Tag Archives: Journal of Neuroscience

Why Painkillers Relieve Men Faster

Does popping a painkiller provide faster relief to you than your wife?
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Thank the middle section of your brain.

Scientists at Georgia State Universitys Neuroscience Institute and Center for Behavioral Neuroscience have for the first time identified the most likely reason why analgesic drug treatment is usually less potent in females than males.

“Opioid-based narcotics such as morphine are the most widely prescribed therapeutic agents for the alleviation of persistent pain. However, it is becoming increasingly clear that morphine is significantly less potent in women compared with men. Until now, the mechanism driving the phenomenon was unknown,” said Anne Murphy, who conducted the research with Dayna Loyd.

Scientists through animal studies have shown that the previously reported differences in morphine’s ability to block pain in male versus female rats are most likely due to sex differences in mu-opioid receptor expression in a region of the brain called the periaqueductal gray area (PAG).

Located in the midbrain area, the PAG plays a major role in the modulation of pain by housing a large population of mu-opioid receptor expressing neurons. Morphine and similar drugs bind to these mu-opioid receptors and ultimately tell the brain to stop responding to pain signals to the nerve cells resulting in the reduced sensation of pain.

The findings have been reported in the December issue of `The Journal of Neuroscience‘.

Scientists say the discovery is a major step toward finding more effective treatments for females suffering from persistent pain.

Reacting to the study, Dr Madhuri Bihari, head of department of neurology at AIIMS said: “There is a difference in reaction of analgesic drugs on male and female bodies even though it is slight. Pain reduces slightly more in men than women after popping a painkiller.”

“It was believed that it’s because of the faster metabolic rate among women. This study is, therefore, significant. How much it will help clinically is yet to be understood,” Dr Bihari said.

Using a series of anatomical and behavioural tests, Murphy and Loyd were able to determine that male rats have a significantly higher level of mu-opioid receptors in the PAG region of the brain compared with females.

This higher level of receptors is what makes morphine more potent in males because less drug is required to activate enough receptors to reduce the experience of pain.

Interestingly, when they used a plant-derived toxin to remove the mu-opioid receptor from the PAG, morphine no longer worked, suggesting that this brain region is required for opiate-mediated pain relief.

Additional tests also found females reacted differently to morphine depending on the stage of their estrous cycle.

Analgesic drug market in India has swelled over the years. Painkiller drug Voveran had emerged as the top brand in the domestic pharmaceutical market with the largest sales for the first seven months of 2007

Sources: The Times Of India

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Why Just One Cigarette Can Get You Hooked

A Canadian study has suggested that it may take only one cigarette for some people to get addicted to nicotine, because of how their brains are wired.

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By manipulating receptors in the brains of rats, researchers were able to control whether the first exposure to nicotine was enjoyable or repulsive. They experimented on two types of receptors for dopamine, a chemical messenger in the brain’s reward circuitry.

By blocking the receptors, the researchers were able to switch how nicotine was processed — from repulsive to rewarding or positive. The natural variations that occur between people may therefore explain why some are more likely to become addicted to nicotine.
Sources:
CBC News August 5, 2008
The Journal of Neuroscience, August 6, 2008, 28(32):8025-8033

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Why Drunk People Take Risks

New brain imaging research shows that social drinkers have decreased sensitivity in brain regions involved in detecting threats, and increased activity in brain regions involved in reward.

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After alcohol exposure, threat-detecting brain circuits can’t tell the difference between a threatening and a non-threatening social situation.

Working with 12 healthy participants who drink socially, researchers used functional magnetic resonance imaging (fMRI) to study activity in emotion-processing brain regions during alcohol exposure. When participants received a placebo instead of alcohol, they showed greater activity in the amygdala, insula, and parahippocampal gyrus — brain regions involved in fear and avoidance — when shown a picture of a fearful facial expression.

Alcohol, meanwhile, activated striatal areas of the brain that are important components of the reward system, but did not increase brain activity in areas involved in fear.

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Sources:

* Science Daily April 30, 2008

* The Journal of Neuroscience April 30, 2008

Video games could improve eyesight

NEW YORK: Playing video games that involve firing guns could improve eyesight, suggests a study….CLICK & SEE

Playing ‘Gears of War‘, ‘Lost Planet‘, ‘Halo‘ and other action video games can improve eyesight, say Daphne Bevelier of the University of Rochester and other researchers who conducted tests on 10 male college students.

The students started out as non-gamers and then received 30 hours of training on first-person shooter action video games, reports the online edition of FOX News.

The participants showed a substantial increase in their ability to see objects accurately in a cluttered space compared to 10 non-gamers given the same test.

Most aspects of vision have to do with the size of one’s eye and the thickness and shape of the cornea and lens. But some visual defects are neural in nature, said Bevelier, author of the latest study on vision and video games.

Source:The Times Of India