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An active compound in morphine—and thus heroin as well—might protect against HIV-related dementia, according to a study announced by researchers at Georgetown University Medical Center in Washington, DC. The study was presented last week at the 2010 meeting of the Society on NeuroImmune Pharmacology in Manhattan Beach, California. “Needless to say we were very surprised at the findings,” said Italo Mocchetti, PhD, a lead author of the study. “We started with the opposite hypothesis—that heroin was going to destroy neurons in the brain and lead to HIV dementia.”
The reason Mocchetti’s team initially eyed morphine as a potential brain-damaging drug is because many HIV-positive injection drug users develop cognitive problems.
To explore this, Mocchetti and his colleagues looked at the brains of rats exposed to both morphine and HIV. Much to the researchers’ surprise, morphine actually inhibited certain toxic properties of an HIV protein called gp120, which plays a prominent role in the infection of immune cells.
Apparently, morphine protects the brain by prompting brain cells known as astrocytes to produce a protein called CCL5. “It is known to be important in blood, but we didn’t know it is secreted in the brain,” Mocchetti said. “Our hypothesis is that it is in the brain to prevent neurons from dying.”
CCL5 blocks a second protein, called CCR5, which sits on the surface of immune cells, and which HIV uses to enter and infect those cells. Mocchetti and his colleagues think that by blocking that second protein, brain cells are protected from infection and damage.
Mocchetti explained that in hindsight, there is evidence for morphine’s protective effect. Though many heroin users develop cognitive problems, he pointed out, a subset in other studies who became infected with HIV by sharing needles and equipment appeared to have lower rates of dementia than expected.
“We believe that morphine may be neuroprotective in a subset of people infected with HIV,” Mocchetti said.“That is not to say that people should use heroin to protect themselves—that makes no medical sense at all—but our findings give us ideas about designing drugs that could be of benefit.”
The Friends of AIDS Foundation is dedicated to enhancing the quality of life for HIV positive individuals and empowering people to make healthy choices to prevent the spread of the HIV virus. To learn more about The Friends of AIDS Foundation, please visit: http://www.friendsofaids.org.
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