Fetal behavioral state patterns during and after prolonged exposure to cocaine in sheep

Article Abstract:

Prolonged exposure to cocaine appears to disrupt normal sleep stages in fetal sheep. Researchers surgically implanted catheters and sensors in the fetuses of six pregnant ewes. Three days later, cocaine was directly infused into the fetus over a six-hour period. Rapid-eye-movement (REM) and non-REM sleep periods before, during, and after cocaine infusion were measured. Cocaine reduced the percentage of time spent in both REM and non-REM sleep. The fetus did not adapt to cocaine as exposure continued. After cocaine was discontinued, the fetus increased REM sleep in order to catch up, which also occurs in human adults after intravenous cocaine use. REM sleep is believed to play a role in the developing nervous system. The disruption of REM sleep may offer one explanation of why cocaine apparently produces adverse neurobehavioral effects in infants born to cocaine-using mothers.

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Myocardial and cerebral oxygen delivery are not adversely affected by cocaine administration to early-gestation fetal sheep

Article Abstract:

Fetal sheep exposed to cocaine may not experience lack of oxygen delivery to the brain or heart. Researchers administered cocaine to 10 sheep fetuses in mid-pregnancy to determine whether cocaine diminishes oxygen delivery to the fetal heart and brain. Cocaine increased fetal blood pressure, heart rates, blood flow, and oxygen delivery to the heart. Blood flow and oxygen delivery to the brain were preserved. Other experiments on sheep fetuses in late pregnancy have found that cocaine reduces blood flow and oxygen delivery. Cocaine may have a constricting effect on blood vessels, and this effect may be separate from the mechanism causing lack of oxygen delivery to the brain or heart. Cocaine's adverse effects on fetuses may result from repeated exposures.

Pregnant women, Oxygen, Oxygen transport, Biological transport, Drug use

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Fetal acoustic stimulation test: stimulus features of three artificial larynges recorded in sheep

Article Abstract:

Vibroacoustic devices used to stimulate fetuses to move during nonstress tests may be comparable in terms of sound pressure levels within the uterus. Researchers measured intrauterine sound pressure levels by inserting hydrophones into the uteri of pregnant sheep. The three electronic artificial larynx devices produced similar sound pressure patterns, with maximum sound pressures of 500 Hz. An electric toothbrush, which was an early fetal vibroacoustic device, had a different sound pressure pattern, but the average sound pressure level was just a bit less than those of the other devices. The electric toothbrush may be less likely to damage fetal hearing than the other devices while sufficiently stimulating the fetus during nonstress testing.

Usage, Evaluation, Testing, Sound-waves, Sound waves, Electroacoustic transducers

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