cycle (P<0.007). MAO-B mRNA exhibited a similar downward trend in the stress-sensitive group. MAO-B OD also correlated with control cycle progesterone (P<0.003). There were significantly fewer serotonin neurons in the stress-sensitive group. All animals contained only the long form of the 5HTTLPR. Thus, all serotonin-related mRNAs examined in the dorsal raphe to date were lower (SERT, MAO-A) or exhibited a lower trend (5HT1A, MAO-B) in the stress sensitive animals, which probably reflects the lower number of serotonin neurons present.