Cocaine blocks extraneuronal uptake of norepinephrine by the pregnant human uterus

Article Abstract:

Cocaine abuse is increasing among pregnant women, particularly in urban areas, and may result in premature delivery, a major cause of disability and death during childbirth. The mechanism whereby cocaine causes premature labor is not clear, but most likely involves enhancing the contraction of the uterus. Cocaine prevents the uptake, or transport, of naturally occurring catecholamines into the nerve, resulting in their accumulation at the nerve. The build-up of catecholamines may cause excessive stimulation of nerves, which activate contraction of the uterus. Because the pregnant uterus has few functioning nerves, cocaine prevention of nerve uptake may not play a major role in uterine contraction. However, cocaine was reported to block another uptake system referred to as Uptake 2, which transports catecholamines into the uterus. The ability of the pregnant human uterus to take up catecholamines, and the effects of cocaine on this uptake, were assessed. Uterine tissue samples were obtained from women undergoing cesarean sections; women exposed to cocaine during pregnancy were excluded from the study. Uterine tissue samples were placed in a perfusion chamber and then exposed to a solution containing cocaine. The catecholamine norepinephrine was taken up by both the endometrium (the inner lining of the uterus) and myometrium (the muscle layer of the uterus). Cocaine prevented this uptake of catecholamines into the uterine layers by up to 55 percent at doses as low as 0.1 micromoles per liter. The drug d-propranolol, which was reported to block cocaine effects on the uterus in animal models, had no effect on cocaine prevention of catecholamine uptake in the pregnant human uterus. The drug hydrocortisone, also reported to inhibit Uptake 2, caused a smaller decrease in norepinephrine uptake into the endometrium, but had no effect on catecholamine transport into the myometrium. These findings show that uptake of catecholamines in the pregnant human uterus is prevented by cocaine, which may result in contraction of the uterus and premature labor. (Consumer Summary produced by Reliance Medical Information, Inc.)

Noradrenaline, Norepinephrine, Cocaine, Drug abuse in pregnancy, Uterus, Pregnant, Pregnant uterus

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The role of chorioamnionitis and prostaglandins in preterm labor

Article Abstract:

Premature labor may cause disability or death at childbirth. Infection may contribute to the onset of premature labor. Gram-negative bacteria have been shown to produce toxic substances that increase the production of prostaglandins (PG) by cells in the amniotic membranes surrounding the fetus. Certain types of prostaglandins, specifically PGE and PGF, can induce parturition, or childbirth. Studies have shown that the production of PGE and leukotriene B4, a substance that promotes inflammation, was increased in the amniotic membranes of premature deliveries where there was also evidence of chorioamnionitis, or inflammation of the fetal membranes. The levels of PG and leukotriene B4 were assessed in the fetal membranes from pregnancies of 35 weeks' or less gestation. The amniotic fluid swallowed by infants was tested for the presence of pus cells and bacteria. The results showed that the levels of PGE, PGF, and leukotriene B4 were increased in the amniotic membranes of premature deliveries complicated by chorioamnionitis. In addition, the PG levels tended to be higher in the stomach fluids of infants from premature deliveries with chorioamnionitis, particularly those infants with pus cells and bacteria. These findings are consistent with a role of chorioamnionitis in the initiation of premature labor. (Consumer Summary produced by Reliance Medical Information, Inc.)

Bacterial toxins, Bacterial infections, Prostaglandins E, Chorioamnionitis

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