WASHINGTON, May 29 (Xinhua) -- American researchers have found a new way to block a root cause of pain, alleviating chemotherapy pain in mice for two months with no side effects.

In a study published on Tuesday in the journal Cell Reports, the researchers at University of California San Diego School of Medicine revealed that a single spinal injection of a naturally occurring protein called apolipoprotein A-I binding protein (AIBP) can prevent and reverse inflammation and cellular events associated with pain processing.

AIBP is found to bind to toll-like receptor 4 (TLR4), a protein that sits on the surface of cells like an antenna, searching for signs of infection or tissue damage.

Unlike opioids that simply dampen a person's perception of pain, the new approach, according to the paper's co-senior author Tony Yaksh, professor in the Department of Anesthesiology at the university, "modifies the pain processing systems themselves."

The researchers noted that inflammation could sometimes transition to chronic pain with all the hallmarks of nerve injury, a cellular event that involves TLR4.

They found AIBP, previously a means to treat atherosclerosis, could inhibit TLR4 in lab test by removing cholesterol from lipid rafts, which are cholesterol-rich areas of a cell's membrane that help control how cells communicate with each other and their environments.

In mice, spinal injections of AIBP reduced lipid rafts in central nervous system immune cells called microglia, and also reduced TLR4 activation, microglial activation and inflammation in the spinal cord, according to the study.

A single intrathecal injection of AIBP completely reversed the chemotherapy-induced pain state and the mice were able to endure normal levels of mechanical stimulation. This pain-relieving effect lasted for two months and the AIBP injection did not affect motor functions.