Association of job stress and Apelin 12: possible contribution to stress and cardiovascular disease pathway

Introduction
Psychosocial factors have been shown to be associated with certain cardiovascular diseases. The mechanisms of this association are waiting for explanation. Apelin has been shown as one of the cardioprotective adiponectins released from adipose tissues. We aimed to explore the association of stress and apelin levels.

Methods
Serum samples were obtained from Balcova’s Heart Project which is an community based project on cardiovascular diseases in Izmir, Turkey. In this Project households were visited and 16603 people were interviewed. Blood samples were obtained from after an overnight fasting and stored in -80 C refrigerators. In the present study 164 serum samples were selected randomly and used for ELISA test to assess serum Apelin-12 levels. Households were then visited by interviewers and a structured questionnaire was applied to asses demographics and stress. Demand Control Questionnaire was used to assess job stress. There were four items for demand, four items for skill discretion, two items for authority over decision, and six items for social support. Median values were used to dicotomize demand and control domains. Independent sample t test and multiple regression models were used for data analysis. The study was supported by The Scientific and Technological Research Council of Turkey (No:SBAG109S277).

Results
The study included 164 participants (110 males, 54 females) and the mean age of the participants was 42.3±7.7. Mean value of the apelin level was 0.78±0.22 µg/dl. Serum apelin level was not significantly different between genders (p=0.517). Serum apelin level was found high in obese individuals (0.82±0.22) than in non-obese individuals (0.76±0.22) but the difference was not statistically significant (p=0.196). Apelin level was significantly high in low stress group (p=0.02). Age and gender adjustment did not change this association.

Discussion
Apelin may play an important role in stress and cardiovascular disease relationship pathway. Follow-up studies may provide detailed information on stress-apelin-CVD pathway.