inhibition of cytotoxic T-cell function, cell division of T-lymphocytes, and the development of TH1 lymphocytes. Neurological effects In response to physiologic and psychologic stress, prostaglandin E2 is involved in several inflammation and immunity pathways. As one of the most abundant prostaglandins in the body, Prostaglandin E2 is involved almost all typical inflammation markers such as redness, swelling, and pain. It regulates these responses through binding to G coupled protein prostaglandin E2 (PGE2) receptors (EP1, EP2, EP3, and EP4). The activation of these different EP receptors is dependent on the type of triggering stress stimuli and results in the corresponding stress response. Activation of EP1 via PGE2 results in the suppression of impulse behaviors in response to psychological stress. Prostaglandin E2 is involved in regulating illness induced memory impairment via activation of EP2. Prostaglandin E2 activation of EP3 results in regulation of illness induced fever. EP4 is functionally similar to EP2 and has also been shown in studies to have a role in hypothermia and anorexia. In addition to inflammatory effects, Prostaglandin E2 has been shown to have anti-inflammatory effects as well, due to its different actions on varying receptors. Smooth muscle effects Prostaglandin E2 (PGE2) serves a significant role in vascular smooth muscle tone regulation. It is a vasodilator produced by endothelial cells. It promotes vasodilation of smooth muscles by increasing the activity of cyclic adenosine monophosphate (cAMP) to decrease intracellular calcium levels via the IP and EP4 receptors. Conversely, Prostaglandin E2 can also induce vasoconstriction via activation of EP1 and EP3 receptors, which activates the Ca2+ pathway and decreased cAMP activity. Within the gastrointestinal tract, PGE2 activates smooth muscles to cause contractions on longitudinal muscle when acting on EP3 receptors. In contrast, PGE2 effects on respiratory smooth muscle result in relaxation. Kidney effects Prostaglandin E2 (PGE2), along with other prostaglandins, are synthesized within the cortex and medulla of the kidney. The role of renal COX-2-derived PGE2 within the kidney is to maintain renal blood flow and glomerular filtration rate (GFR) through localized vasodilation. COX-2-derived prostanoids work to increase medullary blood flow as well as inhibit sodium reabsorption within kidney tubules. PGE2 also assists the kidneys with systemic blood pressure control by modifying water and sodium excretion. In addition, it is also thought to activate EP4 or EP2 to increase renin release, resulting in an elevation of GFR and sodium retention to raise systemic blood pressure levels within the body.