Probing cocaine's effect on the brain.Researchers suspect that chronic cocaine use alters the brain's chemical balance so that decreases in dopamine dopamine (dōp`əmēn), one of the intermediate substances in the biosynthesis of epinephrine and norepinephrine. See catecholamine. dopamine One of the catecholamines, widely distributed in the central nervous system. , a naturally occurring neurotransmitter neurotransmitter, chemical that transmits information across the junction (synapse) that separates one nerve cell (neuron) from another nerve cell or a muscle. Neurotransmitters are stored in the nerve cell's bulbous end (axon). , lead to cravings for more cocaine. However, experiments with animals given cocaine have not revealed much difference in the total amount of dopamine measured in the brain. An advance in analytical chemistry analytical chemistry: see under chemistry. has now provided a clue to the mystery of addiction. By implanting tiny tubes into specific regions of the rat brain, analytical chemist Jay B. Justice at Emory University Emory University (ĕm`ərē), near Atlanta, Ga.; coeducational; United Methodist; chartered as Emory College 1836, opened 1837 at Oxford. It became Emory Univ. in 1915 and in 1919 moved to Atlanta. in Atlanta has detected a delayed effect of long-term cocaine administration. The probes, not much thicker than a juman hair, stick into the fluid that surrounds nerve cells nerve cell n. 1. See neuron. 2. The body of a neuron without its axon and dendrites. deep in the brain and provide a detailed accounting to what is going on there. "That's where we see [dopamine] depletion," Justice told SCIENCE NEWS. Justice gave rats cocaine daily for 10 days. One day after they stopped receiving the drug, and then again 10 days later, he used the implanted tubes to assess their brain chemistry. Although dopamine concentration in fluid samples drawn from the rats was very low, Justice says he was able to detect a 50 percent decrease in dopamine levels 10 days after he stopped giving the rats cocaine. No such change appeared the day after cocaine administration ceased, he adds. |
|
||||||||||||||||
Printer friendly
Cite/link
Email
Feedback
Reader Opinion