From polite petitions to fierce fires, activists opposed to animal research have made their position clear in the U.S. and abroad for many years. But now, medical researchers are being encouraged to press on—and speak out.

Two new commentaries, published online today in The Journal of Neuroscience, highlight recent threats that have befallen some researchers who perform research on animals. "We have seen our cars and homes firebombed or flooded, and we have received letters packed with poisoned razors and death threats via e-mail and voicemail," Dario Ringach of the David Geffen School of Medicine and J. David Jentsch of the University of California, Los Angeles, (U.C.L.A.) wrote in one of the papers.

"These threats do not endanger just these individuals alone, but also the scientific community at large and the health and well-being of millions affected by their research," Thomas Carew, president of The Society of Neuroscience (SfN), said in a prepared statement responding to the commentaries. "Today, it is unacceptable that in the pursiut of better health and understanding of disease, researchers, their families, and their communities face violence and intimidation by extremists."

"Responsible research has played a vital role in nearly every major medical advance of the last century, from heart disease to polio, and is essential to future advances," Carew continued. Animal rights groups, however, maintain that most drugs developed and tested on animals never pass human safety or efficacy trials and never make it to market.

More than half of Americans are in favor of animal testing for scientific research, according to a Pew Research Center survey earlier this year, but animal testing for research and product safety has come under considerable fire in the past several decades.

PETA (People for the Ethical Treatment of Animals), which boasts more than two million members worldwide, asserts on its Web site that "animals should have the right to equal consideration of their interests…An animal's inability to understand and adhere to our rules is as irrelevant as a child's or that of a person with a severe developmental disability."

The medical research community has fired back by forming advocacy groups, such as Americans for Medical Progress (AMP), which "protects society's investment in research by nurturing public understanding of and support for the humane, necessary and valuable use of animals in medicine," according to its Web site. The group is careful to distinguish between animal welfare, which, it notes, should be guarded by research institutions, and animal rights, PETA's position, which places animals on par with humans and may come into conflict with medical research.

Another group, U.C.L.A.'s Pro-Test, founded by Jentsch, staged a Los Angeles rally in April, drawing support from the local research community and a counter-demonstration from animal-rights activists. "Now is the time to stand up and say, 'Enough is enough,'" Jentsch, a professor at U.C.L.A.'s Brain Research Institute, who had his car set on fire earlier this year, wrote on the non-profit's Web site.

Other countries have passed more stringent laws to curb the use of animals in medical research. Last year, a Swiss court ruled that two neuroscience studies that used primates should not be allowed because their practical applications for human benefit were deemed too tenuous and distant.

"It's antiscientific," Daniel Kiper, one of the embattled scientists, who wanted to study brain changes in learning new tasks with the goal of helping stroke victims, said in a September 2008 Scientific American article. "This reflects a lack of trust in science and a lack of respect for scientific progress in general."

To prevent further legal or institutional curtailment of animal research—which is already heavily overseen and regulated by universities, research boards and governments—the commentaries' authors recommend a three-pronged approach to ensuring continued and humane research: university support, increased security and improved communication.

Much of the research community has remained quiet on the issue of threatening or violent activism targeting animal research, however, Ringach and Jentsch assert that, "This attitude is no longer tenable…The time has come for the scientific community to make a concerted effort in condemning animal-rights extremism."

Image of a monkey secretly filmed at a lab's testing facility in 2005 courtesy of Wikimedia Commons/PETA