15 December 2008

Study reveals profound effects of anesthetics on infants

by Kate Melville

Appearing in Molecular and Cellular Proteomics, a study on the brains of newborn mice has provided more evidence that numbing drugs used in obstetric or pediatric medicine can have profound and long-term negative effects, even after minimal exposure.

According to study author Angela M. Kaindl, the findings highlight the delicate state of the developing nervous system and reinforce the use of caution when administering sedatives, anesthetics, or anti-convulsants to pregnant women or infants.

Kaindl explained that compounds that block nerve receptors or activate inhibitory GABA receptors in the brain are clinically useful as anesthetics or for treating disorders like seizures and insomnia. But, just like other chemicals that produce similar mind-soothing effects - alcohol, for example - excessive use can be detrimental.

To examine how far-reaching the physiologic effects of such 'numbing' drugs are, Kaindl and colleagues treated 6-day old mice with two doses of either the NMDA receptor blocker dizocilpine or the GABA receptor activator phenobarbital and then analyzed subsequent changes in brain protein expression.

They observed both acute and sustained effects, with protein changes in the cerebral cortex (the area controlling memory, thought, awareness, and language) evident after just 24 hours, and these changes were still present one week and one month after the one-day drug treatment. The affected proteins are involved in crucial processes like cell growth, cell death, and the formation of neural circuits.

A similar drug dose given to adult mice did not produce such changes, which the authors note clearly shows how susceptible infant brains are compared to adults. Importantly, this study shows that drug overuse on even one occasion (for example, during the delivery procedure) can have long-term implications.

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Source: American Society for Biochemistry and Molecular Biology