Morphine administered to those with spinal cord injuries can slow the recovery of locomotor function, increase tissue loss and even produce symptoms of increased pain in chronic sufferers, according to a Texas A&M associate research professor.
Michelle Hook’s research uses rats with spinal cord injuries to see how they recover with varying doses of self-administered morphine.
“This is a pioneering study — nobody looked at addiction in rats with spinal cord injuries,” Hook said.
Initially her lab at A&M found that rats with spinal cord injuries preventing them from using their rear legs could walk all right within two weeks. The same recovery was not seen in rats administered morphine.
Morphine is administered to the rats intravenously, as it would be to humans in a clinic. In Hooks’ research, a control group of rats is given varying doses of morphine from .75 to 3 mm. The rats can press small levers and doses of morphine are delivered. The maximum amount a rat can receive is 30 mm.
Rats who were only given .75 mm didn’t take too much morphine after their first lever press. Rats given 1.5 were in the middle and rats given 3 mm took well more than the amount needed.
According to the National Spinal Cord Injury Statistical Center, approximately 270,000 people in the U.S. are currently living with spinal cord injuries.
Hook said she understands it’s not that easy when it comes to patients in pain. Her goal is to identify molecular changes that cause adverse effects, block the mechanisms, protect recovery and allow opioids such as morphine to be used efficiently.
She said it can be hard for people to tell whether morphine is helping or not, because many may ask for more if their pain doesn’t change or increases.
“In patients with spinal cord injuries, it’s very difficult for clinicians to find a drug to reduce pain,” she said. “Opioids relieve pain for a lot of patients.”
In many hospitals, opiates such as morphine are given to treat pain after spinal cord injuries, Hook’s co-investigator Jim Grau said via email. Grau said Hook is at the forefront of research that shows caution should be taken when prescribing pain medication after injury.
Hook said they also monitor for potential abuse and addiction.
Her research has found that waiting up to two weeks limits negative effects such as addiction and recovery problems.
“I would be relatively comfortable saying they shouldn’t give it in the ER when the patient is brought in,” Hook said of the immediate administration of morphine after an injury.
As a behavioral neuroscientist, Hook examines the effects of neural changes and the basic biological processes underlying normal and abnormal behavior, she said.
Hook said because she has 15 years experience in psychology she also brings a unique perspective to the study of spinal injury in animal models. Not only does she focus on motor and sensory function, but also the psychological consequences of injury – addiction and depression.
She said these areas of research haven’t been studied in animal models.
The researchers are currently in the second year of the project, which received $293,000 in funding from The National Institute On Drug Abuse.
The project’s end date is Feb. 28, 2015.
Grau said critics question why the research for the project can’t be performed on a computer program to avoid using rats.
“At this time, the answer is ‘no,’ because we simply do not know enough about the factors that influence the recovery process,” he said. “Further, before a new treatment can be brought to the clinic, we must know that the treatment will not adversely affect the patient.”
BY MONICA S. NAGY