IL6 and major depressive disorder: This study aimed to dynamically evaluate the impact of fluoxetine on altering the peripheral (plasma) and central (left brain hemisphere) levels of inflammatory cytokines including IL-1β, IL-6, TNF-α and IL-17 at baseline, day 60, day 90 and day 120 in alleviating depression in a 4-month (equal to 12 years of human [22]) rat model of chronic mild stress (CMS) [23, 24] which closely mirrors depression that manifested in humans after daily stressful life events as opposed to traumatic events introduced in acute stress models [25, 26].