Adrenaline key player with antidepressants

PHILADELPHIA, Jun 04, 2004 (United Press International via COMTEX) -- A U.S. study finds adrenaline is critical for some of the most commonly prescribed antidepressants to work in animals, regardless of the class of drug.

Scientists at the University of Pennsylvania in Philadelphia performed the first test of antidepressants on animals unable to produce norepinephrine or adrenaline.

They found mice genetically altered not to produce adrenaline did not respond to seven of eight commonly prescribed antidepressants, including all of the most common class tested -- selective serotonin reuptake inhibitors that includes Prozac, Zoloft, Paxil and Celexia.

The antidepressants all affected animals that produced adrenaline, however.

"(This study) helps us understand how to redesign better drugs and which treatments will work better for which patients," lead author Irwin Lucki wrote.

There currently are two major classes of antidepressants: norepinephrine reuptake inhibitors, which increase adrenaline activity, and SSRIs, which increase serotonin activity.