Angiogenesis : modulation with opioids

Abstract 1. The effect of β-endorphin (β-EP) and morphine sulfate (MS), in presence and absence of naloxone (NX), on chicken chorioallantoic membrane was studied as a function of blood vessel proliferation. 2. A 50% reduction in blood vessel proliferation occurred by 10 μg of β-EP or by 5 μg of MS per egg compared to controls. 3. An individual dose, i.e. 5 μg of β-EP, did not significantly inhibit blood vessel counts after initial 24 hr period of the drug application when given alone compared to inhibition occurring with combined use of NX. 4. NX (1 μg) did not significantly reverse the angiostatic effects of MS (10 μg) or of β-EP (5 μg). 5. The observed modulation of angiogenesis by opioids suggests involvement of β-EP and MS in the proliferation of vascular endothelial cells. 6. This may be due to an effect of β-EP and MS on cell-mediated immunity factors such as interferons, interleukins and prostaglandin E 2 .