Opioid-induced hibernation protects against stroke

– USF Health neuroscientist led the rat-model study –

Tampa, FL (June 17, 2009) — Using an opioid drug to induce hibernation in rats reduces the damage caused by an artificial stroke, reports a study published today in the open access journal BMC Biology. Researchers found that those animals put into a chemical slumber — a hibernation-like state that cooled their brains — suffered less behavioral impairment after a period of cerebral artery blockage than control rats.

Cesar Borlongan, PhD, a neuroscientist at the University of South Florida Center for Aging and Brain Repair in Tampa, FL, worked with a team of researchers from the National Institutes of Health, to investigate the role of the opioid system in brain injury and protection.

“Studies in hibernating and active squirrels have shown that ‘natural hibernation’ has anti-ischemic effects – protecting against the formation of blood clots. We’ve shown that a drug that induces hibernation can achieve similar results in the brain,” Borlongan said. “Even a small decrease in the brain’s temperature appears to be neuroprotective.”

Borlongan and his colleagues dosed the rats intravenously with [D-ala2,D-leU5]enkephalin (DADLE), a drug from the same pharmaceutical family as morphine and heroin. DADLE is used to cryogenically preserve donated organs to keep them viable for transplantation. The researchers found that, after an experimental stroke, the pre-treated animals performed better than control rats in a series of behavioral tests. DADLE significantly reduced the size of the stroke, and prevented cell death processes and behavioral abnormalities.

“The observation that this substance, previously shown to induce hibernation, improves recovery from cerebral ischemia means it could provide a new pharmacological treatment for stroke,” Borlongan said.

During ischemic stroke, diminished blood flow and oxygen trigger a cascade of events that may cause additional, delayed damage to brain cells. DADLE helped the stroke-damaged area of the brain survive this assault, Borlongan said. More studies, including injection of the drug following a stroke, are needed to determine exactly how the drug works. But Borlongan suggests that it may promote proliferation of the body’s own natural stem cells, which then migrate from bloodstream to the brain to control and repair damage.

– USF Health –

USF Health is dedicated to creating a model of health care based on understanding the full spectrum of health. It includes the University of South Florida’s colleges of medicine, nursing, and public health; the schools of biomedical sciences as well as physical therapy & rehabilitation sciences; and the USF Physicians Group. With more than $360 million in research grants and contracts last year, USF is one of the nation’s top 63 public research universities and one of 39 community-engaged, four-year public universities designated by the Carnegie Foundation for the Advancement of Teaching. For more information, visit www.health.usf.edu

– BMC Biology –

BMC Biology – the flagship biology journal of the BMC series – publishes research and methodology articles of special importance and broad interest in any area of biology and biomedical sciences. BMC Biology (ISSN 1741-7007) is covered by PubMed, MEDLINE, BIOSIS, CAS, Scopus, EMBASE, Zoological Record, Thomson Reuters (ISI) and Google Scholar.

USF neuroscientist advances stem cell therapy for stroke