New research led by Dilip Ghosh of the Horticulture and Food Research Institute in New Zealand, shows that compounds in blackcurrants have a potent protective effect in cultured neuronal cells against the types of stress caused by dopamine and amyloid- , a peptide associated with Alzheimer's disease.
These compounds also work in hippocampal cells taken straight from the brain,' researcher James Joseph of Tufts University told Chemistry & Industry. James says that the effect will likely be reproduced in the human body and that blackcurrants could help prevent or significantly delay the onset of Alzheimer's.
Blackcurrants and boysenberries, more common in the US, both contain anthocyanins and polyphenolics. British blackcurrants are bred to be darker, which means they have more anthocyanins and are likely to be more potent.
Compounds from these berries are already known to act as antioxidants, but a role in neuroprotection has not been demonstrated previously, according to the researchers.
The mechanism of action is unclear. But James said: We have evidence that the compounds protect against Alzheimer's by influencing the early gene expression in learning and memory, which influences cell signaling pathways that help neuronal cells communicate with each other.'
Dilip's team recently demonstrated the potent protective effect of blackcurrant compounds on cultured human promyeloyte and neuroblastoma cells assaulted by hydrogen peroxide (JSFA doi: 10.1002/jsfa.0247).
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His studies focus on an area of the brain called the nucleus accumbens core, a target for drugs of abuse long considered a pleasure center, Dr. Kruzich says. Drugs such as cocaine and methamphetamine stimulate release of dopamine in the nucleus accumbens. Dopamine is a neurotransmitter believed responsible for the euphoria that come with drug use. In fact, animals given dopamine blockers won't self-adminster drugs of abuse, and dopamine has long been a focus of drug-abuse studies.
"These drugs impinge upon the reward centers of the brain that normally food, sex, survival and adaptation impinge upon," says Dr. Kruzich. "When you are having that great piece of cheesecake and thinking, 'Oh man,' that is the kind of response these drug of abuse are evoking but much more so than that cheesecake could ever do."
Glutamate, also released in the nucleus accumbens core, may play an equally important role in drug relapse, he says. Drugs such as cocaine appear to alter glutamate neurotransmission in the core, which may contribute to the rewiring of the brain that occurs with drug use. "It's not that these drugs just damage neurons, which they can, but they rewire the circuitry of the brain so no longer is your spouse or your job or other things in your life important to you. Your brain is tricked into thinking that drugs are the most important thing for your survival," Dr. Kruzich says.
Unfortunately, drugs that restore glutamate function also produce seizures, so scientists are looking for an indirect approach to restore the misdirected rewiring.
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